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TPS92641: Current sense

Takashi Yamaguchi
Genius 13420 points
Part Number: TPS92641

Hi team,

Could you help with the question below from my customer?

How behave this device if the current detection can not be done correctly due to the CSP or CSN pin is open or short each other?
Customer is concerned that the feedback control may not work properly and excessive current may flow.

Regards,

Yamaguchi

  • 0
    TI__Mastermind 18890 points

    Hi Takashi-san,

    The TPS92641 only has the CS pin feeding back there is not CSP or CSN.  If the CS is shorted to ground the control loop will not sense any current and command higher current and as you mentioned will not work properly and cause excessive current.

    Thanks Tuan

  • 0 in reply to Tuan Tran74
    TI__Genius 13420 points

    Hi Tuan-san,

    I received the additional questions about the excessive current. Could you support the following questions?

    1. Does not an excessive current flow when the CS pin is open? How behave the device?

    2. If the CS pin is shorted to GND or open, will the excessive current flow until LED or FET is broken? Does the device have another protection to stop this excessive current?

    Regards,

    Yamaguchi

  • 0 in reply to Takashi Yamaguchi
    TI__Mastermind 18890 points

    Hi Yamaguchi-san,

    The CS pin if open it's floating...There is only leakage that will either pull it up or down.  In this case the current in the LED can ramp up high or not ramp at all depending on the leakage direction.  If the LED current ramps up high then it will reach a point where over-current protection on the high side FET due to RDson will be activate and this is the protective mechanism.  The FET still has to handle this current without damaging for this protection mechanism to work.  Please see section 7.3.11 of the data sheet.

    If CS pin is shorted to ground then excessive current will flow until the switch over current protection is activated same as above.

    Thanks Tuan