The AD654JRZ is a voltage-to-frequency converter from Analog Devices that accepts an analog input voltage and produces a square-wave output whose frequency is proportional to that voltage. It is a single-chip VFC in an 8-SOIC package, rated for a maximum output frequency of 500 kHz with a linearity of ±0.2%. The full-scale drift is specified at ±50 ppm/°C, giving it predictable behaviour across temperature for industrial sensor interfaces and isolated data-acquisition channels.
The 500 kHz maximum frequency sets the upper bound on the input voltage range you can convert. The ±0.2% linearity means the deviation from an ideal straight-line transfer function is no more than 0.2% of full scale. The ±50 ppm/°C full-scale drift tells you how much the output frequency changes with temperature at the top of the range.
It is ROHS3 compliant, which simplifies compliance for EU and global markets.