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_______________General Description

The MAX1246/MAX1247 12-bit data-acquisition systems

combine a 4-channel multiplexer, high-bandwidth

track/hold, and serial interface with high conversion

speed and low power consumption. The MAX1246 oper-

ates from a single +2.7V to +3.6V supply; the MAX1247

operates from a single +2.7V to +5.25V supply. 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 MAX1246/MAX1247

use either the internal clock or an external serial-interface

clock to perform successive-approximation analog-to-

digital conversions.

The MAX1246 has an internal 2.5V reference, while the

MAX1247 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 MAX1246/MAX1247, 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 MAX1246/MAX1247 are available in a 16-pin DIP and

a small QSOP that occupies the same board area as an

8-pin SO.

For 8-channel versions of these devices, see the

MAX146/MAX147 data sheet.

________________________Applications

Portable Data Logging

Data Acquisition

Medical Instruments

Battery-Powered Instruments

Pen Digitizers

Process Control

____________________________Features

o 4-Channel Single-Ended or 2-Channel

Differential Inputs

o Single-Supply Operation:

+2.7V to +3.6V (MAX1246)

+2.7V to +5.25V (MAX1247)

o Internal 2.5V Reference (MAX1246)

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 16-Pin QSOP Package (same area as 8-pin SO)

+2.7V, Low-Power, 4-Channel,

Serial 12-Bit ADCs in QSOP-16

________________________________________________________________

Maxim Integrated Products

1

I/O

SCK (SK)

MOSI (SO)

MISO (SI)

SHDN

SSTRB

DOUT

DIN

SCLK

CS

COM

AGND

DGND

CH3

4.7

µF

0.1

µF

CH0

0V TO

+2.5V

ANALOG

INPUTS

MAX1246

CPU

+3V

VREF

0.047

µF

REFADJ

__________Typical Operating Circuit

19-1071; Rev 1; 3/97

PART

†

MAX1246ACPE

MAX1246BCPE

MAX1246ACEE

0°C to +70°C

0°C to +70°C

0°C to +70°C

TEMP. RANGE

PIN-PACKAGE

16 Plastic DIP

16 Plastic DIP

16 QSOP

EVALUATION

KIT

AVAILABLE

______________Ordering Information

Ordering Information continued at end of data sheet.

†

Contact factory for availability of alternate surface-mount

packages.

MAX1246BCEE

0°C to +70°C

16 QSOP

INL

(LSB)

±1/2

±1

±1/2

±1

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

Pin Configuration appears at end of data sheet.