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PCM1794A: Is it OK to connect VCOML and VCOMR together?

Werner Baumberger
Prodigy 30 points
Part Number: PCM1794A

The data sheet is contradictory concerning VCOMR and VCOML (pins 21/22). The typical application circuit (Fig. 31) suggests two separate 47uF capacitors for these pins, however in the layout example (Fig. 34) they are shorted and a only single 47uF is used.

  • 0
    TI__Guru 52683 points

    Hi Werner,

    Either is acceptable.  The VCOMx pins are essentially just a voltage divider to create the common voltage reference fo the device.  shorting them together forces them to have the same voltage, but you would need to double the capacitor value to achieve the same noise filtering.  For example, if you have the separate with 10µF you would have the same filter cutoff of having 20µF on the shorted pins.

    Either are safe and acceptable in the application.

    Thanks,

    Paul