Rainbow Electronics MAX1145 User Manual

General Description

The MAX1144/MAX1145 are 150ksps, 14-bit ADCs.
These serially interfaced ADCs connect directly to
SPI™, QSPI™, and MICROWIRE™ devices without
external logic. They combine an input scaling network,
internal track/hold, clock, and three general-purpose
digital output pins (for external multiplexer or PGA con­trol) in a 20-pin SSOP package. The excellent dynamic
performance (THD ≥ 90dB), high speed (150ksps in
bipolar mode), and low power (8.0mA) of these ADCs
make them ideal for applications such as industrial
process control, instrumentation, and medical applica­tions.

The MAX1144 accepts input signals of 0 to +6V (unipo­lar) or ±6V (bipolar), while the MAX1145 accepts input
signals of 0 to +2.048V (unipolar) or ±2.048V (bipolar).
Operating from a single 3.135V to 3.465V analog digital
supply, powerdown modes reduce current consump­tion to 0.15mA at 10ksps and further reduce supply
current to less than 20µA slower data rates.

A serial strobe output (SSTRB) allows direct connection
to the TMS320 family digital-signal processors. The
MAX1144/MAX1145 user can select either the internal
clock or an external serial-interface clock for the ADC to
perform analog-to-digital conversions.

The MAX1144/MAX1145 feature internal calibration cir­cuitry to correct linearity and offset errors. On-demand
calibration allows the user to optimize performance.
Three user-programmable logic outputs are provided
for the control of an 8-channel mux or PGA.

The MAX1144/MAX1145 are available in a 20-pin SSOP
package and are fully specified over the -40°C to
+85°C temperature range.

Applications

Industrial Process Control

Industrial I/O Modules

Data-Acquisition Systems

Medical Instruments

Portable and Battery-Powered Equipment

Features

♦ 150ksps (Bipolar) and 125ksps (Unipolar)

Sampling ADC

♦ 14 Bits, No Missing Codes
♦ 1LSB INL Guaranteed
♦ -100dB THD
♦ 3.3V Single-Supply Operation
♦ Low-Power Operation

5mA typ (Unipolar Mode)

♦ 1.2µA Shutdown Mode
♦ Software-Configurable Unipolar and Bipolar Input

Ranges

0 to +6V and ±6V (MAX1144)
0 to +2.048V and ±2.048V (MAX1145)

♦ Internal or External Clock
♦ SPI/QSPI/MICROWIRE TMS320-Compatible Serial

Interface

♦ Three User-Programmable Logic Outputs
♦ Small 20-Pin SSOP Package

MAX1144/MAX1145

14-Bit ADCs, 150ksps, 3.3V Single Supply

________________________________________________________________ Maxim Integrated Products 1

Pin Configuration

Ordering Information

19-2465; Rev 0; 4/02

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.

Ordering Information continued at end of data sheet.

Functional Diagram and Typical Application Circuit appear
at end of data sheet.

SPI and QSPI are trademarks of Motorola, Inc.

MICROWIRE is a trademark of National Semiconductor, Corp.

PART

MAX1144ACAP 0°C to +70°C 20 SSOP ±1

MAX1144BCAP 0°C to +70°C 20 SSOP ±2

MAX1144AEAP -40°C to +85°C 20 SSOP ±1
MAX1144BEAP -40°C to +85°C 20 SSOP ±2

TEMP

RANGE

PIN­PACKAGE

INL

(LSB)

TOP VIEW

REF

AV

AGND

DGND

SHDN

1

2

DD

3

4

DD

MAX1144

5

MAX1145

6

P2

7

8

9

PO

10

SSOP

20

AIN

19

AGND

18

CREF

17

CSAV

DIN

16

DV

15

DD

14

DGND

SCLKP1

13

12

RST

11

DOUTSSTRB

MAX1144/MAX1145

14-Bit ADCs, 150ksps, 3.3V Single Supply

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(AVDD= DVDD= 3.3V ±5%, f

SCLK

= 3.6MHz, external clock (50% duty cycle), 24 clocks/conversion (150ksps), bipolar input, V

REF

=

2.048V, C

REF

= 4.7µF, C

CREF

= 1µF, TA= T

MIN

to T

MAX

, unless otherwise noted. Typical values are at TA= +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.

AVDDto AGND, DVDDto DGND ..............................-0.3V to +6V

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

AIN to AGND ....................................................................±16.5V

CREF, REF to AGND................................-0.3V to (AVDD+ 0.3V)

Digital Inputs to DGND.............................................-0.3V to +6V

Digital Outputs to DGND .........................-0.3V to (DV

DD

+ 0.3V)

Continuous Power Dissipation (T

A

= +70°C)

20-Pin SSOP (derate 8.00mW/°C above +70°C) .........640mW

Operating Temperature Ranges

MAX114_ _CAP...................................................0°C to +70°C

MAX114_ _EAP................................................-40°C to +85°C

Storage Temperature Range .............................-60°C to +150°C

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

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

DC ACCURACY (Note 1)

Resolution 14 Bits

Relative Accuracy INL Bipolar mode (Note 2)

No Missing Codes 14 Bits

Differential Nonlinearity DNL Bipolar mode

Transition Noise 0.47

Offset Error

Gain Error (Note 3)

Offset Drift (Bipolar and Unipolar) Excluding reference drift ±1 ppm/°C

Gain Drift (Bipolar and Unipolar) Excluding reference drift ±4 ppm/°C

D YNA M IC SPEC IF IC A T IO N S ( 5 k Hz SINE- WAVE IN PU T, 1 50 k s ps , 3 .6M H Z C L O CK , BIPO LA R IN PU T M O DE. M A X1 14 4 , 1 2 V
4 .09 6 V

Signal-to-Noise Plus Distortion
(SINAD)

Signal-to-Noise Ratio
(SNR)

Total Harmonic Distortion
(THD)

Spurious-Free-Dynamic Range
(SFDR)

ANALOG INPUT

Input Range

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

.)

P-P

Unipolar ±4

Bipolar ±6

Unipolar ±0.2

Bipolar ±0.3

f

= 5kHz 78 82

IN

= 75kHz 81

f

IN

f

= 5kHz 78 82

IN

f

= 75kHz 81

IN

f

= 5kHz -100 -90

IN

= 75kHz -94

f

IN

f

= 5kHz 92 105

IN

f

= 75kHz 98

IN

MAX1144

MAX1145

MAX114_A ±1

MAX114_B ±2

MAX114_A -1 +1

MAX114_B -1.00 +1.75

. M A X1 14 5 ,

P-P

Unipolar 0 +6

Bipolar -6 +6

Unipolar 0 +2.048

Bipolar -2.048 +2.048

LSB

LSB

LSB

mV

%FSR

dB

dB

dB

dB

RMS

V

MAX1144/MAX1145

14-Bit ADCs, 150ksps, 3.3V Single Supply

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(AVDD= DVDD= 3.3V ±5%, f

SCLK

= 3.6MHz, external clock (50% duty cycle), 24 clocks/conversion (150ksps), bipolar input, V

REF

=

2.048V, C

REF

= 4.7µF, C

CREF

= 1µF, TA= T

MIN

to T

MAX

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

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Input Impedance

Input Capacitance 32 pF

CONVERSION RATE

Internal Clock Frequency 3 MHz

Aperture Delay t

Aperture Jitter t

MODE 1 (24 EXTERNAL CLOCK CYCLES PER CONVERSION)

External Clock Frequency f

Sample Rate

Conversion Time (Note 4)

MODE 2 (INTERNAL CLOCK)

External Clock Frequency
(Data Transfer Only)

Conversion Time (SSTRB low pulse width) 5.3 7 µs

Acquisition Time (Note 5)

MODE 3 (32 EXTERNAL CLOCK CYCLES PER CONVERSION)

External Clock Frequency f

Sample Rate

f

SCLK

t

CONV+ACQ

= 24 / f

AD

AJ

SCLK

f

=

S

MAX1144

MAX1145

Unipolar 7.5 10.5

Bipolar 5.9 8.4

Unipolar 100 1000

Bipolar 3.4 5.3

Unipolar 0.1 3.0

Bipolar 0.1 3.6

Unipolar 4.17 125

/ 24

Bipolar 4.17 150

Unipolar 8 240

SCLK

Bipolar 6.7 240

10 ns

50 ps

Unipolar 1.67

Bipolar 1.39

SCLK

f

SCLK

f

S

Unipolar or bipolar 0.1 3.6 MHz

=

Unipolar or bipolar 3.125 112 ksps

/ 32

MHz

ksps

4 MHz

kΩ

µs

µs

t

Conversion Time (Note 4)

CONV+ACQ

= 32 / f

SCLK

Unipolar or bipolar 8.89 320 µs

EXTERNAL REFERENCE

Input Range (Notes 6, 7) 1.9 2.048 2.2 V

V

= 2.048V, f

REF

V

= 2.048V, f

REF

In power-down, f

= 3.6MHz 110

SCLK

= 0 100Input Current

SCLK

= 0 0.1

SCLK

DIGITAL INPUTS

Input High Voltage V

Input Low Voltage V

Input Leakage I

IH

IL

IN

VIN = 0 or DV

DD

2.4 V

0.8 V

-1 +1 µA

µA

MAX1144/MAX1145

14-Bit ADCs, 150ksps, 3.3V Single Supply

4 _______________________________________________________________________________________

ELECTRICAL CHARACTERISTICS (continued)

(AVDD= DVDD= 3.3V ±5%, f

SCLK

= 3.6MHz, external clock (50% duty cycle), 24 clocks/conversion (150ksps), bipolar input, V

REF

=

2.048V, C

REF

= 4.7µF, C

CREF

= 1µF, TA= T

MIN

to T

MAX

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

TIMING CHARACTERISTICS (Figures 5 and 6)

(AVDD= DVDD= 3.3V ±5%, TA= T

MIN

to T

MAX

, unless otherwise noted.)

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Input Hysteresis V

Input Capacitance C

DIGITAL OUTPUTS

Output High Voltage V

Output Low Voltage V

Three-State Leakage Current I
Three-State Output Capacitance CS = DV

POWER SUPPLIES

Analog Supply AV

Digital Supply DV

Analog Supply Current I

Digital Supply Current I

Power-Supply Rejection Ratio
(Note 8)

HYST

IN

OH

OL

L

DD

DD

DV

-

I

SOURCE

I

SINK

I

SINK

CS = DV

= 0.5mA

= 5mA 0.4

= 16mA 0.8

DD

DD

DD

0.5

-10 +10 µA

3.135 3.3 3.465 V

3.135 3.3 3.465 V

Unipolar mode 3.9 8

ANALOG

Bipolar mode 7 11
SHDN = 0, or software power-down mode 0.1 10 µA

DIGITAL

PSRR AV

Unipolar or bipolar mode 1 2 mA
SHDN = 0, or software power-down mode 1.1 10 µA

= DVDD = 3.135V to 3.465V 65 dB

DD

0.2 V

10 pF

10 pF

mA

V

V

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

DIN to SCLK Setup t

DIN to SCLK Hold t

SCLK to DOUT Valid t

CS Fall to DOUT Enable t
CS Rise to DOUT Disable t
CS to SCLK Rise Setup t
CS to SCLK Rise Hold t

SCLK High Pulse Width t

SCLK Low Pulse Width t

SCLK Fall to SSTRB t

CS Fall to SSTRB Enable t
CS Rise to SSTRB Disable t

SSTRB Rise to SCLK Rise t
RST Pulse Width t

DS

DH

DO

DV

TR

CSS

CSH

CH

CL

SSTRB

SDV

STR

SCK

RS

C

LOAD

C

LOAD

C

LOAD

C

LOAD

C

LOAD

Internal clock mode 0 ns

50 ns

= 50pF 80 ns

= 50pF 80 ns

100 ns

0ns

120 ns

120 ns

= 50pF 80 ns

= 50pF, external clock mode 80 ns

= 50pF, external clock mode 80 ns

278 70 ns

0ns

70 ns

MAX1144/MAX1145

14-Bit ADCs, 150ksps, 3.3V Single Supply

_______________________________________________________________________________________ 5

TIMING CHARACTERISTICS (Figures 5 and 6) (continued)

(AVDD= DVDD= 3.3V ±5%, TA= T

MIN

to T

MAX

, unless otherwise noted.)

Note 1: Tested at AV

DD

= DV

DD

= 3.3V, bipolar input mode.

Note 2: Relative accuracy is the deviation of the analog value at any code from its theoretical value after the gain error and offset

error have been nullified.

Note 3: Offset nullified.
Note 4: Conversion time is defined as the number of clock cycles multiplied by the clock period; clock has 50% duty cycle. Includes

the acquisition time.

Note 5: Acquisition time is 5 clock cycles in short acquisition mode and 13 clock cycles in long acquisition mode.
Note 6: Performance is limited by the converter’s noise floor, typically 300µV

P-P

.

Note 7: When an external reference has a different voltage than the specified typical value, the full scale of the ADC scales propor-

tionally.

Note 8: Defined as the change in positive full scale caused by a ±5% variation in the nominal supply voltage.

Typical Operating Characteristics

(MAX1144/MAX1145, AVDD= DVDD= 3.3V, f

SCLK

= 3.6MHz, external clock (50% duty cycle), 24 clocks/conversion (150ksps),

bipolar input, REF = 2.048V, 4.7µF on REF, 1µF on CREF, TA= +25°C, unless otherwise noted.)

INTEGRAL NONLINEARITY

vs. DIGITAL OUTPUT CODE

MAX1144/45 toc01

DIGITAL OUTPUT CODE

INTEGRAL NONLINEARITY (LSB)

13649

119438531

102373413

5119

6825

1707

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1.0

-1.0
1

15355

DIFFERENTIAL NONLINEARITY

vs. DIGITAL OUTPUT CODE

MAX1144/45 toc02

DIGITAL OUTPUT CODE

DIFFERENTIAL NONLINEARITY (LSB)

13649

119438531

102373413

5119

6825

1707

-0.8

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

1.0

-1.0
1

15355

TOTAL SUPPLY CURRENT

vs. TEMPERATURE

MAX1144/45 toc03

TEMPERATURE (°C)

TOTAL SUPPLY CURRENT (mA)

806020 400-20

8.1

8.2

8.3

8.4

8.5

8.6

8.7

8.8

8.9

9.0

8.0

-40

A: AVDD, DVDD = 3.135V
B: AV

DD

, DVDD = 3.3V

C: AV

DD

, DVDD = 3.465V

C

B

A

MAX1144/MAX1145

6 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(MAX1144/MAX1145, AVDD= DVDD= 3.3V, f

SCLK

= 3.6MHz, external clock (50% duty cycle), 24 clocks/conversion (150ksps),

bipolar input, REF = 2.048V, 4.7µF on REF, 1µF on CREF, T

A

= +25°C, unless otherwise noted.)

OFFSET VOLTAGE

vs. TEMPERATURE

MAX1144/45 toc04

TEMPERATURE (°C)

OFFSET ERROR (mV)

806020 400-20

-2.5

-2.0

-1.0

-0.5

0

-40

A: AVDD, DVDD = 3.135V
B: AV

DD

, DVDD = 3.3V

C: AV

DD

, DVDD = 3.465V

C

B

A

-1.5

GAIN ERROR

vs. TEMPERATURE

MAX1144/45 toc05

TEMPERATURE (°C)

GAIN ERROR (% FULL SCALE)

806020 400-20

0.01

0

0.03

0.02

0.04

0.05

0.06

-40

A: AVDD, DVDD = 3.135V
B: AV

DD

, DVDD = 3.3V

C: AV

DD

, DVDD = 3.465V

C

B

A

TOTAL SUPPLY CURRENT vs.

CONVERSION RATE (USING SHUTDOWN)

MAX1144/45 toc06

CONVERSION RATE (ksps)

TOTAL SUPPLY CURRENT (mA)

1000100101

0.01

100

10

1

0.1

0

FFT PLOT

MAX1144/45 toc07

FREQUENCY (kHz)

AMPLITUDE (dB)

605040302010

-100

-80

-60

-40

-20

0

-120
070

f

SAMPLE

= 150kHz

f

IN

= 5kHz

SINAD PLOT

MAX1144/45 toc08

FREQUENCY (kHz)

AMPLITUDE (dB)

101

10

20

30

40

50

60

70

80

90

100

0

0.1 100

f

SAMPLE

= 150kHz

SFDR PLOT

MAX1144/45 toc09

FREQUENCY (kHz)

AMPLITUDE (dB)

101

10

20

30

40

50

60

70

80

90

100

110

120

0

0.1 100

f

SAMPLE

= 150kHz

THD PLOT

MAX1144/45 toc10

FREQUENCY (kHz)

AMPLITUDE (dB)

101

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

0

-110

0.1 100

f

SAMPLE

= 150kHz

14-Bit ADCs, 150ksps, 3.3V Single Supply