1-/2-Channel 20-Bit µPower No Latency ∆Σ ADCs in MSOP-10

The LTC2421/LTC2422 are 1- and 2-channel 2.7V to 5.5V micropower 20-bit analog-to-digital converters with an integrated oscillator, 8ppm INL and 1.2ppm RMS noise. These ultrasmall devices use delta-sigma technology and a new digital filter architecture that settles in a single cycle. This eliminates the latency found in conventional ∆Σ converters and simplifies multiplexed applications.

Through a single pin, the LTC2421/LTC2422 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 frequency setting components.

These converters accept an external reference voltage from 0.1V to VCC. With an extended input conversion range of –12.5% VREF to 112.5% VREF (VREF = FSSET – ZSSET), the LTC2421/LTC2422 smoothly resolve the offset and overrange problems of preceding sensors or signal conditioning circuits.

The LTC2421/LTC2422 communicate through a 2- or 3-wire digital interface that is compatible with SPI and MICROWIRE™ protocols.

Applications

* Weight Scales

* Direct Temperature Measurement

* Gas Analyzers

* Strain Gauge Transducers

* Instrumentation

* Data Acquisition

* Industrial Process Control

* 20-Bit ADCs in Tiny MSOP-10 Packages

* 1- or 2-Channel Inputs

* Single Supply 2.7V to 5.5V Operation

* Low Supply Current (200µA) and Auto Shutdown

* Automatic Channel Selection (Ping-Pong) (LTC2422)

* No Latency: Digital Filter Settles in a Single Conversion Cycle

* 8ppm INL, No Missing Codes

* 4ppm Full-Scale Error

* 0.5ppm Offset

* 1.2ppm Noise

* Zero Scale and Full Scale Set for Reference and Ground Sensing

* Internal Oscillator—No External Components Required

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

* Reference Input Voltage: 0.1V to VCC

* Live Zero—Extended Input Range Accommodates 12.5% Overrange and Underrange

* Pin Compatible with LTC2401/LTC2402