AD7721ARZ-REEL

Overview

The AD7721ARZ-REEL is a 16-bit sigma-delta analog-to-digital converter manufactured by Analog Devices Inc. It operates from a +5 V supply and accepts differential inputs of 0 V to 2.5 V or ±1.25 V. The device features an output word rate of 468.75 kHz with a maximum input bandwidth of 229.2 kHz when driven by a 15 MHz master clock. It supports both high-speed serial and parallel interfaces, includes on-chip offset and gain calibration, and provides a low-power standby mode consuming only 100 μW.

Feature Summary

• Utilizes a single-bit DAC in the modulator architecture to ensure excellent linearity and DC accuracy without missing codes.
• Integrates two cascaded finite impulse response digital filters that reduce external antialiasing requirements to first order.
• Includes internal calibration logic for minimizing zero-scale and full-scale errors at the endpoints of the transfer function.

Applications

• High-speed data acquisition systems requiring direct interfacing with microcontrollers and DSPs
• Industrial process control applications utilizing differential signal inputs
• Precision measurement equipment requiring low-power operation and integrated filtering

Procurement Notes

Verify the REEL suffix indicates tape-and-reel packaging rather than tube packaging. Confirm the A version temperature range (-40°C to +85°C) matches system requirements. Ensure the SOIC-28 package dimensions align with PCB layout constraints before finalizing orders.

Selection Notes

Select this component for designs requiring high throughput up to 468.75 kS/s with 16-bit resolution. Consider the serial interface for simplified pin counts or parallel mode for faster data access. Verify that the external reference voltage falls within the specified 2.4 V to 2.6 V range for optimal performance.

Part Context

The AD7721 belongs to the Analog Devices AD7721 series of CMOS sigma-delta ADCs. This specific part number represents the industrial temperature grade variant housed in a 28-pin Small Outline Integrated Circuit (SOIC) package. It is designed for applications demanding high speed and precision within a standard surface-mount form factor.

Replacement Considerations

No public confirmed substitute part numbers are available in the provided documentation.

FAQ

Does the AD7721 require an external sample-and-hold circuit?

No, the analog input is continuously sampled by the analog modulator at twice the clock frequency, eliminating the need for external sample-and-hold circuitry.

How is the serial interface clock generated?

The serial interface operates in internal clocking (master) mode, where the AD7721 provides the required serial clock on the SCLK/DB7 pin.

What is the effect of lowering the master clock frequency?

Lowering the clock frequency proportionally reduces the sample rate, filter corner frequency, and output word rate. The minimum guaranteed operating frequency is 100 kHz.