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Original question:

TPSM84624: agnd and pgnd connection

TPSM84624: Far feedback connection to AGND/PGND

Tsvetelin Marinov
Prodigy 20 points
Part Number: TPSM84624

Tool/software:

According to datasheet AGND and PGND must be keep as separate nets and not to be connected together externally, because they are connected inside the module.

Since FB pin is referenced to AGND, how I should do the connection if I want to have far feedback sensing close to the load ?

Is it recommended to have a connection like on the attached picture below? Please advice !

  • 0
    TI__Mastermind 26780 points

    Hello,

    Yes, what you have shown using the AGND pin to reference the FB divider is correct. You may need to add a high frequency bypass cap to avoid jitter as shown in https://www.ti.com/lit/an/slyt467/slyt467.pdf You can add a placeholder for this bypass cap and populate it if there is any noise pickup. Hope this helps.

    Thanks,
    Amod

  • 0 in reply to Amod Vaze
    Prodigy 20 points

    Hi Amod,

    Thank you for sharing this article ! Just to make sure that I understand correctly. In our case TPSM84624 does not have specific differential amplifier for remote sensing. I wonder which of both configurations shown on the pictures below is better? The one with only far connection only from the power rail - Option 1, or the one that also have far connection from load's ground(this will be taken from bypass capacitors located close to load) - Option 2

  • +1 in reply to Tsvetelin Marinov
    TI__Mastermind 26780 points

    Hi Tsvetelin,

    Both configurations will work typically well for lower currents like 6A here for example. As currents are higher, the ground differential may increase to unacceptable levels. Option 2 will work more accurately since the ground differential at the load vs the IC AGND will be negligible compared Option 1. You can use the bypass capacitor idea from that app note by using a placeholder for this cap and then using it if there are jitter issues.

    Thanks,

    Amod