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

The AD7797 is a complete analog front end for high precision bridge sensor applications such as weighscales. The AD7797 contains a ∑-∆ ADC capable of 24-bit resolution. The on-chip instrumentation amplifier has a fixed gain of 128 so signals of small amplitude such as those from bridge sensors can be interfaced directly to the ADC.

The part has one differential input. The device also contains a temperature sensor which is internally connected to the ADC. This temperature sensor can be used to perform temperature compensation of the bridge.

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

The part operates with a power supply from 2.7 V to 5.25 V. It consumes a current of 250 µA typical and is housed in a 16-lead TSSOP package.

Applications

• Weighscales
• Strain Gauges
• Industrial Process Control
• Instrumentation
• Portable instrumentation