I'm seeing some issues with the LT3748. Here is the schematic of mine:
This is the transformer: https://www.mouser.co.za/ProductDetail/Wurth-Elektronik/750310617?qs=%252BUQ4csG8Rscr4kcgwycPjw==
At the output of this I have the following two circuits connected:
If I have either the 5V or 10V LDO connected to the lt3748, the output of the flyback converter is fine.. I get 12V at the output of the flyback and either 5V or 10V at the output of the LDO.
When I have both of these LDO's on the board, the flybacks output voltage drops to about 2V. The gate previously had a switching frequency with a relative high frequency, now that both are connected and the output voltage has dropped, the pulse train to the MOSFETs gate has a very low frequency.
Does anyone know what could be causing this? I thought maybe over current but I cant imagine it being that. I even swapped the 8m ohm resistor with a 2m ohm to double check and nothing changed. The LDO's aren't driving anything( their outputs aren't connected to anything).
What am I doing wrong?
[edited by: EngJunkie at 11:21 PM (GMT -5) on 7 Nov 2021]