1

LTC2401/LTC2402

1-/2-Channel 24-Bit

µPower

No Latency

January 2000

s

Weight Scales

s

Direct Temperature Measurement

s

Gas Analyzers

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Strain-Gage Transducers

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Instrumentation

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Data Acquisition

s

Industrial Process Control

No Latency

∆Σ is a trademark of Linear Technology Corporation.

MICROWIRE is a trademark of National Semiconductor Corporation.

Pseudo Differential Bridge Digitizer

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

The LTC

5.5V micropower 24-bit analog-to-digital converters with

an integrated oscillator, 4ppm INL and 0.6ppm RMS

noise. These ultrasmall devices use delta-sigma technol-

ogy and a new digital filter architecture that settles in a

single cycle. This eliminates the latency found in conven-

tional

∆Σ converters and simplifies multiplexed applica-

tions.

Through a single pin, the LTC2401/LTC2402 can be

configured for better than 110dB rejection at 50Hz or

60Hz

±2%, or can be driven by an external oscillator for

a user defined rejection frequency in the range 1Hz to

120Hz. The internal oscillator requires no external fre-

quency setting components.

These converters accept an external reference voltage

set and overrange problems of preceding sensors or

signal conditioning circuits.

The LTC2401/LTC2402 communicate through a 2- or

3-wire digital interface that is compatible with SPI and

MICROWIRE

s

24-Bit ADC in Tiny MSOP-10 Package

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1- or 2-Channel Inputs

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Automatic Channel Selection (Ping-Pong) (LTC2402)

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Zero Scale and Full Scale Set for Reference

and Ground Sensing

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4ppm INL, No Missing Codes

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4ppm Full-Scale Error

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0.5ppm Offset

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0.6ppm Noise

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Internal Oscillator—No External Components Required

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110dB Min, 50Hz/60Hz Notch Filter

s

Single Conversion Settling Time for

Multiplexed Applications

s

s

Live Zero—Extended Input Range Accommodates

12.5% Overrange and Underrange

s

Single Supply 2.7V to 5.5V Operation

s

Low Supply Current (200

µA) and Auto Shutdown

ANALOG

INPUT RANGE

SCK

CH1

SDO

GND

CS

REFERENCE VOLTAGE

CH0

= INTERNAL OSC/50Hz REJECTION

= EXTERNAL CLOCK SOURCE

= INTERNAL OSC/60Hz REJECTION

3-WIRE

SPI INTERFACE

1

µF

110

9

8

7

6

2

3

4

5

2.7V TO 5.5V

LTC2402

24012 TA01

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

Final Electrical Specifications

Information furnished by Linear Technology Corporation is believed to be accurate and reliable.

However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-

tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

SCK

CH0

SDO

CS

CH1

GND

LTC2402

3-WIRE

SPI INTERFACE

INTERNAL OSCILLATOR

60Hz REJECTION

1

9

2.7V TO 5.5V

8

7

10

6

24012TA02

2

4

3

5