20-Bit No Latency ∆Σ ADCs with Differential Input and Differential Reference

The LTC2430/LTC2431 are 2.7V to 5.5V micropower 20-bit differential ∆Σ analog-to-digital converters with an integrated oscillator, 3ppm INL and 0.56ppm RMS noise. They use delta-sigma technology and provide single cycle settling time for multiplexed applications. Through a single pin, the LTC2430/LTC2431 can be configured for better than 110dB differential mode rejection at 50Hz or 60Hz ±2%, or they can be driven by an external oscillator for a user-defined rejection frequency. The internal oscillator requires no external frequency setting components.

The converters accept any external differential reference voltage from 0.1V to VCC for flexible ratiometric and remote sensing measurement configurations. The fullscale differential input range is from –0.5VREF to 0.5VREF. The reference common mode voltage, VREFCM, and the input common mode voltage, VINCM, may be independently set anywhere within GND to VCC. The DC common mode input rejection is better than 120dB.

The LTC2430/LTC2431 communicate through a flexible 3-wire digital interface that is compatible with SPI and MICROWIRE™ protocols.

Applications

* Direct Sensor Digitizer

* Weight Scales

* Direct Temperature Measurement

* Gas Analyzers

* Strain Gauge Transducers

* Instrumentation

* Data Acquisition

* Industrial Process Control

* DVMs and Meters

* Low Supply Current (200µA in Conversion Mode and 4µA in Autosleep Mode)

* Differential Input and Differential Reference with GND to VCC Common Mode Range

* 3ppm INL, No Missing Codes

* 10ppm Full-Scale Error and 1ppm Offset

* 0.56ppm Noise, 20.8 ENOBs

* No Latency: Digital Filter Settles in a Single Cycle. Each Conversion Is Accurate, Even After an Input Step

* Single Supply 2.7V to 5.5V Operation

* Internal Oscillator—No External Components Required

* 110dB Min, 50Hz/60Hz Notch Filter

* Pin Compatible with 24-Bit LTC2410/LTC2411