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Compiler/LM331: Duty cycle 50/50 with v-to-f converter lm331

Part Number: LM331

Tool/software: TI C/C++ Compiler

I made a voltage to frequency converter with the Lm331, but my problem is that i can't make the duty cycle 50/50. What i want is: when the input voltage on pin 7 increase: my Frequency increase to but the duty cycle stays 50/50. Also the optional offset doesn't work. 

  • Hello Bavo,

    The LM331 utilizes an internal one-shot timer to provide the pulse output which doesn't support maintaining a constant 50 % duty cycle over an assigned V-to-F range. 

    The optional offset control circuit applied in the LM331 datasheet Fig. 14 should be usable. Possibly, the potentiometer resistance you are using is too high. Either try reducing the poteniometer resistance, or lowering the 22 k resistor to gain more adjustment range.

    Regards, Thomas

    Precision Amplifiers Applications Engineering