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BQ24072T: battery start abnormal in BQ24072T

hefang shang
Prodigy 20 points
Part Number: BQ24072T

hi,

I am from DEFA technology in wuxi, our headquarter is in Norway.

Now we are using your BQ24072T in our product, but now I have problem, can you pls. help me check:

When I connect DC source (5VDC) at input pin, it can work well, our load is about 1.4A in out pin; but if I just connect the battery of 3.7V no DC source connected, then sometimes it can start, sometimes it can’t, and when the out pin is about 2V ( normally it should be about 3.7V).  I checked the datasheet of BQ24072T, the battery path can give 4.5A, so I don’t know why, pls. help me double check. Thanks.

 

Below is our schematic drawing, the US? Is the 3.7V Li-battery. (I copyed a PDF in the attachment).

8750.Sheet1.pdf

  • 0
    TI__Guru 67476 points
    Hello
    The schematic look OK.
    I tested this in the lab today up to 3.0A battery to OUT with no DC source, did not see a problems. Also tested at 1.0A, 1.5A and 2.0A and battery can support load.

    On thing to check is the battery voltage under this load, if it is dropping below 3.0V it is possible the circuit is running out of voltage to drive the internal mosfet. In my test with 1.5A problems started at about 2.5V battery voltage.
  • 0 in reply to Bill Johns
    Prodigy 20 points

    hi Bill,

    In this test I use the DC source to simulate battery also, that means just connect DC source to Battery input pin ( no connect at DC source input pin). and I set the input current about 2.1A or 7.1A max. It is also same as battery start.

    I copied the test on out pin and battery input pin, pls. help double check. And I find that if I restart the product in short time interval, then it is easy to start error; and if I restart in a little long time interval, then normally it can start ok. Is there some setting not good in the schematic or cold hot start?

    Thanks.

    battery management Test_BQ24072T.rarcheck.