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TPS23753 with adapter priority

Pedro Morgado
Prodigy 10 points
Other Parts Discussed in Thread: TPS23753

Hi TI,

by looking at the document: http://www.ti.com/lit/df/slvras1/slvras1.pdf I see a diode between Vdd and Vdd1 (named D4).

On the same page, on the remark below it can be seen: "For PoE Priority, populate D4 [...]". This seems to imply that for Adapter Priority we should not populate the design with this diode, and thus leaving an open between Vdd and Vdd1. Is this really correct?

In all other documents for the TPS23753, TI shows that a direct connection must be made between Vdd and Vdd1:

page 10 of http://www.ti.com/lit/an/slva306a/slva306a.pdf

page 3 of http://www.ti.com/lit/an/slva305c/slva305c.pdf

page 1 of http://www.ti.com/lit/ds/symlink/tps23753.pdf

Can you confirm what should be done for a correct adapter priority circuit, regarding the connection between Vdd and Vdd1?

Thank you and best regards, Pedro

  • 0
    TI__Mastermind 42795 points

    Use SLVA306A as a reference for the TPS23753 power scheme needed. The diode between VDD and VDD1 is only needed for schemes that desire PoE priority. For adapter priority, there are several choices as well and the adapter insertion point (option 1,2,3) sections will show certain methods.

    For example, use Figure 8 in section 3.3 for option 2 with adapter priority.

    A better description for option 2, POE priority (for SLVRAS1) would be to refer to figure 3 (12V and 24V adapters) in SLVA306A.