Other Parts Discussed in Thread: UCC28700-Q1, UCC28700
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The UCC28911 for applications below 12 W so the design will work for either application. The device does not come in a Q1 rating. If you require Q1 rating for automotive the UCC28700-Q1 will work for this application and will require an external FET.
If you decide to move forward with the UCC28911 design there is a Webench design tool that will generate a design for you including the bill of materials. You can find the Webench design tool on the following page.
If you decide that the Q1 rating is desired the following link will bring you to the UCC28700-Q1 Webench design tool to aid with the design.
Thanks Mike for the quick response. Q1 rating is currently not needed.
For UCC28911, the only topology that I can see in Web Bench is Flyback, not buck. You also see this?
Also as I can see now the max drain current of UCC28911 is around 1A. So would this be able to provide a buck output of 2A for a duration of 0.5 ms? Wouldn't the over current protection kick in?
I discussed this with my colleagues and the peak FET current is limited to 980 mA for the UCC28911 and operates in critical conduction at max load. This will set the maximum average output current to 490 mA. So the UCC28911 will not be able to work for this application. The UCC28911 is the highest power rated device with an internal FET that Texas Instruments has for this application.
The UCC28911 will work in a PSR fly back for this application. The other option would be to use the UCC28700-Q1 with an external FET in high side buck.
Thanks for finding out. In this case for UCC28700 I can't find any resources for using it in buck mode, every application note, webench tool and spreadsheet calculation tool is for flyback mode. Would it be possible to provide any guidance to using UCC28700 in buck mode?
Also apart from UCC28700, are there any other flyback controllers that can operate in buck mode?
I am checking with the power supply design services team to see what they have in regards to applications on how to design with a PSR controller in a buck application. This is a unique applications and they are hidden challenges.
I will be getting back to you shortly.
The power supply design engineer who specializes in using the UCC28700 and UCC28911 device in buck converter shared his design notes and MathCAD design file, which I have attached for your reference.
Please note if you don't have MathCAD you can download a free trial version from PTC at the following link. https://www.mathcad.com/