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Original question:

CDCV304: about unused output pins

CDCV304: CDCV304 unused pin with cap for confirm

Curry Huang
Prodigy 310 points
Part Number: CDCV304

HI team,

We find in generally CDCV304's unused pin is suggested to floating, but some customer designed the CDCV304's unused pin with a 4.7u cap to ground. Do you think there is any potential issue? thanks for your reply.

Best regards,

Curry Huang

  • 0
    TI__Genius 16845 points

    Hi Curry,

    Unused output pins are recommended to be left floating to reduce consumption in the output drivers. Driving a 4.7uF capacitance is a heavy load and could consume considerable power. It is better to leave them floating.

    Kind regards,
    Lane

  • 0 in reply to Lane Boyd
    TI__Prodigy 310 points

    Hi Lane,

    thanks for your reply.

    It is my typo. the capacitance load is 4.7pF, considering the power consumption it seems be not that worse, but do you think this cap would have good improvement in EMC performance (saying RE etc.)?

  • 0 in reply to Curry Huang
    TI__Genius 16845 points

    Hi Curry,

    A load of 4.7pF is OK. There are several factors which influence EMC, including proper board design. I'm unsure if this capacitor would have an significant effect on the EMC performance but I do not expect that it will have a significant impact.

    I hope this information helps. If you compare the EMC performance between both cases I would be interested in the result.

    Kind regards,
    Lane