Features

• Pin Compatible 4-/8-Channel 20-Bit ADCs
• 8ppm INL, No Missing Codes at 20 Bits
• 4ppm Full-Scale Error and 0.5ppm Offset
• 1.2ppm Noise
• Digital Filter Settles in a Single Cycle. Each
  Conversion is Accurate, Even After Changing
  Channels
• Fast Mode: 16-Bit Noise, 12-Bit TUE at 100sps
• 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
• Single Supply 2.7V to 5.5V Operation
• Low Supply Current (200µA) and Auto Shutdown
• Can Be Interchanged with 24-Bit LTC2404/LTC2408
  if ZS_SET Pin is Grounded

Typical Application

Description

The LTC2424/LTC2428 are 4-/8-channel 2.7V to 5.5V micropower 20-bit A/D converters with an integrated oscillator, 8ppm INL and 1.2ppm RMS noise. They use delta-sigma technology and provide single cycle digital filter settling time (no latency delay) for multiplexed applications. The first conversion after the channel is changed is always valid. Through a single pin the LTC2424/LTC2428 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 800Hz. The internal oscillator requires no external frequency setting components.

The converters accept any external reference voltage from 0.1V to V_CC. With their extended input conversion range of -12.5% V_REF to 112.5% V_REF (V_REF = FS_SET - ZS_SET) the LTC2424/LTC2428 smoothly resolve the offset and overrange problems of preceding sensors or signal conditioning circuits.

The LTC2424/LTC2428 communicate through a flexible 4-wire digital interface which is compatible with SPI and MICROPOWER protocols.