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TPS1653: VIN<VOUT condition

Oba
Genius 15770 points
Part Number: TPS1653

Hello,

 

My customer is asking me what would happen when VOUT>VIN condition in TPS16530.

Because TPS16530 doesn’t have reverse current block function, reverse current would occur.

Then if the reverse current is too large, it would damage the device.

 

Is there any other problem with this condition?

 

Regards,

Oba

  • 0
    TI__Guru* 95911 points

    Hi Oba,

    If TPS16530 is in disable state, the reverse current during Vout>Vin would damage the body diode of the internal FET.

    Best Regards, 

    Rakesh

  • 0 in reply to Rakesh
    TI__Genius 15770 points

    Hello Rakesh,

    Thanks for your reply.
    If it is in enable state, is this condition acceptable?

    Regards,
    Oba

  • 0 in reply to Oba
    TI__Guru* 95911 points

    yes, as MOSFET channels supports bidirectional current flow.

    Best Regards, 

    Rakesh

  • 0 in reply to Rakesh
    TI__Genius 15770 points

    Hello Rakesh,

    Thanks. I checked the customer's concern more detail.
    The efuse output is connected to VM of a motor driver.
    Then the VM voltage could rise upper than the efuse input voltage because of the motor regenerative voltage.

    What would happen in this case?
    Does current limit try to off the switch even though the current direction is reversed?
    Even if it off the switch, it can't prevent the current low. If the current is big, I think nobody can't stop it. 
    I would like to know detail possible story in this case.

    Also, when reverse current happens in enable state, does PGOOD remain high?

     
    Regards,
    Satoshi Obata

  • 0 in reply to Oba
    TI__Guru* 95911 points

    Hi Oba,

    Our devices doesn't provide current limit in reverse direction.

    If the switch is OFF, the large revere current can damage the body Diode of the internal FET.

    Yes PGOOD remains high in enable state 

    Best regards,

    Rakesh 

  • 0 in reply to Rakesh
    TI__Genius 15770 points

    Hello Rakesh,

    Thanks for your reply.
    When the device is enabled(switch is ON) and there is reverse current, how much reverse current is allowed not to damage the device?

    Regards,
    Oba

  • 0 in reply to Oba
    TI__Guru* 95911 points

    Hi Oba,

    The body diode of internal MOSFET is not expected to support high current for long duration. It should be able to handle ~4.5A for short duration (<10 us) and small current (< 100mA) for long duration.

    Best regards,

    Rakesh 

  • 0 in reply to Rakesh
    TI__Genius 15770 points

    Hello Rakesh,

    Thanks. I understand the case when MOSFET is off.


    Q1.

    When MOSFET is ON and there is reverse current, how much reverse current is allowed?


    Q2.

    And let me confirm one more thing for the below your previous comment.

     >Our devices doesn't provide current limit in reverse direction.

     Does it simply mean the MOSFET is never turned off (PG=HIGH) even if there is big reverse current flow in enabled state?


    Regards,
    Oba

  • +1 in reply to Oba
    TI__Guru* 95911 points

    Hi Oba,

    A1) 4.5A

    A2) Yes

    Best regards,

    Rakesh