AD7718BR

Overview

The AD7718BR is a complete analog front-end for low frequency measurement applications, featuring a 24-bit Sigma-Delta ADC. It supports 4/5 fully-differential or 8/10 pseudo-differential input channels with a programmable gain amplifier ranging from 1 to 128. The device operates on a single 3 V or 5 V supply, consuming 3.84 mW typically at 3 V. It utilizes a 32 kHz crystal and internal PLL, offering software-programmable output data rates up to 1.365 kS/s. Factory calibration eliminates the need for field adjustments.

Feature Summary

• Factory-calibrated architecture ensuring high accuracy without requiring field calibration procedures.
• Integrated rail-to-rail input buffer and programmable gain amplifier for direct transducer interfacing.
• Simultaneous 50 Hz and 60 Hz line frequency rejection capabilities for noise immunity.
• VREF Select technology enabling both absolute and ratiometric measurement configurations.

Applications

• Industrial process control systems
• Pressure transducers
• Portable instrumentation
• Smart transmitters

Procurement Notes

Verify the specific package variant (SOIC R-28) against the required board layout. Confirm that the B grade specifications meet the system's error budget requirements. Ensure the design accounts for the -40 °C to +85 °C operating temperature range. Check for end-of-life status as indicated by distributor listings.

Selection Notes

Select this component when 24-bit resolution and multiplexed channel capability are required for low-frequency signals. Compare against the AD7708 if 16-bit resolution suffices, noting their pin-for-pin compatibility allows for future upgrades. Consider the power consumption differences between 3 V and 5 V operation modes during system design.

Part Context

The AD7718BR belongs to the AD7708/AD7718 family of low voltage, low power ADCs. It shares the same physical footprint and interface as the 16-bit AD7708, facilitating hardware reuse across product generations. The 'BR' suffix denotes the industrial temperature range and SOIC package option.

Replacement Considerations

The AD7708BR is a pin-compatible alternative offering 16-bit resolution. Designers may substitute it if higher precision is unnecessary, allowing for potential cost reduction while maintaining identical board layouts and software interfaces.

FAQ

Can the AD7718BR operate with both analog and digital supplies independently?

Yes, the AVDD and DVDD supplies can operate independently within their specified ranges of 2.7 V to 3.6 V or 4.75 V to 5.25 V.

What is the maximum differential input full-scale voltage?

The differential input full-scale voltage is determined by the reference voltage divided by the gain setting, calculated as ±1.024 × REFIN/GAIN, where gain ranges from 1 to 128.

How does the CHOP mode affect performance?

Enabling CHOP mode (CHOP = 0) optimizes the device for analog performance by reducing offset drift, whereas disabling it (CHOP = 1) maximizes channel throughput.