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DRV8873-Q1: Handling of nFAULT of DRV8873H-Q1

Kaji@PAN
Mastermind 7815 points
Part Number: DRV8873-Q1

Hi,

I would like to ask you about the handling of nFAULT in DRV8873H-Q1.
(Configuration)
・MODE = H:PWM
・SR = OPEN:13V/us
・nOL = GND:To run the open-load diagnostic at power up, tie it to ground.
・IN1/IN2 is used in L-Active during motor control(OUT1/2 is not used in Hi-z)
・nFAULT diagnosis is not used for error detection.

(phenomenon)
When the motor is reversed, nFAULT = L may be obtained.
By connecting nOL to DVDD, the phenomenon disappears, so it is presumed that it is detected by OLA of Open load (OLD).

(Question)
Checking the contents of 7.3.2.4.2 Open-Load Detection in Active Mode in the data sheet, it seems that OLA is detected when the device is used with the device set this time in PWM mode.
This can be avoided by setting nOL = DVDD, but I don't want to do it aggressively as it requires layout changes.
This time, the diagnosis with nFAULT is unused, and I understand that it is okay to ignore the fact that nFAULT = L, but is there any problem in using the device?

Best regards,

  • 0
    TI__Guru 55615 points

    Hello,

    For open-load, it is OK to ignore the flag.  The device will still operate normally even with this "false" reporting on an open load.  

    However, if a latched fault occurs like an overcurrent event, OCP, the device would not recover without a reset pulse on nSLEEP.  Without monitoring nFAULT, there would be no way to discover this type of fault.