On 8 Feb 2003, at 23:45, Jai Dhar wrote:

>  I started on getting my MAX787 5V SMPS regulator working. It's a very
> simple connection, so it seems, according to the data sheet on maxim's web
> site (http://www.maxim-ic.com/quick_view2.cfm?qv_pk=1271). I am using their
> EXACT circuit, and getting a nice solid +5V output. The problem is at the
> input from the rectifier. Basically, I have a transformer that goes to a full
> wave rectifier, and then the positive part of the rectifier is fed into the
> input of the regulator. As soon as I connect the input of the regulator to the
> output of the rectifier, the voltage at the input jumps up to ~45V. Without
> the regulator connected, the voltage at the output of the rectifier holds at
> ~25V.
My guess is that you don't have a reservoir (bulk) capacitor and when you say
"connect the input of the regulator to the output of the rectifier" you are
including the 220uF cap which is on the regulator input.

George Smith

--
http://www.piclist.com#nomail Going offline? Don't AutoReply us!
email listserv@mitvma.mit.edu with SET PICList DIGEST in the body