VFC100

® FPO VFC100 Synchronized VOLTAGE-TO-FREQUENCY CONVERTER FEATURES q FULL-SCALE FREQUENCY SET BY SYSTEM CLOCK; NO CRITICAL EXTERNAL COMPONENTS REQUIRED q PRECISION 10V FULL-SCALE INPUT, 0.5% max GAIN ERROR q ACCURATE 5V REFERENCE VOLTAGE q EXCELLENT LINEARITY: 0.02% max at 100kHz FS 0.1% max at 1MHz FS q VERY LOW GAIN DRIFT: 50ppm/°C DESCRIPTION The VFC100 voltage-to-frequency converter is an important advance in VFCs. The well-proven charge balance technique is used; however, the critical reset integration period is derived from an external clock frequency. The external clock accurately sets an output full-scale frequency, eliminating error and drift from the external timing components required for other VFCs. A precision input resistor is provided which accurately sets a 10V full-scale input voltage. In many applications the required accuracy can be achieved without external adjustment. The open collector active-low output provides fast fall time on the important leading edge of output pulses, and interfaces easily with TTL and CMOS circuitry. An output one-shot circuit is particularly useful to provide optimum output pulse widths for optical couplers and transformers to achieve voltage isolation. An accurate 5V reference is also provided which is useful for applications such as offsetting for bipolar input voltages, exciting bridges and sensors, and autocalibration schemes. VOUT 4 Integrator Amplifier – Comparator Input 14 Clock Input 10 +VCC 1 11 fOUT APPLICATIONS q A...