Push Pull Converter with Load - voltage drop Issue

[emaniac]

Hi, with 15 watts load the MOSFETs are safe. The signals are clean. The Power supply is ripple free. I have 3*2200uF bypass capacitor along with 1uF Film capacitor. But I see a total disturbance when connecting to 100 watts load. They are not stable at all. I tried adding bypass capacitors directly to the supply terminals, but that didn't help either. This is not only the case with 7AH but also with 150AH. So I think I'm missing something or possibly a layout issue. Here is the image of my design



Sorry for the poor quality.
This is roughly designed one. I'm going through the layout considerations.
This design is just based on everything I could collect. I might be missing something.

 

[KlausST]

Hi,

or possibly a layout issue.

I think so. With 100W you have high current pulses with sharp edges.
A gnd_plane is essential. Also short and wide traces in the complete power path: input capacitor, switch, diode, coil, output capacitor and the current path via gnd plane.

Klaus

 

[emaniac]

Very Well, I'm Planning for a new Design. I don't have good practice in PCB. I have read few documents though.

I'll upload my new PCB layout, Could You Please comment on that?



The "signal track" that I have mentioned in Image1 bothers me because the track length have got longer. Is that likely to have any issues with track being so long?