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TPS54226 – About VRGE5

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Guru 21045 points
Other Parts Discussed in Thread: TPS54226, TPS54426

Hi,

 

If Enable is Low, is VREG5 of TPS54226 not active?

" VREG5 is not active when EN is low" is described to datasheet of TPS54426

(please refer to page5 of datasheet)

But, it isn’t described to datasheet of TPS54226.

Could you please give us your advice.

 

Regards,

Kanemaru

  • 0
    TI__Guru**** 191445 points

    VREG5 is not active if EN is held low.

  • 0 in reply to JohnTucker
    Guru 21045 points

    Hi, John

     

    Thank you for the information.

    I would like to ask you the following questions.

     

    [Question1]

    My customer would like to know the internal circuit.

    Is "the gate-source-voltage for MOSFET of Power good function" Supplied from VREG5?

    So, if EN pin turned into low from high (VREG5 is not active), Can the MOSFET not turn on?

     

    [Question2]

    My customer would like to know the operation of the PG function when EN pin turned into Low.

    When EN pin turned into low from high, is PG function normal operation?

    So, if the output voltage reached less than 85%,

    is PG pin turned into low form high after a 10ms internal delay? or does power good not function?

     

    Regards,

    Kanemaru

  • 0 in reply to Hide
    Guru 21045 points

    Hi John

     

    Thank you always for your kind support.

    Could you please reply regarding this matter?

    I’m looking forward to your reply.

     

    Regards,

    Kanemaru

  • 0 in reply to Hide
    TI__Guru**** 191445 points

    I'll see what I can find out.  It may take a few days.

  • 0 in reply to JohnTucker
    Guru 21045 points

    Hi John

     

    Thank you for your immediate reply.

    I understood.

    I’m looking forward to your reply.

     

    Regards,

    Kanemaru

  • 0 in reply to Hide
    Guru 21045 points

    Hi John

     

    I appreciate your support and help so much.

    Could you please reply regarding this matter?

    I’m looking forward to your reply.

     

    Regards,

    Kanemaru

  • 0 in reply to Hide
    TI__Guru**** 191445 points

    I don't know about the internal circuitry.  I don't think it is important to know whether it is controlled from VREG5.  You only need to know that the PWRGD function is turned off.  Any external voltage source can pull the PWRGD pin high even though the output voltage is not in regulation.  That is why we recommend to use VREG 5 as a pull up voltage for PWRGD as it will be low also, so PWRGD shows as "not good" when EN is low.  When EN gos low the device is disabled.  The VREG5 regulator is turned off and the PWRGD function also.  When EN is then asserted high, the device turns on.  VREG5 turns on.  When VREG5 gets above the internal UVLO voltage the device will start the slow start.  At the end of the slow start time, the output will be in regulation.  After 1.7 times the SS time, the PWRGD function is activated and PWRGD can be pulled up high.

  • 0 in reply to JohnTucker
    Guru 21045 points

    Hi John,

     

    I'm sorry for the delay in my reply.

    Thank you for the information.

     

    Regards,

    Kanemaru