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LM321: LM321 circuit function

Jacky Chen53
Prodigy 40 points
Part Number: LM321

Hi sir,

Can someone help to explain the circuit function of LM321 as the attachment ? What is this function for ? Many thanks indeed...

  • 0
    TI__Guru*** 139956 points

    Hello Jacky,

    Welcome to the e2e forums. I hope you will find them helpful.

    U6 is a unity gain buffer, the output voltage (pin 4)  will match the input voltage (pin 1).

    The input voltage should be about 10V (D16 zener voltage), if J7 and J14 are disconnected (or J7,J14 voltage is greater than 10V).

    If there is voltage on J7 or J14, that voltage will be present on RT7. The output voltage (and input voltage) of the op amp will be about RT7 voltage + 0.3V

    In summary, the circuit measures the DC voltage on J7 and J14.

  • 0
    Guru 140200 points

    Hi Jacky,

    I agree with Ron.

    Could also be a AC voltage detector, detecting the minimum "peak" voltage of a positive AC signal (DC signal with an AC component).

    Or a detector which detects the presence of a signal, with defined detection time constants for attack and release.

    What kind of signal is arriving J7?

    Kai

  • 0 in reply to Ron Michallick
    Prodigy 40 points

    Hi Ron,

    Good day

    Thank you so much for deeply explanation, I learned a lot.

    Br

    Jacky

  • 0 in reply to kai klaas69
    Prodigy 40 points

    Hi Kai,

    Good day

    Thank you for your reply.

    J7 is connecting to LED dimming controller use.

    Br

    Jacky