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TPS62113: TPS62113 Low-Battery detect function error

Guangyan Liu
Intellectual 2130 points
Part Number: TPS62113

Dear Expert ,

Good day!

Our customer use the TPS62113 Low-Battery detect function, in the datasheet , it describe that when the LBI lower than 1.256V , the device will went into low power mode (suspend) , But in the customer application , when the LBI lower than 1.256V , the LBO become low  , but the output is still exist , until the input voltage level can not support to output , 

Here is the schematic , Vin is 6-8.4V ,Vout is 5.5V /1.3A, the customer set the Vin at 6.5V as the LBI trigger.

I had confirm the device mark , as I thought maybe the customer order the wrong device , but from the device marking , it is TPS62113.

Could you help me to confirm how to solve this issue ?

BR,

Leon.liu

  • 0
    TI__Mastermind 23740 points

    Hi Leon,

    Based on the schematic, you are using adding hysteresis to the LBI input and the calculated resistors seem to align well with the 6.5V trip point.

    However, do you mind confirming the hysteresis value you wish to use for the design - currently it is around 500mV?

    The R5 resistor is quite high and I recommend lowering R2 to get a more reasonable value (<1Mohm) for R5. Please check attached excel file  which I have already tuned but you can play around with numbers if you like. 

    In addition, can you please share the Vin, LBI, LBO and Vout waveforms when VIN is lowered to below trip point - 6.5V? 

    Thanks,

    Amod

  • 0
    Prodigy 30 points

    Hi Both，

    Thanks so much for the support，here are some updates：

    1. About the waveform of the signals you mentioned above，they are nothing special but DC straight lines just the same as normal working status；

    2. i tried removing the R5，still no LBI suspend；

    3. i tried replacing the chip，it works！i tried 5pcs of chips，2 of them are NG；

    4. The NG chip，the LBO falling point is around 6.2V，which is lower than the value 6.5V i‘ve set， no system suspend；

    5. the PG will fall to low when VIN<Vout+0.3；

  • 0
    Prodigy 30 points

    And the hysteresis value is 0.5V，i tested on the good chip board，the working parameters are perfact， just the same as i set

  • 0 in reply to MINMIN ZHU
    TI__Mastermind 23740 points

    Hi Minmin,

    It looks like you swapped out ICs on the same board where the other IC was not shutting down at 6.5V. Is this correct? Do you have any other identical BOM and layout boards where you can try out the other units which have a 6.2V threshold? It would be best if you can measure the LBI pin voltage on these good vs bad units to see if the trip point is close to 1.256V. The accuracy should be +/- 1.5% of 1.256V so we need to confirm if there is an issue with the units or other accuracy concerns like the resistors used in the divider (R1/R2/R5/R4).

    Thanks,

    Amod