AD537SD

Overview

The AD537SD is a monolithic voltage-to-frequency converter manufactured by Analog Devices Inc. It integrates an input amplifier, precision oscillator, internal reference generator, and high-current output stage. The device operates from a single supply of 4.5 V to 36 V or dual supplies of ±5 V to ±18 V, consuming 1.2 mA quiescent current. It supports full-scale frequencies up to 150 kHz with nonlinearity as low as 0.07% max at 10 kHz. The AD537SD features a 1.00 V reference output and a 1.00 mV/K absolute temperature reference. Rated for military specifications, it functions within a temperature range of -55°C to +125°C.

Feature Summary

• Versatile input amplifier supporting positive/negative voltage modes and negative current mode with high input impedance.
• Integrated precision 1.00 V reference and 1.00 mV/K absolute temperature reference outputs.
• High linearity performance with low overall temperature coefficient typically ±30 ppm/°C.
• Open-collector output stage capable of sinking up to 20 mA with logic interface flexibility.

Applications

• True two-wire data transmission schemes using current modulation.
• Frequency-to-voltage conversion via phase-locked loop configurations.
• Absolute temperature-to-frequency conversion circuits.
• Thermocouple interface applications requiring linearization.

Procurement Notes

Verify the specific suffix 'SD' indicates the ceramic DIP package variant rated for the extended -55°C to +125°C temperature range. Confirm compliance with MIL-STD-883 requirements if applicable to the procurement specification. Ensure external timing components are selected to maintain specified linearity and temperature stability characteristics.

Selection Notes

Select the AD537SD when operation in extreme environments below 0°C or above +70°C is required. This model provides superior temperature stability compared to commercial grades. Consider the 14-lead ceramic DIP package for hermetic sealing needs. Evaluate the need for the SYNC pin availability, which is present in the DIP package but absent in metal can variants.

Part Context

The AD537 series represents a family of high-performance voltage-to-frequency converters designed for precision analog signal processing. The AD537SD specifically denotes the military-grade version housed in a 14-lead side-brazed ceramic DIP package. It shares core architecture with the AD537J and AD537K models but offers extended temperature ratings and enhanced reliability suitable for demanding industrial and aerospace applications.

Replacement Considerations

AD537SH

FAQ

How does the AD537SD handle synchronization?

The DIP package includes a SYNC pin (Pin 2) that allows the internal oscillator to be slaved to an external master oscillator or shut off by connecting to the positive supply.

What is the maximum drive current for the output stage?

The open-collector output stage can sink a minimum of 20 mA at a saturation voltage of 0.4 V, with a hard limit of 25 mA.