How to set STUSB4710 PDO profiles

[CMaker]

Hi, I am designing a 25W power supply for the raspberry pi 5 for my battery powered project. The buck regulator I am using has a fixed 5V output and I want to use the STUSB4710 to offer 5V 5A to the Pi. How can I program the registers to do so via I2C? I have checked the datasheets as well as the STUSB47XX register maps but both are still quite vague on how to program.

[Didier HERROUIN]

Dear CMaker,

This profile (5V/5A) is not allowed by USB standard, you must rise the output voltage to 20V before increasing the current above 3A.
Note that above 3A, you must use smart cables which are able to answer some requests from the SOURCE (the SOURCE first checks the cable capabilities before pushing a current > 3A).
The STUSB4710 can support up to 60W (20V/3A), it does not support 5A profiles.

You can use the GUI : STEVAL-ISC004V1 | Product - STMicroelectronics or follow the Technical Note attach to modify the PDO profiles inside the NVM.

[CMaker]

Hey, thanks for the response!

 

I saw in the datasheet which specified that the PDO profiles had a maximum current support of 5A, even if it violates the USB spec. If I were to set it to 5A, would the STUSB4710 have any internal checks to the profile or will it fulfill the request naively?

 

Best,

 

CMaker

[Didier HERROUIN]

Dear CMaker,

Indeed, it is possible to set up the PDO current to 5 A : it will work as the STUSB4710 does not check the cable capability,. But note that this setting is targeted for a charger using a 5A native cable (so you can guarantee that the cable really supports 5A), not for removable cables. 

Best regards.

[CMaker]

Hey,

 

Thank you for your insight. To clarify, when you mean native cable, you mean a cable that is integrated into the PCB like charging bricks with a USB-C output?

 

Best,

 

CMaker

[Didier HERROUIN]

Hello,

Yes, the cable must not be able to be removed (not sure that this is the case for all charging bricks).
Regards.