This document describes the 24-bit, pin-programmable, ultralow power Sigma-Delta ADC AD7780. It features pin-programmable filter response, update rate of 10 Hz or 16.7 Hz, pin-programmable in-amp gain, pin-programmable power-down and reset, and more. It also has simultaneous 50 Hz/60 Hz rejection, power supply range from 2.7 V to 5.25 V, and temperature range of -40°C to +105°C.
The AD7780 is a complete low‑power front‑end solution for bridge‑sensor products such as weigh scales, pressure sensors and portable instrumentation. It integrates a 24‑bit sigma‑delta ADC, an on‑chip programmable gain amplifier and an internal oscillator, consuming as little as 115 µA (gain = 1) to 330 µA (gain = 128).
Key features include pin‑programmable filter response (10 Hz or 16.7 Hz update rates), selectable gain (1 or 128), simultaneous 50 Hz/60 Hz line‑frequency rejection, and a bridge power‑down switch that can shut off sensor power to extend battery life. The device operates from 2.7 V to 5.25 V and is offered in 14‑lead SOIC and 16‑lead TSSOP packages.
| Power Supply Voltage (AVDD) | 2.7 V to 5.25 V |
|---|---|
| Power Supply Current (IDD) – Gain = 1, AVDD = 3 V | 115 µA |
| Power Supply Current (IDD) – Gain = 128, AVDD = 5 V | 330 µA |
| Resolution | 24 bits |
| Update Rate | 10 Hz or 16.7 Hz |
| RMS Noise (Gain = 128, AVDD = 3 V, 10 Hz) | 44 nV |
| Gain Options | 1 or 128 (pin‑programmable) |
| Bridge Power‑Down Switch On‑Resistance | ≤ 9 Ω |
| Bridge Power‑Down Switch Continuous Current Rating | 30 mA |
It switches off the power to the bridge sensor and puts the AD7780 into a low‑power state, reducing battery consumption when the device is not converting.