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Original question:

LM5050-1: LM5050 quiescent current too big

TPS2491: TPS2491 quiescent current too big when un-enabled

Chen Jiao
Intellectual 810 points
Part Number: TPS2491
Other Parts Discussed in Thread: TPS1663

Hi team,

We found TPS2491’s current consumption is around 500uA when enable pin is pulled down to ground. But as datasheet shows, the Iq is around 90uA when un-enabled. And after removing TPS2491, the current decrease by 500uA. The current is read from gauge of the battery pack.

Could you please check customer’s schematic as attached and give some solutions to solve this?

Best regards

Chen

  • 0
    TI__Guru** 102881 points

    Hi Chen,

    What is the output voltage during current measurement in disabled mode ? As per datasheet test condition, it has some influence on the Vout potential. Can you check with VEN = Lo, VSENSE = VVCC = VOUT and see if it is still higher than 90uA (typ).

    Regarding schematic, the diode D203 orientation looks wrong. Cathode of D203 should be connected to the GATE side.

    Best Regards, Rakesh

  • 0 in reply to Rakesh
    TI__Intellectual 810 points

    Hi Rakesh,

    Thanks for the reply.

    The output voltage is around 52V. And we have checked Vsense=Vvcc=Vout.

    When un-enabled, the quiescent current only comes from Vcc, am I right? And theoretically only 90uA total quiescent current in total.

    For D203, it has been corrected, sorry for late update.

    Thanks a lot

    Best regards

    Chen

  • 0 in reply to Chen Jiao
    TI__Guru** 102881 points

    Hi Chen,

    Correct. The quiescent current only comes from Vcc

  • 0 in reply to Rakesh
    TI__Intellectual 810 points

    Hi Rakesh,

    We meet another issue of start-up during debugging TPS2491. The CT value may need to improve.

    Could you please help select the right CT value for us? I have input the voltage, Cout and MOS parameters in the attached Excel.

    I found that larger CT can make TPS2491 meet SOA, could you please tell me what's the influence if the CT value is too big?

    Thanks a lot.

    Copy of TPS249x_8x_Design_Calculator_REV_B.xlsx

  • 0 in reply to Chen Jiao
    TI__Guru** 102881 points

    Hi Chen,

    The FET SOA current support is very poor and please select strong FET such as CSD19502Q5B. Even adjusting Ct value does not help here.

    Alternatively, I suggest to use TPS1663 eFuse to simply the design as it offers better performance and higher integration.

    Best Regards, Rakesh