AD7797 Low Power 24-Bit Sigma-Delta A/D Converter for Bridge Sensors

The AD7796/AD7797 are complete, analog front ends for high precision, bridge sensor applications such as weigh scales. The AD7796/AD7797 contain a Σ-∆ ADC capable of 16-/24-bit resolution, respectively. The on-chip instrumentation amplifier has a fixed gain of 128, allowing small amplitude signals such as those from bridge sensors to be directly interfaced to the ADC.

Each device has one differential input and contains a temperature sensor that is internally connected to the ADC. This sensor can be used to perform temperature compensation of the bridge.

The devices can be operated with the internal clock or an external clock. The output data rate from the devices is software-programmable and can be varied from 4.17 Hz to 123 Hz.

The AD7796/AD7797 operate with a power supply from 2.7 V to 5.25 V. Each device consumes a current of 250 µA typical and is housed in a 16-lead TSSOP.

Applications

Features and Benefits

RMS noise: 65 nV

Instrumentation amp

Temperature sensor

Internal clock oscillator

Simultaneous 50 Hz/60 Hz rejection

Update rate range: 4.17 Hz to 123 Hz

Current: 250 µA typ

Power-down: 1 µA

Power supply range: 2.7 V to 5.25 V

–40°C to +85°C temperature range

Independent interface power supply

16-lead TSSOP

Analog to Digital Converters

A/D Converters

Design Tools

AD7785/AD7790/AD7791/AD7792/AD7793/AD7794/AD7795/AD7796/AD7797/AD7798/AD7799 Digital Filter Model .XLS

Data Sheets

Document	note
AD7796/AD7797: Low Power, 16-/24-Bit Sigma-Delta ADC for Bridge Sensors Low Power, 16-/24-Bit Data Sheet (Rev. B)	PDF 471.33 K

Application Notes

Document	note
AN-968: Current Sources: Options and Circuits (Rev. 0)	PDF 131 kB
AN-607: Selecting a Low Bandwidth (<15 kSPS) Sigma-Delta ADC (Rev. E)	PDF 222 kB