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

o 8-Channel Single-Ended or 4-Channel

Differential Inputs

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

o Internal 2.5V Reference (MAX149)

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

54µA (1ksps, 3V supply)

1µA (power-down mode)

o SPI/QSPI/MICROWIRE/TMS320-Compatible

4-Wire Serial Interface

o Software-Configurable Unipolar or Bipolar Inputs

o 20-Pin DIP/SSOP Packages

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

Serial 10-Bit ADCs

________________________________________________________________

Maxim Integrated Products

1

I/O

SCK (SK)

MOSI (SO)

MISO (SI)

SHDN

SSTRB

DOUT

DIN

SCLK

CS

COM

AGND

DGND

CH7

4.7

µF

0.1

µF

CH0

0V TO

+2.5V

ANALOG

INPUTS

MAX149

CPU

+3V

VREF

0.01

µF

REFADJ

__________Typical Operating Circuit

19-0464; Rev 2; 5/98

PART

†

MAX148ACPP

MAX148BCPP

MAX148ACAP

0°C to +70°C

0°C to +70°C

0°C to +70°C

TEMP. RANGE

PIN-PACKAGE

20 Plastic DIP

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.