General Description

The MAX148/MAX149 10-bit data-acquisition systems

combine an 8-channel multiplexer, high-bandwidth

track/hold, and serial interface with high conversion

speed and low power consumption. They operate from a

single +2.7V to +5.25V supply, and sample to 133ksps.

Both devices’ analog inputs are software configurable for

unipolar/bipolar and single-ended/differential operation.

The 4-wire serial interface connects directly to SPI™/

QSPI™ and MICROWIRE™ devices without external

logic. A serial-strobe output allows direct connection to

TMS320-family digital signal processors. The MAX148/

MAX149 use either the internal clock or an external serial-

interface clock to perform successive-approximation

analog-to-digital conversions.

The MAX149 has an internal 2.5V reference, while the

MAX148 requires an external reference. Both parts have

a reference-buffer amplifier with a ±1.5% voltage-

adjustment range.

These devices provide a hard-wired SHDN pin and a

software-selectable power-down, and can be pro-

grammed to automatically shut down at the end of a con-

version. Accessing the serial interface automatically

powers up the MAX148/MAX149, and the quick turn-on

time allows them to be shut down between all conver-

sions. This technique can cut supply current to under

60µA at reduced sampling rates.

The MAX148/MAX149 are available in a 20-pin DIP and a

20-pin SSOP.

For 4-channel versions of these devices, see the

MAX1248/MAX1249 data sheet.

________________________Applications

Portable Data Logging Data Acquisition

Medical Instruments Battery-Powered Instruments

Pen Digitizers Process Control

____________________________Features

♦ 8-Channel Single-Ended or 4-Channel

Differential Inputs

♦ Single-Supply Operation: +2.7V to +5.25V

♦ Internal 2.5V Reference (MAX149)

♦ Low Power: 1.2mA (133ksps, 3V supply)

54µA (1ksps, 3V supply)

1µA (power-down mode)

♦ SPI/QSPI/MICROWIRE/TMS320-Compatible

4-Wire Serial Interface

♦ Software-Configurable Unipolar or Bipolar Inputs

♦ 20-Pin DIP/SSOP Packages

MAX148/MAX149

+2.7V to +5.25V, Low-Power, 8-Channel,

Serial 10-Bit ADCs

________________________________________________________________

Maxim Integrated Products

I/O

SCK (SK)

MOSI (SO)

MISO (SI)

SHDN

SSTRB

DOUT

DIN

SCLK

COM

AGND

DGND

CH7

4.7µF

0.1µF

CH0

0V TO

+2.5V

ANALOG

INPUTS

MAX149

CPU

+3V

VREF

0.01µF

REFADJ

__________Typical Operating Circuit

19-0464; Rev 2; 5/98

PART

†

MAX148ACPP

MAX148BCPP

MAX148ACAP 0°C to +70°C

0°C to +70°C

TEMP. RANGE PIN-PACKAGE

20 Plastic DIP

20 SSOP

EVALUATION KIT

AVAILABLE

Ordering Information

Ordering Information continued at end of data sheet.

†

Contact factory for availability of alternate surface-mount

packages.

MAX148BCAP 0°C to +70°C 20 SSOP

INL

(LSB)

±1/2

±1

±1/2

±1

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

Pin Configuration appears at end of data sheet.

For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800.

For small orders, phone 408-737-7600 ext. 3468.

MAX148/MAX149

+2.7V to +5.25V, Low-Power, 8-Channel,

Serial 10-Bit ADCs

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

= +2.7V to +5.25V; COM = 0V; f

SCLK

= 2.0MHz; external clock (50% duty cycle); 15 clocks/conversion cycle (133ksps);

MAX149—4.7µF capacitor at VREF pin; MAX148—external reference, VREF = 2.500V applied to VREF pin; T

= T

MIN

to T

MAX

; unless

otherwise noted.)

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.

to AGND, DGND................................................. -0.3V to 6V

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

CH0–CH7, COM to AGND, DGND ............ -0.3V to (V

+ 0.3V)

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

+ 0.3V)

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

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

+ 0.3V)

Digital Output Sink Current .................................................25mA

Continuous Power Dissipation (T

= +70°C)

Plastic DIP (derate 11.11mW/°C above +70°C) ......... 889mW

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

CERDIP (derate 11.11mW/°C above +70°C).............. 889mW

Operating Temperature Ranges

MAX148_C_P/MAX149_C_P.............................. 0°C to +70°C

MAX148_E_P/MAX149_E_P............................ -40°C to +85°C

MAX148_MJP/MAX149_MJP ........................ -55°C to +125°C

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

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

µs1.5t

ACQ

Differential Nonlinearity

Track/Hold Acquisition Time

ns30Aperture Delay

µs

35 65

CONV

Conversion Time (Note 5)

5.5 7.5

MHz1.0Full-Power Bandwidth

MHz2.25Small-Signal Bandwidth

dB-75Channel-to-Channel Crosstalk

dB70SFDRSpurious-Free Dynamic Range

dB-70THDTotal Harmonic Distortion

dB66SINADSignal-to-Noise + Distortion Ratio

LSB±0.05

Channel-to-Channel Offset

Matching

ppm/°C±0.25Gain Temperature Coefficient

±0.5

<50

Bits10Resolution

Gain Error (Note 3)

±1

Aperture Jitter

Offset Error

LSB

±1.0

INLRelative Accuracy (Note 2)

LSB±1DNL

±0.15 ±1

LSB

±0.15 ±2

UNITSMIN TYP MAXSYMBOLPARAMETER

External clock = 2MHz, 12 clocks/conversion

Internal clock, SHDN = V

Internal clock, SHDN = FLOAT

MAX14_A

-3dB rolloff

65kHz, 2.500V

p-p

(Note 4)

Up to the 5th harmonic

MAX14_A

MAX14_B

No missing codes over temperature

MAX14_A

MAX14_B

CONDITIONS

LSB

±2MAX14_B

DC ACCURACY (Note 1)

DYNAMIC SPECIFICATIONS (10kHz sine-wave input, 0V to 2.500Vp-p, 133ksps, 2.0MHz external clock, bipolar input mode)

CONVERSION RATE

MAX148/MAX149

+2.7V to +5.25V, Low-Power, 8-Channel,

Serial 10-Bit ADCs

_______________________________________________________________________________________ 3

Multiplexer Leakage Current

µA0.01 10Shutdown VREF Input Current

kΩ18 25VREF Input Resistance

µA100 150VREF Input Current

1.0

50mV

VREF Input Voltage Range

(Note 9)

pF16Input Capacitance

1.8

MHz

0.225

Internal Clock Frequency

µA±0.01 ±1

UNITSMIN TYP MAXSYMBOLPARAMETER

SHDN = FLOAT

VREF = 2.500V

SHDN = V

On/off leakage current, V

CH_

= 0V or V

CONDITIONS

ELECTRICAL CHARACTERISTICS (continued)

= +2.7V to +5.25V; COM = 0V; f

SCLK

= 2.0MHz; external clock (50% duty cycle); 15 clocks/conversion cycle (133ksps);

MAX149—4.7µF capacitor at VREF pin; MAX148—external reference, VREF = 2.500V applied to VREF pin; T

= T

MIN

to T

MAX

; unless

otherwise noted.)

V2.470 2.500 2.530VREF Output Voltage T

= +25°C (Note 7)

mA30VREF Short-Circuit Current

±30MAX149

mV0.35Load Regulation (Note 8) 0mA to 0.2mA output load

0Internal compensation mode

µF

4.7

Capacitive Bypass at VREF

External compensation mode

µF0.01Capacitive Bypass at REFADJ

%±1.5REFADJ Adjustment Range

0.5

REFADJ Buffer-Disable Threshold

µF

Capacitive Bypass at VREF

Internal compensation mode

2.00

V/V

2.06

Reference Buffer Gain

4.7

MAX148

MAX149

External compensation mode

±10

µA

±50

REFADJ Input Current

MAX148

MAX149

ppm/°CVREF Temperature Coefficient

0 to VREF

±VREF / 2

Input Voltage Range, Single-

Ended and Differential (Note 6)

Unipolar, COM = 0V

Bipolar, COM = VREF / 2

0.1 2.0

MHz

0 2.0

External Clock Frequency

Data transfer only

CONVERSION RATE (continued)

ANALOG/COM INPUTS

INTERNAL REFERENCE (MAX149 only, reference buffer enabled)

EXTERNAL REFERENCE AT VREF (Buffer disabled)

EXTERNAL REFERENCE AT REFADJ

Part #	MAX149AEAP
Description	+2.7V TO +5.25V LOW-POWER 8-CHANNEL SERIAL 10-BIT ADCS - B
Category	CONVERTER
Availability	In Stock
Qty	63

Qty	Price
1 - 13	$12.41688
14 - 26	$9.87707
27 - 39	$9.31266
40 - 52	$8.65419
53 +	$7.71352

MAX149AEAP

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