Hello,
We designed a POE supply 5V / 2.3A (class 0). The schematics are attached.
When the load is lower than 1A, the output is stable at 5V with a less or equal to 100mA => perfectly normal.
The problem is when the load is higher than 1A, the output voltage drop to 4V or less but without any instability or hudge ripple...
I compute again the components value but even with the new one, the results are the same...
Could you help us?
Thanks
Hello,
Here the schematics:
Output with no load:
Output @0.5A:
Output @1A:
Output when load is higher than 1A:
We redo measurements with mosfet gate and transformer secondary
Hello,
Here are captures of Vout, MOS_Gate and Transfo_sec:
@0A load:
@0.5A load:
@1A load:
and @ above 1A load:
Regards,
Jean-Yves
Hello,
Here are captures of Vout, MOS_Gate and Transfo_sec:
@ 0A load:
@0.5A load:
@1A load:
@ above 1A load:
Regards,
Jean-Yves
Hello Michael,
Here the scope screenshots with the three measurements:
Output with 0.5A:
Output with 1A:
Output with >1A:
Hello,
We found the issue:
On schematic, the link between the three current sensing resistors is missing:
So the equivalent value is 1Ω instead of 0.33Ω, and then the switched current is limited three times lower than expected.
After rework, all it's work!
