• LTC4269-1 for LLDP protocol

    Hi,

    According to LTC4269-1 datasheet,

    a Type 2 PD must be able to recognize both layers of communications and identify a Type 2 PSE.

    According to IEEE802.3at-2009,

    Type 2 PDs implement both 2-Event Physical Layer classification (see 33.3.5.2) and Data…

  • 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 POE Not Negotiating

    I have a new LTC4269-1 based on the DC1335B-B eval kit schematic with a 5V output. It works with the AUX input connected but not with POE. It appears that it is not negotiating.

    I am questioning whether I have the RJ45 wired wrong.

    Here are schematics…

  • 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 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…

  • 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…

  • 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…

  • 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…

  • Is this a valid use of the LTC4269-1 SHDN pin to allow for a 24 V auxiliary supply?

    Is this a valid use of the LTC4269-1 SHDN pin to allow for a 24 V auxiliary supply?

    In my application I have two use cases that I need to design for:

    1. A PoE PSE is connected to the input.

    2. A plain +24 V power supply is connected to the input. This…