1

LTC1291

1291fa

The LTC

a serial I/O successive approximation A/D converter. It

uses LTCMOS

form a 12-bit unipolar A/D conversion. The input multi-

plexer can be configured for either single-ended or differ-

ential inputs. An on-chip sample-and-hold is included on

the “+” input. When the LTC1291 is idle, it can be powered

down in applications where low power consumption is

desired. An external reference is not required because the

All these features are packaged in an 8-pin DIP.

The serial I/O is designed to communicate without external

hardware to most MPU serial ports and all MPU parallel

I/O ports allowing data to be transmitted over three or four

wires. Given the accuracy, ease of use and small package

size, this device is well suited for digitizing analog signals

in remote applications where minimum number of inter-

connects, small physical size, and low power consump-

tion are important.

LTCMOS

, LTC and LT are registered trademarks of Linear Technology Corporation.

FEATURES

DESCRIPTIO

KEY SPECIFICATIO S

TYPICAL APPLICATIO

Single Chip 12-Bit

Data Acquisition System

s

Built-In Sample-and-Hold

s

Single Supply 5V Operation

s

Power Shutdown

s

Direct 3- or 4-Wire Interface to Most MPU Serial

Ports and All MPU Parallel Ports

s

Two-Channel Analog Multiplexer

s

Analog Inputs Common Mode to Supply Rails

s

8-Pin DIP Package

s

Resolution: 12 Bits

s

Fast Conversion Time: 12

µs Max Over Temp.

s

Low Supply Current:

6.0mA (Typ) Active Mode

10

µA (Max) Shutdown Mode

5V

CH0

GND

CLK

CS

LTC1291

2-CHANNEL

MUX*

CH1

0.1

µF

22

µF

TANTALUM

*FOR OVERVOLTAGE PROTECTION, LIMIT THE INPUT CURRENT TO 15mA

CONVERSION RESULTS ARE NOT VALID WHEN THE SELECTED CHANNEL OR

SECTION ON OVERVOLTAGE PROTECTION IN THE APPLICATIONS INFORMATION.

1291 TA01

DO

MC68HC11

SCK

MISO

MOSI

CODE

0

–0.5

–0.4

–0.2

–0.1

0

0.5

0.2

1024

2048 2560

1291 TA02

–0.3

0.3

0.4

0.1

512

1536

3072 3584 4096

Channel-to-Channel

INL Matching

2-Channel 12-Bit Data Acquisition System