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TPS2373: about VCIN

T Kishi
Genius 4425 points
Part Number: TPS2373

Hi

My customer has question.

I have confirmed this thread, but please let me know.

What is the reason for applying voltage to the VCIN pin in addition to supplying to VCOUT?
For example, is the VCIN voltage required inside as well as the supply to VCOUT?
And,Are there any current values required for internal drive?

Best Regard

T Kishi

  • 0
    TI__Mastermind 21320 points

    Hello T Kishi,

    The VC_IN and VC_OUT pins are used for the advanced startup feature. A detailed description of this process is in the datasheet for TPS2373 in section:"7.3.7 VC_IN, VC_OUT, UVLO_SEL, and Advanced PWM Startup"

    The short description is that VDD sources a startup current for VC_OUT. Then when the voltage on VC_IN (which is on the transformer auxiliary bias winding) reaches a threshold the two pins are connected. Then the startup current will turn off. 

    Also, the values for the internal current from VDD are listed on page 8. They range from 3.9mA to 29mA, depending on the input and VC_OUT voltage. 

    Regards,

    Michael Pahl

  • 0 in reply to Michael Pahl
    Genius 4425 points

    Hi Michael

    thank you for reply.

    Is it necessary to apply a voltage higher than the threshold voltage to the VC_IN pin even when the VC_OUT voltage is not required?
    If so, please tell us why.

    Regard

    T Kishi

  • 0 in reply to T Kishi
    TI__Mastermind 21320 points

    Hello T Kishi,

    If VC_OUT is not used, VC_IN must be connected to the low voltage bias supply of the PWM controller to ensure proper operation

    Regards,

    Michael Pahl

  • 0 in reply to Michael Pahl
    Genius 4425 points

    Hi Michael

    Thank you for reply.

    What does "ensure proper operation" in you or in the data sheet mean?
    Is VC_IN a voltage necessary for anything other than supplying VC_OUT?
    If so, what block do you need VC_IN voltage for?

    Regard

    T Kishi

  • 0 in reply to T Kishi
    TI__Mastermind 21320 points

    Hello T Kishi,

    The VC_IN pin provides power for the internal circuitry in the IC. If the pin does not go above the threshold voltage the IC will not power on. If you do not plan to use VC_OUT and the startup feature, please use the zener and resistor as Darwin described in the other post. 

    Regards,

    Michael Pahl