• State
  • Locked Locked
  • Replies 5 replies
  • Subscribers 22 subscribers
  • Views 1173 views
  • Users 0 members are here
Support feedback
Options
Options
Similar topics

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.

TPS40170　temperature tolerance of OCP

K.Hamamoto
Guru 12155 points
Other Parts Discussed in Thread: TPS40170

Hi 

Our customer measured TPS40170, They found the unexpected OCP operation.

There is the result of OCP test.

( Fsw=250kHz, L=10uH )

  

At low temperature and low duty(Vo=3.3V) the OCP is lower than at high temp. 

However at low temp and high duty(Vo=12V) the OCP is lower than at high temp.

Is there any reason for this phenomenon? Our customer are going to change the value of external components if it is not any failure mode.

Please let me know if you have any questions.

Regards,

Koji Hamamoto

  • 0
    TI__Mastermind 35115 points

    Hi Homamoto-san,

    Performance where the current limit decreases at low temp and low duty cycle can by caused by too much ringing at the SW node. Generally noise issues are worse at colder temperatures.

    One thing to check is if this is caused by SCP or OCP. This can be done by increasing the SCP multiplier with the LDRV to PGND resistor. If increasing the SCP causes the current limit to be tripped at a higher current level this means the ringing on the SW node at cold is falsely tripping SCP.

    Best Regards,
    Anthony

  • 0 in reply to Anthony F
    Guru 12155 points

    Hi Anthony-san

    Thank you for your comment. That is very helpful advise. 

    There is Tblnk. How much is the time? 

    I think this time is important things to discuss about noise issue.

    Regards,

    Koji Hamamoto

  • 0 in reply to K.Hamamoto
    TI__Mastermind 35115 points

    The blanking time is 55 ns typical.

  • 0 in reply to Anthony F
    Guru 12155 points

    Hi Anthony-san

    Thank you for your support. Also I am sorry for my late reply.

    I had talked with customer for this issue.   We increased the RLDRV but nothing happen.

    However it improved to add the snubber.  It looks the cause was the noise.

    Our customer are wondering that there are any other cause.

    What do you think about the cause of this phenomenon?   Was it the noise?

    Regards,

    Koji Hamamoto

     

  • 0 in reply to K.Hamamoto
    TI__Mastermind 35115 points

    Hi Koji-san,

    Since adding the snubber improved the performance, I agree it was most likely noise getting into the current sensing circuit causing the issue.

    Best Regards,
    Anthony