The datasheet for the LM5085 has an example that is much closer to what I want than Webench.
I had picked a Vishay Si7489DP PFet and then found the datasheet had used a similar Si7465.
I can make a much smaller supply with the LM5085.
Too bad Webench is crippling it at this time!
Bob Stanley
Engineer
Equalia
333 W. El Camino Real, Suite 290
Sunnyvale, CA 94087
rstanley@equalia.com
(650) 967-7100
From: Kevin Ip - WEBENCH Design Center [mailto:bounce-1879818@mail.e2e.ti.com]
Sent: Thursday, June 26, 2014 2:23 PM
To: switcherpro@mail.e2e.ti.com
Subject: RE: [Power and Lighting Tools Forum] Webench won't model LM5085 for my design.
Sent: Thursday, June 26, 2014 2:23 PM
To: switcherpro@mail.e2e.ti.com
Subject: RE: [Power and Lighting Tools Forum] Webench won't model LM5085 for my design.
Hi Robert,
It doesn't look like a custom FET can be added to the BOM yet, but I did find a way to force WEBENCH to create higher frequency designs by lowering VinMax(to 25V) or lowering Ta (to -40degC).
The max frequency is set based on whether a suitable FET can be found, and the frequency keeps being reduced until it can find a FET. Since the switching loss of FET depends on VinMax, reducing this value opens up the designs possible.
However, lowering the VinMax will change the FET voltage rating and other component ratings, so be cautious of using the BOM components selected as they may not have the correct rating.
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