AD654 Voltage-to-Frequency Converter

The AD654 is a monolithic V/F converter consisting of an input amplifier, a precision oscillator system, and a high current output stage. A single RC network is all that is required to set up any full scale (FS) frequency up to 500 kHz and any FS input voltage up to ± 30 V. Linearity error is only 0.03% for a 250 kHz FS, and operation is guaranteed over an 80 dB dynamic range. The overall temperature coefficient (excluding the effects of external components) is typically ±50 ppm/°C. The AD654 operates from a single supply of 5 V to 36 V and consumes only 2.0 mA quiescent current.

The low drift (4 mV/°C typ) input amplifier allows operation directly from small signals such as thermocouples or strain gauges while offering a high (250 MW) input resistance. Unlike most V/F converters, the AD654 voltage to frequency converter provides a square-wave output, and can drive up to 12 TTL loads, optocouplers, long cables, or similar loads.

Features of AD654

• Low Cost

• Single or Dual Supply, 5 V to 36 V, 65 V to 618 V

• Full-Scale Frequency Up to 500 kHz

• Minimum Number of External Components Needed

• Versatile Input Amplifier

                Positive or Negative Voltage Modes

                Negative Current Mode

                High Input Impedance, Low Drift

• Low Power: 2.0 mA Quiescent Current

• Low Offset: 1 mV