PIC18F452 Power-up problem

bloues · Joined: 25 Nov 2003 Posts: 3

Hi all

Yesterday I've posted a topic "PIC18F452 Power-up problem". (Read that post to see the problem). I fixed the problem, but not with a smaller capacitor value to pic up the MCLR line as quickly as possible, but with a much larger capacitor C1 (220uF). When the system starts-up, this capacitor take some time to charge, thus keeping MCLR low for some time and then pulling it high causing the system to start-up correctly.

Can somebody explain to me why this is happening?

Thanks
Willie

Johannes · Posted: Fri Dec 19, 2003 3:06 am

Hi Willie,

I coudn't view your picture from your previous post. This is most likely a problem on my side as we are busy integrating a new proxy server.
However I use the following method on all my circuit boards and haven't had one problem.

www.s4.co.za/temp/18f458.jpg