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DRV8412 DC Output Filter

Denis Alain1
Intellectual 600 points
Other Parts Discussed in Thread: DRV8412, DRV8412DDWEVM

Hi,

In the datasheet of the DRV8412, there is a small section about a low-pass LC filter. From the spec (p.18):

"For TEC driver or other non-motor related applications (e.g. resistive load or dc output), a low-pass LC filter can be used to meet the requirement."

In the evaluation board (DRV8412DDWEVM), the schematic has a suggested LC filter formed by one 4.7uH + 47uF and 680nF for the DC output application. I understand that we need a minimum inductance output for OC protection in case of real short problem. In our case, we decided to use the suggested ferrite from TDK: MPZ2012S300A.

For the "C" part of the filter, what is the purpose of the 47uF output? The 680nF should be for EMI purpose, but do I need the 47uF if I don't care about the noise on the 24VDC outputs? (we will SW ON/OFF solenoids or brushed motors). Since I have 20x 24VDC outputs (we have 5x DRV8412 on our PCB), I need to optimize this filter.

Thanks,

Denis

 

  • 0
    TI__Guru** 114905 points

    Hi Denis,

    If you are using brushed solenoids or brushed motors, you do not need the LC filter. It was placed on the EVM to allow multiple configurations.

    Figure 9 (for high current) or figure 10 (for multiple motors)  on page 16 is more in line with your needs.