AD7788ARM

Overview

The AD7788ARM is a low-power, 16-bit Sigma-Delta analog-to-digital converter (ADC) manufactured by Analog Devices Inc. It features a single differential input and operates on a 2.5 V to 5.25 V supply. The device utilizes an internal clock oscillator, eliminating the need for external timing components. It provides a fixed output data rate of 16.6 Hz, which enables simultaneous rejection of 50 Hz and 60 Hz interference. Key electrical specifications include a maximum normal mode current of 75 µA, a power-down current of 1 µA, and typical integral nonlinearity of 3.5 ppm. The component is housed in a 10-lead MSOP package.

Feature Summary

• Integrated internal clock oscillator removes requirement for external clock sources
• Sigma-Delta architecture with digital filtering optimized for simultaneous 50 Hz and 60 Hz line frequency rejection
• Low noise performance supporting high resolution measurements
• VDD monitor channel allows direct measurement of the power supply voltage

Applications

• Smart transmitters
• Battery-powered portable instrumentation
• Temperature and pressure sensor measurement
• Weigh scales
• 4 to 20 mA loop monitoring

Procurement Notes

Verify the specific grade suffix when ordering, as the AD7788 is available in A grade (-40°C to +85°C) and B grade (-40°C to +105°C). Confirm that the ARMZ variant corresponds to the required temperature range and packaging type. Ensure the external reference voltage meets the specified operational limits relative to the supply voltage.

Selection Notes

Select this component for applications requiring low-frequency precision with minimal power consumption. The fixed 16.6 Hz update rate is suitable for slow-varying signals but may not support higher throughput requirements. Consider the AD7789 if 24-bit resolution is necessary. Verify that the system can accommodate the bipolar or unipolar coding configurations supported by the mode register.

Part Context

The AD7788 serves as the 16-bit resolution counterpart to the AD7789 within the same product family. Both devices share identical pinouts, interfaces, and functional blocks, differing primarily in ADC resolution and effective bits. They are designed as analog front ends for low-frequency measurement systems where power efficiency and noise performance are critical constraints.

Replacement Considerations

The AD7788BRMZ is a parameter-equivalent alternative from Analog Devices Inc. The AD7790BRMZ is listed as a similar replacement option. Verify compatibility regarding resolution, interface timing, and register configuration before substitution.

FAQ

Does the AD7788 require an external clock source?

No, the device contains an internal clock oscillator, so no external clock source is required for operation.

How does the device handle 50 Hz and 60 Hz interference?

The digital filter is optimized for simultaneous rejection of both 50 Hz and 60 Hz frequencies when operating at the standard 16.6 Hz output data rate.

What is the function of the VDD monitor channel?

The VDD monitor channel allows the ADC to measure the voltage on the power supply, which is useful for monitoring power supply variations.