Hi,
I am new in power supply circuit design and recently I have used LM5119 to design my own power supply circuit board. This power supply circuit board is designed to take input from 11V - 55V and output 2 power sources: 5V/8A, 12V/8A (here I am not too sure if the module is capable of supplying the 2 outputs). I have attached my schematics here.
The problems are as below:
1) The input power is from a power supply and I found when input voltage is below 35V, the current drained is 0.08A, which is a little bit high. When the input voltage goes beyond 35V, the current also increases with the voltage and the boards heats up very fast. But the output voltage can still maintain at 5V and 12V even if the current drained going crazy. There are no loads when I tested the boards.
2) The ripple voltage of 5V and 12V are quite high around 500mV, which is much higher than what I have designed to be.
3) I have recorded the signal of the HO1 and LO1 (I have used PSMN5R5 as both high side MOSFET and low side MOSFET), which are also quite different from the simulation results I got from Webench, as below:
and a zoom in view:
4) I have also recorded the signal of VCC1, the average of the signal is around 7-8V, but ripple is very obvious.
And the signal of HB1, also very different from the simulation result.
Here is my schematics. I have no idea what caused the oscillation comes into almost all of the signals and why the pace of HO1 and LO1 are not sync. Hope the professionals can give me some suggestions.
Thank you so much!!!!
Raymond