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TPS756: TPS75633KTTT

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Part Number: TPS756

I have a basic doubt. Suppose I am using TPS75633KTTT to generate an output of 3.3 V and the voltage at input pin number 2 is connected to a battery of range 4.2 V (Max, when full charge) to 2.8 V (Min). Also 3.3 V is connected to many active ICs whose total current will be 1.173 A. My doubt to you is that will the input current (current through pin number 2) be always greater than output current,i.e., 1.173 A), when the battery discharges slowly from 4.2 V to 2.8 V.

Also note that my EN pin is connected to IN pin. So how much will be the EN current be, when the battery discharges slowly from 4.2 V to 2.8 V.

  • Hi Ameet, 

    The UVLO for TPS756 has a maximum value of 2.75V, which means for your Vin at 2.8V, the LDO is on and in dropout. During dropout, the pass-FET switch of the LDO will be on to allow current flowing from Vin to the Vout. You will have some current flowing from Vin to Ground at the same time, so the input current will be higher than your load current during the process that the battery voltage drops from 4.2V to 2.8V. 

    For voltage higher than 2V, the EN signal will turn on the part, so the EN will not affect the LDO running in dropout when the input voltage drops to the point it's no longer in regulation. 

    Regards, 
    Jason Song

    Please click the "Resolved" link at the bottom of this post if I have answered your question.

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