• Does LTC4269-1 support power demotion?

    Does LTC4269-1 support power demotion? Power demotion was introduced in IEEE 802.3at. LTC4269-1 is a IEEE 802.3at compliant PD. Suppose I have defined LTC4269-1 in my circuit as a type 2 class 4 PD (Rclass = 30.9 Ω). If I connect the LTC4269-1 to a…

  • LTC4269-1 current spikes

    I'd like to use the LTC4269-1 (LTC4269IDKD-1#TRPBF) in a design, but I'm seeing current spikes that are too high on the eval board (DC1335B-C). How can you explain this and what can I do to reduce them below the peak current threshold (684 mA)?…

  • LTC4269-1 start-up problem

    Why do I have an unstable output using the LTC4269-1?  What you see in the scope is measured between +12VE and DGND. Refer to my schematic. Other than equivalent component replacements, it matches the DC1335B-C evaluation board. I've also attached my bill…

  • LTC4269-1 VCC pin oscillation

    Hi,

    I used the the typical application circuit from the datasheet of the ltc4269-1 for the 3.3V output.

    My problem is that it seems like the chip is unable to turn on. The voltage on the VCC pin is oscillating between 9.7V and 15.3V, which according…

  • LTC4269-1 with cisco switch Catalyst 2960 series

    Hi,

    Does LTC4269-1 support LLDP protocol?

    We have encounter a issue with cisco switches.

    please see below handshaking waveform. Seems abnormal but power on and get only af power.

    However, it's function well with LTC4279 detection, classification, power…

  • When should I use soft-start on the LTC4269-1?

    When should I use soft-start on the LTC4269-1? I am using the LTC4269-1 on a circuit that has a lot of capacitance on the secondary. It's about 1.5 mF, but could be more in future designs. What I have noticed is the Vcc oscillates for small values of…

  • LTC4269-1 output current issue

    Hi all,

    I am debugging my LTC4269-1 POE power board, and encounter some problem, is there any one can help us that would be appreciate. 

    Problem as below,

    If i disconnect the load, the POE power(LTC4269-1) output 11.9v,  seems every thing is right.

  • What is the most elegant way to use the LTC4269-1 with an 30 V auxiliary supply?

    What is the most elegant way to use the LTC4269-1 with an 30 V auxiliary supply? Take the Demonstration circuit 1335B-C, (DC1335B-C) as your starting point This is a high-power supply featuring the LTC4269IDKD-1, LTC4269-1. I need to plan for the scenario…

  • How do I calculate the minimum ET Volt-Microsecond Constant for a pulse transformer used with the LTC4269-1?

    What's the right way to calculate the minimum ET Volt-Microsecond Constant for a pulse transformer used with the LTC4269-1?

    The reference designs for the LTC4269-1 use this transformer

    Pulse Electronics Power
    PE-68386NLT
    PULSE XFMR 1:1 785UH
    ET Volt…

  • LTC4269 output cycles, why?

    I'm trying to debug a PoE circuit which is pretty much a clone of the application example on page 31 of the datasheet. The main difference is that the output voltage needs to be 12V so the transformer is a PA2694 and the resistors around the TLV431 that…