UCC28810 LED Driver - output voltage range modification of PMP5732

D9 needs changing to 42 vdc zener and not sure on the transformer. i would test it slowly upping from 33vdc to 36vdc . going to 39 you will need to see how much headroom exist since output power is increased.

Hello Mike,

Thanks for your reply.

 What do you mean by "slowly upping from 33vdc to 36vdc . going to 39"?

I have another question regarding MOSFET;

The schematics of PMP5732(100-277 VAC input, 25-36VDC, 1.5A output) mentions that it is based on PMP5560(180-264VAC input, 12-25VDC, 2A output),

and the former uses IRFB9N65A(650V, 8.5A) while the latter uses SPP11N80(800V, 11A).

What makes the design changes?

May I replace the MOSFET with lower ratings for my modified circuits(100-277VAC input, 33-39VDC, 1A output)?

Best regards,

Yesok Yoon

We know the supply is designed for a 36 vdc LED string with an ovp originally of 39 VDC which we are changing to 42 vdc without changing the transformer design to gain additional output voltage. This voltage impacts the reflected voltage via the turns ratio impacting the Primary FET as well as upping the bias winding voltage which should be monitored hence the warning to proceed carefully with the design change. There may be little impact or worst case a change is needed in the transformer to accommodate the higher output voltage that can be confirmed through testing and monitoring.

I would not change the mosfet since there is good reason why the designer chose it.  High line voltage, transformer reflected secondary voltage, and the leakage inductance spike add to the voltage stress seen by the mosfet which  the designer took into account when picking  the device.

Hello Mike,

Thanks for your reply.

If OVP of 39VDC is already provided for PMP5732 it is good enough for my project.

One more question regarding FBT design;

On examining schematics of PMP2698(180-264VAC, 8-28VDC, 3.5A), PMP5560(180-264VAC, 12-25VDC, 2A) and PMP5732(100-277VAC, 25-36VDC, 1.5A), it appears that  they use same FBT(G084231LF). My question is when we need to design a new FBT using MathCad design Tool?

Best regards,

Yesok Yoon

An example for requiring a design change would occur if the PMP2698 had to cover an input range of 100-264VAC.

Hello Mike,

Thanks for your reply.

May I ask the side effects if we use the FBT(470uH) designed  for PMP2698 in PMP5732?

Best regards,

Yesok Yoon