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DRV8220: driver shuts off in PH/EN Control Mode for duty cycle between 0-20%

Jan Bock
Intellectual 2525 points
Part Number: DRV8220

Hello Team, 

My customer uses the H-Bridge with the following parameters:

VM: 10V

Max. Strom: 450mA

Mode: PH/EN Control Mode

Logic-Level: 3.3V

nSLEEP: controlled with MCU

PWM-Freuqenz: 30kHz

As long he is driving the H-Bridge with 20-100% duty cycle the bridge works as expected. 

When he is driving the bridge with 10% duty cycle the drive shuts down after 1.2ms

nSLEEP was at logic high for all his tests and the EN pin was triggered with the PWM Signal. 

Do you know the route cause for this behavior. Does the device turn into auto sleep mode ?

Thank you 

Jan

  • 0
    TI__Mastermind 37683 points

    Hi Jan,

    Jan Bock said:
    Do you know the route cause for this behavior. Does the device turn into auto sleep mode ?

    Yes, even though there is an SLEEP pin, when EN is low for longer than the t_sleep time (0.9ms to 3ms), the device will go into sleep mode. However, at 30kHz frequency and OFF-time duty cycle of 90% (10% ON-time duty cycle) is not close enough to the t_sleep time. Therefore, it should not have caused the driver to go into sleep mode automatically. 

    Can you ask the customer to remove the load and drive the outputs at 10% duty cycle (30kHz frequency)? Do the outputs shutdown?. My guess is that there might be a fault happening when the load is connected forcing the outputs to shutdown?

    -Pablo 

  • 0 in reply to Pablo Armet
    Prodigy 10 points

    Hi,

    i tested with different ohmic loads and even with no load but same result. When i am switching from duty cycle 100% (30kHz) to duty cycle 10%(30kHz) the output shuts down after 1.2ms. 

  • 0 in reply to Maurizio Kempf
    TI__Mastermind 37683 points

    Hello Maurizio,

    Are you continuously driving the motor all the time or are there pauses when the EN=0 for a while?

    Regards,

    Pablo Armet