MAXIM MAX1270, MAX1271 Technical data

General Description

The MAX1270/MAX1271 are multirange, 12-bit dataacquisition systems (DAS) that require only a single +5V supply for operation, yet accept signals at their analog inputs that can span above the power-supply rail and below ground. These systems provide eight analog input channels that are independently software programmable for a variety of ranges: ±10V, ±5V, 0 to +10V, 0 to +5V for the MAX1270; ±V

REF

, ±V

REF

/2, 0 to

REF

, 0 to V

REF

/2 for the MAX1271. This range switching increases the effective dynamic range to 14 bits and provides the flexibility to interface 4–20mA, ±12V, and ±15V powered sensors directly to a single +5V system. In addition, these converters are fault protected to ±16.5V; a fault condition on any channel will not affect the conversion result of the selected channel. Other features include a 5MHz bandwidth track/hold, softwareselectable internal/external clock, 110ksps throughput rate, and internal 4.096V or external reference operation.

The MAX1270/MAX1271 serial interface directly connects to SPI™/QSPI™ and MICROWIRE™ devices without external logic.

A hardware shutdown input (SHDN) and two softwareprogrammable power-down modes, standby (STBYPD) or full power-down (FULLPD), are provided for low-current shutdown between conversions. In standby mode, the reference buffer remains active, eliminating startup delays.

The MAX1270/MAX1271 are available in 24-pin narrow PDIP or space-saving 28-pin SSOP packages.

Applications

Features

♦ 12-Bit Resolution, 0.5 LSB Linearity

♦ +5V Single-Supply Operation

♦ SPI/QSPI and MICROWIRE-Compatible

3-Wire Interface

♦ Four Software-Selectable Input Ranges

MAX1270: 0 to +10V, 0 to +5V, ±10V, ±5V MAX1271: 0 to V

REF

, 0 to V

REF

/2, ±V

REF

±V

REF

♦ Eight Analog Input Channels

♦ 110ksps Sampling Rate

♦ ±16.5V Overvoltage-Tolerant Input Multiplexer

♦ Internal 4.096V or External Reference

♦ Two Power-Down Modes

♦ Internal or External Clock

♦ 24-Pin Narrow PDIP or 28-Pin SSOP Packages

MAX1270/MAX1271

Multirange, +5V, 8-Channel,

Serial 12-Bit ADCs

________________________________________________________________ Maxim Integrated Products 1

CH0 CH1 CH2 CH3 CH4 CH5 CH6 CH7

DGND



4.7µF

0.1µF

0.01µF

SHDN

MAX1270 MAX1271

+5V

ANALOG

INPUTS

SCLK

DIN

DOUT

SSTRB

I/O SCK MOSI MISO

REF REFADJ

AGND

MC68HCXX

Typical Operating Circuit

PART

TEMP RANGE

PIN-PACKAGE

INL

(LSB)

MAX1270ACNG

±0.5

MAX1270BCNG

±1

MAX1270ACAI

28 SSOP

±0.5

MAX1270BCAI

28 SSOP ±1

Ordering Information

19-4782; Rev 2; 9/04

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.

Pin Configurations appear at end of data sheet.

SPI and QSPI are trademarks of Motorola, Inc. MICROWIRE is a trademark of National Semiconductor Corp.

Ordering Information continued at end of data sheet.

EVALUATION KIT

AVAILABLE

Industrial Control Systems Data-Acquisition Systems Battery-Powered Instruments

Automatic Testing Robotics Medical Instruments

0°C to +70°C 24 Narrow PDIP 0°C to +70°C 24 Narrow PDIP 0°C to +70°C 0°C to +70°C

MAX1270/MAX1271

Multirange, +5V, 8-Channel, Serial 12-Bit ADCs

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VDD= +5.0V ±5%; unipolar/bipolar range; external reference mode, V

REF

= +4.096V; 4.7µF at REF; external clock; f

CLK

= 2.0MHz,

50% duty cycle (MAX127_B); f

CLK

= 1.8MHz, 50% duty cycle (MAX127_A); 18 clock/conversion cycle, TA= T

MIN

to T

MAX

, unless

otherwise noted. Typical values are T

= +25°C.)

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 AGND............................................................-0.3V to +6V

AGND to DGND.....................................................-0.3V to +0.3V

CH0–CH7 to AGND ......................................................... ±16.5V

REF, REFADJ to AGND ..............................-0.3V to (V

+ 0.3V)

SSTRB, DOUT to DGND.............................-0.3V to (V

+ 0.3V)

SHDN, CS, DIN, SCLK to DGND..............................-0.3V to +6V

Max Current into Any Pin ....................................................50mA

Continuous Power Dissipation (T

= +70°C) 24-Pin Narrow DIP (derate 13.33mW/°C above +70°C)..1067mW

28-Pin SSOP (derate 9.52mW/°C above +70°C) ..........762mW

Operating Temperature Ranges

MAX127_C_ _......................................................0°C to +70°C

MAX127_E_ _......................................................-40°C to +85°C

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

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

PARAMETER

CONDITIONS

UNITS

ACCURACY (Note 1)

Resolution 12 Bits

MAX127_A

Integral Nonlinearity INL

MAX127_B

LSB

Differential Nonlinearity DNL No missing codes over temperature ±1 LSB

MAX127_A ±3

Unipolar

MAX127_B ±5 MAX127_A ±5

Offset Error

Bipolar

MAX127_B ±10

LSB

Unipolar

Channel-to-Channel Offset Error Matching

Bipolar

LSB

MAX127_A ±7

Unipolar

MAX127_B ±10 MAX127_A ±7

Gain Error (Note 2)

Bipolar

MAX127_B ±10

LSB

Unipolar, external reference ±3

Gain Error Temperature Coefficient (Note 2)

Bipolar, external reference ±5

ppm/°C

DYNAMIC SPECIFICATIONS (10kHz sine-wave input, ±10V

P-P

(MAX1270), or ±4.096V

P-P

(MAX1271), f

SAMPLE

= 110ksps

(MAX127_B), f

SAMPLE

= 100ksps (MAX127_A))

SINAD 70 dB Total Harmonic Distortion THD Up to the 5th harmonic -87 -78 dB Spurious-Free Dynamic Range SFDR 80 dB

50kHz (Note 3) -86

Channel-to-Channel Crosstalk

DC, V

= ±16.5V -96

Aperture Delay External clock mode 15 ns

External clock mode

Aperture Jitter

Internal clock mode 10 ns

SYMBOL

MIN TYP MAX

±0.5 ±1.0

Signal-to-Noise + Distortion Ratio

±0.1 ±0.3

<50

MAX1270/MAX1271

Multirange, +5V, 8-Channel,

Serial 12-Bit ADCs

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VDD= +5.0V ±5%; unipolar/bipolar range; external reference mode, V

REF

= +4.096V; 4.7µF at REF; external clock; f

CLK

= 2.0MHz,

50% duty cycle (MAX127_B); f

CLK

= 1.8MHz, 50% duty cycle (MAX127_A); 18 clock/conversion cycle, TA= T

MIN

to T

MAX

, unless

otherwise noted. Typical values are T

= +25°C.)

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

ANALOG INPUT

MAX127_A, f

CLK

= 1.8MHz 3.3

Track/Hold Acquisition Time t

ACQ

MAX127_B, f

CLK

= 2.0MHz 3.0

µs

±10V or ±V

REF

range

±5V or ±V

REF

range

2.5

0 to 10V or 0 to V

REF

range

2.5

Small-Signal Bandwidth -3dB rolloff

0 to 5V or 0 to V

REF

/2 range

MHz

RNG = 1 0 10

MAX1270

RNG = 0 0 5 RNG = 1 0

Unipolar (BIP =

0), Table 3 MAX1271

RNG = 0 0 RNG = 1 -10

MAX1270

RNG = 0 -5 +5 RNG = 1

Input Voltage Range (Table 3)

Bipolar (BIP =

1), Table 3 MAX1271

RNG = 0

REF

0 to 10V range

-10

MAX1270

0 to 5V range

-10

Unipolar

MAX1271 -10 0.1

±10V range

MAX1270

±V

REF

range

Input Current I

Bipolar

MAX1271

±V

REF

range

µA

Unipolar 21

Dynamic Resistance

Bipolar 16

kΩ

Input Capacitance (Note 4) 40 pF

∆VIN/∆I

±5V range -600 +360

1.25

-V

REF

-V

REF

-1200 +720

-1200 +10

-600 +10

REF

+10

+720

+360

+10

REF

MAX1270/MAX1271

Multirange, +5V, 8-Channel, Serial 12-Bit ADCs

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(VDD= +5.0V ±5%; unipolar/bipolar range; external reference mode, V

REF

= +4.096V; 4.7µF at REF; external clock; f

CLK

= 2.0MHz,

50% duty cycle (MAX127_B); f

CLK

= 1.8MHz, 50% duty cycle (MAX127_A); 18 clock/conversion cycle, TA= T

MIN

to T

MAX

, unless

otherwise noted. Typical values are T

= +25°C.)

PARAMETER

CONDITIONS

UNITS

INTERNAL REFERENCE

REF Output Voltage V

REF

TA = +25°C

MAX1270_C/MAX1271_C

REF Output Tempco

MAX1270_E/MAX1271_E

ppm/°C

Output Short-Circuit Current 30 mA Load Regulation 0 to 0.5mA output current (Note 5) 10 mV Capacitive Bypass at REF 4.7 µF Capacitive Bypass at REFADJ

µF

REFADJ Output Voltage

REFADJ Adjustment Range Figure 1

Buffer Voltage Gain

V/V

REFERENCE INPUT (Reference buffer disabled, reference input applied to REF)

Input Voltage Range

Normal or STBYPD 400

Input Current V

REF

= 4.18V

FULLPD 1

µA

Normal or STBYPD 10 kΩ

Input Resistance V

REF

= 4.18V

FULLPD

MΩ

REFADJ Threshold for Buffer Disable

VDD -

0.5

POWER REQUIREMENT

Supply Voltage V

Bipolar range 18

Normal

Unipolar range 6 10

STBYPD power-down mode (Note 6)

850

Supply Current I

FULLPD power-down mode

220

µA

External reference = 4.096V

Power-Supply Rejection Ratio (Note 7)

PSRR

Internal reference

LSB

TIMING

MAX127_A 0.1 1.8

External Clock Frequency Range

SCLK

MAX127_B 0.1 2.0

MHz

MAX127_A 3.3

External clock mode (Note 8)

MAX127_B 3.0

Acquisition Phase

Internal clock mode, Figure 9 3 5

µs

SYMBOL

TC V

REF

MIN TYP MAX

4.076 4.096 4.116

0.01

2.465 2.500 2.535

2.40 4.18

4.18

4.75 5.25

±15 ±30

±1.5

1.638

700 120

±0.1 ±0.5 ±0.5

MAX1270/MAX1271

Multirange, +5V, 8-Channel,

Serial 12-Bit ADCs

_______________________________________________________________________________________ 5

ELECTRICAL CHARACTERISTICS (continued)

(VDD= +5.0V ±5%; unipolar/bipolar range; external reference mode, V

REF

= +4.096V; 4.7µF at REF; external clock; f

CLK

= 2.0MHz,

50% duty cycle (MAX127_B); f

CLK

= 1.8MHz, 50% duty cycle (MAX127_A); 18 clock/conversion cycle, TA= T

MIN

to T

MAX

, unless

otherwise noted. Typical values are T

= +25°C.)

PARAMETER

CONDITIONS

UNITS

MAX127_A 6.6

External clock mode (Note 8)

MAX127_B 6.0

Conversion Time t

CONV

Internal clock mode, Figure 9 6 7.7 11

µs

MAX127_A 100

External clock mode

MAX127_B 110

Throughput Rate

Internal clock mode 43

ksps

Bandgap Reference Startup Time

Power-up (Note 9)

µs

REF

= 4.7µF 8

Reference Buffer Settling Time

To 0.1mV, REF bypass capacitor fully discharged

REF

= 33µF 60

DIGITAL INPUTS (DIN, SCLK, CS, and SHDN)

Input High Threshold Voltage V

2.4 V

Input Low Threshold Voltage V

0.8 V

Input Hysteresis V

HYS

0.2 V

Input Leakage Current I

VIN = 0 to V

-10

µA

Input Capacitance C

(Note 4) 15 pF

DIGITAL OUTPUTS (DOUT, SSTRB)

SINK

= 5mA 0.4

Output Voltage Low V

SINK

= 16mA 0.4

Output Voltage High V

SOURCE

= 0.5mA

DD -

0.5

Tri-State Leakage Current I

CS = V

-10

µA

Tri-State Output Capacitance C

OUT

CS = V

(Note 4) 15 pF

SYMBOL

MIN TYP MAX

200

+10

MAX1270/MAX1271

Multirange, +5V, 8-Channel, Serial 12-Bit ADCs

6 _______________________________________________________________________________________

Note 1: Accuracy specifications tested at VDD= +5.0V. Performance at power-supply tolerance limit is guaranteed by power-supply

rejection test.

Note 2: External reference: V

REF

= 4.096V, offset error nulled. Ideal last-code transition = FS - 3/2 LSB.

Note 3: Ground “on” channel; sine wave applied to all “off” channels. V

= ±5V (MAX1270), VIN= ±4V (MAX1271).

Note 4: Guaranteed by design, not production tested. Note 5: Use static external loads during conversion for specified accuracy. Note 6: Tested using internal reference. Note 7: PSRR measured at full scale. Tested for the ±10V (MAX1270) and ±4.096V (MAX1271) input ranges. Note 8: Acquisition phase and conversion time are dependent on the clock period; clock has 50% duty cycle (Figure 6). Note 9: Not production tested. Provided for design guidance only.

TIMING CHARACTERISTICS

(VDD= +4.75V to +5.25V; unipolar/bipolar range; external reference mode, V

REF

= +4.096V; 4.7µF at REF; external clock; f

CLK

2.0MHz (MAX127_B); f

CLK

= 1.8MHz (MAX127_A); TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are TA= +25°C.)

(Figures 2, 5, 7, 10)

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

DIN to SCLK Setup t

DIN to SCLK Hold t

0ns

SCLK Fall to Output Data Valid t

CS Fall to Output Enable t

LOAD

= 100pF

CS Rise to Output Disable t

LOAD

= 100pF

CS to SCLK Rise Setup t

CSS

CS to SCLK Rise Hold t

CSH

0ns

SCLK Pulse-Width High t

SCLK Pulse-Width Low t

SCLK Fall to SSTRB t

SSTRB

LOAD

= 100pF

CS to SSTRB Output Enable t

SDV

LOAD

= 100pF, external clock mode only

CS to SSTRB Output Disable t

STR

LOAD

= 100pF, external clock mode only

SSTRB Rise to SCLK Rise t

SCK

Internal clock mode only (Note 4) 0 ns

100

200 200

170 120 100

200 200 200

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