24-bit sigma-delta ADC at 312 kSPS — precision data acquisition workhorse
It communicates over an SPI interface and requires an external voltage reference. The device operates from a dual analog supply of 2.5 V and 5 V, with a separate 2.5 V digital supply.
At 312 kSPS, this ADC can digitize a 100 kHz bandwidth signal with adequate oversampling for anti-alias filter relaxation. The 24-bit resolution delivers a theoretical dynamic range of about 146 dB, though practical noise performance depends on the external reference and analog supply cleanliness. For a three-phase motor current sensing application, one AD7764BRUZ per phase with a multiplexed reference covers the bandwidth and accuracy requirements.
Differential input and external reference — layout and drive considerations
The differential input architecture rejects common-mode noise from the sensor or signal chain, but it requires a balanced driver — a single-ended source needs an op-amp stage to convert to differential before the ADC. The external reference pin lets you set the full-scale range independently; a low-noise reference like the ADR4550 matches the 24-bit noise floor. The 28-TSSOP footprint is a standard 4.4 mm wide body, so the layout fits a two-layer board with a solid ground plane under the analog section.
It is ROHS3 compliant.