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DRV8432: how to select the output inductor of DRV8432

Erwin Xie
Intellectual 935 points

Part Number: DRV8432

hi, 

we are designing a TEC Driver with DRV8432, in our datasheet reference design, we found there is a 4.7uH inductor in OUT path.

we hope to know, whether this inductor is must need?? if yes, how can we select the value of this inductor??

Our application is, 12V 6A.

Thank you

Erwin

  • 0
    TI__Guru 56650 points

    Erwin,

    According to "Figure 17. Application Diagram Example for TEC Driver Schematic", the 4.7uH can:

    1.  eliminate the OUTA/B or OUTC/D shoot through

    2. provide output filter

    For shoot through, the propagation delay is 38ns. If we assume two input to output channels have 100% error on propagation delay, delta I = 12V * 38ns / (2*4.7uH) = 48mA. It should be OK for 6A application.

    For output filter, we may want to control the ripple less than 30~40% of the DC current level as other buck converter design (https://www.richtek.com/Design%20Support/Technical%20Document/AN009 ). So, you can pick an inductor and set PWM frequency to optimize the converter efficiency and thermal performance. BTW, some inductor companies provide the buck converter efficiency calculation/estimation.