Hello, I used the WBench tool and received the below output in Figure 1. My question is - in the parts list there are qty 2 of M1, are these two parts connected in parallel and the gate of each driven by HO? (See Figure 2 Q1 and Q2)
Figure 1: WBench output
Figure 2: Altium design with WBench output
Hi Tim,
Thanks for the quick response and resource suggestions. Unfortunately my cloud version of excel is having issues loading the quickstart tool. Instead, I re-ran the WBench tool with the "balanced" option selected instead of "small footprint". This actually gave me a smaller footprint area, one less FET, and a Fsw of 255kHz. This seems like an improvement, please let me know if you have any input to this.
Hi Tim,
Some final questions on this topic...hopefully it is ok to stay in this same thread.
In regards to the PCB layout, I am trying to replicate the layout found in the LM5146 datasheet but I have less space availability compared to the reference design. I am keeping the in/out bulk caps, FETs, and inductor on the top layer (red). I am putting the LM5146 and its external components on the bottom layer (blue) of the board. I am having trouble deciding what would be the best location underneath the power components to place the LM5146. Below are a couple of options: underneath the FETs, or underneath the inductor.
Option 1: Underneath FET - Pros: shorter gate drive signal trace, Cons: it is right underneath the main source of noise but based on the reading in the LM5146, the noise should be blocked by the 2 internal ground layers in the board.
Option 2: Underneath the Inductor - Pros: LM5146 is moved away from noisy FETs, Cons: gate drive traces are longer (~14mm long)
I am leaning towards Option 1 but would greatly appreciate any input you have. See reference pics below.
Figure 1: Option 1 and Option 2
Figure 2: Option 1 with LM5146 and external parts preliminarily placed under FETs
Figure 3: Option 1 with LM5146 and external parts preliminarily placed under Inductor
