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Problems with the BQ24617EVM

Markus Kwasny
Prodigy 30 points
Other Parts Discussed in Thread: BQ24617EVM

Hello Everybody,

I have some problems with the BQ24617EVM.
I did everything according to the datasheet, but now it seems the second board to be broken again.

To load 4 Li-Ion cells I changed the resistors R25 and R28. R25 is now 715K Ohms and R28 102k Ohms.
So I get 16.8V to charge the batteries.

Then I connected a power supply with 24V and 3A to J1. After that I connected a power supply with 1.8V on J4 (TS).
Then still connected the batteries and set the jumper 5.

Now everything seemed to work.
The charging current was 3A and the voltage slowly increased.

After about half an hour of charging it suddenly stopped and the LEDs ACDRV, BATDRV and STAT1 are flickering alternating.
If I remove the batteries or JP5 can be heard a high-frequency tone. This was not previously the case.

Nothing changes if I reconnect the power supplys.
Now I think this board is also broken, but without external influence. Nobody touched the board during charging.

Does anyone have an idea what causes this error here?

  • 0
    TI__Expert 5565 points

    Markus,

    To isolate the problem to the EVM, please replace the battery pack in your setup with a voltage source that has the ability to sink current. This will be your battery simulator. Slowly raise the voltage of the battery simulator from 0V to 17V and observe the charge current. Do does the problem still persist with the battery simulator? If so, could you provide a scope capture of the following nodes: Input adapter voltage, SRN voltage, HIDRV, LODRV, and inductor current.

  • 0 in reply to Smriti B
    Prodigy 30 points

    Hello There,
    Thank you for your reply.

    I do not have an electronic load to simulate the battery.
    I only have a potentiometer with 100 Ohm - 60W. Maybe I can use it to simulate.

    My input voltage is ok (no frequencies on it).
    The same is for the PS#2 at the TS-Pin.

    What is the SRN voltage?
    How to measure the inductor current?

    If there is no load at J5(BAT) the scope shows the following:

    When no load is connected, you will hear a high frequency sound.

    When I plug in the batteries, the LEDs starts to flicker an the scope shows the following:

    When I connect the potentiometer and turn it to 0 ohms, there is a current of 0,3A. (ISET2 = 0,3A)
    The scope shows the following:

    If I slowly increase the resistance at the potentiometer, the voltage also increases at J5 (BAT) and the current is stable at 0,3A.
    When the voltage reaches 12V, the current begins to increase to 0.5A.
    If I increase the resistance a bit more, then the voltage suddenly jumps to 17V an the current drops to 0,3A again.

    When I put the probe on the left side of the inductor, the scope shows the following:
    I hope this informations could help.
  • 0 in reply to Markus Kwasny
    TI__Expert 5565 points

    I resistive load won't work with a battery charger since it will fail the battery detection algorithm. Do you have access to a large cap (>10mF)? If so, try using a large cap instead.

    For your last imag (of the PH node), what is the test condition for that scope capture? Can you also post a scope capture of the PH node when no battery is connected?

  • 0 in reply to Smriti B
    Prodigy 30 points

    Here is the capture without a battery.
    Now only the 24V connected to J1 and 1.8V to J4 (TS). The Probe is connected to PH (TP8).

    The Last picture of my previous Post was taken with the resistor. The probe was connected to PH (TP8) and 24V to JP1 and 1,8V to JP4 (TS).

    I ordered a capacitor, it should arrive in the next few days.