UCC28910: the purpose of the resistors at the output?

Hi Sedar,

I will need to ask the original designer, they may have been intended to provided some form of identification voltage to the load system.

In general a pre-load resistor in the the position of R10 must be fitted to allow for good no-load regulation. The UCC28910 datasheet provides guidance on the application design procedure.

www.ti.com/.../ucc28910.pdf

Regards

Peter

Hello Serdar

I didn't design this circuit so I'm guessing (a little).

R10 is almost certainly a provision for a preload resistor - a small load to prevent the output voltage peaking up at no load - the designer probably found that it was un necessary in practice.

The other resistors R11 and R12 allow the user to put a voltage on the two data pins of the USB connector. This is sometimes needed to allow the target device to 'recognise' the charger is present and to accept charge from it - see http://www.eetimes.com/document.asp?doc_id=1279469  for example.

None of these resistors is necessary for the basic functioning of the power circuit of course.

Regards

Colin