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DRV8880: Heater operation

Part Number: DRV8880
Other Parts Discussed in Thread: DRV8800

Dear Technical Support Team,

I have a question about the capacitor connected between CPH  and CPL.

There is an instruction to use 0.1μF of X7R characteristic on datasheet.
I would like to change this to a small ceramic capacitor (1005 size) for EOL of ceramic capacitor , but the actual capacitance is about 0.06μF.

1).  Is this capacitance (0.06μF) acceptable for the charge pump to function properly?
2.) If it is not acceptable, please tell us how much capacitor should be connected specifically.
3.) Is X7R required for temperature characteristics? (For example, is X5R use NG?)
 

Best Regards,

ttd

  • Hi ttd,

    1).  Is this capacitance (0.06μF) acceptable for the charge pump to function properly?

    Yes, this is acceptable. This may result in higher switching frequency when the device is under regulating current at fast off times.


    2.) If it is not acceptable, please tell us how much capacitor should be connected specifically.

    This question is not applicable. 


    3.) Is X7R required for temperature characteristics? (For example, is X5R use NG?)

    X7R should be used if the temperature of the capacitor exceeds 85C. This condition can occur if the ambient temperature exceeds 85C or if the DRV8800 temperature heats the capacitor above 85C.

  • Hi Rick Duncan,

    Thank you for your reply.

    >Yes, this is acceptable. This may result in higher switching frequency when the device is under regulating current at fast off times.

     Does it meas that ƒVCP of 0.06uF is faster than 0.1uF of ƒVCP ? 

     Otherwise does it mean  toff  and PWM frequency?

     I think that you mean first case(fVCP).

    Best Regards,

    ttd

  • Hi tdd,

    The charge pump switching frequency  may be faster.

    All other clocks and timing remain the same.