• LT4275 PoE controller PWRGOOD not turning on


    I am working on a PoE circuit designed around the LT4275 controller and the LT3748 converter. When I don't use the PWRGD pin, but instead use the 2 resistors in the voltage divider at the EN pin of the LT3748, the circuit works as expected (and…

  • LT4275 Voltage at AUX pin is less than the AUX threshold

    We test the circuit shown in page 12 of the datasheet.

    When V_AUX is less than V_AUXT (typ 6.3V), we find both PWRGD and HSGATE are low and PoE is not activated.  We further reduce the AUX voltage until the V_AUX is 3.2V, then PoE is active (both PWRGD…

  • LT4275 Cannot deliver power and ethernet signal together

    hi, I am working design an LTPoE++ PD which require 90W power. I am using LT4275 as PD controller and ENC28J60 as ethernet controller. The goal is making a pi compute module(raspberry pi CM3) powered and connected to the internet. right now, the ENC28J60…

  • Will LT4275 be supportive for PSE switches other than linear make?


    I have been working with power over ethernet project and using PD -LT4275. Tested PD board with PSE - 1815A-D and is working well. I would like to know whether the PD will support of other PSE like cisco pse switch. Or LT4275 will works only compatible…

  • LT4275 cannot deliver power above 30W eventhough designed for LTPoE++

    Hi, I am working design an LTPoE++ PD which require 90W power. I am using LT4275 as PD controller, Normal bridge, with a controller. The goal is making an led driver powered by PoE. Even though the circuit is designed for LTPoE++ standards, power will shut…

  • RE: What is the output voltage of LT4275BIDD POE


    the datasheet contains more than I know about the LT4275 ;-)

    You should check out the available demoboards resp. their schematics:


  • RE: Output voltage settings of LT4275BI POE controller


    The LT4275 is a PD Interface with Hotswap Controller. It provides IEEE or LTPoE++ compliant signaling and inrushes the downstream bulk capacitance in a controlled manner. The output voltage is effectively the input voltage. You'll need a DC-DC…

  • RE: Can the LT4295, LT4293, LT4275A and LT4276A handle dual-signature in PD applications?


    IEEE 802.3bt defines two PD topologies: single-signature and dual-signature. Single-signature PDs present a valid detection signature on both pairsets, while dual-signature PDs present separate detection signatures on each of the two pairsets.…

  • PD Design Query for UltraPWR Mode of LTC4279


    My customer wants to implement PoE system up to 123W using the LTC4279's UltraPWR mode.

    However, ADI's PD devices only support up to 90W(LT4275, LT4276, LT4293...).

    Could you please provide reference material for a PD design that supports 123W…

  • LTC4266A-3 fail to output 70w


          We  design POE++ with LTC4266A-3 , but now the output can be only around  30w  with 90w PD (LT4275), can you kindly help to advice,

    1. How can i get the software programming documentation.

    2. Things to improve with the design...