AD7870BQ

Overview

The AD7870BQ is a complete monolithic 12-bit analog-to-digital converter featuring a 2 μs track-and-hold amplifier and an 8 μs successive approximation ADC. It operates from ±5 V power supplies with a typical power dissipation of 60 mW. The device accepts a bipolar input voltage range of ±3 V and includes an on-chip 3 V buried Zener reference. Dynamic performance specifications include a signal-to-noise ratio of 72 dB at a 10 kHz input frequency. Data access time is 57 ns, supporting parallel, byte, and serial digital interfaces.

Feature Summary

• Integrated laser-trimmed internal clock oscillator eliminates the need for external timing components.
• Versatile interface logic supports single 12-bit parallel words, two 8-bit bytes, or serial data formats.
• Fast bus access times ensure compatibility with modern microprocessors and digital signal processors.

Applications

• Data acquisition systems requiring high-speed conversion
• Digital signal processing applications
• Industrial control systems

Procurement Notes

Verify the specific suffix BQ against the manufacturer's current ordering guide to confirm temperature range and package availability. Ensure the component matches the required industrial operating specifications before integration into the design.

Selection Notes

Select this model for applications requiring a ±3 V input range and 12-bit resolution. Compare dynamic performance metrics such as SNR and THD against system requirements. Verify that the ±5 V supply rails are compatible with the target power architecture.

Part Context

This component belongs to the AD7870/AD7875/AD7876 family of 12-bit sampling ADCs. While sharing core architecture, variants differ in input ranges and packages. The AD7870 specifically targets bipolar ±3 V signals, distinguishing it from the unipolar AD7875 and wide-range AD7876.

Replacement Considerations

Direct substitutes within the same family include the AD7870JNZ and AD7870KNZ. These parts share identical electrical characteristics but may differ in temperature grade or package type. Verify pinout compatibility and thermal specifications before substitution.

FAQ

How is the internal clock configured?

The internal laser-trimmed clock is enabled by tying the CLK pin to VSS. An external TTL-compatible clock can be applied if override is required.

What is the maximum recommended capacitance on the REF OUT pin?

The maximum recommended capacitance for normal operation on the REF OUT pin is 50 pF.

How does the HBEN pin function?

When 12/8/CLK is low, HBEN selects between upper byte (High) or lower byte (Low) output during byte-mode interfacing.