AD7791BRMZ

Overview

The AD7791BRMZ is a low-power, buffered 24-bit Sigma-Delta analog-to-digital converter (ADC) from Analog Devices Inc. It features a single differential input with an internal rail-to-rail buffer and operates on a supply voltage of 2.5 V to 5.25 V. The device includes an internal clock oscillator, eliminating the need for external timing components. Key electrical specifications include a maximum output update rate of 120 Hz and a minimum rate of 9.5 Hz. At the lowest update rate, the RMS noise is specified at 1.1 µV. The ADC provides 24 bits of no-missing-codes resolution and achieves simultaneous 50 Hz and 60 Hz line frequency rejection. Power consumption is typically 75 µA in normal mode and drops to 1 µA in power-down mode.

Feature Summary

• Integrated rail-to-rail input buffer for high-impedance signal sources
• Internal clock oscillator removes requirement for external crystal or clock source
• Software-programmable output data rates with simultaneous 50/60 Hz rejection
• Low power operation with dedicated power-down mode

Applications

• Smart transmitters
• Battery-powered portable instrumentation
• Precision sensor measurement systems
• Weigh scales
• 4 to 20 mA loop monitoring

Procurement Notes

Verify the specific suffix 'BRMZ' against the manufacturer's current ordering guide to confirm package type and temperature range. Ensure the component matches the required industrial temperature specifications. Cross-reference the datasheet revision to confirm pinout compatibility and electrical characteristics before finalizing procurement orders.

Selection Notes

Select this component when a complete analog front end with integrated buffering and filtering is required. The internal buffer allows direct connection to high-impedance sensors without gain errors. Consider the trade-off between update rate and noise performance; lower update rates provide superior noise rejection but slower response times. Verify that the external reference voltage falls within the acceptable range relative to the supply voltage.

Part Context

The AD7791 belongs to the AD779x family of precision Sigma-Delta ADCs designed for low-frequency measurement applications. It shares architectural similarities with the AD7790 but offers higher resolution and integrated buffering capabilities. The BRMZ designation indicates a specific industrial-grade variant housed in a compact 10-lead MSOP package suitable for space-constrained PCB layouts.

Replacement Considerations

The AD7790 is a related part number within the same product family. However, it lacks the integrated input buffer found in the AD7791. Substitution requires evaluating whether the application can tolerate unbuffered inputs or if additional external circuitry is needed to drive the ADC input.