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TPS61235P: TPS61235P didn't back to active mode with 100mA

Kay Chen53
Expert 2225 points
Part Number: TPS61235P
Other Parts Discussed in Thread: BQ24195

TPS61235P didn't back to active mode with 100mA

Hi There:

Greeting~ I'd like to need your help to provide some suggestion about our customer who use the TPS61235 & BQ24195 as power bank solution (see attached file schematic)

They now have an problem about TPS61235 mode change from inactive mode to active mode. (see the attached 1.jpg)

detail desription:

1. EN-pin low->High, with a current raise (about 40mA, less than INACT_th), INACT pin enable and turn into inactive mode

2. After about 450ms, with a current (about 100mA, greater than INACT_th), INACT pin didn't disable and turn into active mode

our customer would like to know:

a. why device didn't change the status when the 100mA loading occurs?

b. the INACT_th & INACT whether have the tolerance with threshold current & time?

Thanks again~

B&R

  • 0
    TI__Mastermind 46905 points
    Do you see the problem in every system board? does the INACT output low logic if customer further increase the load condition? the datasheet don't specify the min/max the data, but i would expect this current not higher than 120mA
  • 0 in reply to Jasper Li
    Expert 2225 points
    Hi Jasper:

    thanks for your respond, I'd like to make some more clarification about this one issue.

    1. For this power bank application, customer side didn't specific the total failure rate, but according the information, there were 2~3PCS could see this symptom.

    2. For the increase the load condition, is there any suggestion timing for that? But this case would be the MCU didn't see the TPS61235P become active mode once the second load current (100mA) occurs.

    3. From the datasheet 8.3.6 Load status indication says, the boost shall enters active status when output current is detected higher than INACT_th (50mA), but in this case it wasn't.

    Please reply the command to me if there is anything unclear or misunderstanding, we'd like to feedback to customer as possible as we can.

    Thanks again.
  • 0 in reply to Kay Chen53
    Expert 2225 points
    Hi Jasper:

    Sorry for bother you again, we've an urgen case and been pushed by end customer today, could you help to prvide us some commend within this week?
  • 0 in reply to Kay Chen53
    TI__Mastermind 46905 points
    1. we need to make sure this problem is caused by our device. so i suggest to increase the load to 150mA or higher with an E-load to check when the INACT become low logic. it is not related to the timing.
    2. the 50mA is typical value. currently i don't know why the device doesn't pull down INACT at IOUT=100mA condition, so we need to debug to find the root cause.
  • 0 in reply to Jasper Li
    Expert 2225 points
    Hi Jasper:

    1. Purely use the E-load is OK when INACT below logic
    2. Any suggestion we could check from the schematic of customer's TPS6123?

    Thanks again.
  • 0 in reply to Kay Chen53
    TI__Mastermind 46905 points
    1. No sure your meaning. do you mean the device operates well with e-load, and INACT becomes low logic at IOUT>50mA?
    2. about the schematic, i don't find a problem that can cause this behavior.

    could you swap the ICs of good board and bad board? so we can know the problem is caused by the IC or its external components.
  • 0 in reply to Jasper Li
    Expert 2225 points
    Hi Jasper:

    Thanks!~
    With e-load and INACT becomes low logic at Iout > 50mA ---> TPS61235 works normally
    with the issue PCB, we'll try to swap IC and test again.
  • 0 in reply to Kay Chen53
    TI__Mastermind 46905 points
    so you are saying that the device operate normally with E-LOAD: INACT logic low when IOUT > 50mA. however, with actually load, the INACT keep at logic high even when IOUT=100mA. do i understand correctly?
  • 0 in reply to Jasper Li
    Expert 2225 points
    Hi Jasper:

    Yes~ Your understanding is correctly. We're also trying to modify the INACT pull-Hi resistor (1M) to see whether will impact or not.

    Thanks again.