LM5155: Dual output DC to DC converter isolated

Hi Niklas,

Thanks for the immediate reply. I appreciate your quick response.

I am trying to use the LM5155 calculator. Here I am attaching the circuit with calculations.

Should I connect secondary coil 2 positive output to secondary coil 1 ground path (return path) & use the secondary coil 2 return patch as Negative output.

Hi Brigitte,

Thanks for the reply...!

Ok. I will design as per your recommendation and approach's you for questions, if any...!

Hi Brigitte,

There is no auxiliary winding to supply the power to the LM5155. Where should I connect that VCC pin of the LM5155.

Hi Sanjay,

Thanks for the feedback.

If the VCC pin is not supplied from an aux winding of the transformer, it will be generated internally through an LDO from the BIAS voltage.
In this case, VCC is just connected to a capacitor to GND.
At high input voltages, there will be larger losses inside the IC due to the LDO voltage drop.
A reference design with a VCC connection from an aux winding can be found here:
https://www.ti.com/tool/LM5155EVM-FLY

Best regards,
Niklas

Hi Niklas,

Thanks for the reply...!

OK. I will follow as guided and update you.