AD7821TQ

Overview

The AD7821TQ is an 8-bit analog-to-digital converter utilizing a half-flash conversion technique and LC2MOS fabrication. It features a built-in track-and-hold function with a maximum sampling rate of 1 MHz and a conversion time of 660 ns in WR-RD mode. The device supports unipolar (0 V to +5 V) or bipolar (±2.5 V) input ranges via external reference inputs. It operates from a single +5 V supply for unipolar applications or dual ±5 V supplies for bipolar operation, consuming 50 mW typical power. The T suffix indicates an extended temperature range of -55°C to +125°C.

Feature Summary

• Half-flash architecture eliminates the need for an external clock signal.
• Integrated track-and-hold circuit handles input signals up to 100 kHz bandwidth.
• Flexible reference inputs support ratiometric, unipolar, and bipolar configurations.
• Three-state data outputs interface directly with standard microprocessor buses.

Applications

• Digital signal processing systems requiring precise sampling intervals
• Voice recognition and echo cancellation circuits
• Adaptive filtering applications

Procurement Notes

Verify the specific ordering suffix against the manufacturer's current documentation to confirm package type and temperature grade. Ensure that any /883B military processing requirements are explicitly stated during procurement if applicable. Confirm availability status as distribution channels may vary.

Selection Notes

Select this component when high-speed conversion without an external clock is required. The built-in track-and-hold simplifies front-end design for signals up to 100 kHz. Verify that the source impedance allows for proper settling within the specified delay times between conversions.

Part Context

This part belongs to the AD7821 family of high-speed ADCs. It serves as an improved version of the AD7820, offering faster conversion times and higher signal bandwidth. The TQ variant specifically denotes the ceramic DIP package option suitable for industrial and military environments.

Replacement Considerations

The AD7820 is a related model but offers slower performance characteristics. Direct pin-compatible replacements should be verified against the latest datasheet specifications to ensure timing and electrical parameter compatibility.