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Original question:

LM5050-1: Difference between LM5050-1, LM5050-2

LM5050-1: LM5050-1 solution to reduce Iq

Chen Jiao
Intellectual 810 points
Part Number: LM5050-1
Other Parts Discussed in Thread: LM74700-Q1

Hi team,

Could you please give some comment as below：

  1. Customer wants to use the solution of disconnect VS (as 8.2.4 shows), as it can only reduce Iq, could you please tell the Iq of this solution? We want to confirm if there is leakage from In and Out pin.

  2. In figure 29 of datasheet, D2 and D3 is used for reverse input voltage protection, could you please tell how to select diode and key parameter requirement?

  3. Customer has some concern of disconnect GND, floating GND may damage device. The application is battery pack connected with Vin. Appreciate if you can give some comment on this application, is there some risk comparing with disconnecting VS?

Thanks a lot.

Best reards

Chen

  • 0
    TI__Guru** 105361 points

    Hi Jiao,

    What is the target Iq? Can customer use LM74700-Q1 ?

    Best Regards, Rakesh

  • 0 in reply to Rakesh
    TI__Intellectual 810 points

    Hi Rakesh,

    Customer want to shut down LM5050 completely, it is used for product storage and transport.

    It is hard to change to LM74700, customer has evaluated LM5050 for a long time and project is urgent.

    Thanks.

    Best regards

    Chen

  • 0 in reply to Chen Jiao
    TI__Guru** 105361 points

    Hi Jiao,

    Thanks for the details and confirmation.

    There is no concern of GND disconnect but if we disconnect Vs as below, it will reduce the leakage current from OUT

    D2 prevents Vin from going below gnd in excess of the DS limits (in the case of reverse polarity like automotive apps).  D3 is for reverse polority protrection of the LM5050-1.  If you don't have reverse polarity requirements, you can eliminate these.  What we actually found is that using Q2 in the gnd does not fully eliminate the leakage path and it will instead divert more current to IN. The best way to eliminate the leakage is by removing Vs (no Q2 needed).  See attached test report.  Vs can still be a separate supply, but use a transistor under on/off control to remove bias to the LM5050-1 and the leakage from Out to In is eliminated.

    7762.PMP20096_LIQ_REVA_TEST_BJT.pdf

    Regards, Rakesh