The AD652 Synchronous Voltage-to-Frequency Converter (SVFC) is a powerful building block for precision analog-to-digital conversion, offering typical nonlinearity of 0.002% (0.005% maximum) at a 100 kHz output frequency. The inherent monotonicity of the transfer function and wide range of clock frequencies allows the conversion time and resolution to be optimized for specific applications.
The AD652 uses a variation of the popular charge-balancing technique to perform the conversion function. The AD652 uses an external clock to define the full-scale output frequency, rather than relying on the stability of an external capacitor. The result is a more stable, more linear transfer function, with significant application benefits in both single and multichannel systems.
Gain drift is minimized using a precision low drift reference and low TC on-chip thin-film scaling resistors. Furthermore, the initial gain error is reduced to less than 0.5% by the use of laser-wafer-trimming.
The analog and digital sections of the AD652 have been designed to allow operation from a single-ended power source, simplifying its use with isolated power supplies.
The AD652 is available in five performance grades. The 20-pin PLCC packaged JP and KP grades are specified for operation over the 0°C to +70°C commercial temperature range. The 16-pin CERDIP-packaged AQ and BQ grades are specified for operation over the -40°C to +85°C industrial temperature range, and the AD652SQ is available for operation over the full -55°C to +125°C extended temperature range.
