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DRV8848: EMI and its solution

Part Number: DRV8848


My customer is running a single board test using their board with DRV8848 on it and has detected EMI radiation from DRV8848's output. They tried connecting capacitors to the AOUT and the BOUT and this resolved the issue.

This issue was detected when they took the board out of their system for test, there's no EMI radiation detected when this board was in the system.(Probably connection problem?) So they're considering connecting the capacitor to solve this problem and continue the test, but worrying if connecting the capacitor to the output will create a filter with the motor and bring bad influence on the driver.

Here's the question from the customer:

Is it ok to connect capacitors to the output?

What's the minimum pulse width of the driver's output? The test result shows it's 5us, is it correct?


  • Hello, David,

    1. It is ok to connect a small capacitor to the output. What is the capacitor capacitance? Please check the power loss due to this capacitor's charge and discharge in every PWM switching cycle.

    2. Current sense blanking time is about 1.8us. That's the minimum pulse width of the driver's output. What is the output current setting? Can they share a test waveform?


    Wang Li

  • Hi Wang

    Thanks for your reply.

    Here's the answers & the questions from the customer regarding your questions.

    1. The capacitor being used is around 100pF~0.01uF, is this value ok for the function? The pulse width of the input signal is driven by a minimum of 200us.

    2. The waveform is shown below(Ch1:AIN1, Ch2:AIN2, Ch3:AOUT1). The drive voltage was at 12V, the current limit was set to 880mA. The timing 5us test's waveform was not taken, can do a retest and take it if necessary. 



  • David,

    1. Since the switching frequency is not high, 100pF~0.01uF should be Ok.

    2. I would think 1.8us blanking time is the minimum pulse width. Since the high side FET turn-on time is much longer than 1.8us blanking time, I think it should be Ok.