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TPS27S100: In case of negative voltage at Out pin

Hirotaka Matsumoto
Guru 27525 points
Part Number: TPS27S100

Hi all

Would you mind if we ask TPS27S100?
When negative voltage occurs at Out pin, Reverse current occurs.
And then, does the current flow into Vin via FET's body diode?
It seems that there are no back to back FETs internally.

There is the description on the datasheet P17 as follows;
"Excessive negative voltage could cause the power FET to break down. To protect the power FET, an internal clamp between drain and source is implemented, namely V DS(clamp) ."
This voltage clamp is protection for FET, right?
We recognize that there is no protection for reverse current.

Kind regards,

Hirotaka Matsumoto

  • 0
    TI__Mastermind 24740 points
    Hello,

    The negative voltage appears on output when shwitching off an inductive load. In this case the current flows in the same direction and the body diode is not conducting any current. The clamp is protecting the FET is case of swtching off an inductive load.
    Body diode conducts only if VOUT is higher than VIN. The reverse current protection is described in the datasheet page 22, Method 1 and Method 2.
    Reverse current value is specified in the datasheet under OUTPUT DIODE CHARACTERISTICS section.

    Regards