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UCD3138 Light Load Module

Gerhard Kreuzer
Expert 2580 points
Other Parts Discussed in Thread: BQ24261

Hi

just tried out this module, but ... didn't work.

I get pulses in the regular distance dictated by the switching frequency, the pulses were very small and so some sort of Regulation is established. As I set the Minimum pulse width to protect my power stage, the Regulation is lost. ==> so LL didn't work.

Any tricks?

Has anybody bring it to work?

As I know, I should get pulses with at least my Minimum pulse width, but some cycles skipped to kept Regulation working, or I am wrong?

I attached the code for configuring the DPWM and the LoopMux to have LL, so whats wrong?

With best regards

Gerhard

UCD3138 code for LL.zip
  • 0
    Expert 2580 points

    Hi,

    it is  now more than 2 weeks waiting for any reaction ....

    Gerhard

  • 0 in reply to Gerhard Kreuzer
    TI__Expert 4970 points

    Gerhard,

    It looks like you might have missed the burst mode enable for the DPWM modules in your code:

    Dpwm0Regs.DPWMCTRL1.bit.BURST_EN = 1; //Burst (Light Load) Mode Detection Enable

    Dpwm1Regs.DPWMCTRL1.bit.BURST_EN = 1;

    Dpwm2Regs.DPWMCTRL1.bit.BURST_EN = 1;

    Dpwm3Regs.DPWMCTRL1.bit.BURST_EN = 1;

    I sent you an E2E conversation which includes some example code which uses the hardware burst mode as an example.

    Here is a waveform of how this code behaves in it's application:

    I hope this helps to answer your question. Please let me know if you need anything else. Thanks!

    Regards,

    Brandon Vonk
     

  • 0 in reply to Brandon Vonk
    Expert 2580 points

    Hi Brandon,

    aha. As far as I know I have both enabled, but I want to verify that. Unfortunately, after using the USB-to-GPIO Adapter with the bq24261 EVM, and a Firmware update the Software for the bq24261 EVM needed to do, the Design Fusion GUI didnt find the adaper any more, so I can#t do anything before this new issue is solved ....

    Yes I only used one Software at a time and yes I restarted the PC and reconnect the adaperet and have done this some times not only once. No Chance.

    With best regards

    Gerhard

  • 0 in reply to Brandon Vonk
    Expert 2580 points

    Hi Brandon,

    sorry, but issue isn't solved. I had this settings, so this doesnt help.

    There were some points:

    When I changed the LL Settings, nothing happens. So lastly I think, the LL module didn't work or isn't configured correctly.

    The minimal puls width is 40ns, that is far to short. The MOSFET didn't switch on fully, but, fortunately some energy is delivered to the output and so the system seems to be working. It gives some stable output, but I think, that isn't the way this chip should be used.

    I include some images and my project, maybe someone can find out whats wrong with the LL module.

    Facit: The power source is working now, it is a constant current source with limited output voltage, I only have one phase working but extending to three phases shouldn't the big deal. I am able to deliver 50µA (regulated) to 500mA and my load resistant range is 40 Ohms to 10M, thats what I tested uptil now.

    Problems: LL module. When output power is less than 0.5W or so output isn't that stable, hope the LL module can help. MOSFET isn't fully switched, cause minimal pulswidth is too short, but can't set a minimum.

    ToDo: Phase balancing.

    With best regards

    Gerhard

    LL Module issues.zip

  • 0 in reply to Gerhard Kreuzer
    Expert 2580 points

    ... no Response here for a looooooong time ......

    With best regards

    Gerhard

  • 0 in reply to Gerhard Kreuzer
    TI__Genius 17090 points
    I'm not an expert on the light load controller, but I would try increasing the DPWM_ON_TIME in the light load control register, and see if that makes the pulses longer. In the code you sent, you've got it set to min_pulse_width.