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TPS65132B / short circuit protection

K.Yaita
Guru 29720 points
Other Parts Discussed in Thread: TPS65132BEVM
Hi Team,
 
I have 2 questions about short circuit protection of TPS65132B.
Could you please give me your advice?
 
(1)
My customer concerned if TPS65132B has short circuit protection for VPOS and VNEG.
Do these have short circuit protection?
I'd also like to know how much curret could flow in short circuit.
 
(2)
Does VREG(boost output) have short circuit protection? I supposed VREG capacitor is damaged to be short.
If VREG doesn't have, I also concerned how much current could flow under VREG<VIN condition. 
I think valley current limit works in VREG>VIN, but VREG<VIN isn't the case.
 
Best Regards,
Yaita / Japan disty
  • Guru 29720 points
    Could you give me your comment?
    Your help would be appreciated.
     
    Best Regards,
    Yaita
  • TI__Prodigy 140 points

    Hello Yaita,

    The TPS65132B device does not have a special short circuit protection. At a short circuit condition on VPOS or VNEG the short-circuit currents are defined by the current limits of the converters and also by the device mode (for VNEG only).

    If Vreg has a short to GND then the IC continuously tries to startup. The short-circuit current is limited by the startup current limit (which is not the valley current limit).

     For instance, for short circuit conditions measured on the TPS65132BEVM for the IC in the tablet mode the short-circuit current values are:

     VNEG short to GND: Iin=155mA @Vin=3.3V; Iout=100mA

     VPOS short to GND: Iin=610mA @Vin=3.3V; Iout=370mA

     VREG short to GND: Iin=60mA  @Vin=3.3V; Iout=45mA

    Best regards,

    Natasha

     

  • in reply to Natasha Novik
    Guru 29720 points
    Hi Natasha-san,
     
    I really appreciate for your support.
    I will inform to my customer about that.
     
    Best Regards,
    Yaita
  • in reply to K.Yaita
    Guru 29720 points
    Hi Natasha-san,
     
    I would like to ask additonal question.
     
    My customer considers to set a fuse at primary side(Battery side) for short protection.
    If SW pin shorts to GND, I think a large current flow from Vin to GND and then Inductor become saturation.
    How about CFLY1(CFLY2) shorts to GND?
    Does large current flow from Vin to GND under this situation?
     
    Best Regards,
    Yaita
  • in reply to K.Yaita
    TI__Prodigy 140 points

    Hello Yaita,

     you are right, shortening of the switch pin of the boost converter to ground  will cause a short Vin to GND through the inductor that leads to high current and to inductor saturation.


     If CFLY2 is shorten to ground then a short-circuit current is  defined by the current limit of the charge pump converter and also by the device mode (for instance, 50mA for Smartphone mode).

    Shortening of CFLY1 to GND leads to high current ( 1A or higher). 

     

    Best regards,

    Natasha

  • in reply to Natasha Novik
    Guru 29720 points
    Hi Natasha-san,
     
    Thank you for your clear explanation.
    I appreciate for your support.
     
    Best Regards,
    Yaita