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[ DRV8303 ] Overcurrent Protection Issue

Kenichiro
Mastermind 9165 points
Other Parts Discussed in Thread: DRV8303

[ DRV8303 ] Overcurrent Protection Issue

Hi,

My customer is facing overcurrent protection issue which cause false shut down with much smaller current than expectation. Here are information and observations from my customer.

---

* DRV8303

* Protection mode: Current Limit, CBC. However customer tried several different modes, result still same (protection activated smaller than expected.)

* According to customer, one of low side (U-phase) always detect overcurrent from V-phase. They have tested both 6-PWM Mode and 3-PWM mode, but result was same.

* Changing GATE_CURRENT: no change

* Changing gate resistor from 22 ohm to 10 ohm: no change

* Changing 2.2uF Caps from 2.2uF to larger one (double or more): small improvement

---

From last finding, we assume that some of noise on PVDD rail would cause this issue. Do you have any ideas of the potential root cause of this issue? Also it's greatly appreciated, if you share some points where customer should check and/or try.

Thank you for your help in advance.
Regards,
Ken

  • 0
    TI__Guru** 114905 points
    Hi Kenichiro-san,

    Our expert has been notified and should reply soon.
  • 0
    TI__Mastermind 21320 points

    Hi Ken,

    We have seen in the past that excessive noise on either sense line can cause false trips. This may explain why the capacitors help to improve the issue. Layout can also effect signals that are coupling into the monitor. I would not expect the PWM mode or Overcurrent mode to make a significant difference.

    Can you check the layout connection between SH_X and SL_X or provide the schematic/layout files. These are the connections for the low-side monitor. The high-side monitor is between PVDD and SH_X.

    Can you also capture a waveform when the overcurrent event occurs? You can monitor nFAULT or nOCTW. It would be good to see PVDD, SH_X, nFAULT or nOCTW, and SL_X. A differential probe between SH_X and SL_X is the best way to make the measurement.