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TPS61232: Issue with overloading

user4928902
Prodigy 50 points
Part Number: TPS61232
Other Parts Discussed in Thread: BQ24253, , TPS61230, TPS61230A

Hello

I'm designing a small battery bank for a product, and I picked the mentioned step up IC.
I designed a PCB to test it along with the bq24253 battery management IC and it works fine.
I tried to stick with the recommended PCB layout for the TPS to avoid issues.
It all was fine until I connected the Moto G Play smartphone to charge it, that is when the issue appeared.
When that particular phone was being charged, the TPS would short the switching inductor to ground as long the phone was being connected.
That would result into a constant DC current of 5A flowing through the inductor and IC, overheating and damaging both components.
At first I did not use the recommended components found in the datasheet so I ordered the exact one specified but the issue persisted.
In no other scenario I managed to replicate the issue, I tried using static DC loads (programmable load), and charging various other phones.
I'm suspecting that the switching mosfet latches up somehow due to some interference caused by the phone, but I'm not sure.
Another thing I noticed is that when charging that specific phone with a regular wall charger, the charger would make an unusual noise.
The issue happens very abruptly so its hard to probe what is going on. Charging the same phone with another step up IC did not cause any issues.

What could be wrong here and is there a way to fix the issue?

  • 0
    TI__Mastermind 46905 points
    could you share the schematic and layout? it is unlike that the switching mosfet latches up. it seem the IC is damaged and cause the SW pin short to ground, then large current flowing through the inductor.
  • 0 in reply to Jasper Li
    Prodigy 50 points
    I copied reference schematic (exactly), and followed the reference layout. I built multiple boards, and I replaced all of the components (IC included) multiple times, so that is not the problem as ti seems. All of the components were sourced from Mouser, so I don't think they are bad.
    Also if the IC was damaged the problem would persist when using any other loads, not exclusively that particular phone model.
  • 0 in reply to user4928902
    TI__Mastermind 46905 points
    from your description, currently i have no clue that why this happen. please help to do this experiment
    1. power the TPS61232 with a power supply, and using e-load to simulate the phone load. this can check if the TPS61232 can operates well.
    2. apply an TPS61230EVM, connect the EVM with the system board to charge the phones. this can check if the problem is related to the system board.
  • 0 in reply to Jasper Li
    Prodigy 50 points
    Hi

    1. Yes, I already tried that and the device works flawlessly. The issue appears only with that specific phone model, all other phones brands/models charge without any issue.
    2. I don't have one, I'll have to order one and test it.
  • 0 in reply to Jasper Li
    Prodigy 50 points

    Today the eval board arrived, and I was able to test it.
    The results are a bit different, but the problem persists.
    Instead of a complete short, the eval board starts consuming 3A, but is sill capable of providing 5V at the output.
    Again the issue is only present with the mentioned phone model, other phones do not show such an issue.
    Test setup:
    3.7V high C rating battery connected at the input, current measurements were done using the Keysight 34461A and verified with a cheap multimeter (just in case).
    An micro usb connector was soldered with very short wires at the output, and phone connected to it.
    The situation is identical even when bypassing the ampermeter by directly connecting the battery to the eval board with short wires, I can see the problem persists by the board heating up rapidly.

  • 0 in reply to user4928902
    TI__Mastermind 46905 points
    1. when you said the eval board consumes 3A, do you mean the input current of the eval board is 3A?
    2. not sure about the charging current for the special phone, if the charging current is very high, 2.5A for example, the TPS61230 could be very hot. for this high current application, i would suggest using TPS61230A or TPS61236 because of better efficiency. and the layout should be also careful for thermal dissipation.
  • 0 in reply to Jasper Li
    Prodigy 50 points

    Hi

    With that particular phone, the phone charging current goes up to 1.7A, but the eval board consumes 3.7A, which is way to much.
    I actually don't need the battery pack I'm building to work on every device, its intended to power another specific device, but since it has a microsub connector its possible to connect it to anything else. The main difference between my board and the eval is mostly that the eval board has components spread out a bit more, where I packed them closely together so I can reduce pcb size.
    I don't actually need high power output from it, the maximum it should ever deliver is 1A for the intended use.