Hi Michael,
The bulk input caps on this design were sized for the steady state output power of 50W. If you want to size them for the peak loading of 100W, you are correct, it would require more capacitance. I typically use a factor of 1.5-2 uF/W for…
Hi ,
The PMP8740 design does use the UCC28951 to control the power stage. Yes, it is possible to use the UCC2895x devices to generate 0-120V output. The PMP8740 design can be used as a starting point, but obviously, the power stage would need to be…
Hi Daniel,
The value is not that critical. Lower is better for minimizing the voltage spike, but you have to keep the impedance significantly larger than the CST impedance to ensure the primary current flows through the CST (as you pointed out.)
…
Hi Sarumathi,
You can safely use the same output inductor and capacitor as used in the reference design, since your input range falls within the input range of the reference design.
If you want to use the buck equations for selecting the output inductor…
Hi Amr,
C13 bridges the isolation boundary and will need to be safety rated. You will need to check the isolation requirements for your application to make sure you pick an appropriately safety rated capacitor. Typically this would have either a Y1…
Hi Mikha,
I am happy that we finally came up with a resolution. Yes, I think this is an acceptable solution for production. I suggest adding a 20V zener to the 5V rail just in case that output is unloaded. It will protect the TPS71533 from any possibility…
Hi Hsu,
Increasing the filter cap on the current sense (C21) to 100pF resolves this issue. The problem was noise on the current sense caused the switching pulse to terminate early at higher input voltages, which increases the frequency in low power…
Hi Mohith,
Sorry, we don't have any waveforms of the bias voltage/current saved. The secondary bias winding only supplies a few mA for the TL431 regulation and the downstream LED drivers. It sounds like something on the bias is shorted. Check for…
