LTC2378 16-/18-/20-Bit 1 Msps Low Power SAR ADCs

Analog Devices' LTC2378 are a series of low noise, low power, high-speed approximation register (SAR) analog-to-digital converters (ADCs) that come in 16-, 18-, and 20-bit versions. Operating from a 2.5 V supply, these SAR ADCs have a ±V_REF fully differential input range with V_REF ranging from 2.5 V to 5.1 V.

The LTC2378 have a high-speed SPI-compatible serial interface that supports 1.8 V, 2.5 V, 3.3 V, and 5 V logic while also featuring a daisy-chain mode. The fast 1 Msps throughput with no cycle latency makes these ADCs ideally suited for a wide variety of high-speed applications. An internal oscillator sets the conversion time, easing external timing considerations. The LTC2378-20 automatically powers down between conversions, leading to reduced power dissipation that scales with the sampling rate.

The LTC2378 features a unique digital gain compression (DGC) function, which eliminates the driver amplifier’s negative supply while preserving the full resolution of the ADC. When enabled, the ADC performs a digital scaling function that maps zero-scale code from 0 V to 0.1 • V_REF and full-scale code from V_REF to 0.9 • V_REF. For a typical reference voltage of 5 V, the full-scale input range is 0.5 V to 4.5 V, which provides adequate headroom for powering the driving amplifier from a single 5.5 V supply. The LTC2378 is ideal for low power battery applications use in medical imaging, test, and measurement instrumentation.