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DRV8703-Q1: The external capacitor on SO pin

user6321073
Prodigy 70 points
Part Number: DRV8703-Q1

Dear support team,

I have the confirmation about the external capacitor on SO pin of DRV8703-Q1.

On the specification sheet, it describes "No capacitor is required on the SO pin." on "7.3.5 Amplifier Output (SO)".

On the other hands, it describes "Place an external capacitor on this pin." on "7.3.5.1 SO Sample and Hold Operataion".

Does this mean that if we set SH_EN : Low (default), no capacitor is required on SO pin, and if we set SH_EN : High, need the capacitor on SO pin?

And, in that case, if we set SH_EN  : High, is your recommended value 1nF?

Best Regards,

Matsunaga

  • 0
    TI__Guru 55605 points

    Matsunaga,

    With "sample and hold" enabled, the SO output will HIZ during current recirculation when the current is NOT flowing thru the external shunt resistor.  A capacitor is required to hold up the last voltage available on this pin when the device was in the drive state and prior to going to the HIZ state.  

    The amount of capacitance required will depend on how long the current is recirculating.  This will need to be experimented.

    We do recommend buffering the output of the amplifier with a series resistor before the capacitor so that with larger capacitors, the amplifier does not go unstable.