• State
  • Locked Locked
  • Replies 6 replies
  • Subscribers 65 subscribers
  • Views 176 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

TPS53647: inruch current OCP condition

Tommy Tzeng
Genius 5780 points
Part Number: TPS53647
Other Parts Discussed in Thread: CSD95410RRB,

Tool/software:

Hi Sir,

We are using the TPS53647 with a 2-phase CSD95410RRB configuration.

The input voltage is 12V, output is 0.83V, and the OCP threshold is set at 46A (with each phase rated for 30A).

Currently, we are encountering an OCP event, and it behaves as described in Figure 114 of the TI datasheet — i.e., entering hiccup mode.

We have the following questions:

1. Can OCP be disabled entirely? Also, is it acceptable to short IMON to ground?

2. At power-up, we suspect a large inrush current is triggering OCP. Since the load may have very low impedance at startup, is there any way to:  slow down the power-up speed (soft-start adjustment), or temporarily disable or bypass OCP during startup?

We have adjusted the SLEW MODE setting (now 0.34), but there is no improvement at all, 

Any recommendations on how to handle high inrush conditions at startup would be greatly appreciated.

the schematic as follows:

TPS53647(1).pdf

  • 0
    Prodigy 51 points

    Hello Sir:

    we used the other DC to DC solution to test our system, there only about 3A there, so we have no idea why  solution TPS53674 will got so much current just like short ??

    there must so thing wrong there can you show us which point we ned check??

  • 0 in reply to al chang
    TI__Prodigy 210 points

    Hi,

    To me it looks like a short at output. Can you see the is there any short at output rail and SW nodes (SW node after removing inductors)

    Regards,

    Shamveel

  • 0
    TI__Expert 6980 points

    Hi Tommy,

    Thanks for reaching out. 

    I understand your concern. 

    Can you please let me know the following parameters you are setting in the contoller:

    1. Start up Slew Rate 

    2. Min Ton Start

    3. Total Output Capacitance and Inductor.

    Can you also do the following experiment?

    Probe VIOUT-VREF, Vout during start up and trigger it with respect to first PWM high. 

    Is the problem always occuring during start up? Or is it coming during operation?

    Thanks & regards,

    Abhishek

  • 0 in reply to MUHAMMED SHAMVEEL TM
    Prodigy 51 points

    Hello Sir:

    we aleady used the other DC/DC solution fir test is , and result is ok, so it not short case

    thanks

    Best Regards

    Al

  • 0 in reply to Abhishek Vishwa1
    Prodigy 51 points

    Start up Slew Rate  0.68 we modify to 0.34 seem not work either

    total cap is about 600UF

    and here is the wavw form on IMON pin

  • 0 in reply to al chang
    TI__Expert 6980 points

    Hi Al,

    Thanks for sharing the data. 

    It looks like a lot of noise is coupling. Can you limit the bandwidth to 20 MHz on IMON. 
    Also, can you please explain the setup condition in details for the 2 waveforms. What exactly is the difference between the two?

    1. In both the cases, the output seems to rise properly. So it is not a start up shutdown issue? Am I right?

    2. Do you have any load on the output in waveform 1?

    Thanks & regards,
    Abhishek