AD7870AJN

Overview

The AD7870AJN is a complete monolithic 12-bit successive approximation analog-to-digital converter (ADC) from the AD7870 series. It integrates a track-and-hold amplifier, an 8 μs ADC core, and a laser-trimmed internal clock. The device operates on ±5 V power supplies and accepts a bipolar analog input range of ±3 V. Key electrical specifications include a typical signal-to-noise ratio of 70 dB at a 10 kHz input frequency, a maximum conversion time of 9 μs with the internal clock, and a data access time of 57 ns. It features parallel, byte, and serial digital interfaces.

Feature Summary

• Integrates a 2 μs track-and-hold amplifier for accurate high-frequency signal capture.
• Includes a factory-trimmed internal 3 V buried Zener reference requiring no external components.
• Offers versatile data output formats including 12-bit parallel, two 8-bit bytes, and serial modes.
• Features a self-contained laser-trimmed clock oscillator to ensure precise conversion timing.

Applications

• Digital signal processing systems requiring fast microprocessor interfacing.
• Industrial control applications utilizing bipolar signal ranges.
• Data acquisition systems needing integrated reference and clock functionality.

Procurement Notes

Verify the specific suffix 'JN' against the manufacturer's ordering guide to confirm package type and temperature range. Ensure the design supports ±5 V supply rails and ±3 V input limits. Confirm interface compatibility with the target microprocessor for parallel or serial data modes.

Selection Notes

Select this component when a single-chip solution with integrated reference and clock is required for 12-bit resolution. Compare dynamic performance metrics like SNR against system noise floors. Verify that the ±3 V input range matches the sensor output levels before finalizing the design.

Part Context

The AD7870AJN belongs to the AD7870/AD7875/AD7876 family of 12-bit sampling ADCs. While sharing the same core architecture and pinout, variants differ in input voltage ranges and temperature grades. The AJN designation specifically denotes the industrial temperature range variant within the plastic DIP package lineup.

Replacement Considerations

Direct functional replacements within the same family include the AD7870KNZ for commercial temperature range applications. Other variants such as the AD7875 or AD7876 require circuit modifications due to different input voltage ranges.