UCD3138 PFC and LLC

Depending on the PFC topology, the UCD3138 has enough basic resources to control both a PFC and an LLC. It has 3 control loops, including high speed ADC inputs. It has 8 channels of DPWM outputs.

In general it hasn't been done though, because:

1. The isolation requirements make it difficult and expensive to run either the PFC or LLC power supply signals across the isolation barrier.
2. The requirements for efficiency, performance, monitoring and communication may require too much in processor resources to support both.
3. It's difficult to write and debug firmware to support both functions at the same time.
4. The UCD3138 may not have enough I/O pins to support the actual requirements for the application, even though it does have enough for the power supply function. (Other family members have more pins, up to 80, so this isn't a real issue)

So while the UCD can run an LLC and a PFC at the same time, normally the UCD is used because there is a need for more than just a power supply. It has to be very efficient, the PFC has to have great THD and Power Factor over a wide range of input voltage and output load, it has to have great transient and AC drop handling and recovery, it has to be controllable, it has to frequently and accurately report the state of the power supplies, and so on.

So if you have relatively simple and non-demanding requirements, and are willing to pay to cross the isolation barrier, you should be able to do it.