_______________________________________________________________ Maxim Integrated Products 1

For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,

or visit Maxim’s website at www.maxim-ic.com.

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

Serial 10-Bit ADCs

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 SPIK/

QSPIK and MICROWIREK 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 seri-

al-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 Q1.5% 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

conversion. 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

60FA 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

S

8-Channel Single-Ended or 4-Channel Differential

Inputs

S

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

S

Internal 2.5V Reference (MAX149)

S

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

54µA (1ksps, 3V Supply)

1µA (Power-Down Mode)

S

SPI/QSPI/MICROWIRE/TMS320-Compatible 4-Wire

Serial Interface

S

Software-Configurable Unipolar or Bipolar Inputs

S

20-Pin DIP/SSOP Packages

19-0464; Rev 4; 1/10

Typical Operating Circuit

Ordering Information

Ordering Information continued at end of data sheet.

†Contact factory for availability of alternate surface-mount

package. Specify lead-free by placing + by the part number

when ordering.

*Contact factory for availability of CERDIP package, and for

processing to MIL-STD-883B. Not available in lead-free.

Pin Configuration appears at end of data sheet.

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

PART†

TEMP RANGE

PIN-

PACKAGE

INL

(LSB)

MAX148ACPP

0°C to +70°C

20PlasticDIP

±1/2

MAX148BCPP

0°C to +70°C

20PlasticDIP

±1

MAX148ACAP

0°C to +70°C

20 SSOP

±1/2

MAX148BCAP

0°C to +70°C

20 SSOP

±1

CPU

DGND

AGND

COM

SCLK

DIN

DOUT

SSTRB

READJ

VREF

CH7

CH0

+3V

0.1FF

4.7FF

O TO

+2.5V

ANALOG

INPUTS

0.01FF

I/O

SCK (SK)

MOSI (SO)

MISO (SI)

MAX149

CS

SHDN