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I'm trying to understand how i can inject power to a 4 bank RJ45. I want to use these parts : - LTC 4266 4 ports PSE (802.3 at compliant for GbE, in type1 class3 for 13W at each port) - Marvell 88E1543 4 ports Gigabit Ethernet

In the 4266 datasheet p.32, they use a ETH1-230LD magnetics to inject the power. My questions are :

  • do I need to use RJ45 jack with integrated magnetics in this case ?
  • where should be placed the 50 ohm terminations? before the ETH1-230?

I'm a bit confused at the moment.

many thanks, J.

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do I need to use RJ45 jack with integrated magnetics in this case ?

No you don't - the linear technology LTC4266 data sheet you linked doesn't show integrated magnetics on page 32: -

enter image description here

where should be placed the 50 ohm terminations? before the ETH1-230?

You don't need to place terminations - the PHY connected equipment provides a 50 ohm termination and whatever you have connected to the RJ45 will see the 50 ohms produced by the PHY connected equipment because the magnetics largely pass this impedance through unhindered. However, whatever connects to the RJ45 will need proper termination resistors to avoid data corruptions.

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  • \$\begingroup\$ Alright Andy, thank you. \$\endgroup\$ – NoRest NR May 29 at 15:49

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