AD652SQ

Overview

The AD652SQ is a monolithic synchronous voltage-to-frequency converter (SVFC) manufactured by Analog Devices Inc. It operates over an extended temperature range of −55°C to +125°C and utilizes a charge-balancing technique with an external clock to define full-scale output frequency, reaching up to 2 MHz. The device features extremely low linearity error, typically 0.002% at 100 kHz output, and includes an accurate buffered 5 V reference. It supports dual or single-supply operation and accepts voltage or current inputs.

Feature Summary

• Synchronous architecture using an external clock for stable, linear transfer functions independent of internal capacitor drift.
• Integrated precision 5 V reference voltage source with low temperature drift characteristics.
• Flexible input configuration supporting both voltage and current modes with single-ended power supply compatibility.
• Open-collector output stage capable of driving TTL/CMOS logic, optical couplers, and pulse transformers.

Applications

• Precision analog-to-digital conversion systems requiring high resolution.
• Isolated analog signal transmission via synchronous frequency-to-voltage conversion.
• Single-line multiplexed data acquisition networks.
• Bridge transducer interfaces for sensor signal conditioning.

Procurement Notes

Verify the specific SQ grade designation confirms the extended temperature rating of −55°C to +125°C. Ensure the package type matches the required 16-lead CERDIP form factor. Confirm that the application environment does not exceed the absolute maximum ratings for supply voltage or input signals. Check for MIL-STD-883 compliance requirements if the design mandates military-grade specifications.

Selection Notes

Select the AD652SQ when extended temperature performance is critical compared to commercial grades. Consider the device for applications requiring minimal external components due to the integrated reference and scaling resistors. Evaluate the need for synchronous operation to simplify multi-channel system timing. Verify that the available clock frequency supports the desired output resolution and conversion speed.

Part Context

The AD652 series comprises synchronous voltage-to-frequency converters available in multiple performance grades. The SQ grade specifically denotes the version rated for the full −55°C to +125°C extended temperature range. It shares the core SVFC architecture with JP, KP, AQ, and BQ grades but offers broader environmental tolerance suitable for harsh industrial or aerospace conditions.

Replacement Considerations

No direct public substitute part numbers are documented for this component.

FAQ

How does the AD652 achieve superior linearity compared to standard VFCs?

It uses an external clock to define the full-scale frequency rather than relying on the stability of an external capacitor, resulting in a more stable and linear transfer function.

What is the maximum full-scale output frequency supported by the AD652?

The full-scale frequency can be set by an external system clock up to a maximum of 2 MHz.

Can the AD652 operate with a single power supply?

Yes, the analog and digital sections are designed to allow operation from a single-ended power source, simplifying use with isolated supplies.