Other Parts Discussed in Thread: LM5156
Hi,
After solving the issues from a previous question (I'll go and update the post), I have a new design that works much better and no longer destroys the LM5156.
The issue I'm now having is an inconsistent gate drive output and audible noise. The DITHOFF pin is connected to Vcc. At certain loads and voltages (especially the transition between 115V at 0.4A and 115V at 0.5A), the gate drive goes from a nice, consistent square wave to a number of short, inconsistent pulses. Audible noise and voltage noise skyrockets when this happens.
What could be causing this? It's like the LM5156 is changing in to another operating mode.
Vin = 48VDC
Vout = 115VDC
Fsw = 500kHz
L = 10uH coupled (Wurth 74485542101)
Compensation components:
115VDC@0.4A. Good voltage noise, no audible noise.
Yellow: Vout
Blue: LM5156 gate drive signal
115V@0.5A. Inconsistent gate drive, lots of voltage noise and audible noise.
Yellow: Vout
Blue: LM5156 gate drive signal
