Other Parts Discussed in Thread: LM5148, LM5146, LM5145
Tool/software:
Hi Team,
I am planning to use the LM5148-Q1 controller for an automotive buck DC-DC converter and wanted to confirm the meaning of the listed maximum load current rating of 20A.
For context on our design:
- Synchronous buck DC-DC converter, 60V input to 14V output
- Switching frequency 500 kHz
- Max DC load 25A (20% of lifetime), Continuous load 10A (80% of lifetime)
- Designing for 10A peak-to-peak inductor current ripple (so absolute max current around 30A)
- FETs top-cooled with heat sink
Most of the TI LM514x controllers have programmable overcurrent protection limit, and I want to program the LM5148-Q1 for a limit above 30A. However, the listed maximum load current rating is 20A, which is rather odd since the load current flows through the power stage components and not the controller itself. We have scrutinized the choice of FETs and thermal management in our design to comfortably handle 30A, even with power derating at elevated temperature. So we should be okay as long as the controller does not trip at lower current limit.
Looking around the forum, this thread and this thread more or less confirm my thoughts that the max current rating is just an arbitrary marketing spec in the product and is rather determined by the power stage and thermal management. But I wanted to make this post anyway to obtain a greenlight from TI that the LM5148-Q1 could indeed be programmed for current rating well above the listed 20A, provided that the power stage is designed appropriately. We just want to be very certain about this in order to not waste time and resources on designing for a controller that wouldn't work in the first place.
Thank you so much for your help!