We have succesfully used the LM5071MT-50 with 13W transformer (coilcraft POE13P-50L) before.
In a new design we only require 3W output, therefore I chose the smaller transformer from Coilcraft: POE30P-50L, which is capable of 3W output.
When testing the new design, I noticed that the ripple on the output voltage is much higher than with the previous design using the 13W transformer.
Output ripple is approx. 800mVp-p (in previous design with 13W transformer around 100mVp-p), measured at the output capacitor. Even when placing additional 3x 100uF/X5R ceramic capacitors in parallel with the output, the ripple does not get lower than 500mVp-p.
I also notice that the 3W transformer gets very hot (around 70 C at maximum load).
I suspect that the problem occurs due to the larger leakage inductance of the smaller transformer (4.5uH vs. 0.95uH).
I attached the schematic of the 3W version of the schematic, I would appreciate any feedback on how to resolve this. Thanks!
Below also attached a screenshot of the output ripple, and of the transformer primary + secondary winding voltages.
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