Other Parts Discussed in Thread: TPS2372-3EVM-757, TPS23861, , TPS23861EVM-612, TPS2372
Hi,
I have a PoE circuit for LED Lighting that uses the TPS2378 as the PD interface. The 48V is then taken to a LED constant current circuit to power my LED. A LED constant current driver is connected to the 48V supply from the TPS2378.
- If i connect the PD to the PSE with the LED connected and the CC driver enabled, then the LED comes on but the TPS2378 gets uncomfortably hot.
- If i connect the PD to the PSE with the LED disconnected and the CC driver enabled, then the TPS2378 is thermally ok. When i then connect the LED, which comes on, the TPS2378 stays cool.
- If i carry on with 2 above and turn the CC driver OFF and then ON, then the TPS2378 gets uncomfortably hot again. I don't disconnect the PoE cable for this.
My (limited) understanding of this is that, if the load on the TPS2378 tries to draw more than 140mA at start up (80mS) then the TPS2378 goes into current limit mode which is why its getting hot? So i need to delay turning on the 'load' until 80mS has passed?
However, this doesnt explain what happens when i turn the CC driver OFF and then ON as in (3) above. This I will need to overcome as i plan to control the LED CC driver ON or OFF remotely.
I would be grateful for any guidance on this.