• State Resolved
  • Locked Locked
  • Replies 7 replies
  • Answers 2 answers
  • Subscribers 29 subscribers
  • Views 233 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.

DRV8830EVM: FAULTn leakage current through ESD protection

DinoAU
Prodigy 110 points
Part Number: DRV8830EVM
Other Parts Discussed in Thread: DRV8830

Hi,

For low power operation, the DRV8830 datasheet recommends removing power from the FAULTn pullup resistor to eliminate a current path from the FAULTn pin through an ESD protection diode to VCC.

What is the magnitude of this leakage current?

Thanks.

Dino

  • 0
    TI__Guru 56650 points

    DinoAU,

    What is the FAULTn pin pull-up source voltage? If it is VCC, there is no leakage current because there is no voltage across the ESD protection diode if FAULTn pin output is "high".

    If FAULTn pin pull-up source voltage is much lower than the VCC, the leakage current should be lower than 1uA.

  • 0 in reply to Wang5577
    Prodigy 110 points

    Hi Wang,

    Thanks for your reply.  The FAULTn pin pull-up source is 3.3V and VCC is 6V.  It doesn't sound like the leakage current is significant.

    I have been seeing a high sleep current of about 600uA when placed into standby mode (IN1 & IN2 = 0).

    I found a couple of similar issues posted in the forum, but without a resolution.  The device functions as expected apart from this.

    Is there a particular sequence or something that I'm missing for entering sleep mode?

    This thread is similar to what I am seeing: https://e2e.ti.com/support/motor-drivers/f/38/t/914706?tisearch=e2e-sitesearch&keymatch=DRV8830%20sleep

    Thanks.

    Dino

  • 0 in reply to DinoAU
    TI__Guru 56650 points

    Dino,

    FAULTn may not affect the standby current or sleep current very much even the FAULTn pin pull-up source is 3.3V and VCC is 6V.

    SDA, SCL pin voltage is high, even without communication. If the external SDA, SCL pull-up source clamp the SDA, SCL to 3.3V (lower than VCC voltage), the internal SDA and SCL pull-up source will have some current consumption. That current could flows into the external SDA, SCL pull-up source.

    To prevent this current from SDA, SCL pin to the external SDA, SCL pull-up source, we can try to add a blocking diode in series with the pull-up resistor which can block the leakage current. from SDA, SCL pin to the external SDA, SCL pull-up source. In this case, we need to make sure the host controller's SDA, SCL pin can survive with VCC voltage.

  • 0 in reply to Wang5577
    Prodigy 110 points

    Hi Wang,

    Thanks for your explanation.  The pull-up resistors on the I2C bus seem to be causing the excessive sleep current (600uA).  Would you expect such a high current if the I2C pull-up source (3.3V) clamps the voltage as you mentioned?  Is it a known issue? 

    I managed to reduce the sleep current down to a few uA with a work around by removing the external pull-up resistors and using the internal pull-up resistors in the micro-controller.  I just need to disable the internal pull-up resistors before entering sleep mode and re-enable the pull-ups when I need to use the bus.

    Regards,

    Dino

  • 0 in reply to DinoAU
    TI__Guru 56650 points

    Dino,

    With 6V VCC, I expect such a high current if the I2C pull-up source (3.3V) clamps the voltage. I didn't know this issue before. But, after checking the test data and reading the datasheet, I would think this is the root cause.

    Thank you for sharing your solution.

  • 0 in reply to Wang5577
    Prodigy 110 points

    Hi Wang,

    Thanks for confirming that.  I will just use the work around for the moment.  Do TI have any recommended solutions to this problem?

    Thanks for your help with this issue.

    Dino

  • 0 in reply to DinoAU
    TI__Guru 56650 points

    Dino,

    I didn't find any other recommended solution besides the series diode with pull-up resistor or disable the pull-up resistors before entering sleep mode and re-enable the pull-ups when enable the bus.

    I would think those are good solution.