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TPS62120: Power Management

Akshay Waghamare
Prodigy 80 points
Part Number: TPS62120

Hello team, We are using BUCK IC of Part number TPS62120DCNR  in one of our designs.

Input  to the BUCK is 6.5V from the two cr123a batteries in sereis, output we are setting to 2.8 V. 

We want to know that if we feed the 2.75V or more externally to the 2.8V trace is it going to affect the IC or not and is it affect the Battery? 

  • 0
    TI__Guru**** 191445 points

    Akshay,

    TPS62120 will be switching and regulating to 2.8 V.  It will depend on the source impedance of your external voltage supply.  Can you tell me what it is?

  • 0 in reply to JohnTucker
    Prodigy 80 points

    Hi John,

    Actually we are not giving any input to the buck IC but we have an option for supplying 2.8V externally(where the output of Buck IC of  2.8V and the external 2.8V are having the common trace/ Power Plane).

    We want to know that whether the external voltage supply of 2.8V will affect the Buck IC or the Batteries.

    Regards,

    Akshay

  • 0 in reply to Akshay Waghamare
    TI__Guru**** 191445 points

    Akshay,

    There are some different scenarios.  If the TPS62120 is powered and enabled it will try to regulate to its set 2.8 V operating point.  There is no provision for current sharing so one supply may provide all or most of the load current while the other supplies little or none.  If the TPS62120 is not powered one, then when an external supply is attached to the output the high side body diode can conduct and the input voltage will become one diode drop below the output.  If 2.8 V is externally applied, then the input may be at 2.2 V.  This is high enough that the TPS62120  can start to switch if EN is high or tied to VIN.  It is possible that the output may boost up the input.  You do not want this.  You should ensure that when no input voltage is present and there is 2.8 V externally applied to the output, that EN is held low.  Even better would be to use a load switch on the output.