View lm231a lm231 lm331a lm331 datasheet:

June 1999 LM231A/LM231/LM331A/LM331 Precision Voltage-to-Frequency Converters over the full operating temperature range, at power supplies General Description as low as 4.0V. The precision timer circuit has low bias cur- The LM231/LM331 family of voltage-to-frequency converters rents without degrading the quick response necessary for are ideally suited for use in simple low-cost circuits for 100 kHz voltage-to-frequency conversion. And the output analog-to-digital conversion, precision frequency-to-voltage are capable of driving 3 TTL loads, or a high voltage output conversion, long-term integration, linear frequency modula- up to 40V, yet is short-circuit-proof against VCC. tion or demodulation, and many other functions. The output when used as a voltage-to-frequency con