LTC4290
Production
The LTC4290/LTC4271 chipset is an 8-port power sourcing equipment (PSE) controller designed for use in IEEE 802.3at Type 1 and Type 2 (high power) compliant...
Datasheet
LTC4290 on Analog.com
Dear Sir,
We are using the LTC4290AIUJ/LTC4271IUF (Auto mode) as our PSE controller.
When we plug in a Class 2, 3, or 4 PD device,
the PSE port status register always reports the device as Class 4, regardless of the actual PD device class is 2/3/4.
then measuring LTC4290A output port voltage event. event is 3 finger.
may i ask way? this event finger not meet datasheet power on sequence.
The waveform we measured at below. thanks.
Class 2 PD device:
Class3 PD device:
Class 4 PD device:
LTC4290 datasheet power on sequence:
Have you confirmed the PDs are drawing the correct class currents for Class 2, 3 and 4 during the first class event?
The three waveforms show a similar voltage for the first class event. This could mean each PD is presenting a Class 4. But the difference can be very subtle and reading class current is the only sure way to determine this.
Please provide a waveform of the current to the PD during classification.
If a current probe is not available, a DC voltage of 18V can be applied to the PD on Ethernet pairs 1/2 and 3/6 by splicing Ethernet cable.
