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Original question:

DRV8832: Current Limit Sense Voltage

DRV8832: DRV8832: No "Fault' report during a stall condition

Vine Yuan
Prodigy 135 points
Part Number: DRV8832

 

Hi James,

   Nice to meet here!

  Question related to Vilim & “Fault” report, need your helps.

  As you described, “the device must hit the Vilim threshold for every PWM cycle within the 275 ms time frame for the fault to report (this is the tilim spec)”, from which can deduce that the voltage of Risense during stall status should present the waveform like as PWM cycle. The following scope waveform is captured from problem which cannot trigger “fault” report. But it likely meet the requirement you described.


 

"Hit the Vilim" means the high level of  the votage of the Risense must be more than 200mv, regardless of low level of the voltage. Could you help elaberate the process of trigger "Fault" report? Recently, encoutering the problem: no "fault" report duing a stall condition. It's urgent for us to solve.

 

Best regards,

Qingfeng, Yuan

 

 

  • 0
    TI__Genius 14487 points
    Hello Yaun,

    The datasheet specifies a range for Vilim from 160 mV to 240 mV. This range is determined over process and temperature. It is possible that the Vilim threshold on the particular device is greater than 200 mV. Try increasing your sense resistor so the voltage on the ISENSE pin is greater than 240 mV.
  • 0 in reply to James Lockridge19
    Prodigy 135 points
    HI Jiames,
    If increasing sense resistor, it will induce other problem that Vout cannot reach designed voltage with Vset becuase of a big resistance of the sense resistor, which will decrease the current during a stall condition. Therefore, the voltage of the ISENSE never reach the threshold. Do you think so??

    Best regards,
    Qingfeng, Yuan
  • 0 in reply to Vine Yuan
    TI__Genius 14487 points
    Yuan,

    This should not be an issue. The VSET pin controls the duty cycle for the switching of the OUTx pins. If a larger resistance is used, the duty cycle of the OUTx pins will just increase to maintain the set voltage. In the case of a stall or high-torque condition, the device will only regulate the current, not voltage.