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DRV8706-Q1: Doubler(DRV8706) or Tripler(DRV8718) Charge Pump

21710070
Prodigy 80 points
Part Number: DRV8706-Q1

Hi team,

Why does DRV8706 choose doubler charge pump instead of tripler charge pump just like DRV8718? I'm afraid that doubler charge pump can't pump enough energy when VM is too low or any other conditions. Thanks.

BR,

Robin

  • 0
    TI__Mastermind 23240 points

    Hey Robin,

    I am not sure why a doubler charge pump was chosen instead of a tripler charge pump, it could have been that the DRV8706 comes in a 32-pin package vs the DRV8718 40-pin package, so the DRV8706 didn't have any spare pins for the additional charge pump capacitors required for the tripler circuit.  

    Regardless, the device should still perform within all of its rated specs with sufficient external bulk capacitance and following our recommended guidelines.  You're welcome to order an EVM and test it out in your system to see if it works for you. 

    Regards,

    Jacob

  • 0 in reply to Jacob Thompson
    Prodigy 80 points

    Hi Jacob,

    Since DRV8718/DRV8714 has 8/4 half bridges while DRV8706 has only two half bridges, do you think this is the reason to choose doubler or tripler charge pump? Another point is that DRV8718/8714 says tripler will change to doubler charge pump when VM is lower than 17.5V,  I want to know why DRV8718/8714 set such high voltage, because I think it's too high for high side MOSFET's Vgs.

    Besides, I find DRV8706's charge pump supports spread spectrum function, could you let me know the spread frequency and its variation percentage? It's important for me to design the EMI filter. Thanks.

    BR,

    Robin

  • 0 in reply to 21710070
    TI__Mastermind 23240 points

    Hey Robin,

    The DRV8718/8714 high voltage allows it to support a wider range of applications and MOSFETs with a single device, instead of having a low-voltage variant and a higher voltage variant.  

    The primary frequency of the spread spectrum for the charge pump on DRV8706 is 400kHz.  I don't have data about the variation percentage.  

    Regards,

    Jacob