I am using a LT8652S and a LT8364 to generate +15V, +5V and -15V from 18V.
Overall its working, but I am measuring some noise (not switching noise) on the +-15V outputs, which I cant really identify. Also the +5V output starts oscillating at >0.5A at 300kHz.
I have attached the schematic, the layout is mostly as in the application notes. In LTspice aswell as LTpowerCAD it simulates just fine, without the noise.
I took the meaurements with 1.5A at +15V, 1A at -15V and 1A at +5V using the tip & barrel method on the output caps. The switching frequency is about 1.8 MHz,
Can anybody help me with that?
+15V at 1.5A 50uS measurement:
+15V at 1.5A 1uS measurement:
-15V at 1A 50uS measurement:
-15V at 1A 1uS measurement:
+5V at 1A 50uS measurement:
+5V at 1A 1uS measurement: