1

LTC2420

20-Bit

µPower

No Latency

January 2000

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Weight Scales

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Direct Temperature Measurement

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Gas Analyzers

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Strain-Gage Transducers

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Instrumentation

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Data Acquisition

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Industrial Process Control

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4-Digit DVMs

No Latency

∆Σ is a trademark of Linear Technology Corporation.

MICROWIRE is a trademark of National Semiconductor Corporation.

Total Unadjusted Error vs Output Code

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

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20-Bit ADC in SO-8 Package

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8ppm INL, No Missing Codes at 20 Bits

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4ppm Full-Scale Error

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0.5ppm Offset

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1.2ppm Noise

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Digital Filter Settles in a Single Cycle. Each

Conversion Is Accurate, Even After an Input Step.

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Internal Oscillator—No External Components

Required

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Fast Mode: 16-Bit Noise, 12 Bits TUE at 100sps

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110dB Min, 50Hz/60Hz Notch Filter

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Live Zero—Extended Input Range Accommodates

12.5% Overrange and Underrange

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Single Supply 2.7V to 5.5V Operation

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Low Supply Current (200

µA) and Auto Shutdown

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Pin Compatible with 24-Bit LTC2400

The LTC

an integrated oscillator, 8ppm INL and 1.2ppm RMS

noise that operates from 2.7V to 5.5V. It uses delta-sigma

technology and provides a digital filter that settles in a

single cycle for multiplexed applications. Through a single

pin, the LTC2420 can be configured for better than 110dB

rejection at 50Hz or 60Hz

±2%, or it can be driven by an

external oscillator for a user-defined rejection frequency

in the range 1Hz to 800Hz. The internal oscillator requires

no external frequency setting components.

The converter accepts any external reference voltage from

resolves the offset and overrange problems of preceding

sensors or signal conditioning circuits.

The LTC2420 communicates through a flexible 3-wire

digital interface which is compatible with SPI and

MICROWIRE

SCK

SDO

1

2

3

4

8

7

6

5

GND

CS

REFERENCE

VOLTAGE

ANALOG

INPUT RANGE

= INTERNAL OSC/50Hz REJECTION

= EXTERNAL CLOCK SOURCE

= INTERNAL OSC/60Hz REJECTION

3-WIRE

SPI INTERFACE

1

µF

2.7V TO 5.5V

LTC2420

2420 TA01

OUTPUT CODE (DECIMAL)

0

524,288

1,048,575

2420 TA02

10

8

6

4

2

0

–2

–4

–6

–8

–10

DESCRIPTIO

FEATURES

APPLICATIO S

TYPICAL APPLICATIO

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.

Final Electrical Specifications