Low Cost Monolithic Voltage-to-Frequency Converter
The AD654 combines an input amplifier, a precision oscillator, and a high‑current output stage in a single monolithic IC. It requires only a single RC network to set full‑scale frequency and input voltage, and can operate from a single 5 V to 36 V supply or dual supplies.
The device provides a square‑wave output capable of sinking over 10 mA, features a 250 MΩ input resistance, low offset (≤1 mV), and low quiescent current (~2 mA). Detailed specifications, circuit diagrams, and application examples such as temperature‑to‑frequency conversion and optoisolator coupling are included.
| Full‑Scale Frequency Range | 0 – 500 kHz |
|---|---|
| Input Resistance (Non‑inverting) | 250 MΩ |
| Input Bias Current (typ) | 30 nA |
| Quiescent Current (typ) | 2.0 mA |
| Supply Voltage (single supply) | 4.5 V to 36 V |
| Supply Voltage (dual supply) | +18 V to –18 V |
| Operating Temperature Range | -40 °C to +85 °C |
| Maximum Output Sink Current | 10 mA (typ) |
The AD654 can generate frequencies from 0 up to 500 kHz at full scale.
It operates from a single supply of 4.5 V to 36 V or from dual supplies of ±18 V.
Typical quiescent current is about 2.0 mA.
The non‑inverting input resistance is 250 MΩ.