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DRV8889-Q1: DRV8889

xujian.yu
Prodigy 20 points
Part Number: DRV8889-Q1

Tool/software:

hi expert,

Now when we are using 8889, adding a 2.2UF capacitor to the AOUT port improves EMC-CEI. Will this have a significant impact on the driver itself?

  • 0
    TI__Mastermind 44525 points

    Hi Xujian,

    I think you may have meant 2.2 nF not uF please confirm. It is common to use capacitors on each xOUTx pin between 2.2 nF and 10 nF to mitigate EMI with certain stepper motors. Higher value capacitors than 10 nF likely will load the output FETs while it is switching and result in over current shutdown. Thanks.

    Regards, Murugavel 

  • 0 in reply to Murugavel4637
    Prodigy 20 points

    Thank you for your reply,
    We originally used 10nF, but now we have found that increasing the ESD capacitance from 10nF can improve the low frequency exceedance of CEI. Therefore, we need to pay attention to whether there is a possibility of increasing the capacitance value。

  • 0 in reply to xujian.yu
    Prodigy 20 points

    Or do you have any suggestions to reduce CEI

  • 0 in reply to xujian.yu
    TI__Mastermind 44525 points

    Hi Xujian,

    How much capacitance is needed? Higher value is okay as long as it does not trigger a thermal shutdown in your application. At switching frequencies used for current regulation for example 30 kHz, higher value capacitors have lower reactance, Xc = 1/(2*Π*f*C). This means higher switching losses causing more power dissipation (thermals) and leading to OTS. 

    Regards, Murugavel