AD7870KN

Overview

The AD7870KN is a monolithic 12-bit successive approximation analog-to-digital converter (ADC) from Analog Devices. It integrates a track-and-hold amplifier, an internal laser-trimmed clock, and a 3 V buried Zener reference. The device operates on ±5 V supplies with a typical power dissipation of 60 mW. It supports parallel, byte, and serial digital interfaces, offering a data access time of 57 ns. The AD7870 handles bipolar input signals within a ±3 V range. Key performance metrics include a signal-to-noise ratio of 72 dB at +25°C and a conversion time of 8 μs using an external 2.5 MHz clock.

Feature Summary

• Complete monolithic integration of a 12-bit ADC, track-and-hold amplifier, and internal reference.
• Versatile digital interface supporting parallel, byte, and serial data output formats.
• Internal laser-trimmed clock oscillator eliminates the need for external timing components.
• Fast microprocessor interfacing with 57 ns data access time.

Applications

• Data acquisition systems requiring high-speed sampling
• Digital signal processing (DSP) front-ends
• Industrial control systems
• Medical instrumentation

Procurement Notes

Verify the specific suffix KN against the manufacturer's ordering guide to confirm package type and temperature range. Ensure supply voltage requirements match the ±5 V specification. Confirm RoHS compliance status if required by the target application. Cross-reference pin configurations with the official datasheet to ensure compatibility with existing PCB layouts.

Selection Notes

Select the AD7870KN when a bipolar ±3 V input range is required. Compare dynamic performance specifications such as SNR and THD against system noise floor requirements. Evaluate interface flexibility needs to determine if parallel or serial modes are optimal. Consider thermal management given the 60 mW typical power dissipation in enclosed environments.

Part Context

The AD7870 belongs to the LC2MOS family of complete 12-bit sampling ADCs. It shares architectural similarities with the AD7875 and AD7876, differing primarily in analog input voltage ranges. The KN suffix typically denotes a plastic DIP package variant intended for commercial or industrial temperature ranges, distinct from hermetic ceramic options.

Replacement Considerations

Direct replacements include other variants within the AD7870 series, such as AD7870JPZ or AD7870JNZ, provided pinout and electrical characteristics align. Verify that substitute parts maintain the same ±3 V input range and interface logic levels before implementation.