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TPS536C9T: Non Linear Control-OSR/USR

Ringo Chen
Prodigy 10 points
Part Number: TPS536C9T

Tool/software:

Hi,

This is Wistron power team,

We have some questions about using Fusion Design Online v7.10.5 on TPS536C9T,

(1) While we knew that TBLANK is the controller also limits the time between sending pulses to any two adjacent phases,

but I wanna know how we can use OSR_TBLANK for Transient? Is it used for multiphase only?

What's the impact if we chose smaller or larger value?

(2) What's OSR_BLANK meaning? For example, when we choose 11b:8uS which means we choose Pulse
Truncation Only at TONmin? Besides, what's the note meaning "Time for which OSR is blanked after OSR get set"? 

Sincerely,

Ringo

  • +1
    TI__Intellectual 1945 points

    Hi Ringo,

    OSR_TBLANK sets the time between PWM pulses during an OSR event. So having a higher OSR_TBLANK will cause more effective overshoot reduction but also a slower recovery time. Since the time between pulses on a single phase is longer than OSR_TBLANK, it won't have an affect in single phase operation.

    OSR_BLANK sets the duration of the OSR response. It sets how long the controller will act in OSR before going back to normal operation. It does not change OSR_CFG, which selects what OSR response the controller will take.

    Regards,

    Troy

  • 0 in reply to Troy Johnson
    Prodigy 10 points

    Hi Troy,

    Thank you.

    So USR_TBLANK means the same thing right? The only difference is that USR is for Vundershoot.

    I also noticed there are "USR TBLANK EN" & "USR_NAP" as below,

    (1) What's the meaning of Enable/Disable USR1 based Tblank and how can we use it for improving Transient?

    (2) What's USR_NAP? Number of adding phases?

    (3) USR is just for Multiphase right? Does it take effect on single phase?

    Sincerely,

    Ringo

  • +1 in reply to Ringo Chen
    TI__Intellectual 1945 points

    Hi Ringo,

    Yes, USR_TBLANK sets the time between pulses during a USR event, if USR_TBLANK is enabled.

    USR_TBLANK_EN sets whether USR_TBLANK will be used in place of the normal TBLANK during USR. If disabled the normal TBLANK will be used, but USR will still be active.

    USR_NAP is the number of available phases that the controller can add during USR.

    Since adding phases and TBLANK are only for multiphase, USR will not effect single phase.

    Regards,

    Troy

  • 0 in reply to Troy Johnson
    Prodigy 10 points

    Hi Troy,

    So there are 3 kinds of TBLANK in Non Linear control includes OSR_TBLANK, USR_TBLANK and TBLANK1 in the Timing section,

    (1) You mentioned normal TBLANK, is it Timing's TBLANK1?

    (2) Is Timing's TBLANK1 meaning of controlling the time of PWM pulse within adjacent phases during Transient event 

    and it only effects multiphase, not for single phase right?

    Is the shorter the TBLANK1, the better Transient Vundershoot?

    If so, is it recommended of setting it to 0nS? As I know, if the blank time between phases is too short, it will impact 12Vin stability.

    (3) What's the "START" meaning and the beginning of START timing? How can I use it for improving Transient?

    (4) Let me check again, Non Linear control's Timing for PWM pulse only effects during Transient event right?

    It shouldn't impact PWM pulse during static state.

    (5) What's the priority you recommend of using these Non Linear Control with OSR/USR and Timing for improving Transient?

    Tuning "OSR/USR" first or "Timing" first?

    Sincerely,

    Ringo

  • +1 in reply to Ringo Chen
    TI__Intellectual 1945 points

    Hi Ringo,

    1. Yes, TBLANK1 is the normal TBLANK that will be used when not in an OSR or USR event. It applies during steady state and during transients that don't exceed the set OSR or USR limits.

    2. TBLANK1 adjusts the minimum time between PWM pulses. It will only have an effect during multiphase as the normal delay between pulses on a single phase will be longer than TBLANK. Decreasing TBLANK1 will improve transient speed, but decrease stability. It should not be set lower than required for your desired transient performance.

    3. START parameters are used during startup, or when the system is first enabled. TBLANK_START and MINTON_START should be shorter than TBLANK1 and MINTON, so that the system gets to steady state faster.

    4. The Timing settings will apply during steady state, as well as transients that do not trigger the OSR or USR settings.

    5. OSR and USR should only be adjusted if you are having issues with overshoot and undershoot respectively, otherwise Timing should be the Non Linear control adjusted.

    Regards,

    Troy

  • 0 in reply to Troy Johnson
    Prodigy 10 points

    Troy,

    Thanks for your thorough explanation and patience!

    Sincerely,

    Ringo