This is a follow up to my previous question regarding USB-C power delivery as a power source. There's been a fair about of development since when that question was asked and since STM have released a chip that will do everything I need in terms of negotiation with the USB-C power supply. (STUSB4500)

The long and short of wanting to use USB-C is that I eventually require 5A @ 5V. I also want to use one connector for both power and data (although bear in mind that these won't be both used at the same time).

I'll be negotiating a 3A @ 20V supply. So I need a buck converter that can fit the specifications. Obviously there's plenty of things around, however the important thing is that the height of the components is less than 4mm.

I'm unclear to the intricacies of buck converter, but they seem to require an electrolytic capacitor and an inductor. Will I be able to achieve a design that can do what I need? Any pointers toward suitable chips would be great.

  • \$\begingroup\$ How should we answer this question without doing your complete work? Whether you are able to achieve a working design or not depends primarily upon whether you are smart or not. Therefore I recommend to buy a book on switching converters and read it thoroughly. Use TI webench or whatever to get a reference design. Then modify it according to your needs. \$\endgroup\$ – Ariser Apr 15 at 6:28

Modern buck-converters do not essentially require an electrolytic capacitor. They run on ceramic ones very good, and due the high frequency the capacictor can be smaller. The higher the frequency, the lower the capacitor value.

For your desired project, the biggest problem will be finding a small height coil for the converter.

You have two options here

Either you use a micro-module, which are specifically designed parts that include the inductor and all components in one part and only need feedback resistors and capacitors. Usually these modules are pretty pricy, but deliver a proofen, working and optimized solution for the task, saving you all of the design procedure. Most common IC Manufacturers (Texas, Maxim, Analog Devices) have such modules in ther Portfolio. One example would be LTM4612 which shows a 5V, 5A solution right on top of the datasheet

The other option would be designing your own circuit. Since most convert IC's today are QFN or LGA packages, the height of the IC will not be a problem. But finding a suitable inductor could be a problem. Also it will not be an easy process to design a working and efficient design for such a high current. The LT8636 could to the job for the ic part, and maybe a inductor out of the XEL6030 Series could suit as a inductor

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