Maxim MAX1295BEEI, MAX1295BCEI, MAX1295AEEI, MAX1295ACEI, MAX1297BEEG Datasheet

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General Description

The MAX1295/MAX1297 low-power, 12-bit analog-to­digital converters (ADCs) feature a successive-approxi­mation ADC, automatic power-down, fast wake-up
(2µs), on-chip clock, +2.5V internal reference, and
high-speed 12-bit parallel interface. They operate with
a single +2.7V to +3.6V analog supply.

Power consumption is only 5.4mW at the maximum
sampling rate of 265ksps. Two software-selectable
power-down modes enable the MAX1295/MAX1297 to
be shut down between conversions; accessing the par­allel interface returns them to normal operation.
Powering down between conversions can reduce sup­ply current below 10µA at lower sampling rates.

Both devices offer software-configurable analog inputs
for unipolar/bipolar and single-ended/pseudo-differen­tial operation. In single-ended mode, the MAX1295 has
six input channels and the MAX1297 has two (three
input channels and one input channel, respectively,
when in pseudo-differential mode).

Excellent dynamic performance and low power combined
with ease of use and small package size make these con­verters ideal for battery-powered and data-acquisition
applications or for other circuits with demanding power­consumption and space requirements. The MAX1295 is
offered in a 28-pin QSOP package, while the MAX1297
comes in a 24-pin QSOP. For pin-compatible +5V, 12-bit
versions, refer to the MAX1294/MAX1296 data sheet.

Applications

Industrial Control Systems Data Logging
Energy Management Patient Monitoring
Data-Acquisition Systems Touchscreens

Features

♦ 12-Bit Resolution, ±0.5LSB Linearity
♦ +3V Single-Supply Operation
♦ Internal +2.5V Reference
♦ Software-Configurable Analog Input Multiplexer

6-Channel Single-Ended/
3-Channel Pseudo-Differential (MAX1295)

2-Channel Single-Ended/
1-Channel Pseudo-Differential (MAX1297)

♦ Software-Configurable Unipolar/Bipolar

Analog Inputs

♦ Low Current

1.8mA (265ksps)

1.0mA (100ksps)
400µA (10ksps)
2µA (shutdown)

♦ Internal 3MHz Full-Power Bandwidth Track/Hold
♦ Parallel 12-Bit Interface
♦ Small Footprint

28-Pin QSOP (MAX1295)
24-Pin QSOP (MAX1297)

MAX1295/MAX1297

265ksps, +3V, 6-/2-Channel, 12-Bit ADCs

with +2.5V Reference and Parallel Interface

________________________________________________________________

Maxim Integrated Products

1

19-1530; Rev 0; 9/99

EVALUATION KIT

AVAILABLE

28 QSOP ±10°C to +70°CMAX1295BCEI

INL

(LSB)

±0.528 QSOP

PIN-PACKAGETEMP. RANGE

0°C to +70°C

MAX1295ACEI

PART

Ordering Information

Pin Configurations

Typical Operating Circuits appear at end of data sheet.

Pin Configurations continued at end of data sheet.

28 QSOP ±0.5-40°C to +85°CMAX1295AEEI
28 QSOP ±1-40°C to +85°CMAX1295BEEI

24 QSOP ±0.5-40°C to +85°CMAX1297AEEG
24 QSOP ±1-40°C to +85°CMAX1297BEEG

24 QSOP ±10°C to +70°CMAX1297BCEG

±0.524 QSOP0°C to +70°C

MAX1297ACEG

TOP VIEW

1

D9

2

D8

3

D7

4

D6

5

D5

D4

D3

D2

D1

D0

INT

RD

WR

CLK

MAX1295

6

7

8

9

10

11

12

13

14

QSOP

28

27

26

25

24

23

22

21

20

19

18

17

16

15

D10

D11

V

DD

REF

REFADJ

GND

COM

CH0

CH1

CH2

CH3

CH4

CH5

CS

MAX1295/MAX1297

265ksps, +3V, 6-/2-Channel, 12-Bit ADCs
with +2.5V Reference and Parallel Interface

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VDD= +2.7V to +3.6V, COM = GND, REFADJ = VDD, V

REF

= +2.5V, 4.7µF capacitor at REF pin, f

CLK

= 4.8MHz (50% duty cycle),

T

A

= 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.

VDDto GND..............................................................-0.3V to +6V

CH0–CH5, COM to GND............................-0.3V to (VDD+ 0.3V)

REF, REFADJ to GND.................................-0.3V to (VDD+ 0.3V)

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

Digital Outputs (D0–D11, INT) to GND.......-0.3V to (V

DD

+ 0.3V)

Continuous Power Dissipation (T

A

= +70°C)

24-Pin QSOP (derate 9.5mW/°C above +70°C)..........762mW

28-Pin QSOP (derate 8.00mW/°C above +70°C)........667mW

Operating Temperature Ranges

MAX1295_C_ _ /MAX1297_C__ ........................0°C to +70°C

MAX1295_E_ _ /MAX1297_E__ ......................-40°C to +85°C

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

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

External acquisition or external clock mode

Internal acquisition/internal clock mode

MAX129_A

External acquisition/internal clock mode

External clock mode

-3dB rolloff

SINAD > 68dB

fIN= 125kHz (Note 4)

f

IN1

= 49kHz, f

IN2

= 52kHz

MAX129_B
No missing codes over temperature

CONDITIONS

ns50Aperture Delay

ns625t

ACQ

Track/Hold Acquisition Time

3.2 3.6 4.1

2.5 3.0 3.5

µs

3.3

t

CONV

Conversion Time (Note 5)

MHz

3

Full-Power Bandwidth

kHz

250

Full-Linear Bandwidth

dB

-78

Channel-to-Channel Crosstalk

dB

76

IMDIntermodulation Distortion

dB

80

SFDRSpurious-Free Dynamic Range

dB

Total Harmonic Distortion
(including 5th-order harmonic)

-78

THD

±0.5

INLRelative Accuracy (Note 2)

Bits

12

RESResolution

dB

67 70

SINADSignal-to-Noise Plus Distortion

LSB

±0.2

Channel-to-Channel Offset
Matching

ppm/°C

±2.0

Gain Temperature Coefficient

LSB

±1

LSB

±1

DNLDifferential Nonlinearity

LSB

±4

Offset Error

LSB

±4

Gain Error (Note 3)

UNITSMIN TYP MAXSYMBOLPARAMETER

Internal acquisition/internal clock mode

External acquisition or external clock mode

<200

ps

<50

Aperture Jitter

MHz0.1 4.8f

CLK

External Clock Frequency

%30 70Duty Cycle

DC ACCURACY (Note 1)

DYNAMIC SPECIFICATIONS (f

IN(sine-wave)

= 50kHz, VIN= 2.5Vp-p, 265ksps, external f

CLK

= 4.8MHz, bipolar input mode)

CONVERSION RATE

MAX1295/MAX1297

265ksps, +3V, 6-/2-Channel, 12-Bit ADCs

with +2.5V Reference and Parallel Interface

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VDD= +2.7V to +3.6V, COM = GND, REFADJ = VDD, V

REF

= +2.5V, 4.7µF capacitor at REF pin, f

CLK

= 4.8MHz (50% duty cycle),

T

A

= T

MIN

to T

MAX

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

CONDITIONS UNITSMIN TYP MAXSYMBOLPARAMETER

0 to 0.5mA output load

To power down the internal reference

For small adjustments

On/off-leakage-current, VIN= 0 or V

DD

Unipolar, V

COM

= 0

Bipolar, V

COM

= V

REF

/2

V

1.0

V

DD

+

50mV

V

REF

REF Input Voltage Range

µF

4.7 10

Capacitive Bypass at REF

µF

0.01 1

Capacitive Bypass at REFADJ

mV/mA

0.2 0.5

Load Regulation (Note 7)

V

VDD- 1

REFADJ High Threshold

mV

±100

REFADJ Input Range

mA

15

REF Short-Circuit Current

V

2.49 2.5 2.51

REF Output Voltage

pF

12

C

IN

Input Capacitance

µA

±0.01 ±1

Multiplexer Leakage Current

V

0 V

REF

Analog Input Voltage Range
Single-Ended and Differential
(Note 6)

-V

REF

/2 +V

REF

/2

V

IN

CS = V

DD

I

SOURCE

= 1mA

I

SINK

= 1.6mA

VIN= 0 or V

DD

V

REF

= 2.5V, f

SAMPLE

= 265ksps

µA

±0.1 ±1

I

LEAKAGE

Three-State Leakage Current

V

VDD- 0.5

V

OH

Output Voltage High

V

0.4

V

OL

Output Voltage Low

pF

15

C

IN

Input Capacitance

µA

±0.1 ±1

I

IN

Input Leakage Current

mV

200

V

HYS

Input Hysteresis

V

0.8

V

IL

Input Voltage Low

V

2.0

V

IH

Input Voltage High

µA

200 300

I

REF

REF Input Current

CS = V

DD

V

2.7 3.6

V

DD

Analog Supply Voltage

pF

15

C

OUT

Three-State Output Capacitance

Internal reference

2.3 2.6

ppm/°C

±20

TC

REF

REF Temperature Coefficient

Shutdown mode

2

External reference

1.9 2.3

0.9 1.2

Positive Supply Current

Shutdown mode

210

µA

Power-Supply Rejection PSR VDD= 2.7V to 3.6V, full-scale input

±0.4 ±0.7

mV

I

DD

0.5 0.8

mA

Operating mode,
f

SAMPLE

= 265ksps

Internal reference
External reference

Standby mode

CONVERSION RATE (continued)ANALOG INPUTS

INTERNAL REFERENCE

EXTERNAL REFERENCE AT REF

DIGITAL INPUTS AND OUTPUTS

POWER REQUIREMENTS

MAX1295/MAX1297

265ksps, +3V, 6-/2-Channel, 12-Bit ADCs
with +2.5V Reference and Parallel Interface

4 _______________________________________________________________________________________

t

TR

20 70

nsC

LOAD

= 20pF, Figure 1

RD Rise to Output Disable

WR to CLK Fall Setup Time

t

CWS

40

ns

nsCLK Pulse Width High

nsCLK Period

t

CH

40

RD Fall to Output Data Valid

t

DO

20 70

ns

RD Fall to INT High Delay

t

INT1

100

ns

CS Fall to Output Data Valid

t

DO2

110

ns

C

LOAD

= 20pF, Figure 1

C

LOAD

= 20pF, Figure 1

C

LOAD

= 20pF, Figure 1

t

CP

208

CLK Pulse Width Low t

CL

40

ns

Data Valid to WR Rise Time

t

DS

40

ns

WR Rise to Data Valid Hold Time

t

DH

0

ns

CLK Fall to WR Hold Time

t

CWH

40

ns

CS to CLK or WR Setup Time

t

CSWS

60

ns

CLK or WR to CS Hold Time

t

CSWH

0

ns

CS Pulse Width

t

CS

100

ns

WR Pulse Width (Note 8)

t

WR

60

ns

t

TC

20 100

nsC

LOAD

= 20pF, Figure 1

PARAMETER SYMBOL MIN TYP MAX UNITSCONDITIONS

CS Rise to Output Disable

Note 1: Tested at VDD= +3V, COM = GND, unipolar single-ended input mode.
Note 2: Relative accuracy is the deviation of the analog value at any code from its theoretical value after offset and gain errors have

been removed.

Note 3: Offset nulled.
Note 4: On channel is grounded; sine wave applied to off channels.
Note 5: Conversion time is defined as the number of clock cycles times the clock period; clock has a 50% duty cycle.
Note 6: Input voltage range referenced to negative input. The absolute range for the analog inputs is from GND to V

DD

.

Note 7: External load should not change during conversion for specified accuracy.
Note 8: When bit 5 is set low for internal acquisition, WR must not return low until after the first falling clock edge of the conversion.

TIMING CHARACTERISTICS

(VDD= +2.7V to +3.6V, COM = GND, REFADJ = VDD, V

REF

= +2.5V, 4.7µF capacitor at REF pin, f

CLK

= 4.8MHz (50% duty cycle),

T

A

= T

MIN

to T

MAX

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

Figure 1. Load Circuits for Enable/Disable Times

V

DD

3k

DOUT

6k

GND GND

a) HIGH-Z TO VOH AND VOL TO V

C
20pF

LOAD

OH

DOUT

b) HIGH-Z TO VOL AND VOH TO V

C

LOAD

20pF

OL

MAX1295/MAX1297

265ksps, +3V, 6-/2-Channel, 12-Bit ADCs

with +2.5V Reference and Parallel Interface

_______________________________________________________________________________________

5

Typical Operating Characteristics

(VDD= +3V, V

REF

= +2.500V, f

CLK

= 4.8MHz, CL= 20pF, TA = +25°C, unless otherwise noted.)

0.1

1k

100k

101100

10k

1M

SUPPLY CURRENT

vs. SAMPLE FREQUENCY

MAX1295/7-02A

f

SAMPLE

(Hz)

I

DD

(µA)

0

10

100

1000

10,000

WITH EXTERNAL REFERENCE

WITH INTERNAL REFERENCE

INTEGRAL NONLINEARITY vs.

DIGITAL OUTPUT CODE

0.5

0.4

0.3

0.2

0.1

0

INL (LSB)

-0.1

-0.2

-0.3

-0.4

-0.5
0 20001000 3000 4000 5000

DIGITAL OUTPUT CODE

SUPPLY CURRENT vs. SUPPLY VOLTAGE

2.10

2.05

2.00

(mA)

1.95

DD

I

1.90

1.85

R

L

CODE = 101010100000

= ∞

MAX1295/7-01

MAX1295/7 toc03

DIFFERENTIAL NONLINEARITY vs.

DIGITAL OUTPUT CODE

0.5

0.4

0.3

0.2

0.1

0

DNL (LSB)

-0.1

-0.2

-0.3

-0.4

-0.5
0 20001000 3000 4000 5000

DIGITAL OUTPUT CODE

SUPPLY CURRENT vs. TEMPERATURE

2.2

2.1

2.0

(mA)

1.9

DD

I

1.8

1.7

R

= ∞

L

CODE = 101010100000

MAX1295/7-02

MAX1295/7 toc04

STANDBY CURRENT vs. SUPPLY VOLTAGE

930

920

(µA)

910

DD

900

STANDBY I

890

MAX1295/7 toc05

MAX1295/7 toc07

880

2.7 3.33.0 3.6
V

(V)

DD

POWER-DOWN CURRENT

vs. TEMPERATURE

1.2

1.1

(µA)

DD

1.0

POWER-DOWN I

0.9

0.8

-40 35-15 10 60 85

TEMPERATURE (°C)

MAX1295/7 toc08

1.80

2.7 3.0 3.3 3.6
VDD (V)

1.6

-40 10-15 35 60 85

TEMPERATURE (°C)

POWER-DOWN CURRENT

STANDBY CURRENT vs. TEMPERATURE

MAX1295/7 toc06

1.50

1.25

(µA)

DD

1.00

POWER-DOWN I

0.75

0.50

2.7 3.0 3.3 3.6

930

920

(µA)

910

DD

900

STANDBY I

890

880

-40 10-15 35 8560

TEMPERATURE (°C)

vs. SUPPLY VOLTAGE

VDD (V)

MAX1295/MAX1297

265ksps, +3V, 6-/2-Channel, 12-Bit ADCs
with +2.5V Reference and Parallel Interface

6 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VDD= +3V, V

REF

= +2.500V, f

CLK

= 4.8MHz, CL= 20pF, TA = +25°C, unless otherwise noted.)

MAX1295/7-10

V

REF

(mA)

85

2.48

2.49

2.51

2.50

2.52

2.53

INTERNAL REFERENCE VOLTAGE

vs. TEMPERATURE

TEMPERATURE (°C)

-40 60

35

10

-15

-2.5

-2.0

-1.0

-1.5

-0.5

0

OFFSET ERROR vs. SUPPLY VOLTAGE

MAX1295/7 toc11

VDD (V)

OFFSET ERROR (LSB)

2.7 3.33.0 3.6

-2.5

-1.5

-2.0

-0.5

-1.0

0

0.5

-40 10-15 35 60 85

OFFSET ERROR vs. TEMPERATURE

MAX1295/7 toc12

TEMPERATURE (°C)

OFFSET ERROR (LSB)

-3.0

-1.0

-2.0

0

1.0

2.7 3.33.0 3.6

GAIN ERROR vs. SUPPLY VOLTAGE

MAX1295/7 toc13

VDD (V)

GAIN ERROR (LSB)

-2.0

-1.5

-0.5

-1.0

0

0.5

GAIN ERROR vs. TEMPERATURE

MAX1295/7 toc14

TEMPERATURE (°C)

GAIN ERROR (LSB)

-40 10-15 35 60 85

MAX1295/7-09

V

REF

(V)

3.6

2.48

2.49

2.51

2.50

2.52

2.53

INTERNAL REFERENCE VOLTAGE vs.

SUPPLY VOLTAGE

V

DD

(V)

2.7

3.33.0

-140

-120

-100

-80

-60

-40

-20

0

20

0 200 400 600 800 1000

FFT PLOT

MAX1295/7-15

FREQUENCY (kHz)

AMPLITUDE (dB)

V

DD

= 3V

f

IN

= 50kHz

f

SAMPLE

= 250ksps