AD7791BRM

Overview

The AD7791BRM is a low power, complete analog front end for low frequency measurement applications. It contains a low noise 24-bit Sigma-Delta ADC with one differential input that can be buffered or unbuffered. The device operates from an internal clock and features software programmable output data rates from 9.5 Hz to 120 Hz. At the lower update rate of 9.5 Hz, the RMS noise is 1.1 μV. The part operates with a power supply from 2.5 V to 5.25 V. When operating from a 3 V supply, the power dissipation is 225 μW maximum. It is housed in a 10-lead MSOP package.

Feature Summary

• Low power operation with normal mode current of 75 μA max and power-down mode current of 1 μA max.
• High resolution 24-bit Sigma-Delta ADC with 19.5-bit peak-to-peak resolution at 9.5 Hz update rate.
• Internal clock oscillator eliminates the need for an external clock source.
• Rail-to-rail input buffer allows connection of high source impedances without gain errors.

Applications

• Smart transmitters
• Battery applications
• Portable instrumentation
• Sensor measurement
• Weigh scales

Procurement Notes

Verify the specific ordering suffix BRM corresponds to the 10-lead MSOP package variant when sourcing components. Confirm the revision level matches the required datasheet specifications. Ensure the supplier provides traceability documentation consistent with Analog Devices quality standards. Check for any environmental compliance certifications required by your manufacturing process.

Selection Notes

Select this component for applications requiring high precision at low frequencies with minimal power consumption. The internal clock simplifies design by removing external crystal requirements. Consider the buffered input stage if driving high impedance sensors directly. Evaluate the available update rates against the necessary noise performance and line rejection requirements for the specific signal environment.

Part Context

The AD7791 belongs to a family of low power Sigma-Delta ADCs from Analog Devices. It shares architectural similarities with the AD7790 but offers higher 24-bit resolution compared to the 16-bit AD7790. This device is designed to replace discrete amplifier and ADC solutions in compact sensor interfaces. It integrates the modulator, digital filter, and reference inputs into a single small footprint.

Replacement Considerations

The AD7791BRMZ is a lead-free version of the same component. The AD7790 is a similar device but offers 16-bit resolution instead of 24-bit. Verify pin compatibility and register configuration differences when substituting with other members of the AD779x family.