Power-on reset. Start-up timer.

[Dave]

Lasse1 , You could also use an Processor supervisor device like MAX690 or something like it. It will hold the processor in reset until the power is stable and above the minimum level. The other thing it can do for you is an external watch dog timer as well as low power supply monitor...

Dave Purola,
N8NTA

[BrianT]

PIC18F4620 parameter D004 says 0.05V/mSec is the minimum dV/dT to get a reliable startup. A few years ago I had a dodgy system (with a Motorola xxxx supervisor chip) that was intermittent until I reduced the inlet filter capacitors to ensure faster voltage rise at power up.

Your mileage may vary but adding the supervisor did nothing for me.

HTH
BrianT

[Dave]

Brian, Actually, that is exactly what they are made for. I have used them for about the last 5 or so years on all of my products and projects. I have never had a problem with the reset line except when I forget to toggle the watchdog input.....

Dave Purola,
N8NTA

[Lasse1]

Brian, Actually, that is exactly what they are made for. I have used them for about the last 5 or so years on all of my products and projects. I have never had a problem with the reset line except when I forget to toggle the watchdog input.....

Dave Purola,
N8NTA

Thank you all. I will try a MAX-unit and see. Then I will let you know, here.
/ Lasse