Features

• 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 V_CC
• Live Zero—Extended Input Range Accommodates 12.5% Overrange and Underrange
• Pin Compatible with LTC2401/LTC2402

Typical Application

Description

The LTC®2421/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 DeltaSigma 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 V_CC. With an extended input conversion range of –12.5% V_REF to 112.5% V_REF (V_REF = FS_SET – ZS_SET), 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.