Rainbow Electronics MAX1464 User Manual

General Description

The MAX1464 is a highly integrated, low-power, lownoise multichannel sensor signal processor optimized for industrial, automotive, and process-control applications such as pressure sensing and compensation, RTD and thermocouple linearization, weight sensing and classification, and remote process monitoring with limit indication.

The MAX1464 accepts sensors with either single-ended or differential outputs. The MAX1464 accommodates sensor output sensitivities from 1mV/V to 1V/V. The MAX1464 provides amplification, calibration, signal linearization, and temperature compensation that enable an overall performance approaching the inherent repeatability of the sensor without requiring any external trim components.

Two 16-bit voltage-output DACs and two 12-bit PWMs can be used to indicate each of the temperature-compensated sensor signals independently, as a sum or difference signal, or user-defined relationship between each signal and temperature. Uncommitted op amps are available to buffer the DAC outputs, drive heavier external loads, or provide additional gain and filtering.

The MAX1464 incorporates a 16-bit CPU, user-programmable 4kB of FLASH program memory, 128 bytes of FLASH user information, one 16-bit ADC, two 16-bit DACs, two 12-bit PWM digital outputs, four rail-to-rail op amps, one SPI™-compatible interface, two GPIOs, and one on-chip temperature sensor.

The MAX1464 operates from a single 5.0V (typ) supply and is packaged for automotive, industrial, and commercial temperature ranges in a 28-pin SSOP package.

Applications

Pressure Sensor Signal Conditioning

Weight Measurement Systems

Thermocouple and RTD Linearization

Transducers and Transmitters

Process Indicators

Calibrators and Controllers

GMR and MR Magnetic Direction Sensors

Features

♦ Programmable Amplification, Calibration,

Linearization, and Temperature Compensation

♦ Two Differential or Four Single-Ended ADC Input

Channels

♦ Accommodates Sensor Output Sensitivities from

1mV/V to 1V/V

♦ Two DAC/PWM Output Signal Channels

♦ Supports 4–20mA Current Loop Applications

♦ 4kB of FLASH Memory for Code and Coefficients

♦ 128 Bytes of FLASH Memory for User Information

♦ Integrated Temperature Sensing

♦ Flexible Dual Op-Amp Block

♦ Programmable Sensor Input Gain and Offset

♦ Programmable Sensor Sampling Rate and

Resolution

♦ No External Trim Components Required

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

19-3579; Rev 0; 2/05

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

*Dice are tested at TA= +25°C, DC parameters only.

Functional Diagram and Detailed Block Diagram appear at end of data sheet.

SPI is a trademark of Motorola, Inc.

Pin Configuration

PART TEMP RANGE PIN-PACKAGE

MAX1464CAI 0°C to +70°C 28 SSOP

MAX1464C/W* 0°C to +70°C Die

MAX1464EAI -40°C to +85°C 28 SSOP

MAX1464AAI -40°C to +125°C 28 SSOP

TOP VIEW

OUT1SM

AMP1M

AMP1P

OUT1LG

CKSEL

CKIO

SCLK

MAX1464

N.C.

SSOP

OUT2SM

AMP2M

AMP2P

OUT2LG

REF

INP1

INM1

INP2

INM2

SSF

GPIO2

GPIO1

DDF

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

DDF

= VDD= 4.5V to 5.5V, V

SSF

= VSS= 0V, f

CLK

= 4.0MHz, TA= T

MIN

to T

MAX

. Typical values are at V

DDF

= VDD= 5.0V, V

SSF

= VSS= 0V,

= +25°C, unless otherwise noted.) (Note 1)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

VDDto VSS.............................................................-0.3V to +6.0V

DDF

to VSS...........................................................-0.3V to +6.0V

SSF

to VSS............................................................-0.3V to +0.3V

All Other Pins to V

...................................-0.3V to (VDD+ 0.3V)

Continuous Power Dissipation (T

= +70°C)

28-Pin SSOP (derate 9.1mW/°C above +70°C) ..........727mW

Operating Temperature Ranges

MAX1464CAI .....................................................0°C to +70°C

MAX1464C/W.....................................................0°C to +70°C

MAX1464EAI...................................................-40°C to +85°C

MAX1464AAI ................................................-40°C to +125°C

Junction Temperature......................................................+150°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) ................................ +300°C

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

SUPPLY

Supply Voltage V

VSS = V

SSF

= 0V 4.5 5.0 5.5 V

FLASH Supply Voltage V

DDF

VSS = V

SSF

= 0V 4.5 5.0 5.5 V

Base Operating Current I

CPU stopped (Note 2)

µA

CPU Current I

CPU

All modules off, CPU = on, additive to IBO, I

CPU

= IDD + I

DDF

(Note 3)

µA

All modules off, ADC = on, ADC clk = 1MHz, additive to I

; the CPU and ADC

are not on at the same time

ADC Current (Note 3) I

ADC

All modules off, ADC = on, ADC clk = 7kHz, additive to I

; the CPU and ADC are not

on at the same time

µA

DAC Current I

DACn

All modules off, DAC = on, additive to I

(n = 1 or 2) (Note 4)

µA

Large Op-Amp Current I

OPLGn

All modules off, CPU stopped, large op amp = on (n = 1 or 2)

µA

Small Op-Amp Current I

OPSMn

All modules off, CPU stopped, small op amp = on (n = 1 or 2)

µA

POWER-ON RESET

DDF

POR Threshold VDD > V

DDF

3.6 4.0 4.3 V

DDF

POR Hysteresis

ANALOG INPUT

PGA[4:0] = 00000, CLK[2:0] = 000

PGA[4:0] = 01010, CLK[2:0] = 000 55

PGA[4:0] = 11111, CLK[2:0] = 000 36

kΩ

PGA[4:0] = 00000, CLK[2:0] = 011 3.4 MΩ

PGA[4:0] = 01010, CLK[2:0] = 011

PGA[4:0] = 11111, CLK[2:0] = 011

kΩ

PGA[4:0] = 00000, CLK[2:0] = 110 27

PGA[4:0] = 01010, CLK[2:0] = 110 3.5

Differential Input Impedance (INP1 to INM1 and INP2 to INM2)

DIN

PGA[4:0] = 11111, CLK[2:0] = 110 2.3

MΩ

575 720 890

540 840 1240

690 1040 1394

-0.85

430

440

288

465 765 1060

425 550 730

430 673 1020

110 190 265

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

DDF

= VDD= 4.5V to 5.5V, V

SSF

= VSS= 0V, f

CLK

= 4.0MHz, TA= T

MIN

to T

MAX

. Typical values are at V

DDF

= VDD= 5.0V, V

SSF

= VSS= 0V,

= +25°C, unless otherwise noted.) (Note 1)

Single-Sided Input Impedance (INP1 to V INP2 to V

Common-Mode Rejection Ratio CMRR Common-mode voltage VCM = V

Differential Signal-Gain Range Selectable in 17 steps (Note 5) 0.99 to 244 V/V

Differential Signal Gain A

Gain-Error Temperature Coefficient

COARSE-OFFSET DAC

Resolution 3-bit plus sign 4 Bits

Effective Offset Adjustment at the ADC Input

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

, INM1 to VSS,

, INM2 to VSS)

VDIFF

GETC

SIN

ADC

PGA[4:0] = 00000, CLK[2:0] = 000 430

PGA[4:0] = 01010, CLK[2:0] = 000 55

PGA[4:0] = 11111, CLK[2:0] = 000 36

PGA[4:0] = 00000, CLK[2:0] = 011 3.4 MΩ

PGA[4:0] = 01010, CLK[2:0] = 011 440

PGA[4:0] = 11111, CLK[2:0] = 011 288

PGA[4:0] = 00000, CLK[2:0] = 110 27

PGA[4:0] = 01010, CLK[2:0] = 110 3.5

PGA[4:0] = 11111, CLK[2:0] = 110 2.3

PGA[4:0] = 00000 0.95 0.99 1.05

PGA[4:0] = 00001 7.3 7.7

PGA[4:0] = 01010 71 77 82

PGA[4:0] = 10100 137 153 168

PGA[4:0] = 11110 203 244 283

PGA[4:0] = 00000 -8 ppm/°C

REF = VDD, CO[3:0] = 0111

REF = VDD, CO[3:0] = 0011

REF = VDD, CO[3:0] = 0000

to V

PGA[4:0] = 00000 to 01000

PGA[4:0] = 01010 to 10000

PGA[4:0] = 10100 to 11110

PGA[4:0] = 00000 to 01000

PGA[4:0] = 01010 to 10000

PGA[4:0] = 10100 to 11110

PGA[4:0] = 00000 to 01000

PGA[4:0] = 01010 to 10000

PGA[4:0] = 10100 to 11110

0.008 %FS

137 147 157

273 291 308

525 578 630

57 64 69

113 126 136

228 251 276

-3 -1 +1

-7 -2.4 +2

-11 -4 +3

8.2

kΩ

MΩ

V/V

% of ADC

Ref

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

DDF

= VDD= 4.5V to 5.5V, V

SSF

= VSS= 0V, f

CLK

= 4.0MHz, TA= T

MIN

to T

MAX

. Typical values are at V

DDF

= VDD= 5.0V, V

SSF

= VSS= 0V,

= +25°C, unless otherwise noted.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Effective Offset Adjustment at the ADC Input

SMALL OP AMP

Input Offset Voltage VOS_

Input Bias Current IB_

DC Gain A

Gain Bandwidth Product GBW_

Slew Rate SR_

Common-Mode Input Range CMR_

Common-Mode Rejection Ratio CMRR_SMV

Power-Supply Rejection Ratio PSRR_

Input-Referred Noise Voltage VN_

Output High Voltage VOH_

Output Low Voltage VOL_

Output Source Current I

Output Sink Current I

Maximum Output Load Capacitance

REF = VDD, CO[3:0] = 1000

ADC

REF = VDD, CO[3:0] = 1011

REF = VDD, CO[3:0] = 1111

VOL_SM

OUTnSM = 0.5V to 4.5V (n = 1 or 2), R

LOAD

SMAVOL_SM

VOL_SM

CM_OPAMP

At DC 70 dB

0.1Hz to 1kHz 8.5

0.1Hz to 1MHz 100

SRC_SMVOUTnSM

SNK_SMVOUTnSM

LOAD

PGA[4:0] = 00000 to 01000

PGA[4:0] = 01010 to 10000

PGA[4:0] = 10100 to 11110

PGA[4:0] = 00000 to 01000

PGA[4:0] = 01010 to 10000

PGA[4:0] = 10100 to 11110

PGA[4:0] = 00000 to 01000

PGA[4:0] = 01010 to 10000

PGA[4:0] = 10100 to 11110

= ∞

= +1V/V 2.7 MHz

= +1V/V 2.2 V/µs

= VSS to V

= ∞ VDD - 0.1

= 4.7kΩ to V

= ∞ 0.1

= 4.7kΩ to V

= V

OH_SM

OL_SM

, R

LOAD

= 4.7kΩ to V

LOAD

= 4.7kΩ to V

= ∞, phase margin > 55° 120 pF

-15 -10 -4

-29 -19 -10

-56 -38 -20

-79 -73 -66

-155 -145 -135

-317 -287 -257

-162 -156 -150

-327 -309 -293

-675 -614 -555

0 ±15 mV

±1 nA

100 dB

VSS + 0.02 VDD - 0.02 V

70 dB

VDD - 0.15

-1.04 mA

% of

ADC

Ref

µV

RMS

0.15

1.04 mA

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

_______________________________________________________________________________________ 5

ELECTRICAL CHARACTERISTICS (continued)

DDF

= VDD= 4.5V to 5.5V, V

SSF

= VSS= 0V, f

CLK

= 4.0MHz, TA= T

MIN

to T

MAX

. Typical values are at V

DDF

= VDD= 5.0V, V

SSF

= VSS= 0V,

= +25°C, unless otherwise noted.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

LARGE OP AMP

Input Offset Voltage

Input Bias Current IB_

DC Gain A

Gain Bandwidth Product GBW_

Slew Rate SR_

Common-Mode Input Range CMR_

Common-Mode Rejection Ratio CMRR_LGV

Power-Supply Rejection Ratio PSRR_

Input-Referred Noise Voltage VN_

Output-Voltage High VOH_

Output-Voltage Low VOL_

Output Source Current I

Output Sink Current I

Maximum Output Load Capacitance

OP-AMP SWITCH

Analog Signal Range V

On-Resistance R

Off-Isolation V

DIGITAL-TO-ANALOG CONVERTER

Resolution RES

Integral Nonlinearity INL

Differential Nonlinearity DNL

Offset Error V

Bit Weight BW

Power-Supply Rejection PSR

Output Noise ON

Output Settling Time ST

PULSE-WIDTH MODULATOR

Resolution RES

Period P

OS_LG

VOL_LG

OUTnLG = 0.5V to 4.5V (n = 1 or 2), R

LOAD

LGAVOL_LG

VOL_LG

CM OPAMP

At DC 70 dB

0.1Hz to 1kHz 19

0.1Hz to 1MHz 160

LOAD

SRC_LGVOUTnLG

SNK_LGVOUTnLG

ISO

DAC OS

DAC

PWMfCLK

DAC

LOAD

DAC ref = VDD, DAC data = 0000h

DAC ref = 5VDC 91.55 µV/LSB

DAC

At DC, DAC ref = V

DAC

DAC buffer is the small op amp ±3 LSB

DAC

To 0.1% of final value 250 µs

(Note 6) 12 Bits

PWM

= 4.0MHz 8.192 ms

= ∞

= +1V/V 4.0 MHz

= +1V/V 3.2 V/µs

= VSS to V

= ∞ VDD - 0.1

= 1kΩ to V

= ∞ 0.03

= 1kΩ to V

= V

OH_LG

= V

OL_LG

= ∞, phase margin > 55° 200 pF

, R

= 1kΩ to V

LOAD

, R

REF

LOAD

= 1kΩ to V

VSS + 0.02 V

VDD - 0.125

/ 2

- 0.06

0±6mV

±225 nA

100 dB

- 0.02 V

70 dB

µV

RMS

0.13

-4.9 mA

4.9 mA

5kΩ

80 dB

16 Bits

3 Bits

±1 Bits

/ 2

+ 0.06

0.02 %FS

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

6 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

DDF

= VDD= 4.5V to 5.5V, V

SSF

= VSS= 0V, f

CLK

= 4.0MHz, TA= T

MIN

to T

MAX

. Typical values are at V

DDF

= VDD= 5.0V, V

SSF

= VSS= 0V,

= +25°C, unless otherwise noted.) (Note 1)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Bit Weight BW

Offset Error V

Gain Error GE

Output Jitter OJ

EXTERNAL REFERENCE INPUT

Reference Input Voltage Range V

Reference Input Resistance R

INTERNAL VOLTAGE REFERENCE

Internal Voltage Reference V

Temperature Coefficient TC

TEMPERATURE SENSOR

Sensitivity Sens

Nonlinearity Error INL

Hysteresis Hist

ANALOG-TO-DIGITAL CONVERTER

Resolution RES

Integral Nonlinearity INL

Differential Nonlinearity DNL

ADC Offset Error V

Channel-to-Channel Offset Error Matching

ADC Offset-Supply Rejection OSR

ADC Gain-Supply Rejection GSR

Offset Temperature Coefficient TA = -40°C to +125°C 0.03 %FS

Ratiometricity PGA[4:0] = 00000 to 01000 0.02 %FS

PWM_OS

REF

ADC_OS

∆V

ADC_OS

PWM

ADC

PWM data = 0000h ±1 µs

(Note 7) ±0.025 %

= 2.5V, ADC = ON, DACs = ON 100 kΩ

REF

(Note 8) 4.5 4.92 5.35 V

PGA[4:0] = 00001, CO[3:0] = 0110

PGA[4:0] = 00000 (0.99), CO[3:0] = 0000 (Note 9)

At DC, ADC ref = V

= 5V 0.3 %FS

REF

= 5V 0.005 %FS

REF

2 µs/LSB

1/4 LSB

2.25 2.5 2.75 V

±110 ppm/°C

+2 mV/°C

+95 LSB/°C

±0.5 %FS

±0.1 %FS

16 Bits

2 Bits

±1 LSB

4 %FS

±1 LSB

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

_______________________________________________________________________________________ 7

ELECTRICAL CHARACTERISTICS (continued)

DDF

= VDD= 4.5V to 5.5V, V

SSF

= VSS= 0V, f

CLK

= 4.0MHz, TA= T

MIN

to T

MAX

. Typical values are at V

DDF

= VDD= 5.0V, V

SSF

= VSS= 0V,

= +25°C, unless otherwise noted.) (Note 1)

Note 1: Current into a pin is defined as positive. Current out of a pin is defined as negative. All voltages are referenced to V

Note 2: All modules are off, except internal reference, oscillator, and power-on reset (POR) and CKSEL bit is set to zero. Note 3: The CPU and ADC are not on at the same time. The ADC and CPU currents are not additive. Note 4: I

DACn

does not include output buffer currents (I

OPLGn

or I

OPSMn

Note 5: For gains above 240, an additional digital gain can be provided by the CPU. Note 6: The PWM input data is the 12-bit left-justified data in the 16-bit input field. Note 7: PWM gain error measured as:

Note 8: The internal reference voltage has a nominal value of 5V (4

✕ V

) even when VDDis greater or less than 5VDC.

Note 9: Input-referred offset error is the ADC offset error divided by the PGA gain. Note 10: When the CKIO is configured in output mode to observe the internal oscillator signal, the total current is above the

specified limits.

Note 11: f

CLK

must be within 5% of 4MHz.

Note 12: Allow a minimum elapsed time of 4.2ms when executing a FLASH erase command, before sending any other command.

Allow a minimum elapsed time of 80µs between FLASH write commands.

Note 13: FLASH programming current is guaranteed by design.

PWM F Xh PWM Xh

PWM

OUT OUT

()−()

00 100

3584

100%

DIGITAL INPUTS (GPIO1, GPIO2, SCLK, DI, CKSEL, CKIO, CS)

Input High Threshold Voltage V

Input Low Threshold Voltage V

Input Hysteresis V

Input Leakage Current I

Input Capacitance C

DIGITAL OUTPUTS (GPIO1, GPIO2, DO, CKIO)

Output-Voltage High V

Output-Voltage Low V

FLASH MEMORY

Maximum Erase Cycles (Notes 11, 12) 10k Cycles

Minimum Erase Time t

Minimum Write Time t

FLASH Programming Current I

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

IHYS

ERASE

WRITE

DDFP

CKSEL, CS = V

GPIO1, GPIO2, SCLK, DI, CKIO = V

= ∞

LOAD

= 2kΩ to V

LOAD

= ∞

LOAD

= 2kΩ to V

LOAD

(Notes 11, 12) 4.2 ms

(Notes 11, 12) 80 µs

Writing to the FLASH or erasing the FLASH (Note 13)

GPIO1, GPIO2, DO VDD - 0.1

CKIO (Note 10) 4.9

GPIO1, GPIO2, DO VDD - 0.15

CKIO (Note 10) 4.6

GPIO1, GPIO2, DO 0.05

CKIO (Note 10) 0.1

GPIO1, GPIO2, DO 0.2

CKIO (Note 10) 0.4

0.8 x V

0.2 x

0.2 V

38 -90

38 +90

5pF

30 mA

µA

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

8 _______________________________________________________________________________________

TIMING CHARACTERISTICS

DDF

= VDD= 4.5V to 5.5V, V

SSF

= VSS= 0V, f

CLK

= 4.0MHz, TA= T

MIN

to T

MAX

. Typical values are at V

DDF

= VDD= 5.0V, V

SSF

= VSS= 0V,

= +25°C, unless otherwise noted.) (Note 1)

PARAMETER

CONDITIONS

UNITS

Programming Temperature T

PROG

°C

Internal Oscillator Clock Frequency

ICLK

OSC[4:0] = 00000 3.3

5.3

MHz

Min 0.2

External Clock Frequency f

ECLK

CKSEL

= 0

Max 5

MHz

External Master Clock Input Low Time

ECLK

= 1 / f

ECLK

40 60

ECLK

External Master Clock Input High Time

ECLK

= 1 / f

ECLK

40 60

ECLK

SERIAL INTERFACE (Figure 1)

SCLK Setup to Falling Edge CS t

30 ns

CS Falling Edge to SCLK Rising Edge Setup Time

CSS

30 ns

CS Idle Time t

CSI

CLK

= 4MHz 1.5 µs

CS Period t

CLK

= 4MHz 4 µs

SCLK Falling Edge to Data Valid Delay

LOAD

= 200pF 80 ns

Data Valid to SCLK Rising Edge Setup Time

30 ns

Data Valid to SCLK Rising Edge Hold Time

30 ns

SCLK High Pulse Width t

SCLK Low Pulse Width t

CS Rising Edge to SCLK Rising Edge Hold Time

CSH

30 ns

CS Falling Edge to Output Enable

LOAD

= 200pF 25 ns

CS Rising Edge to Output Disable

LOAD

= 200pF 25 ns

SYMBOL

ECLKIN_LO

ECLKIN_HI

MIN TYP MAX

125

4.15

100

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

_______________________________________________________________________________________ 9

Typical Operating Characteristics

(VDD= 5.0V, TA= +25°C, unless otherwise noted.)

SUPPLY CURRENT

vs. SUPPLY VOLTAGE

MAX1464 toc01

SUPPLY VOLTAGE, VDD (V)

SUPPLY CURRENT, I

(mA)

5.35.14.7 4.9

2.30

2.35

2.40

2.45

2.50

2.55

2.60

2.65

2.25

4.5 5.5

CPU ON 2% OF TIME ADC ON 98% OF TIME ADC

CLK

= 1MHz DAC1 ON SMALL OP AMP ON

TA = +125°C

TA = +25°C

TA = -40°C

SUPPLY CURRENT

vs. INTERNAL CLOCK FREQUENCY

MAX1464 toc02

INTERNAL CLOCK FREQUENCY (MHz)

SUPPLY CURRENT, I

(mA)

4.54.03.5

2.25

2.30

2.35

2.40

2.45

2.50

2.55

2.60

2.65

2.70

2.20

3.0 5.0

CPU ON 2% OF TIME ADC ON 98% OF TIME ADC

CLK

= 1MHz DAC1 ON SMALL OP AMP ON

MODULE CURRENT vs. TEMPERATURE

MAX1464 toc03

TEMPERATURE (°C)

MODULE CURRENT (mA)

98704315-13

0.7

0.9

1.1

1.3

1.5

1.7

1.9

2.1

2.3

2.5

0.5

-40 125

DAC + LARGE OP AMP

DAC + SMALL OP AMP

ADC

BASE

BASE OPERATING CURRENT

vs. SUPPLY VOLTAGE

MAX1464 toc04

SUPPLY VOLTAGE, VDD (V)

BASE OPERATING CURRENT, I

(mA)

5.35.14.7 4.9

0.67

0.69

0.71

0.73

0.75

0.77

0.79

0.81

0.65

4.5 5.5

TA = +125°C

TA = +25°C

TA = -40°C

ADC RATIOMETRICITY ERROR

vs. SUPPLY VOLTAGE

MAX1464 toc05

SUPPLY VOLTAGE, VDD (V)

ADC RATIOMETRICITY ERROR (%FS)

5.35.14.7 4.9

-0.03

-0.02

-0.01

0.01

0.02

0.03

0.04

-0.04

4.5 5.5

ADC INPUT = 0.75 x V

ADC INPUT = 0.5 x V

ADC INPUT = 0

ADC INPUT = -0.75 x V

ADC INPUT = -0.5 x V

ADC

REF

= V

PGA[4:0] = 00000

ADC INL

MAX1464 toc06

1.00.5-0.5 0-1.0

INPUT VOLTAGE NORMALIZED TO FULL SCALE

ADC NONLINEARITY ERROR (%FS)

-0.004

-0.002

0.002

0.004

0.006

-0.006

PGA[4:0] = 01000

Figure 1. Serial Interface Timing Diagram

SCLK

CSS

tCLt

CSI

CSS

CSH

tCLt

CSH

TEMPERATURE SENSOR OUTPUT

vs. TEMPERATURE

MAX1464 toc13

TEMPERATURE (°C)

TEMPERATURE SENSOR OUTPUT (ADC CODE)

97.5 125.070.042.515.0-12.5

-2000

4000

2000

8000

12,000

10,000

14,000

6000

16,000

-4000

-40.0

PGA[4:0] = [00001]

CO[3:0] = 0110

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

10 ______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VDD= 5.0V, TA= +25°C, unless otherwise noted.)

INTERNAL OSCILLATOR FREQUENCY

vs. SUPPLY VOLTAGE

MAX1464 toc12

SUPPLY VOLTAGE, VDD (V)

INTERNAL OSCILLATOR FREQUENCY (MHz)

5.35.14.94.7

3.85

3.90

3.95

4.00

4.05

4.10

4.15

3.80

4.5 5.5

TA = -40°C

TA = +125°C

= +25°C

OSCILLATOR FREQUENCY TRIMMED TO 4MHz AT +25°C, V

= 5V

-1

ADC DNL ERROR (LSB)

-2

-3

-4

-1.0 1.0 INPUT VOLTAGE NORMALIZED TO FULL SCALE

1V/div

ADC DNL

PGA[4:0] = 01000

0.50-0.5

DAC DYNAMIC RESPONSE

DAC CODE = C000h

MAX1464 toc07

DAC CODE = 4000h

200µs/div

0.04

DAC INL

0.03

0.02

0.01

-0.01

-0.02

DAC NONLINEARITY ERROR (%FS)

-0.03

-0.04

-0.8 0.8 INPUT NORMALIZED TO FULL SCALE

MAX1464 toc10

ERROR (%FS)

MAX1464 toc08

-1

DAC DNL ERROR (LSB)

-2

0.60.4-0.6 -0.4 -0.2 0 0.2

-3

-0.8 0.8 INPUT VOLTAGE NORMALIZED TO FULL SCALE

DAC RATIOMETRICITY ERROR

vs. SUPPLY VOLTAGE

0.05

0.04

0.03

0.02

0.01

-0.01

-0.02

-0.03

-0.04

-0.05

DAC INPUT = 5555CH (4.5V AT VDD = 5V)

DAC INPUT = 0000CH (2.5V AT VDD = 5V)

DAC INPUT = AAABCH (0.5V AT VDD = 5V)

4.5 5.5 SUPPLY VOLTAGE, VDD (V)

DAC DNL

MAX1464 toc09

0.60.40.20-0.2-0.4-0.6

MAX1464 toc11

5.35.14.94.7

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

______________________________________________________________________________________ 11

Pin Description

PIN NAME FUNCTION

1 OUT1SM Small Op Amp 1 Output

2 AMP1M Op Amp 1 Negative Input

3 AMP1P Op Amp 1 Positive Input

4 OUT1LG Large Op Amp 1 Output

5, 7 N.C. No Connection

6VDDPositive Supply Voltage Input. Bypass VDD to VSS with a 0.1µF ceramic capacitor.

8 CKSEL Clock-Select Digital Input

9 CKIO Clock Digital Input/Output

10 CS SPI Chip-Select Digital Input. Active low.

11 DO SPI Data Output

12 DI SPI Data Input

13 SCLK SPI Interface Clock

14, 19 V

15 V

16 GPIO1 General-Purpose Digital Input/Output 1

17 GPIO2 General-Purpose Digital Input/Output 2

18 V

20 INM2 Negative Input for ADC Channel 2

21 INP2 Positive Input for ADC Channel 2

22 INM1 Negative Input for ADC Channel 1

23 INP1 Positive Input for ADC Channel 1

24 V

25 OUT2LG Large Op Amp 2 Output

26 AMP2P Op Amp 2 Positive Input

27 AMP2M Op Amp 2 Negative Input

28 OUT2SM Small Op Amp 2 Output

DDF

SSF

REF

Negative Power-Supply Input

Positive Supply Voltage for FLASH Memory. Bypass V

Negative Power-Supply Input for FLASH Memory

External Reference Voltage Input for ADC and DACs

to VSS with a 0.1µF ceramic capacitor.

DDF

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

12 ______________________________________________________________________________________

Typical Application Circuit

Analog ratiometric output configuration (Figure 2) provides an output that is proportional to the power-supply voltage. Ratiometricity is an important consideration for automotive, battery-operated instruments, and some industrial applications.

Detailed Description

The MAX1464 is a highly integrated, low-power, lownoise multichannel sensor signal processor optimized for industrial, automotive, and process-control applications, such as pressure sensing and compensation, RTD and thermocouple linearization, weight sensing and classification, and remote process monitoring with limit indication.

The MAX1464 incorporates a 16-bit CPU, user-programmable 4kB of FLASH memory, 128 bytes of FLASH user information, 16-bit ADC, two 16-bit DACs, two 12-bit PWM digital outputs, four rail-to-rail op amps, SPI interface, two GPIOs, and one on-chip temperature sensor.

Each sensor signal can be amplified, compensated for temperature, linearized, and the offset and full scale can be adjusted to the desired value. The MAX1464 can provide outputs as analog voltage (DAC) or digital (PWM, GPIOs), or simple on/off alarm indication (GPIOs). The uncommitted op amps can be used to implement 4–20mA current loops or for additional gain and filtering. Each DAC output is routed to either a small or large op amp. Large op amps are capable of driving heavier external loads. The unused circuit functions can be turned off to save power.

All sensor linearization and on-chip temperature compensation is done by a user-defined algorithm stored in FLASH memory. The user-defined algorithm is programmed over the serial interface and stored in 4kB of integrated FLASH memory.

The MAX1464 uses an internal 4MHz oscillator or an externally supplied 4MHz clock. CPU code execution and ADC operation is fully synchronized to minimize the noise interference of a CPU-based sensor processor system. The CPU sequentially executes instructions stored in FLASH memory.

Sensor Input

The MAX1464 provides two differential signal inputs, INP1-INM1 and INP2-INM2. These inputs can also be configured as four single-ended signals. Each input can have a common-mode range from VDDto VSSand a 0.99V/V to 244V/V programmable-gain range. The differential input signals are summed with the output of the coarse offset DAC (CO DAC) for offset correction prior to being amplified by the programmable-gain amplifier (PGA). The resulting signal is applied to the differential input of the ADC for conversion.

The CPU can be programmed to measure one or two differential inputs plus the internal temperature sensor defined in user-supplied algorithm. For example, the differential inputs can be measured many times while the temperature can be measured less frequently.

Figure 2. Basic Bridge Sensor Ratiometric Output Configuration

22Ω

DDF

INPn

OUTnSM OUT

5VDC

SENSOR

INMn

MAX1464

0.1µF

0.1µF 100pF

GND

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

______________________________________________________________________________________ 13

On-Chip Temperature Sensing

The on-chip temperature sensor changes +2mV/°C over the operating range. The ADC converts the temperature sensor in a similar manner as the sensor inputs. During an ADC conversion of the temperature sensor, the ADC automatically uses four times the internal 1.25V reference as the ADC full-scale reference (5V). The temperature data format is 15-bit plus sign in two’s-complement format. Gain offset compensation can be programmed to utilize the full-scale range of the ADC. Offset compensation by the CO DAC is provided so that the nominal temperature measurement can be centered at the ADC output value. Use the CPU to provide additional digital gain and offset correction.

Output Format

There are two output modules in the MAX1464—DOP1 (DAC Op Amp PWM 1) and DOP2 (DAC Op Amp PWM

2). Each of the DOP modules contains a 16-bit DAC, a 12-bit digital PWM converter, a small op amp, and a large op amp with high-output-drive capability. Each module can be configured in several different modes to suit a wide range of output signal requirements. Either the DAC or the PWM can be selected as the primary output signal. The DAC output signal must be routed to one of the two op amps before being made available to a device pin. See the DAC, Op Amp, PWM Modules (DPOn) section for details. Additional digital outputs are available on the GPIOs.

Initialization

A user-defined initialization routine is required to configure the oscillator frequency and various analog modules, e.g., PGA gain, ADC resolution, ADC clock settings, etc. After the initialization routine, the CPU can start execution of the main program.

Power-On Reset (POR)

The MAX1464 contains a POR circuit to disable CPU execution until adequate VDDand V

DDF

voltage are available for operation. Once the power-on state has been reached, the MAX1464 is kept under reset condition for 250µs before the CPU starts execution. Below the POR threshold, all internal CPU registers are set to their POR default state. Power-on control bits for internal modules are reset to the OFF condition.

CPU Architecture

The CPU provides a wide range of functionality to be incorporated in an embedded system. The CPU can compensate nonlinear and temperature-dependent sensors, check for over/underlimit conditions, output sensor or temperature data as an analog signal or pulse-widthmodulated digital signal, and execute control strategies.

The CPU can perform a limited amount of signal processing (filtering). A timer is included so that uniform sampling (equally spaced ADC conversions) of the input sensors can be performed.

The CPU registers and ports are implemented in volatile, static memory. There are several registers contained in various peripheral modules that provide module configuration settings, control functions, and data. These module registers are accessible through an indirect addressing scheme as described in detail in the CPU Registers, CPU Ports, and Modules sections. Figure 3 shows the CPU architecture.

CPU Registers

The MAX1464 incorporates a CPU with 16 internal registers. All the CPU registers have a 16-bit data word width. Five of the 16 registers have predefined functional operations that are dependent on the instruction being executed. The remaining registers are general purpose.

The CPU registers are embedded in the CPU itself and are not all directly accessible by the serial interface. The accumulator register (A), the pointer register (P), and the instruction (FLASH data) can be read through the serial interface when the CPU is halted. This enables a single-

Figure 3. CPU Architecture

SCLKDIDO

SERIAL INTERFACE

CPU

PC PD PE

CPU PORTS

R0 POINTER (P)

R1 ACCUMULATOR (A)

R3 MULTIPLICAND (N)

R4 MULTIPLIER (M)

R5 INDEX (I)

CPU REGISTERS

INSTRUCTION

ADDRESS

FLASH DATA

FLASH MEMORY

(4kB)

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

14 ______________________________________________________________________________________

step mode of code execution to ease code writing and debugging. A special program instruction sequence is required to observe the other CPU registers. Table 1 lists the CPU registers.

CPU Ports

The MAX1464 incorporates 16 CPU ports that are directly accessible by the serial interface. All the CPU ports have a 16-bit data word width. The contents of the ports can be read and written by transferring data to and from the accumulator register (A) using the RDX and WRX instructions. No other CPU instructions act on the CPU ports. Three CPU ports PD, PE, and PF have uniquely defined operation for reading and writing data to and from the peripheral modules. All CPU ports are static and volatile. Table 2 lists the CPU ports.

Modules

The MAX1464 modules are the functional blocks used to process analog and digital signals to and from the CPU. Each module is addressed through CPU ports PD, PE, and PF, as described in the CPU Ports section. All modules use static, volatile registers for data retention. There are three types of module registers: configuration, data, and control. They are used to put a module into a particular mode of operation. Configuration registers hold configuration bits that control static settings such as PGA gain, coarse offset, etc. Data registers hold input data such as DAC and PWM input words or output data such as the result of an ADC conversion. Control registers are used to initiate a process (such as an ADC conversion or a timer) or to turn modules on and off (such as op amps, DAC outputs, PWM outputs, etc.) Table 3 lists the module registers.

ADC Module

The ADC module (Figure 4) contains a 9-bit to 16-bit sigma-delta converter with multiplexed differential and single-ended signal inputs, a CO DAC, four reference voltage inputs, two differential or four single-ended external inputs, and 15 single-ended internal voltages for measurement. The ADC output data is 16-bit two’scomplement format. The conversion channel, modes, and reference sources are all set in ADC configuration registers. The conversion time is a function of the selected resolution and ADC clock frequency. The CPU can be programmed to convert any of the inputs and the internal temperature sensor in any desired sequence. For example, the differential inputs may be converted many times and conversions of temperature performed less frequently. See Table 4.

The ADC reference can be selected as VDDfor conversions ratiometric to the power supply, 2 x V

REF

input for

conversions relative to an external voltage, and VBGx 4,

which is an internally generated bandgap reference voltage. Note that because V

REF

external = 2.5V and

= 1.25V, the ADC’s reference voltage is always close to 5.0V. The ADC voltage reference is also used by the CO DAC to maintain a signal conversion that is completely ratiometric to the selected reference source.

The four analog inputs (INP1, INM1, INP2, INM2) and several internal circuit nodes can be multiplexed to the ADC for a single-ended conversion relative to V

. The selection of which circuit node is multiplexed to the ADC is controlled by the ADC_Control register. The ADC can measure each of the op-amp output nodes with gain for converting user-defined circuits or incorporating system diagnostic test functions. The DAC outputs can be converted by the ADC with either op amp arranged as unity-gain buffers on the DAC outputs. The internal power nodes, VDDand VSS, and the bandgap reference, V

can be multiplexed to the ADC for conversion as well. These measurement modes are defined and initiated in the ADC_Control register. See Tables 5 and 7 for the single-ended configuration.

ADC Registers

The ADC module has 10 registers for configuration, control, and data output. There are three conversion channels in the ADC; channel 1, channel 2, and temperature. Channels 1 and 2 are associated with the differential signal input pairs INP1-INM1 and INP2-INM2, respectively. The temperature channel is associated with the integrated temperature sensor. Each channel has two configuration registers (ADC_Config_nA and ADC_Config_nB where n = 1, 2, or T) for setting conversion resolution, reference input, coarse offsets, etc. The data output from a conversion of channel 1, 2, or T is stored in the respective data output register ADC_Data_n where n = 1, 2, or T. Each of the channels can be used to convert single-ended inputs as listed in Table 7. The ADC_Control register controls which channel is to be converted and what single-ended input, if any, is to be directed to that channel. See Tables 8 through 13.

Conversion Start

To initiate an ADC conversion, a word is written to the ADC_Control register with either CNVT1, CNVT2, or CNVTT bit set to a 1 (Table 6). When an ADC conversion is initiated, the CPU is halted and all CPU and FLASH activities cease. All CNVT1, CNVT2, and CNVTT bits are cleared after the ADC conversion is completed.

Upon completion of the conversion, the ADC result is latched into the respective ADC_Data_n register. In addition, the convert bits in control register 0 are all reset to zero. The CPU clock is then enabled and program execution continues

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

______________________________________________________________________________________ 15

Single-ended inputs can be converted by either channel 1 or 2 by initiating a conversion on the appropriate channel with the SE[3:0] bits set to the desired single-ended input (Table 7). Several of the single-ended signals are converted with a fixed gain. The reduced gain of 0.7V/V allows signals at or near the supply rails to be converted without concern of saturation. Other single-ended signals can be converted with the full selectable PGA gain range.

Programmable-Gain Amplifier

The gain of the differential inputs and several single-ended inputs can be set to values between

0.99V/V to 244V/V as shown in Table 14. The PGA bits are set in ADC_Config_nA where n = 1, 2, or T. The gain setting must be selected prior to initiating a conversion.

ADC Conversion Time and Resolution

The ADC conversion time is a function of the selected resolution, ADC clock (f

ADC

), and system clock frequen-

cy (f

CLK

). The resolution can be selected from 9 bits to 16

bits in the ADC_Config_nA (where n = 1, 2, or T) register

by bits RESn[2:0]. The lower resolution settings (9 bit) convert faster than the higher resolution settings (16 bit). The ADC clock f

ADC

is derived from the primary system

clock f

CLK

by a prescalar divisor. The divisor can be set

from 4 to 512, producing a range of f

ADC

from 1MHz

down to 7.8125kHz when f

CLK

is operating at 4.0MHz.

Other values of f

CLK

produce other scaled values of

ADC

. See Tables 15 and 16.

Systems operating with very low power consumption benefit from the reduced f

ADC

clock rate. Slower clock speeds require less operating current. Systems operating from a larger power consumption budget can use the highest f

ADC

clock rate to improve speed perfor-

mance over power performance.

The ADC conversion times for various resolution and clock-rate settings are summarized in Table 17. The conversion time is calculated by the formula:

CONVERT

= (no. of f

ADC

clocks per conversion) /

ADC

Figure 4. ADC Module

INP1

INM1

INP2

INM2

TEMPERATURE

SENSOR

2 x V

REF

4 x V

REF

DAC

M U X

NO. SINGLE-ENDED

OUTnSM

OUTnLG

DACnOUT VIA OUTnSM

DACnOUT VIA OUTnLG

INPn

INMn

PGA

ADC

VBG

00h ADC_Control

01h ADC_Data_1

02h ADC_Config_1A

03h

ADC_Config_1B

04h ADC_Data_2

05h ADC_Config_2A

06h ADC_Config_2B

07h ADC_Data_T

08h ADC_Config_TA

09h ADC_Config_TB

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

16 ______________________________________________________________________________________

Coarse-Input Offset Adjustment

Differential input signals that have an offset can be partially nulled by the input coarse-offset (CO) DAC. An offset voltage is added to the input signal prior to gaining the signal. This allows a maximum gain to be applied to the differential input signal without saturating the conversion channel. The CO signal added to the differential signal is a percentage of the full-scale ADC reference voltage as referred to the ADC inputs. Low PGA gain settings add smaller amounts of coarse offset to the differential input. Large PGA gain settings enable correspondingly larger amounts of coarse offset to be added to the input signal. The CO DAC also applies to the temperature channel enabling offset compensation of the temperature signal. See Table 18.

Bias Current Settings

The analog circuitry within the ADC module operates from a current bias setting that is programmable. The programmable levels of operation are fractions of the full bias current. The operating power consumption of the ADC can be reduced at the penalty of increased conversion times that may be desirable in very-lowpower applications. It is recommended operating the ADC at full bias when possible. The amount of bias as a fraction of full bias is shown in Table 19. The setting is controlled by the BIASn[2:0] bits in the ADC_config_nb registers where n = 1, 2, or T.

Reference Input Voltage Select

The ADC can use one of three different reference voltage inputs depending on the conversion channel and REFn setting as shown in Table 20. The differential inputs can be converted ratiometrically to the supply voltage (V

), converted ratiometrically to an externally

supplied voltage at V

REF

, or converted nonratiometrically using a fixed voltage source derived from the internal bandgap voltage source. The temperature channel is always converted using the internal bandgapderived voltage source and therefore is not selectable.

Output Sample Rate

Generally, the sensor and temperature data are converted and calculated by an algorithm in the execution loop. The output sample rate of the data depends on the conversion time, the CPU algorithm loop time, and the time to store the result in the DOPn_DATA register. To achieve uniform sampling, the instruction code must be written to provide a consistent algorithm loop time, including branch instruction variations. This total loop time interval should be repeatable for a uniform output rate.

The MAX1464 has a built-in timer that can be used to ensure that the sampling interval is uniform. The timeout value can be set so the CPU computations and the read-

ing of the serial interface, if required, can be completed before timeout. The GPIO pins can be utilized to interrupt an external master microcontroller when the ADC conversion is done and/or when the CPU computations are done so the serial interface can be read quickly.

DAC, Op Amp, PWM Modules (DOPn)

There are two output modules in the MAX1464—DOP1 and DOP2 (Figure 5). Each of the DOP modules contains a 16-bit DAC, a 12-bit digital PWM converter, a small op amp, and a large op amp with high-outputdrive capability. Switches in the DOP module enable a range of interconnectivity among the converters, op amps, and the external pins. Either the DAC or the PWM can be selected as the primary output signal. The DAC output signal is routed to one of the op amps and made available to a device pin. The signal-switching arrangement also allows the unused op amp to be configured as an uncommitted device with all connections available to external pins.

The DAC and op amps have a power-control bit in the power module. When power is disabled, all circuits in the DAC and the op amp are disabled with inputs and outputs in a tri-state condition. The proper bits in the power module must be enabled for operation of the DAC and op amps.

The DAC input is a 16-bit two’s-complement value. An input value of 0000h produces an output voltage of one half the DAC reference voltage. The DAC output voltage increases for positive two’s-complement numbers, and decreases for negative two’s-complement numbers.

The PWM input is a 12-bit two’s complement value. It shares the same input register (DOPn_Data) as the DAC, using the 12 MSBs of the 16-bit register. An input value of 000Xh produces a 50% duty cycle waveform at the output. The PWM output duty cycle increases for positive two’s-complement numbers, and decreases for negative two’s-complement numbers.

DOP_n Configuration Options

Each of the DOP modules can be configured in several different modes to suit a wide range of output signal requirements. The Functional Diagram shows the various switch settings of the configuration and control registers. In situations where configuration settings create a conflict in switch activation, a priority is applied to the switch logic to prevent the conflict.

The DAC and/or the PWM can be selected as the output signal source. The DAC output signal is routed to one of the op amps and made available to a device pin. Selecting the large op amp as the DAC output driver device enables a robust current drive capability for driving signals into low-impedance loads or across

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

______________________________________________________________________________________ 17

long lengths of wire. The unity-gain buffer configuration is automatically selected, and it provides the DAC output signal directly to the device pin OUTnLG. With the large op amp selected, the small op amp can be used as an independent device for external circuit applications when the PWM is disabled. Alternatively, the PWM can also be enabled to drive the OUTnSM device pin, in which case the small op amp is OFF.

Selecting the small op amp as the DAC output driver device is useful for routing the output signal to other circuits in an embedded control system with high-impedance load connections. The unity-gain buffer configuration is automatically selected, and it provides the DAC output signal directly to the device pin OUTnSM. With the small op amp selected, the large op amp can be used as an independent device for external circuit applications when the PWM is disabled. Alternatively, the PWM can also be enabled to drive the OUTnLG device pin, in which case the large op amp is OFF.

The DAC has two reference voltage sources available by selection, VDDand V

REF

input. When the external refer-

ence is selected (V

REF

), the actual DAC reference is 2 x

REF

. See V

REF

to 2.5V for nominal operation. The output of the DAC is a voltage proportional to the reference voltage selected, where the proportionality scaling (DAC input) is set in the data input register DOPn_Data.

The DOP module also provides a 12-bit digital PWM output. At a nominal 4MHz frequency, the frequency of the PWM is 122Hz (PWM period = 8.192ms). The DAC and the PWM share the same input register, DOPn_Data, where the PWM uses the 12 MSBs, in two’s-complement format. An input of 000Xh (4 LSBs are ignored) outputs a 50% duty cycle waveform at the selected output pin (either OUTnSM or OUTnLG). The PWM bit weight is 2µs, at a nominal frequency of 4MHz. The minimum duty cycle is obtained when the input is 800Xh (duty cycle is 0 / 4096 = 0), and the maximum duty cycle at 7FFXh (duty cycle is 4095 / 4096 =

99.98%). A new PWM input word is only effective at the end of a current PWM cycle, therefore preventing PWM glitches on the output.

Either the small or the large op amp in the DOP module can also be selected as an uncommitted op amp in the MAX1464. The op amps can be configured as a unitygain buffer, where the output is internally connected to the negative terminal of the op amp, or a stand-alone op amp, where both AMPnM and AMPnP can be externally connected for various analog functions. In the case of a buffer, the device pin AMPnM is in high-impedance mode, as the feedback loop around the op amp is connected internally.

OUTnSM

Figure 5. DOP1 and DOP2 Modules

AMPnM

SW10

SW0

SW1

SW2

SW3

REF

DAC

SW4

2 x V

REF

10h OR 13h DOPn_Data

11h OR 14h DOPn_Control

12h OR 15h DOPn_Config

AMPnP

OUTnLG

SW11

SW5

SW6

SW7

30h OpAmp_Config

SW8

PWM

SW9

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

18 ______________________________________________________________________________________

Every function of the DOP module can be selected individually (DAC, PWM, or op amp), or two out of the three functions of the DOP module can be selected at the same time (PWM and op amp, or DAC and PWM, or DAC and op amp), as there are only two output pins for the module, OUTnSM and OUTnLG. The various configuration options for the DOP are shown in Table 21. The PWRDAC and PWROP bits are in the power-on control register (address = 31h), and the remaining bits are in the DOP registers. See Tables 21 through 27.

Timer Module

The timer module (Figure 6) comprises a 12-bit counter, a 4-bit prescalar, and control and configuration registers. When the timer is enabled and initiated, the system master clock, MCLK, is prescaled by the divisor set by PS[3:0] in the TMR_Config register and the result applied to the 12bit upcounter. When the counter value matches the timeout value TO[11:0] in register TMR_Config, bit TMDN is set to 1. The CPU can poll the timer done bit TMDN to check its status.

The timer module provides a feature that enables the CPU to be put into a low-power halt mode for the duration of the timer interval. Setting the ENAHALT bit in the TMR_Control register while starting the timer (setting the timer enable bit TMEN to 1), or while the timer is already enabled and counting halts the CPU at the present instruction until the TMDN bit becomes set by the counter. The CPU commences execution with the next instruction. All CPU registers and ports are fully static and retain all data during the elapsed time interval.

The time interval between TMEN being set to 1, and TMDN being set to 1 can be computed as follows:

Time Interval = (2 / f

OSC

) x {(prescale value N)

x (timeout value TO[11:0]) + 1.5}

The maximum time interval given f

OSC

= 4MHz clock is

786ms.

Power Control

The power to various subcircuits in the MAX1464 can be turned on and off by CPU control and by the serial interface. Unused subcircuits and modules can be turned off to reduce power consumption. The default state after power-on is all subcircuits and modules powered off. This enables low-power embedded systems to turn on only the needed modules after exiting a low-power CPU halt timer interval. Modules can be turned on and off as needed; however, care must be exercised to allow for module initialization and settling prior to use.

Oscillator Control

The MAX1464 has a fully integrated oscillator with a nominal 4MHz frequency. An external clock source can be used when the clock-select pin CKSEL = 0, operating all internal timing functions. CKIO can also be configured as an output source of the internal oscillator clock.

GPIO Module

The MAX1464 contains two general-purpose digital input/output (GPIO) modules, GPIO1 and GPIO2, which can be written and read by CPU control and by the serial interface. These two I/O pins operate independently of each other. They can be configured as inputs, outputs, or one input and one output. When configured as an input, there are two modes of sensing digital inputs; as a voltage or logic level, or as an edge detector. In edge-detector mode, either a rising or falling edge can be selected for detection. A bit is set in the GPIO control register upon detection of the selected edge.

The GPIO pins have nominal 100kΩ pulldown resistors to V

as in Figure 6. Pulldown resistors provide a low logic level when the pin is unconnected. The GPIO may also serve as an input pin and its state is read from the GPIO control register (Tables 28 and 29). When using the GPIO pin as a general-purpose output, its output state is defined by writing to the GPIO control register.

The GPIOn pins can be configured as an alert output that goes low or high whenever a fault condition happens, e.g., remote sensor line disconnection, overflow conditions in the CPU program execution, etc.

All input and output control for the GPIO1 and GPIO2 pins are contained in GPIO1_Control (address = 40h) and GPIO2_Control (address = 41h), respectively. Figure 7 shows the GPIO1 and GPIO2 modules.

Serial Interface Timing and Operation

The MAX1464 serial interface is a high-speed asynchronous data input and output communication port, providing access to internal registers for calibration of embedded control sensor systems. All the FLASH memory is read and write accessible by the serial inter-

Figure 6. Timer Module

20hTMR_Control

21hTMR_Config

12-BIT COUNTER

TIMEOUT VALUE

PRESCALER

MCLK

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

______________________________________________________________________________________ 19

face for programming of instruction code and calibration coefficients. The MAX1464 serial interface can operate in 4-wire SPI-compatible mode or in a 3-wire mode (default on power-up). In 3-wire mode, the DI and DO lines can be connected together, forming a bidirectional data line. The serial interface lines consist of chip-select (CS), serial clock (SCLK), data in (DI), and data out (DO).

The MAX1464 serial interface is selected by asserting CS low. The serial input clock, SCLK, is gated internally to begin sequencing the DI input data and outputting the output data onto DO. When CS rises, the data that was clocked into DI is loaded into an internal register set (IRS[7:0]). The MAX1464 chip-select line CS cannot be connected low continuously for normal operation.

The serial interface can be used both during sensor calibration, as well as during normal operation. Each byte of data written into the MAX1464 serial port contains a 4-bit addresses nibble (IRSA [3:0]) and a 4-bit data nibble (IRSD [3:0]). The IRS register holds both the IRSD and IRSA nibbles as follows:

IRS [7:0] = IRSD [3:0], IRSA [3:0]

Four bytes of IRS information must be written into the serial interface to transfer 16 bits of data through IRSD into a MAX1464 internal register. All serial data written into the MAX1464 is transferred through the IRS register. The DI is read in with the LSB of the IRSA nibble first and the MSB of the IRSD nibble last. Figure 8 shows serial interface data input.

The IRSA bits are decoded to determine which register the IRSD bits should be latched into. The IRSA bits can address the DHR, the PFAR, the CR, and the IMR.

All serial data read from the serial interface is sourced from the 16-bit DHR. Any data to be read by the serial interface must first be placed into the internal DHR register before being accessible for reading by the serial interface.

The entire 16-bit content of the DHR register is read out through the DO pin by applying 16 successive clock pulses to SCLK while CS remains low. DHR is clocked out MSB bit first. Figure 9 shows the 4-wire mode data read from the DHR register

In 4-wire mode, data is transferred into DI during the clocking of data out of DO. Therefore, the last 8 bits clocked into the DI pin during this data transfer are latched into the IRS register and decoded when CS returns high.

When the MAX1464 serial interface is configured in 3wire mode, the 16-bit DHR data is read out immediately following the command for 3-wire mode enable. Figure 10 shows the 3-wire enable command (IRS[7:0] = 19h) clocked into DI with a subsequent 16-bit read of DHR on DO. DO remains in high impedance (tri-state) until the 3-wire enable command is received. Then DO goes into low-impedance drive mode during the next low cycle of CS. As SCLK is clocked 16 times, the data in DHR is clocked out at DO. The 3-wire enable command is the command that sets the MAX1464 ready for output on DO on the next low cycle of CS. Following the DHR output on the low cycle of CS, the DO line returns to high-impedance state until the next 3-wire enable command is received. The MAX1464 can receive an indefinite number of inputs to DI without the need for a 3-wire enable command to be received.

When the IRSD[3:0] nibble is written to the command register (CR), i.e., when IRSA[3:0] = 1000, the nibble is decoded and a command operation is initiated. The command register decoding is shown in Table 39.

When the IRSD[3:0] nibble is written to the IMR, i.e., when IRSA[3:0] = 1000, the nibble is decoded and a command operation is initiated. The IMR decoding is shown in Table 40.

Note that after power is applied and the POR function completes, the serial interface default is the 3-wire mode for receiving data on DI only. The DO line is a highimpedance output until the MAX1464 receives either the 4-wire or 3-wire mode command in the IMR. In the case of a 3-wire mode command, DO switches from a highimpedance state to a driving state only for the next cycle of CS, returning to high impedance afterwards.

All commands, with the exception of programming or erasing the FLASH memory, are completed within eight internal master clock cycles of CS returning from low to high. This is 4µs for a 4MHz oscillator frequency or external clock input (1 internal master clock = 2 external/internal oscillator periods). FLASH memory programming and erasing require additional time of 80µs and 4.2ms, respectively.

Figure 7. GPIO1 and GPIO2 Modules

40h OR 41hGPIOn_Control

EDGE OR LEVEL DETECT

GPIOn

100kΩ

TRI-STATE BUFFER

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

20 ______________________________________________________________________________________

FLASH Memory

There are 4096 bytes of programmable/erasable FLASH memory for CPU program instructions and coefficients storage. In addition, there are 128 bytes of FLASH memory accessible only by the serial interface for storage of user information data.

These two FLASH memory locations are separated as partitions. The program/coefficient memory is FLASH partition 0 and the information memory is FLASH partition 1. Each partition is accessible by the serial interface for reading, erasing, and writing data. Program/ coefficient memory partition 0 is accessible by the CPU as read only, and partition 1 is not accessible by the CPU. The CPU cannot erase or write data to either of the FLASH memory partitions.

FLASH partition 0 is selected during the POR cycle. FLASH partition 1 is selected by sending the halt CPU command (IRS[7:0] = 78h) and changing the partition selected by sending the change partition command

(IRS[7:0] = F8h). A following halt command (IRS[7:0] = 78h) resets the selected partition to partition 0.

Modifying the FLASH Contents

The MAX1464 FLASH memory contents must be erased (contents = FFh) before the desired contents can be written. There is no individual byte-erase command, but either a total-erase command (IRS[7:0] = E8h) where all the selected partition is erased (4kB for partition 0 or 128 bytes for partition 1) or a page-erase command (IRS[7:0] = D8h), where only 64 bytes are erased, and the page is selected by PFAR[11:6]. There are 64 pages in FLASH partition 0, and only 2 pages in FLASH partition 1.

The programming of the MAX1464 FLASH memory must use the following procedure (all the commands are to be sent through the serial interface, and are hexadecimal values of IRS[7:0]):

Figure 8. Serial Interface Data Input

Figure 9. 4-Wire Mode Data Read from DHR Register

Figure 10. 3-Wire Mode Data Read from DHR Register

SCLK

IRS1

IRS0

IRSA1

IRSA0

DHR15 DHR14 DHR13 DHR12 DHR11 DHR10 DHR9 DHR8 DHR7 DHR6 DHR5 DHR4 DHR3 DHR2 DHR1 DHR0

IRS2

IRSA2

IRS0

IRSA0

IRS3

IRSA3

IRS1

IRSA1

IRS4

IRSD0

SCLK

IRSA00IRSA10IRSA21IRSA31IRSD00IRSD10IRSD20IRSD3

IRS5

IRSD1

IRS2

IRSA2

IRS3

IRSA3

IRS6

IRS7

IRSD2

IRSD3

DHR15 DHR14 DHR13 DHR12 DHR11 DHR10 DHR9 DHR8 DHR7 DHR6 DHR5 DHR4 DHR3 DHR2 DHR1 DHR0

IRS0

IRSA0

IRS4

IRSD0

IRS1

IRSA1

IRS5

IRSD1

IRS2

IRSA2

IRS3

IRSA3

IRS6

IRSD2

IRS4

IRSD0

IRS7

IRSD3

IRS5

IRSD1

IRS6

IRSD2

IRS7

IRSD3

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

______________________________________________________________________________________ 21

1) Halt the CPU:

2) If partition 1 is to be modified, enter the following command:

Otherwise, partition 0 is selected.

3) Turn off all analog modes:

03 02 01 00 (write 0000h to DHR[15:0])

D4 (write Dh to PFAR[3:0])

08 (write DHR, 1000h to CPU port

pointed by PFAR[3:0], port D)

03 02 31 10 (write 0031h to DHR[15:0])

E4 (write Eh to PFAR[3:0])

08 (write DHR, 0031h to CPU port

pointed by PFAR[3:0], port E)

83 02 01 00 (write 8000h to DHR[15:0])

F4 (write Fh to PFAR[3:0])

08 (write DHR, 8000h to CPU port

pointed by PFAR[3:0], port F)

At this point, all the MAX1464 analog modules are off.

4) For erasing the whole partition, send the following command:

Otherwise, if only a page erase is required, first write PFAR[11:6] with the page address, as:

07 X6 X5 04 (write 0XX0h to PFAR[15:0])

Note that the 2 lower bits of PFAR[7:4] should be zero, and only the upper 2 bits of that nibble should be set to the desired value. Then, after writing the page address, send the page-erase command:

5) Wait at least 4.2ms before sending any other command to allow the necessary time for the erase operation to complete.

6) Write the address of the FLASH byte to be written to PFAR[15:0]:

07 X6 X5 X4 (write 0XXXh to PFAR[15:0])

7) Write the contents of the byte to DHR[7:0]:

X1 X0 (write XXh to DHR[7:0], high nibble

at DHR[7:4])

8) Send the command to execute the FLASH write:

9) Repeat steps 6, 7, and 8 for all the bytes to be written. It is not necessary to send the whole address and data for every byte that is written. Only the nibbles that are modified in the PFAR and in the DHR from previous values must be changed. The time interval between successive write commands (18h) must be at least 80µs.

10) If partition 1 was selected in step 2, and the user wants to switch back to partition 0, send the follow ing command:

At this point, partition 0 is selected. The user may want to go back to step 4 to program partition 0, or just continue on.

Reading the FLASH Contents

The procedure to read the FLASH contents is no different from reading any other information from the MAX1464. The FLASH contents must be copied to the DHR and read through the serial interface:

1) If the CPU is not halted, halt the CPU:

2) If partition 1 is to be read, enter the following command:

Otherwise, partition 0 is selected.

3) Write the address of the flash byte to be read to PFAR[15:0]:

07 X6 X5 X4 (write 0XXXh to PFAR[15:0])

4) Copy the contents of FLASH addressed by PFAR to DHR:

5) If the interface is configured in 3-wire mode, send

19 to enable DO on the next CS cycle. Then tri-

state the DI driver, and send 16 SCLK pulses on the following CS cycle, and DO outputs DHR[15:0]. The FLASH data is present at DHR[7:0]. See Figure 10 for details.

If the interface is configured in 4-wire mode, there is no need to enable the DO line, as it has already been enabled by a previous IRS command 09h. Send the 16 SCLK pulses and retrieve the data on the DO line.

6) Repeat steps 3, 4, and 5 for every byte to be read. Only the nibbles that are modified in the PFAR register are required to be sent.

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

22 ______________________________________________________________________________________

Program and Coefficient Memory

The program and coefficient memory, FLASH partition 0, is addressed by the CPU and by the serial interface sequentially from 0000h (0 dec) to 0FFFh (4095 dec). Program execution by the CPU always begins at address 0000h and proceeds toward 0FFFh in 1-byte increments.

Although both the CPU and the serial interface can address a 16-bit field, the FLASH size only uses 12 bits. Therefore, the leading 4 MSBs of the address field are ignored. It is advisable to have all leading bits of the 16-bit address in PFAR[15:0] set to zero.

The FLASH memory in partition 0 can be erased in individual 64-byte pages using the page-erase command, or erased in bulk using the all-erase command. The information data memory (partition 1) is unaffected by any operation performed on partition 0.

Information Data Memory

The information data memory, FLASH partition 1, is addressed by bytes sequentially from 00h (0 dec) to 7Fh (127 dec). The addressed byte should have all leading bits of the 16-bit address in PFAR[15:0] set to zero.

The FLASH memory in partition 1 has only two 64-byte pages that can be erased separately using the pageerase command, or erased together using the all-erase command. Data in partition 0 is not affected by any operation performed on partition 1.

MAX1464 CPU Instruction Set

The MAX1464 CPU has 16 instructions used to perform all calculations for sensor compensation, linearization, and signal output functions. Each instruction comprises a 4-bit op code and a 4-bit CPU register address. The op code describes what operation to perform; the register address describes what register, or registers, to perform the operation on.

Instruction Format

All instructions are single-byte instructions with the exception of load data from instruction memory. LDX fetches the 2 following bytes of instruction memory and loads them into a register. This is how calibration and compensation coefficients are stored within the MAX1464. Any number of coefficients can be stored in instruction memory. The instruction code format is as follows:

Instruction Set Details

LDX Load Register X

Op-code: 0000 XXXX

BINARY

0Xh

Operation:

X-register ← [PC+1] : [PC+2]

PC-register ← PC + 3 (point to next instruction)

CPU Cycles required:

3 cycles

Instruction:

Loads the next 2 bytes of program memory into CPU register X. Register X can be any of the 16 CPU registers. Program counter (PC) is incremented twice during the fetches of the next 2 bytes and incremented a third time to point to the next instruction in program memory.

Two’s-complement data format is preserved.

No branching occurs.

No other registers are affected.

CLX Clear Register X

Op-code: 0001 XXXX

BINARY

1Xh

Operation:

X-register ← 0000h

PC-register ← PC + 1 (point to next instruction)

CPU Cycles required:

1 cycle

Description:

Clear the contents of register X to 0000h.

PC is incremented once to point to the next instruction in program memory.

Two’s-complement data format is preserved.

No branching occurs.

No other registers are affected.

ANX AND Register X with Register A

Op-code: 0010 XXXX

BINARY

2Xh

Operation:

A-register ← A-register AND X-register

PC-register ← PC + 1 (point to next instruction)

CPU Cycles required:

1 cycle

COMMAND OP CODE

(BITS 7–4)

Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

MSB LSB

(BITS 3–0)

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

______________________________________________________________________________________ 23

Description:

Perform a 16-bit logical AND operation, bit for bit, on the contents of the A-register and the contents of the Xregister. Store the 16-bit result back into the A-register. The previous contents of the A-register are overwritten and lost.

PC is incremented once to point to the next instruction in program memory.

Two’s-complement data format is not preserved.

No branching occurs.

No other registers are affected.

ORX OR Register X with Register A

Op-code: 0011 XXXX

BINARY

3Xh

Operation:

A-register ← A-register OR X-register

PC-register ← PC + 1 (point to next instruction)

CPU Cycles required:

1 cycle

Description:

Perform a 16-bit logical OR operation, bit for bit, on the contents of the A-register and the contents of the X-register. Store the 16-bit result back into the A-register. The previous contents of the A-register are overwritten and lost.

PC is incremented once to point to the next instruction in program memory.

Two’s-complement data format is not preserved.

No branching occurs.

No other registers are affected.

ADX ADD Register X to Register A

Op-code: 0100 XXXX

BINARY

4Xh

Operation:

A-register ← A-register + X-register

PC-register ← PC + 1 (point to next instruction)

CPU Cycles required:

1 cycle

Description:

Perform a 16-bit arithmetic addition of the A-register and the contents of the X-register. Store the low 16 bits of the result back into the A-register. Any overflow bit resulting from the addition operation is lost. The previ-

ous contents of the A-register are overwritten and lost.

PC is incremented once to point to the next instruction in program memory.

Two’s-complement data format is preserved.

No branching occurs.

No other registers are affected.

STX Store Register X

Op-code: 0101 XXXX

BINARY

5Xh

Operation:

X-register ← A-register

PC-register ← PC + 1 (point to next instruction)

CPU Cycles required:

1 cycle

Description:

Perform a 16-bit move operation from the A-register into the X-register. The A-register contents are unchanged. The previous contents of the X-register are overwritten and lost.

PC is incremented once to point to the next instruction in program memory.

Two’s-complement data format is preserved.

No branching occurs.

No other registers are affected.

SLX Shift Left Register X

Op-code: 0110 XXXX

BINARY

6Xh

PC-register ← PC + 1 (point to next instruction)

CPU Cycles required:

1 cycle

Operation when X ≠ 6h:

1415 13 12 11 10 9 8 7 6 5 4 3 2 1 0

BIT:

Operation when X = 6h:

15 13 12 11 10 9 8 7 6 5 4 3 2 1 0BIT:

1415 13 12 11 10 9 8 7 6 5 4 3 2 1 0BIT:

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

24 ______________________________________________________________________________________

Description:

Perform a 16-bit shift-left operation on the contents of X-register. The most significant bit, bit 15, is truncated and lost. If register X is any CPU register other than register R6, then a zero is appended into the LSB, bit 0. If X is CPU register R6, then the data appended into the LSB bit 0 is copied from the MSB of register R4. The contents of register R4 are not affected. The operation does not preserve the two’s-complement sign bit-15. The operation is equivalent to an arithmetic multiplication by 2 on an unsigned integer value stored in register X. The result is stored back into the X-register. The previous contents of the X-register are overwritten and lost.

PC is incremented once to point to the next instruction in program memory.

Two’s-complement data format is not preserved.

No branching occurs.

No other registers are affected.

SRX Shift Right Register X

Op-code: 0111 XXXX

BINARY

7Xh

PC-register ← PC + 1 (point to next instruction)

CPU Cycles required:

1 cycle

Description:

Perform a 15-bit shift-right operation on the contents of X-register, preserving the contents of the two’s-complement sign bit-15 and propagating the sign bit, bit-15, into bit-14. The least significant bit, bit 0, is truncated and lost. The operation is equivalent to an arithmetic division by 2. The result is stored back into the X-register. The previous contents of the X-register are overwritten and lost.

PC is incremented once to point to the next instruction in program memory.

Two’s-complement data format is preserved.

No branching occurs.

No other registers are affected.

INX Increment Register X

Op-code: 1000 XXXX

BINARY

8Xh

Operation:

X-register ← X-register + 1

PC-register ← PC + 1 (point to next instruction)

CPU Cycles required:

1 cycle

Description:

Perform a 16-bit increment operation on the contents of the X-register. Should the increment result in an overflow, the overflow bit is truncated and lost. The result is stored back into the X-register. The previous contents of the X-register are overwritten and lost.

PC is incremented once to point to the next instruction in program memory.

Two’s-complement data format is preserved.

No branching occurs.

No other registers are affected.

DEX Decrement Register X

Op-code: 1001 XXXX

BINARY

9Xh

Operation:

X-register ← X-register - 1

PC-register ← PC + 1 (point to next instruction)

CPU Cycles required:

1 cycle

Description:

Perform a 16-bit decrement operation on the contents of the X-register. Should the decrement result in an underflow, the underflow bit is truncated and lost. The result is stored back into the X-register. The previous contents of the X-register are overwritten and lost.

PC is incremented once to point to the next instruction in program memory.

Two’s-complement data format is preserved.

No branching occurs.

No other registers are affected.

NGX Negate Register X

Op-code: 1010 XXXX

BINARY

AXh

Operation:

X-register ← NOT X-register

Operation

BIT:

1415 13 12 11 10 9 8 7 6 5 4 3 2 1 0

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

______________________________________________________________________________________ 25

PC-register ← PC-register + 1 (point to next instruction)

CPU Cycles required:

1 cycle

Description:

Perform a 16-bit logical NOT operation on the contents of the X-register. Each bit is flipped to its complementary value. The result is stored back into the X-register. The previous contents of X-register are overwritten and lost.

PC is incremented once to point to the next instruction in program memory.

Two’s-complement data format is not preserved.

No branching occurs.

No other registers are affected.

BPX Branch If Positive Or Zero

Op-code: 1011 XXXX

BINARY

BXh

Operation:

If MSB(Register I) = 0 then:

PC-register ← PC-register + X-register

Else:

PC-register ← PC + 1 (point to next instruction)

CPU Cycles required:

1 cycle

Description:

Perform a 16-bit check of I-register for a positive (two’s complement) or zero value and branch the number of instructions indicated in register-X. The test operation checks the most significant bit, bit-15, for a 0Band, if true, adds the contents of the X-register to the program counter register. This causes an immediate jump to the new program memory location. The next instruction to execute is fetched from the program memory byte pointed to by the new contents of the PC-register.

A 1Bin bit-15 of the I-register is indicative of a negative number (two’s complement) to which the test for positive-or-zero value fails. This causes the “else” operation to be performed and the PC-register is incremented by one pointing to the next sequential instruction in program memory to be executed. The effect bypasses the branch mechanism and normal, sequential, code execution results.

The next instruction to execute is fetched from the program memory byte pointed to by the new contents of the PC-register. The previous contents of the PC-register are overwritten and lost.

Two’s-complement data format is preserved.

Branching may occur.

No other registers are affected.

BNX Branch If Not Zero

Op-code: 1100 XXXX

BINARY

CXh

Operation:

If I-register ≠ 0000h then:

PC-register ← PC-register + X-register

Else:

PC-register ← PC-register + 1 (point to next instruction)

CPU Cycles required:

1 cycle

Description:

Perform a 16-bit check of the I-register for a nonzero condition and, if true, add the contents of the X-register to the program pointer register. This causes an immediate jump to the new program memory location. The next instruction to execute is fetched from the program memory byte pointed to by the new contents of the PCregister.

A 1Bin any bit of the I-register is indicative of a nonzero number to which the test for a zero value fails. This causes the “else” operation to be performed and the PC-register is incremented by one pointing to the next sequential instruction in program memory to be executed. The effect bypasses the branch mechanism and normal, sequential, code execution results.

The next instruction to execute is fetched from the program memory byte pointed to by the new contents of the PC-register. The previous contents of the PC-register are overwritten and lost.

Two’s-complement data format is preserved.

Branching may occur.

No other registers are affected.

RDX Read Port X

Op-code: 1101XXXX

BINARY

DXh

Operation:

A-register ← port-X

PC-register ← PC + 1 (point to next instruction)

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

26 ______________________________________________________________________________________

CPU Cycles required:

1 cycle

Description:

Perform a 16-bit move operation from port-X to the Aregister.

The port-X contents are unchanged.

The previous contents of A-register are overwritten and lost.

The port-X can be any of the CPU ports.

PC is incremented once to point to the next instruction in program memory.

Two’s-complement data format is preserved.

No branching occurs.

No other registers are affected.

WRX Write Port X

Op-code: 1110 XXXX

BINARY

EXh

Operation:

Port-X ← A-register

PC-register ← PC + 1 (point to next instruction)

CPU Cycles required:

1 cycle

Description:

Perform a 16-bit move operation from the A-register to port-X.

The A-register contents are unchanged.

The previous contents of port-X are overwritten and lost.

The port-X can be any of the CPU ports.

PC is incremented once to point to the next instruction in program memory.

Two’s-complement data format is preserved.

No branching occurs.

No other registers are affected.

MLT Multiply

Op-code: 1111 0011

BINARY

F3h

Operation:

A-register | M-register ← N-register x M-register

PC-register ← PC + 1 (point to next instruction)

CPU Cycles required:

16 cycles

Description:

Perform a 16-bit by 16-bit arithmetic multiplication of the M-register and the N-register producing a 32-bit result. The 32-bit result is stored in two 16-bit registers; the A-register receives the most significant word of the result and the M-register receives the least significant word of the result.

The A-register must be cleared to zero (CLX A) before executing the MLT instruction. The previous contents of the A-register are overwritten and lost.

The previous contents of the M-register are overwritten and lost.

The contents of the N-register are not altered.

The register op code must be 3h.

PC is incremented once to point to the next instruction in program memory.

Two’s-complement data format is preserved.

No branching occurs.

No other registers are affected.

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

______________________________________________________________________________________ 27

Table 1. CPU Registers

ADDRESS REF ALT NAME FUNCTION

0h R0 P

1h R1 A

2h R2 —

3h R3 N

4h R4 M

5h R5 I

Pointer Register. This register contains the address of the instruction or data in FLASH memory to be fetched.

Accumulator Register. This register generally contains the result of any operation involving two or more registers. It is the accumulator for the multiregister operation result and can be used effectively to carry data from one computation to the next. The A register can read and write data to and from any other CPU port or register.

General-Purpose Register. Used to hold intermediate calculation results, calculation coefficients, loop counter values, event counter values, comparison limit values, etc.

Multiplicand Register. This register has a dedicated function when executing a multiply (MLT) instruction, but can be used as a general-purpose register otherwise. The contents of the N register are not modified by the MLT instruction.

Multiplier Register. This register has a dedicated function when executing a multiply (MLT) instruction, but can be used as a general-purpose register otherwise. The contents of the M register are modified by the MLT instruction. The data contents prior to the execution of the MLT instruction are overwritten with the LSBs resulting product, and hence lost.

Index Register. The branch not zero (BNX) and branch positive (BPX) instructions test the index register, I, for conditions to determine if branching should occur. If the index register tests true for the condition to branch, then the contents of register X are added to the pointer register, therefore executing a branch in the program.

6h–Fh R6–RF —

General-Purpose Registers. Used to hold intermediate calculation results, calculation coefficients, loop counter values, event counter values, comparison limit values, etc.

Table 2. CPU Ports

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

28 ______________________________________________________________________________________

ADDRESS REF FUNCTION

General-Purpose Ports. These ports, P0–PC, can be used to hold intermediate calculation results,

0h–Ch P0–PC

Dh PD

Eh PE

Fh PF

often-used calculation coefficients, loop counter values, event counter values, comparison limit values, etc.

Module Data Port. This port is used to transfer data to and from the various functional modules in the MAX1464. Data loaded into PD can be transferred to the data, configuration, or control register of any of the functional modules. The data transfer is initiated using the module control port (PF). The contents of PD are not changed during module write operations, but are overwritten by module read operations.

Module Address Port. This port is used to address a module register. A module address is loaded into PE prior to initiating a data transfer or control function in the module control port. All modules in the MAX1464 are accessed through this indirect addressing method. The contents of PE are not changed by the read or write operations to module registers. Only the lower 8 bits are used. The upper 8 bits are not decoded.

Module Control Port. This port initiates an operation on the module addressed by PE. Data can be written to, or read from, module registers. Specific bits are assigned in the module control port to initiate operations on the MAX1464 modules: Bit 15 (CTRL): 1 = Initiate action defined in bit 14, 0 = no action initiated. Autoreset to zero after operation is completed. Bit 14 (RD/WR): 1 = read data, 0 = write data. Bits 13–0: Not decoded.

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

______________________________________________________________________________________ 29

Table 3. Module Registers

Table 4. ADC Module Registers

MODULE

NAME

ADC

Timer

Op Amp Opamp_Config 30h Set op amps as unity-gain buffers. R/ W

Power PO_Control 31h Turn on power to modules with power-control function. R/ W

Oscillator OSC_Control 32h Trim oscillator frequency, enable clock input/output. R/ W

GPIO1 GPIO1_Control 40h Enable I/O, set output value, read input value. R/ W GPIO2 GPIO2_Control 41h Enable I/O, set output value, read input value. R/ W

NAME

ADC_Control 00h Initiate conversions and select ADC input. R/ W

ADC_Data_1 01h Result of ADC conversion on channel 1 input. R

ADC_Config_1A 02h Settings for channel 1 input and conversion. R/ W ADC_Config_1B 03h Settings for channel 1 input and conversion. R/ W

ADC_Data_2 04h Result of ADC conversion on channel 2 input. R

ADC_Config_2A 05h Settings for channel 2 input and conversion. R/ W ADC_Config_2B 06h Settings for channel 2 input and conversion. R/ W

ADC_Data_T 07h Result of ADC conversion on temperature input. R

ADC_Config_TA 08h Settings for temperature input and conversion. R/ W

ADC_Config_TB 09h Settings for temperature input and conversion. R/

DOP1_Data 10h Input setting for the analog DAC and digital PWM outputs. R/ W

DOP1_Control 11h Enable and reference selection. R/ WDOP1

DOP1_Config 12h Select DAC or PWM output. R/

DOP2_Data 13h Input setting for the analog DAC and digital PWM outputs. R/ W

DOP2_Control 14h Enable and reference selection. R/ WDOP2

DOP2_Config 15h Select DAC or PWM output. R/

TMR_Control 20h Initiate timer. R/ W

TMR_Config 21h Set prescaler value and timeout value. R/

ADDRESS DESCRIPTION R/W

NAME ADDRESS DESCRIPTION POR VALUE

ADC_Control 00h Initiate conversions and set signal source. 0000h

ADC_Data_1 01h Result of ADC conversion on channel 1 input. 0000h

ADC_Config_1A 02h Settings for channel 1 input and conversion. 0000h

ADC_Config_1B 03h Settings for channel 1 input and conversion. 0070h

ADC_Data_2 04h Result of ADC conversion on channel 2 input. 0000h

ADC_Config_2A 05h Settings for channel 2 input and conversion. 0000h

ADC_Config_2B 06h Settings for channel 2 input and conversion. 0070h

ADC_Data_T 07h Result of ADC conversion on temperature input. 0000h

ADC_Config_TA 08h Settings for temperature input and conversion. 0000h

ADC_Config_TB 09h Settings for temperature input and conversion. 0070h

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

30 ______________________________________________________________________________________

Table 5. ADC_Control (Address = 00h)

Table 6. Initiate Conversion (CNVT1, CNVT2, CNVTT)

*The value bbbb is any nonzero single-ended setting.

BITS NAME DESCRIPTION

15–12 — Unused.

11–8 SE[3:0] Single-ended signal source multiplexer. SE[3] = MSB.

7–3 — Unused.

1 = Initiate conversion on channel 1 using ADC settings specified in registers ADC_Config_1A and

2 CNVT1

1 CNVT2

0 CNVTT

CNVT1 CNVT2 CNVTT SE[3:0]

0 0 0 XXXX — No measurement.

0 0 1 0000 T

ADC_Config_1B. The ADC result is stored in ADC_Data_1. CPU is halted during the conversion process. This bit is automatically reset to zero when conversion is completed.

1 = Initiate conversion on channel 2 using ADC settings specified in registers ADC_Config_2A and ADC_Config_2B. The ADC result is stored in ADC_Data_2. CPU is halted during the conversion process. This bit is automatically reset to zero when conversion is completed.

1 = Initiate conversion on temperature sensor using ADC settings specified in registers ADC_Config_TA and ADC_Config_TB. The ADC result is stored in ADC_Data_T. CPU is halted during the conversion process. The bit is automatically reset to zero when conversion is completed.

RESULT DATA_n

Convert the temperature sensor signal using the settings in ADC_Config_TA and ADC_CONFIG_TB, storing the result in the ADC_Data_T register.

DESCRIPTION

Convert the differential signal INP2-INM2 using the settings in

0 1 X 0000 2

1 X X 0000 1

0 0 1 bbbb* — Not used for any setting of SE[3:0] ≠ 0000.

0 1 X bbbb* 2

1 X X bbbb* 1

ADC_Config_2A and ADC_Config_2B, storing the result in the ADC_Data_2 register.

Convert the differential signal INP1-INM1 using the settings in ADC_Config_1A and ADC_Config_1B, storing the result in the ADC_Data_1 register.

Convert the single-sided signal indicated by SE[3:0] using the settings in ADC_Config_2A and ADC_Config_2B, if appropriate, storing the result in the ADC_Data_2 register.

Convert the single-sided signal indicated by SE[3:0] using the settings in ADC_Config_1A and ADC_Config_1B, if appropriate, storing the result in the ADC_Data_1 register.

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

______________________________________________________________________________________ 31

Table 7. Single-Ended (SE[3:0])

*The PGA operates at a fixed reduced gain of 0.7V/V to enable conversion of input signals at and near VDDand VSS. This gain set- ting is not selectable. **When measuring V

, use the external reference or the 4 x VBGsetting.

Table 8. ADC_Config_1A (Address = 02h)

Table 9. ADC_Config_1B (Address = 03h)

Table 10. ADC_Config_2A (Address = 05h)

SE[3:0]

0001 0.99 VBG V

0010 0.99 to 244 OUTnSM V

0011 0.99 to 244 OUTnLG V

0100 0.7* VDD** V

0101 0.7* V

0110 0.7*

0111 0.7*

1000 0.99 to 244 INPn V

1001 0.99 to 244 INMn V

PGA

RANGE (V/V)

ADC

+INPUT

DACn_OUT using

OUTnSM

DACn_OUT using

OUTnLG

ADC

-INPUT

DESCRIPTION

Bandgap voltage.

Output of small op-amp n.

Output of large op-amp n.

Power-supply voltage.

Power-supply ground.

DACn output through small op-amp n configured as unity-gain buffer.

DACn output through large op-amp n configured as unity-gain buffer.

Single-ended input on INPn.

Single-ended input on INMn.

BIT NAME DESCRIPTION

15–11 PGA1[4:0] Programmable-gain amplifier setting to use during conversion of channel 1. PGA1[4] = MSB.

10–8 CLK1[2:0] ADC clock setting to use during conversion of channel 1. CLK1[2] = MSB.

7 — Unused.

6–4 RES1[2:0] ADC resolution setting to use during conversion of channel 1. RES1[2] = MSB.

3 CO1[3] Coarse-offset sign bit.

2–0 CO1[2:0] Coarse-offset DAC setting to use during conversion of channel 1. CO1[2] = MSB.

BIT NAME DESCRIPTION

15–7 — Unused.

6–4 BIAS1[2:0] ADC bias setting to use during conversion of channel 1. BIAS1[2] = MSB.

3–2 — Unused.

1–0 REF1[1:0] Reference select for conversion on channel 1. REF1[1] = MSB.

BIT NAME DESCRIPTION

15–11 PGA2[4:0] Programmable-gain amplifier to use during conversion of channel 2. PGA[4] = MSB.

10–8 CLK2[2:0] ADC clock setting to use during conversion of channel 2. CLK2[2] = MSB.

7 — Unused.

6 RES2[2:0] ADC resolution setting to use during conversion of channel 2. RES2[2] = MSB.

3 CO2[3] Coarse-offset DAC sign bit.

2–0 CO2[2:0] Coarse-offset DAC setting to use during conversion of channel 2. CO2[2] = MSB.

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

32 ______________________________________________________________________________________

Table 11. ADC_Config_2B (Address = 06h)

Table 12. ADC_Config_TA (Address = 08h)

BITS NAME DESCRIPTION

15–7 — Unused.

6–4

ADC bias setting to use during conversion of the temperature sensor. BIAST[2] = MSB.

3–0 — Unused.

Table 13. ADC_Config_TB (Address = 09h)

PGAn[4:0] GAIN (V/V)

00000 0.99

00001 7.7

00010 15.5

00011 23

00100 31

00101 39

00110 46

00111 54

01000 62

01010 77

01100 92

01110 107

10000 123

10100 153

11000 183

11100 214

11110 244

Table 14. Programmable-Gain Amplifier (PGAn[4:0], Where n = 1, 2, or T)

CLKn[2:0] DIVISOR n f

ADC

(Hz)

000 4 1M

001 8 500k

010 16 250k

011 32 125k

100 64 62.5 k

101 128 31.25k

110 256 15.625k

111 512 7.8125k

Table 15. ADC Clock (CLKn[2:0], Where n = 1, 2, or T; f

CLK

= 4MHz)

BIT NAME DESCRIPTION

15–7 — Unused.

6–4 BIAS2[2:0] ADC bias setting to use during conversion of channel 2. BIAS2[2] = MSB.

3–2 — Unused.

1–0 REF2[1:0] Reference select for conversion on channel 2. REF2[2] = MSB.

BITS NAME DESCRIPTION

15–11 PGAT[4:0] Programmable gain to use during conversion of temperature sensor. PGAT[4] = MSB.

10–8 CLKT[2:0] ADC clock setting to use during conversion of the temperature sensor. CLKT[2] = MSB.

7 — Unused.

6–4 REST[2:0] ADC resolution setting to use during conversion of the temperature sensor. REST[2] = MSB.

3 COT[3] Coarse-offset DAC sign bit.

2–0 COT[2:0] Coarse-offset DAC setting to use during conversion of the temperature sensor. COT[2] = MSB.

BIAST[2:0]

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

______________________________________________________________________________________ 33

Table 16. ADC Resolution (RESn[2:0], Where n = 1, 2, or T)

COARSE OFFSET ADDED AS % OF ADC REFERENCE*

ADC REFERENCE EQUAL TO VDD or 2 x V

REF

ADC REFERENCE EQUAL TO 4 x V

COn

[3:0]

10100 TO 11110

0111

+147 +291 +578 +137 +270 +539

0110

+124 +245 +487 +116 +229 +456

0101

+104 +206 +409 +97 +192 +383

0100

+82 +162 +322 +76 +151 +300

0011

+64 +126 +251 +59 +116 +231

0010

+41 +81 +160 +38 +75 +148

0001

+21 +41 +83 +19 +38 +76

0000

-1 -2.4 -4 -1.7 -3.3 -7

1000

-10 -19 -38 -4.6 -9 -19

1001

-30 -61 -120 -26 -51 -101

1010

-50 -100 -199 -44 -87 -174

1011

-73 -145 -287 -65 -129 -257

1100

-91 -181 -360 -82 -163 -326

1101

-113 -225 -447 -104 -205 -409

1110

-133 -264 -526 -122 -242 -482

1111

-156 -309 -614 -143 -283 -565

Table 18. Coarse-Offset DAC (3 Bits Plus Sign, Where n = 1, 2, or T)

CONVERSION TIME (ms)

RESOLUTION

(BITS)

CLKn[2:0] =

000

CLKn[2:0] =

100

CLKn[2:0] =

111

9 0.256 4.096 32.768

10 0.320 5.120 40.960

12 0.512 8.192 65.536

13 0.640 10.240 81.920

14 0.800 12.800 102.400

15 1.280 20.480 163.840

16 2.048 32.768 262.140

Table 17. ADC Conversion Time (RESn[2:0] and CLKn[2:0], Where n = 1, 2, or T)

*Measured at the ADC input.

NO. OF f

RESn[2:0] RESOLUTION (BITS)

000 9 256

001 10 320

010 12 512

011 13 640

100 14 800

101 15 1280

110 16 2048

CLOCKS PER CONVERSION

ADC

PGAn = 1 TO 59 PGAn = 71 TO 114 PGAn = 137 TO 220 PGAn = 1 TO 59 PGAn = 71 TO 114 PGAn = 137 TO 220

00000 TO 01000 01010 TO 10000

00000 TO 01000 01010 TO 10000 10100 TO 11110

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

34 ______________________________________________________________________________________

Table 19. ADC Bias Current (BIASn[2:0], Where n = 1, 2, or T)

REFn[1:0] ADC REFERENCE

00 V

01 2 x V

REF

(external)

1X 4 x VBG (internal bandgap)

Table 20. ADC Reference Voltage Source (REFn[1:0], Where n = 1 or 2)

FRACTION

BIASn[2:0]

000 1/8 125k 011

001 2/8 250k 011

010 3/8 250k 010

011 4/8 500k 010

100 5/8 500k 001

101 6/8 500k 001

110 7/8 1M 000

111 8/8 1M 000

OF FULL

BIAS

CURRENT

MAXIMUM

ADC CLOCK

FREQUENCY

(Hz)

CLKn[2:0]

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

______________________________________________________________________________________ 35

Table 21. DOPn Configuration Options

DOP CONFIGURATION PWRDAC PWROP SELDAC SELPWM ENDAC ENPWM BUF

DAC OFF, PWM OFF, op amp OFF. 0 0 X X 0 0 X

DAC OFF, PWM OFF, op amp ON. AMPnP and AMPnM routed to LG op amp.

DAC OFF, PWM OFF, op amp ON. LG op amp configured as unity-gain buffer.

DAC OFF, PWM OFF, op amp ON. AMPnP and AMPnM routed to SM op amp.

DAC OFF, PWM OFF, op amp ON. SM op amp configured as unity-gain buffer.

DAC OFF, PWM ON, op amp OFF. PWM output on OUTnSM. AMPnP and AMPnM disabled.

DAC OFF, PWM ON, op amp OFF. PWM output on OUTnLG. AMPnP and AMPnM disabled.

DAC OFF, PWM ON, op amp ON. AMPnP and AMPnM routed to LG op amp. PWM output on OUTnSM.

DAC OFF, PWM ON, op amp ON. LG op amp configured as unity-gain buffer. PWM output on OUTnSM.

DAC OFF, PWM ON, op amp ON. AMPnP and AMPnM routed to SM op amp. PWM output on OUTnLG.

010X000

010X001

011X000

011X001

000001X

000101X

0100010

0100011

0111010

DAC OFF, PWM ON, op amp ON. SM op amp configured as unity-gain buffer. PWM output on OUTnLG.

DAC ON, PWM OFF, op amp OFF. DAC output on OUTnSM. AMPnP and AMPnM disabled.

DAC ON, PWM OFF, op amp OFF. DAC output on OUTnLG. AMPnP and AMPnM disabled.

DAC ON, PWM OFF, op amp ON. DAC output on OUTnSM. AMPnP and AMPnM routed to LG op amp.

DAC ON, PWM OFF, op amp ON. DAC output on OUTnSM. LG op amp configured as unity-gain buffer.

DAC ON, PWM OFF, op amp ON. DAC output on OUTnLG. AMPnP and AMPnM routed to SM op amp.

DAC ON, PWM OFF, op amp ON. DAC output on OUTnLG. SM op amp configured as unity-gain buffer.

DAC ON, PWM ON, op amp OFF. DAC output on OUTnSM. PWM output on OUTnLG. AMPnP and AMPnM disabled.

DAC ON, PWM ON, op amp OFF. DAC output on OUTnLG. PWM output on OUTnSM. AMPnP and AMPnM disabled.

0111011

100X10X

101X10X

110X100

110X101

111X100

111X101

1X0111X

1X1011X

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

36 ______________________________________________________________________________________

Table 24. DOP1_Config (Address = 12h)

BIT NAME DESCRIPTION

15–5 — Unused.

4 ENPWM2 Enable pulse-width modulator 2: 1 = PWM2 active, 0 = PWM2 inactive.

3–1 — Unused.

0 ENDAC2 Enable digital-to-analog converter 2: 1 = DAC2 active, 0 = DAC2 inactive.

Table 25. DOP2_Control (Address = 14h)

NAME ADDRESS DESCRIPTION POR VALUE

DOP1_Data 10h DAC1/PWM1 input data. 0000

DOP1_Control 11h Initiate DAC1 and/or PWM1 conversions. 0000

DOP1_Config 12h DAC1/PWM1 output and DAC 1 reference selection. 0000

DOP2_Data 13h DAC2/PWM2 input data. 0000

DOP2_Control 14h Initiate DAC2 and/or PWM2 conversions. 0000

DOP2_Config 15h DAC2/PWM2 output and DAC 2 reference selection. 0000

OpAmp_Config 30h Settings for op amps in DOPn modules. 0000

Table 22. DOP Module Registers

BIT

NAME

DESCRIPTION

15–5 — Unused.

4 ENPWM1 Enable pulse-width modulator 1: 1 = PWM1 active, 0 = PWM1 inactive.

3–1 — Unused.

0 ENDAC1 Enable digital-to-analog converter 1: 1 = DAC1 active, 0 = DAC1 inactive.

Table 23. DOP1_Control (Address = 11h)

BIT NAME DESCRIPTION

15–9 — Unused.

8 SELPWM1 Select PWM1 output: 1 = OUT1LG, 0 = OUT1SM.

7–5 — Unused.

4 SELDAC1 Select DAC1 output: 1 = OUT1LG (large op-amp buffer), 0 = OUT1SM (small op-amp buffer).

3–1 — Unused.

0 SELREF1 Select voltage reference for DAC1: 0 = VDD, 1 = 2 x V

REF

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

______________________________________________________________________________________ 37

Table 26. DOP2_Config (Address = 15h)

BIT NAME DESCRIPTION

15–2 — Unused.

1 BUF2 1 = buffer mode of both large and small op amps of DOP2, 0 = normal.

0 BUF1 1 = buffer mode of both large and small op amps of DOP1, 0 = normal.

Table 27. OpAmp_Config (Address = 30h)

BIT NAME DESCRIPTION

15–9 — Unused.

8 SELPWM2 Select PWM2 output: 1 = OUT2LG, 0 = OUT2SM.

7–5 — Unused.

4 SELDAC2 Select DAC2 output: 1 = OUT2LG (large op-amp buffer), 0 = OUT2SM (small op-amp buffer).

3–1 — Unused.

0 SELREF2 Select voltage reference for DAC2: 0 = VDD, 1 = 2 x V

REF

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

38 ______________________________________________________________________________________

Table 31. TMR_Config (Address = 21h)

Table 29. GPIO2_Control (Address = 41h)

Note 14: A pulse or level must remain on GPIOn for four periods of f

OSC

to be latched into IN.

Note 15: The CLRn bit must be cleared to zero to reenable GPIO to value tracking. Note 16: The CLRn bit must be cleared to zero to reenable GPIO edge detection.

BIT NAME DESCRIPTION

15 TMDN

Timer done bit set by the counter; 1 = timeout value reached, 0 = timeout not reached. Read-only

bit.

14 TMEN

Timer enable bit; A 1 written to TMEN resets TMDN to zero and starts counter. TMEN is reset to

zero by the counter when timeout value is reached.

13–1 — Unused.

0 ENAHALT Enable CPU halt; 1 = CPU halted for duration of timer interval, 0 = CPU not halted.

Table 30. TMR_Control (Address = 20h)

BITS NAME DESCRIPTION

15–6 — Unused.

5 OUT1 OUT1 value is driven onto the GPIO1 pin when the output driver is enabled.

4 EN1 Enable the output driver; 1 = enabled, 0 = disabled, and OUT tri-stated.

3 IN1

When EDGE1 = 0: The value input on GPIO1 is clocked into this bit (Notes 14, 15). When EDGE1 = 1: An edge detection on GPIO1 causes a 1 to be clocked into this bit.

2 CLR1 Clear IN1 bit; 1 = clear IN1 to 0, 0 = IN1 retains its status (Note 16).

1 INV1

When EDGE1 = 0: Invert the logic value IN1; 1 = invert input, 0 = do not invert. When EDGE1 = 1: Select edge capture type; 1 = falling edge detect; 0 = rising edge detect.

0 EDGE1 Select level or edge detection at IN1; 1 = detect edges, 0 = detect and track logic levels.

Table 28. GPIO1_Control (Address = 40h)

BITS NAME DESCRIPTION

15–6 — Unused.

5 OUT2 OUT2 value is driven onto the GPIO2 pin when the output driver is enabled.

4 EN2 Enable the output driver; 1 = enabled, 0 = disabled, and OUT tri-stated.

3 IN2

2 CLR2 Clear IN2 bit; 1 = clear IN2 to 0, 0 = IN2 retains its status (Note 16).

1 INV2

0 EDGE2 Select level or edge detection at IN2; 1 = detect edges, 0 = detect and track logic levels.

When EDGE2 = 0: The value input on GPIO2 is clocked into this bit (Notes 14, 15). When EDGE2 = 1: An edge detection on GPIO2 causes a 1 to be clocked into this bit.

When EDGE2 = 0: Invert the logic value IN2; 1 = invert input, 0 = do not invert. When EDGE2 = 1: Select edge capture type; 1 = falling edge detect; 0 = rising edge detect.

BIT NAME DESCRIPTION

15–12 PS[3:0]

11–0 TO[11:0] Timeout value to use during the timing interval. TO[11] = MSB.

Prescaler setting to use during the timing interval. PS[3 ] = MSB.

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

______________________________________________________________________________________ 39

Table 32. Timer Prescaler Settings (PS[3:0])

BITS NAME DESCRIPTION

15–9 — Unused.

8 PWRA2D Power for ADC: 1 = power enabled, 0 = disabled.

7–6 — Unused.

5 PWRDAC2 Power for DAC2 in DOP2: 1 = power enabled, 0 = disabled.

4 PWRDAC1 Power for DAC1 in DOP1: 1 = power enabled, 0 = disabled.

3–2 — Unused.

1 PWROP2

Power for both large and small op amps in DOP2: 1 = power enabled, 0 = disabled, op-amp outputs are high impedance.*

0 PWROP1

Power for both LG and SM op amps in DOP1: 1 = power enabled, 0 = disabled, op-amp outputs are high impedance.*

Table 33. Power-On Control (Address = 31h)

*Whenever the DACs are enabled, the large and/or small op amps are automatically powered up and configured as buffers, regardless of the state of the PWROPn and BUFn bits.

PS[3:1] PS[0] PRESCALER N

000 0 1

001 0 2

010 0 4

011 0 8

100 0 16

101 0 32

110 0 64

111 0 128

000 1 3

001 1 6

010 1 12

011 1 24

100 1 48

101 1 96

110 1 192

111 1 384

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

40 ______________________________________________________________________________________

Table 35. Oscillator Trim Settings (Two’s Complement)

ENCKOUT

CKSEL

CKIO DESCRIPTION

X 0 Input

Internal oscillator is halted. An external clock must be supplied to CKIO pin.

High

Internal oscillator is running. CKIO output driver is disabled.

1 1 Output

Internal oscillator is running. CKIO output driver is enabled driving clock output.

Table 36. Internal Oscillator and CKIO Control

BITS

NAME DESCRIPTION

15–13

— Unused.

12–8

Oscillator trim setting. OSC[4] = MSB.

7–6 — Unused.

5–4 — Reserved 0.

3–1

— Unused.

Enable clock output: 1 = enable internal clock output on CKIO based on CKSEL inputs, 0 = disable.

Table 34. Oscillator Control (Address = 32h)

OSC[4:0]

ENCKOUT

OSC[4:0]

BINARY DECIMAL

01111 15 +43.7 01110 14 +42.2 01101 13 +40.1 01100 12 +38.4 01011 11 +35.2 01010 10 +32.8 01001 9 +28.8 01000 8 +25.5 00111 7 +17.7 00110 6 +14.1 00101 5 +10.0 00100 4 +8.4 00011 3 +5.4 00010 2 +3.6 00001 1 +1.4 00000 0 0 11111 -1 -3.4 11110 -2 -4.9 11101 -3 -7.2 11100 -4 -9.1 11011 -5 -12.6 11010 -6 -15.1 11001 -7 -18.5 11000 -8 -21.0 10111 -9 -25.3 10110 -10 -27.2 10101 -11 -29.9 10100 -12 -32.1 10011 -13 -35.8 10010 -14 -38.1 10001 -15 -40.9 10000 -16 -43.0

(PIN)

impedance

% CHANGE FROM NOMINAL

CLOCK FREQUENCY (%)

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

______________________________________________________________________________________ 41

Table 37. Module Registers Summary

Bit 15 Bit 14 Bit 13 Bit 12 Bit 11 Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

X X X X SE[3] SE[2] SE[1] SE[0] X X X X X CNVT1 CNVT2 CNVTT

MSB LSB

PGA1[4] PGA1[3] PGA1[2] PGA1[1] PGA1[0] CLK1[2] CLK1[1] CLK1[0] X RES1[2] RES1[1] RES1[0] CO1[3] CO1[2] C O1[ 1] CO1[0]

X X X X X X X X X BIAS1[2] BIAS1[1] BIAS1[0] X X REF1[1] REF1[0]

MSB LSB

PGA2[4] PGA2[3] PGA2[2] PGA2[1] PGA2[0] CLK2[2] CLK2[1] CLK2[0] X RES2[2] RES2[1] RES2[0] CO2[3] CO2[2] C O2[ 1] CO2[0]

X X X X X X X X X BIAS2[2] BIAS2[1] BIAS2[0] X X REF2[1] REF2[0]

MSB LSB

PGAT[4] PGAT[3] PGAT[2] PGAT[1] PGAT[0] CLKT[2] CLKT[1] CLKT[0] X REST[2] REST[1] REST[0] COT[3] COT[2] C OT[ 1] COT[0]

X X X X X X X X X BIAST[2] BIAST[1] BIAST[0] X X X X

MSB LSB

X X X X X X X X X X X ENPWM1 X X X ENDAC1

X X X X X X X SELPWM1 X X X SELDAC1 X X X SELREF1

MSB LSB

X X X X X X X X X X X ENPWM2 X X X ENDAC2

X X X X X X X SELPWM2 X X X SELDAC2 X X X SELREF2

TMDN TMEN X X X X X X X X X X X X X ENAHALT

Bit 15 Bit 14 Bit 13 Bit 12 Bit 11 Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0

PS[3] PS[2] PS[1] PS[0] TO[11] TO[10] TO[9] TO[8] TO[7] TO[6] TO[5] TO[4] TO[3] TO[2] TO[1] TO[1]

X X X X X X X X X X X X X X BUF1_LG BUF1_S

X X X X X X X PWRA2D X X PWRDAC2 PWRDAC1 X X PWROP2 PWROP1

X X X OSC[4] OSC[3] OSC[2] OSC[1] OSC[0] X X X X X X X ENCKOU

X X X X X X X X X X OUT1 EN1 IN1 CLR1 INV1 EDGE1

X X X X X X X X X X OUT2 EN2 IN2 CLR2 INV2 EDGE2

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

42 ______________________________________________________________________________________

Table 39. Command Register (CR) Decoding

Note 17: Reading and writing the CPU ports by the serial interface is allowed while the CPU is executing its program. In the case of

simultaneous access of the ports by both the CPU and the serial interface, the CPU has priority. Although this procedure is allowed, it is not recommended, as the serial interface may change values previously written by the CPU. If a “snapshot” of the ports and module register contents is required while the CPU is running, halt the CPU, read the contents of the ports and/or module registers, and restore the original port/module register values prior to starting the CPU again.

IRSA[3:0]

NIBBLE

DESCRIPTION

0000 DHR[3:0] Write IRSD[3:0] to DHR[3:0].

0001 DHR[7:4] Write IRSD[3:0] to DHR[7:4].

0010

Write IRSD[3:0] to DHR[11:8].

0011

Write IRSD[3:0] to DHR[15:12].

0100 PFAR[3:0] Write IRSD[3:0] to PFAR[3:0].

0101 PFAR[7:4] Write IRSD[3:0] to PFAR[7:4].

0110

Write IRSD[3:0] to PFAR[11:8].

0111

Write IRSD[3:0] to PFAR[15:12].

1000 CR[3:0] Write IRSD[3:0] to CR[3:0].

1001 IMR[3:0] Write IRSD[3:0] to IR[3:0].

1010–1110

— Unused.

Table 38. Internal Register Set Address (IRSA) Decoding

ADDRESSED

DHR[11:8]

DHR[15:12]

PFAR[11:8]

PFAR[15:12]

CR DESCRIPTION CPU HALTED

0000 Write 16-bit DHR contents into the CPU port specified by PFAR[3:0]. No (Note 17)

0001 Write 8-bit DHR[7:0] contents into FLASH memory location specified by PFAR[11:0]. Yes

0010 Read 16-bit CPU port specified by PFAR[3:0] into DHR. No (Note 17)

0011 Read 8-bit FLASH location specified by PFAR[11:0] into DHR[7:0]. Yes

0100 Read 16-bit CPU accumulator register (A) into DHR. Yes

0101

0110 Read 16-bit CPU PC to DHR. Yes

0111 Halt the CPU. No

1000 Start the CPU, i.e., clear the HALT CPU bit from the current PC location. Yes

1001 Single step the CPU. Only one CPU clock cycle is executed. Yes

1010 Reset the PC to zero. Yes

1011 Reset the modules, FLASH controller, and CPU registers D, E, F. Yes

1100 No operation. —

1101 Erase a 64-byte “page” of FLASH as specified by PFAR[11:6]. Yes

1110 Erase the entire FLASH partition (4kB, PS0, or 128 bytes, PS1). Yes

1111

Read 8-bit FLASH location specified by the CPU program counter (PC) (CPU instruction or data) to DHR[7:0].

Change from FLASH partition PS0 to FLASH partition PS1 (128 byte auxiliary). A subsequent halt CPU command resets the partition selection back to PS0.

Yes

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

______________________________________________________________________________________ 43

Table 40. Interface Mode Register (IMR) Decoding

Table 41. Instruction Set

IRSD DESCRIPTION

0000

0001

0010–1111 Unused.

OP CODE (hex) MNEMONIC OPERATION

Place the MAX1464 into a 4-wire serial interface (DI cannot be connected to DO).

Place the MAX1464 into a 3-wire serial interface (DI can be externally connected to DO).

0X LDX Load register X from program memory. Y 1 3 3

1X CLX Clear X-reg. Y 1 1 1

2X ANX A-reg = A-reg AND X-reg. N 2 1 1

3X ORX A-reg = A-reg OR X-reg. N 2 1 1

4X ADX A-reg = A-reg ADD X-reg. Y 2 1 1

5X STX X-reg = A-reg. Y 2 1 1

6X SLX Shift left X-reg. N 1 or 2 1 1

7X SRX Shift right X-reg propagating sign bit. Y 1 1 1

8X INX X-reg = X-reg + 1. Y 1 1 1

9X DEX X-reg = X-reg - 1. Y 1 1 1

AX NGX X-reg = NOT X-reg. N 1 1 1

BX BPX Branch positive I-reg by amount in X-reg. Y 2 1 1

CX BNX Branch not zero I-reg by amount in X-reg. Y 2 1 1

DX RDX A-reg = CPU port-X. Y 1 1 1

EX WRX CPU port-X = A-reg. Y 1 1 1

F3 MLT

A-reg | M-reg = M-reg multiplied by N-reg; register op code must be 3h.

TWO’S

COMP

Y 3 16 1

NO. OF

REGISTERS

INVOLVED

NO. OF

CYCLES

NO. OF BYTES

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

44 ______________________________________________________________________________________

Functional Diagram

Chip Information

TRANSISTOR COUNT: 70,921 (not including FLASH)

PROCESS: CMOS

SUBSTRATE CONNECTED TO: V

INP1

INM1

INP2

INM2

TEMP

SENSOR

DAC

PGAMUX

LG SM

PWM

ADC

LG SM

SCLKDIDO

SERIAL

INTERFACE

16-BIT CPU

DAC

DDF

SSF

CKIO

CKSEL

GPIO2

GPIO1

REF

PWM

4kB

FLASH

MEMORY

POWER-

RESET

DIGITAL

I/O

EXTERNAL

REFERENCE

INPUT

BANDGAP

REFERENCE

AMP1P

OUT1LG

AMP1M

OUT1SM

AMP2P

OUT2LG

AMP2M

OUT2SM

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

______________________________________________________________________________________ 45

Detailed Block Diagram

SCLK

BANDGAP

REFERENCE

EXTERNAL

REFERENCE

CPU REGISTERS

CPU PORTS

REF

INPUT

FLASH DATA

INSTRUCTION

ENCKOUT

32h OSC_CONTROL

CKSEL

÷ 2MCLK

4MHz

CKIO

OUT

OSCILLATOR

DDVSSVDDFVSSF

RESET

POWER-ON

(4kB)

FLASH MEMORY

ADDRESS

R0 POINTER (P)

R1 ACCUMULATOR (A)R2R3 MULTIPLICAND (N)

R4 MULTIPLIER (M)

R5 INDEX (I)R6R7R8R9RARBRCRDRERF

SERIAL INTERFACE

P0P1P2P1P3P4P5P6P7

CPU

PAPBPCPDPE

REF

4 x VBG2 x V

REF

00h ADC_Control

VBG

DAC

INP1

02h ADC_Config_1A

01h ADC_Data_1

INM1

ADC_Config_1B

04h ADC_Data_2

03h

ADC

PGA

INP2

INM2

06h ADC_Config_2B

05h ADC_Config_2A

08h ADC_Config_TA

07h ADC_Data_T

09h ADC_Config_TB

123456789

NO. SINGLE-ENDED

SENSOR

TEMPERATURE

OUTnSM

OUTnLG

VDDVSSDACnOUT VIA OUTnSM

ADC MODULE

INPn

DACnOUT VIA OUTnLG

INMn

MAX1464

Low-Power, Low-Noise Multichannel Sensor Signal Processor

46 ______________________________________________________________________________________

Detailed Block Diagram (continued)

GPIO1

MCLK

PRESCALER

TIMEOUT VALUE

12-BIT COUNTER

21hTMR_Config

20hTMR_Control

REF

2 x V

10h DOP1_Data

11h DOP1_Control

12h DOP1_Config

30h OpAmp_Config

EDGE OR LEVEL DETECT

40hGPION_Control

DOP1 MODULE

100kΩ

TRI-STATE

BUFFER

REF

2 x V

13h DOP2_Data

EDGE OR LEVEL DETECT

41hGPION_Control

15h DOP2_Config

14h DOP2_Control

GPIO2

30h OpAmp_Config

100kΩ

TRI-STATE

BUFFER

DOP2 MODULE

REF

DAC1

SW3

SW4

SW2

SW1

SM1

SW0

SW10

OUT1SM

AMP1M

AMP1P

PWM1

SW8

SW9

SW7

SW6

LG1

SW5

SW11

OUT1LG

REF

DAC2

SW3

SW4

SW2

SW1

SM2

SW0

SW10

OUT2SM

AMP2M

AMP2P

PWM2

SW8

SW9

SW7

SW6

LG2

SW5

SW11

OUT2LG

MAX1464

Low-Power, Low-Noise Multichannel

Sensor Signal Processor

Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.

Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 47

Package Information

(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages

SSOP EPS

MAX

0.078

0.008

0.015

0.008

0.212

0.311

0.037

8∞

MILLIMETERS

MAX

MIN

1.73 1.99

0.21

0.05

0.38

0.25

0.20

0.09

5.38

5.20

0.65 BSC

7.90

7.65

0.63

0.95

0∞

8∞

INCHES

MIN

0.239

0.278

0.317

0.397

MAX

0.249

0.289

0.328

0.407

MILLIMETERS

MAX

MIN

6.07

6.33

6.07

6.33

7.07

7.33

8.07

8.33

10.07

10.33

14L 16L

20L

24L

28L

INCHES

DIM

MIN

0.068

0.002

0.010

0.004

SEE VARIATIONS

0.205

0.0256 BSC

0.301

0.025

0∞

NOTES:

1. D&E DO NOT INCLUDE MOLD FLASH.

2. MOLD FLASH OR PROTRUSIONS NOT TO EXCEED .15 MM (.006").

3. CONTROLLING DIMENSION: MILLIMETERS.

4. MEETS JEDEC MO150.

5. LEADS TO BE COPLANAR WITHIN 0.10 MM.

PROPRIETARY INFORMATION

TITLE:

PACKAGE OUTLINE, SSOP, 5.3 MM

21-0056

REV.DOCUMENT CONTROL NO.APPROVAL

Rainbow Electronics MAX1464 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual