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BQ24072 Input current limited to 330mA

Jay Carlo De Claro
Prodigy 160 points
Other Parts Discussed in Thread: BQ24072

Hi,

Using BQ24072, I have done a pretty standard design. (Schematic similar to the typical application circuit on page1) The boards are back and one of the first things we tested was input current. Due to EN1/2 settings we expect input current to be limited to 500mA but once we try we cannot go beyond 330mA. 

Any pointers from the group where we should look?

Thx,

Jay

  • 0
    TI__Guru**** 166106 points

    Is the ISET resistor properly sized? Is the TS pin function being used properly and if not, is there a 10kohm resistor to ground to disable the TS function?  How close is the battery voltage to regulation voltage, i.e. has the current begun to taper off?  Is the IC's thermal pad properly soldered down so that the IC is not getting too hot and going into thermal limiting?

  • 0 in reply to Jeff F
    Prodigy 160 points

    Hi Jeff,

    Thanks for your respond.

    I set the ISET resistor exactly the same as the application note Also configure using USB500 (EN2=0 EN1=1) but I can get upto 330mA input current. And the TS function I put 10K resistor for that. My Vin=5V and I can get at the Vout 4.4V without battery installed.Thermal pad of the IC is connected to the GND and I touch the IC its not getting hot.

    Any other pointers?

    Thanks,

    Jay

  • 0 in reply to Jay Carlo De Claro
    TI__Guru**** 166106 points

    What is voltage of battery when installed?  As explained on page 16 at Power On, the device switches on the input FET Q1 with a 100mA current limit to checks for a short circuit at OUT. When VOUT is above VSC, the FET Q1 switches to the current limit threshold set by EN1, EN2 and RILIM and the device enters into the normal operation.

  • 0 in reply to Jeff F
    Prodigy 160 points

    The voltage when installed is around 3.7V. I checked also the eval kit and I cant reproduce the USB500 mode.

    Basically we want to use the BQ24072XXX for USB500 application, but I cant reproduce the input limit to 0.5A.

    However,In TI (BQ24072 eval kit) I can reproduce the USB100 settings with this I can observed a 95mA input current limit, when I change the settings of the eval kit to USB500 I can reach only to 330mA.

    WIth this test I let the battery charger work first then apply a Load on the output.

    Can you help me solve this issue, I'm now worried if I'm on a right track with my design.

    Thanks a lot.

    See below for our schematic of BQ24072.

  • 0 in reply to Jay Carlo De Claro
    Prodigy 160 points

    Hi Guys,


    Did anyone already design using BQ2407X family using USB500 settings?

    Any tips and pointers? Because even the Eval kit I cant set thru this settings.

    Please help guys.