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TPS54A20: Pin connection between NC and SCAP

Ryotaro Fukui
Intellectual 2345 points
Part Number: TPS54A20

Hello team,

My customer has some questions about the pin connection of the TPS54A20.

  • Does 11pin (NC) need to be connected to 20pin (SCAP)? The data sheet describes as follows in the pin functions.

“NC: No connect. This pin is not electrically connected to the IC and is included for board level reliability (BLR) purposes. Connect this pin to the SCAP trace.”

  • Since 9pin (SCAP) and 20pin (SCAP) are connected inside the IC, is it okay to understand that it is not necessary to connect externally from 9pin to 20pin?

The layout example in the datasheet is as follows.(https://www.tij.co.jp/jp/lit/ds/symlink/tps54a20.pdf#page=33)

Best Regards,

Ryotaro Fukui

  • 0
    TI__Mastermind 35165 points

    Hi ,

    Yes, pin 11 should be connected to the SCAP trace as the SCAP should be placed on the same side of the board as the TPS54A20. The SCAP is an important bypass capacitor for the power stage so it's placement is critical. It is used when the HS FET of phase B turns on (Q1b in Figure 43).

    Also, yes, pin 9 and pin 20 do not need to be connected on the PCB as they are connected internally. We also did not make this connection in our EVM layout. Link to the layout image for our EVM below.

    https://www.ti.com/lit/pdf/slvuam8#page=14

    Let me know if you have any additional questions.

    Anthony

  • 0 in reply to Anthony F
    TI__Intellectual 2345 points

    Hello Anthony-san,

    Thank you for the quick response. The customer was satisfied with the answer, and will refer to the recommended circuit diagram..

    The question is now closed. Thank you all for your help.

    Best Regards,
    Ryotaro Fukui