hi,
I was asked to build a DC step down voltage regulator. The problem i am facin is that I have never done this sort of thing before and have absolutely no clue of how to do it. can any one please help. The requirements are

input voltage - 18V
Outuput voltage - 12V
Output current - 2A
Power rating - 24W
He also wants mminimal amounts of ripple.

 

Presumably "HE" is thinking of a switch-mode design since ripple was mentioned.

Or is a linear regulator allowable?

 

2A at 6V drop, 12W. This is for analog. Switching is a lot more efficient, and cooler.

 

He is basically looking for a pulse width modulation through a timer triggered through a driver, which will give pulses into the circuit. I have attached a link of a picture which might give u some ideas

http://ewb-uiuc.org/system/files/images/buck-converter.preview.png

I am struggling to work out the values of the components.
Thanks

 

There is a nice Webench Power Designer tool at the National Semiconductor web site, www.national.com, that can be very useful at determining switching regulator devices as well as supporting components.

 

thanks for the info. it was good help.
but I just realised that i didnt mention.
I have access only to 555 timer.
sorry for not being able to mention earlier