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I am reading the TI POE IC(TPS23730's datasheet), and I have some questions I would like to ask you, if you can help me I will very much appreciate it.

1.) What's the internal hot-swap MOSFET, I have no idea what's this use for? 2.) What's Oring? 3.) What's APD function and PPD function. 4.) Why need to use RTN pin, GND pin, and RTN pin, all three are ground why cannot just use one. 5.) What's beat frequency

I have read this datasheet but I still cannot understand the above question, hope someone can give some help.

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  • \$\begingroup\$ Have you tried googling hot-swap MOSFET, ORing, APD, PPD and beat frequency? What did your search results turn up and where are you stuck? \$\endgroup\$
    – winny
    Jul 12, 2021 at 14:49
  • \$\begingroup\$ @winny Yes, I try it, but I still cannot understand \$\endgroup\$
    – EEC
    Jul 12, 2021 at 15:17
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    \$\begingroup\$ What parts do you understand? Where are you stuck? \$\endgroup\$
    – winny
    Jul 12, 2021 at 15:42
  • \$\begingroup\$ @winny I don't know why need to use hot-swap MOSFET, it is for safe? \$\endgroup\$
    – EEC
    Jul 13, 2021 at 13:53
  • \$\begingroup\$ @winny other pins I understand now. \$\endgroup\$
    – EEC
    Jul 13, 2021 at 13:54

1 Answer 1

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Q1: The hotswap switch disconnects the load from the PoE power source in various transitional conditions, some of which may occur when making PoE connections under load.

Q2: Oring is the capability to get powered alternatively by several power sources.

Q3: APD = Auxiliary Power Detect (for supporting an alternative power source other than PoE). PPD = Power Detect (a different input for the same purpose)

Q4: Connecting RTN and GND would defeat the hotswap feature and disable current limiting. You would thereby lose some protection features.

Q5: A low frequency signal that results from mixing two higher frequency signals of similar frequency. This may result from a switching frequency of the TPS23730 that is near a frequency within the powered system. By locking those two frequencies together you may control or eliminate the beat frequency.

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  • \$\begingroup\$ Thanks for your answer. \$\endgroup\$
    – EEC
    Jul 13, 2021 at 13:53

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