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DRV8251: Does DRV8251 have output signal jittering issue?

Brian Dang
Genius 5040 points
Part Number: DRV8251
Other Parts Discussed in Thread: DRV8874, DRV8870

Our product currently have the A4950 driver and I want to use DRV8251 in HSOP package  to upgrade the product with higher output current.  My concern is the potential output signals jitter of the DRV8251 due to deglitch logic on the input. Can someone please confirm if this driver has jitter output or not? Output jitter causes audible noise issue in this application.

Also, I would like to know if there are other drivers with similar package and pin compatible that have higher OCP than DRV8251 which has  3.7A

Thanks,

Brian

  • 0
    TI__Mastermind 37683 points

    Hello Brian,

    Brian Dang said:
    Can someone please confirm if this driver has jitter output or not? Output jitter causes audible noise issue in this application.

    The output voltage during the DEAD time will vary from -Vd and VM+Vd where Vd is the forward voltage of the FET body diode. This may cause a small jitter in the current depending on your load. However, every driver with dead time insertion will create small jitters.

    Brian Dang said:
    Also, I would like to know if there are other drivers with similar package and pin compatible that have higher OCP than DRV8251 which has  3.7A

    Just to clarify, the 3.7A peak limit is for 4.5 ≤ VM < 5.5 V. For VM>5.5V, the max peak voltage is 4.1A. There are no direct pin-to-pin device with higher current. The DRV8874 is not exactly pip-to-pin but is similar in functionality and has max peak current of 6A.

    Regards,

    Pablo Armet

  • 0 in reply to Pablo Armet
    Genius 5040 points

    Hi Pablo,

    Pablo Armet said:

    The output voltage during the DEAD time will vary from -Vd and VM+Vd where Vd is the forward voltage of the FET body diode. This may cause a small jitter in the current depending on your load. However, every driver with dead time insertion will create small jitters.

    Brian Dang said:

    I'm not worried about the output PWM signal amplitude  varies slightly due to the FET body diode forward drop, but the pwm pulse width varying even when the input pwm is not changing. I.e. if input pwm is 20%  duty cycle but the output jumping around  with 20% duty +/- 100ns cycle by cycle. This would cause audible noise. If the inputs passing through the deglitch logic block, due to the asynchronous of the external input signal and internal clock, this causes jittering on the deglitch filtered outputs. 

    This issue had been well  discussed before with Ryan. I just want to confirm if the 8251 driver also has the same jitter output issue.

  • 0 in reply to Brian Dang
    TI__Mastermind 37683 points

    Brian,

    Thanks for the clarification.

    Brian Dang said:
    I just want to confirm if the 8251 driver also has the same jitter output issue.

    This other thread explains the reasoning for the jitter at the output. You already seem to know the explanation as well. 

    The linked thread above is regarding the DRV8870. The DRV8251 is a refreshed version of the DRV8870 so I expect the behavior of the jitter to be the same. 

    Is audible noise the only concern with the jitter in your design? 

    Regards,

    Pablo Armet

  • 0 in reply to Pablo Armet
    Genius 5040 points
    Pablo Armet said:

    This other thread explains the reasoning for the jitter at the output. You already seem to know the explanation as well. 

    The linked thread above is regarding the DRV8870. The DRV8251 is a refreshed version of the DRV8870 so I expect the behavior of the jitter to be the same. 

    Is audible noise the only concern with the jitter in your design? 

    Hi Pablo,

    I wasn't aware  that the DRV8870 was on my first post "Other Parts Discussed in Thread: DRV8874, DRV8870" - it was automatically added by TI to my thread. So no, I don't know for sure if the 8851 has the jitter output issue or not and wanted to be sure. We're spending times on this because the datasheet doesn't mention anything about output jitter. 

    Yes, audible noise is the major problem for us. As long long any driver chips have same pin assignment and footprint, with 4.5A peak current or high then they are good candidates.  

  • 0 in reply to Brian Dang
    TI__Mastermind 37683 points

    Brian,

    Almost all of our devices will have this jitter. Unfortunately, we don't have a device that is pin2pin with the DRV8251 with 4.5A peak current. The DRV8874 is the closest device in functionality that fit your requirements but not Pin2Pin.

    Regards,

    Pablo Armet