• State
  • Locked Locked
  • Replies 5 replies
  • Subscribers 63 subscribers
  • Views 94 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.

Original question:

TPS61088: Why the tps61088 locked after load a motor during the opration

TPS61088: TPS61088 output voltage drops from 7V to 4.4V while input voltage is 5V

qing fang
Prodigy 30 points
Part Number: TPS61088

Tool/software:

Hello

We use TPS61088 to convert 5V to 7.2V. This is out circuit:

This is our PCB Layout:

Recently we met a issue when doing Damp Heat/High Temperature operating test: the output of this circuit suddenly drop to 4.4V. The output will return to normal after power on/off.

Please help analyze the possible reasons.

Thanks

  • 0
    TI__Genius 12395 points

    Hi Fang,

    The schematic look ok.

    For the layout, the output capacitors are too far away from the output side that could cause high spike.

    We once met similar case that the device suddenly shut down like yours when there is large noise in environment.

    It could be the same case with yours that the long switching loop could cause large noise.

    One solution is to optimize the layout and environment,

    another possible solution is to change the MODE to PWM mode, as we found the PWM mode has higher anti-interference capability.

    Best Regards,

    Fergus

  • 0 in reply to Fergus He
    Prodigy 30 points

    This is the location of the output capacitors. The lower layer is paved with a layer of GND. Are you sure they are too far away from the output side?

  • 0 in reply to qing fang
    TI__Genius 12395 points

    Hi fang,

    Please see recommended layout and current one.

    the critical switching loop should be designed with smallest loop.

    For your design, the capacitor's GND connection contains vias and is far from the device, which increase the parasitic inductor a lot.

    This easily causes the spike and thus GND signal will be influenced as well.

    The PFM mode will detect the zero current cross and the GND spike can lead to a logic failure.

    Best Regards,

    Fergus

  • 0 in reply to Fergus He
    Prodigy 30 points

    As you same PWM mode has higher anti-interference capability, but the output voltage ripple is larger in PWM mode at light load . Are there any other solutions?

  • 0 in reply to qing fang
    TI__Genius 12395 points

    Hi Fang,

    The output ripple can be reduced by increasing the inductor or adding some capacitance.

    For your case the difference should be small, please have a test.

    The main concern is the PWM mode's efficiency will be lower than that in PFM.

    Regards,

    Fergus