LM5143: LM5143 Output oscillation at independent dual output operation

Tool/software:

Hi,

I'm using LM51343 for converter (9V to 12Vin, Vout1- 8.5V at 5A and Vout2 - 5V at 5A). At 12Vin my converter was working fine.

But 10.5Vin my 5V output starts to oscillate at 1Khz to 5Khz. So I suspected it was compensation loop issue.

So I disabled the 8.5V and tested the 5V output. It was working fine and no oscillation at output.

Also I disabled the 5V and tested the 8.5V, No oscillation at output.

But I tested it dual output configuration. The 5V was oscillating.

Also it switch node was oscillating at cycle by cycle.

My inductor value 6.8uH, DCR 6.15m ohm

CS RC value:

5V: 7.5K ohm & 0.2uF

8.5V: 12.7K ohm & 0.1uF

Compensation value

C: 330pF

RC: 20K ohm & 0.01uF

Regards 

Roshan