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DRV8889-Q1: Flying cap larger than 0.022uF

Masatoshi Oguri
Expert 4780 points
Part Number: DRV8889-Q1

Hello,

The flying capacitor between CPH and CPL is recommended as 0.022uF in the datasheet. But is there any concern with a larger capacitor (0.1uF)?

Thanks.

Regards,

Oguri (TIJ automotive FAE)

  • 0
    TI__Guru 56650 points

    Oguri,

    Two concerns:

    1. VCP capacitor, Cvcp is charged by the capacitor between CPL and CPH, Ccpl_h, every charge pump switching cycle. If Ccpl_h is increased, Cvcp's ripple goes up. To keep Cvcdp ripple, the Cvcp should be increased also. At the same time, assume the input VM net has enough capacitance.

    2. Ccpl_h and Cvcp increasing means the charge pump switches may have a higher current and longer charging time during the start-up. So far, we didn't check the 100nF Ccpl-h.  According to other product experience, the Ccpl_h can be 47nF without an issue. But, please we recommend 22nF for the DRV8889-Q1 capacitor between CPL and CPH.