FEATURES
Low Cost Single or Dual Supply, 5 V to 36 V, ؎5 V to ؎18 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 Low Cost Monolithic Voltage-to-Frequency Converter AD654 FUNCTIONAL BLOCK DIAGRAM +VS CT 8 7 CT –VS 6 5 DRIVER OSC AD654 1 2 3 FOUT LOGIC COMMON RT 4 +VIN PRODUCT DESCRIPTION
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 low drift (4 µV/°C typ) input amplifier allows operation directly from small signals such as thermocouples or strain gauges while offering a high (250 MΩ) input resistance. Unlike most V/F converters, the AD654 provides a square-wave output, and can drive up to 12 TTL loads, optocouplers, long cables, or similar loads.
Analog Devices
