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Regarding the GUI adjustment frequency, it is limited to ±20%.

Martin
Prodigy 170 points

Part Number: PMP23340UCD
Other Parts Discussed in Thread: UCD3138A

Hi，

Thank u for ur time.

I have some doubts about PMP23340UCD.

      Hardware：PMP23340UCD(UCD3138A) 
      Firmware：TI supplied routines——UCDIBCFirmware 

Issues：

  1. I found that the frequency_switch is adjusted through the GUI and eventually written to pmbus_dcdc_config[0].min_period.And then how does the firmware reconfigure the DPWM module output frequency? (I didn't find the correlation logic for this, and didn't notice configure_dpwm_timing() being called after this)
  2. The GUI can only set frequency_switch within (1±20%) 1000KHZ, is it because the Filter output camp is limited?
  3. I found that the limiting issue is related to the following two functions, but I can't read the period_change() function, it doesn't seem to change the filter limit value？
  4. After adjusting the frequency through the GUI, where does it determine if the threshold is exceeded (if it's at the filter output, why go through the filter just to change the frequency)？

Best Regards.

  • 0
    TI__Genius 14580 points

    Hello,

    1. The filter is configured at resonant mode, and changing the filter output , the frequency is changed. This is done from UCD hardware. 

    2. Yes.

    3. period_change() function is called to update the new period when GUI sends a new period command.

    .4.

  • 0 in reply to Sean Xu
    Prodigy 170 points

    Hi,Sean

    Thank you for your reply.

    I got it.

    But then I have a new doubt.Thank u again for ur time.

    Issues：

    1. If VIN changes, the frequency should increase or decrease to keep VOUT constant.I understand that  Filter YN  is clamped at 1MHZ when it is greater than the Filter Yn Camp High, and the output frequency is unchanged.So if the Filter YN is less than the maximum clamp value, what maintains the frequency at 1 MHZ?
    2. In handle_ramp_up_state(), I modify 1.25 to 2 to expand the lower limit of frequency modification to 500KHZ.I modified 0.84 to 0.65, and the output waveform no longer changes when the frequency is greater than 1250KHZ.It's because the YN isn't affected by the modified clamp value anymore (or rather, without the clamp value, the system's output frequency should be 1250KHZ)?
    3. Modifying TH from (1/(1000e3)) to (1/(1500e3)) can make the output frequency 1MHZ-1.5MHZ; but modifying TH to ((1/(900e3)), the board has no waveform output. There is a hidden danger in this modification, but I'm trying to figure out why there is no output when TH is greater than ((1/(900e3))?

    Best Regards.

  • 0 in reply to Martin
    TI__Genius 14580 points

    Martin,

    Maybe something is changed if the frequency is out of rang., I need verify it on the board. Give me few days.

    Regards,
    Sean

  • 0 in reply to Sean Xu
    Prodigy 170 points

    Hi,Sean

    Thank you for the reply.

    Perhaps you could start by helping me puzzle out the first two questions.

    I'm a little confused about that.Increasing or decreasing VIN（48v）, why is Filter YN all clamped at 1M by Filter Yn Camp High?

    Also, when I increase the Filter Yn Camp High and the output frequency is around 1250KHZ, it seems that Filter YN is no longer clamped by Filter Yn Camp High, right?

    Does the RESON_DEADTIME_COMP_EN bit need to be enabled in resonant mode? I didn't find it in the source program.

    Best Regards.

  • +1 in reply to Martin
    TI__Genius 14580 points

    Hi, Martin,

    If Vin is low, YN is always clamped to 1MHz. If Vin is too high, it will trigger OVP before the frequency increases.

    I need check your this question: when I increase the Filter Yn Camp High and the output frequency is around 1250KHZ, it seems that Filter YN is no longer clamped by Filter Yn Camp High. 

     RESON_DEADTIME_COMP_EN is not used in UCD3138A.

  • 0 in reply to Sean Xu
    TI__Genius 14580 points

    Hi, Martin,

    The output frequency is clamped only if it is in regulation state. 

    Regards,
    Sean

  • 0 in reply to Sean Xu
    Prodigy 170 points

    Hi，Sean.

    Thank you for your reply.

    Do you mean that adjustment of the frequency via the GUI in the regulated state is limited to ±20%？

    I understand that.

    The problem I'm having is:Change the frequency adjustment limit from ±20% to ±50%，but it can only be adjusted from 500KHZ to 1250KHZ ，setting over 1250KHZ, the frequency remains unchanged.

    I have a guess：The output frequency is clamped at 1 MHZ by FILTERYNCLPHI, at which point YN_HIGH_CLAMP = 1.The GUI adjusts the frequency by modifying the value of FILTERYNCLPHI.Now，unable to adjust frequencies greater than 1250KHZ via GUI.Is it because the maximum output of the frequency is 1250KHZ when it is not clamped by FILTERYNCLPHI?

    If I'm not thinking correctly, can you give some advice?

    Meanwhile，here's a question about Ramp, can you help me out?

    PMP23340UCD: DAC Ramp Model——softstart - Simulation, hardware & system design tools forum - Simulation, hardware & system design tools - TI E2E support forums

    Regards,
    Martin

  • 0 in reply to Martin
    TI__Genius 14580 points

    Hi, Martin,

    I made change both coefficients to 0.6,  and 0.56, the frequency can be changed to 1300KHz from GUI.

    About the other question, can you restart the post?

    Thanks,
    Sean

  • 0 in reply to Sean Xu
    Prodigy 170 points

    Hi,Sean,

    Thank you for your reply.

    With a coefficient of 0.84, the upper limit of the output frequency adjusted through the GUI is 1200KHZ.

    Changing the coefficient to 0.6, shouldn't the maximum output frequency adjustable by the GUI be 1670KHZ (1000KHZ * (1/0.6))?

    I was confused about this part.

    About the other question, i will restart the post.

    Regards,
    Martin