Programming 18F2455 issue

jspencer · Joined: 22 Dec 2003 Posts: 57 Location: Boise, ID USA

This is just a notice to those who are using this chip. If you plan on using a programmer that applies > 12.5V on the MCLR pin, you will need to add a voltage divider to your circuit/programming fixture as the 18F2455 is not rated to handle voltages higher then 12.5V on the MCLR pin. I found this out after ruining three of them during programming.

James

Vroop1 · Joined: 11 Apr 2006 Posts: 2

I am using the same chip, and I'm ready to start programming with ICD-U40. Needless to say, your post concerns me. Are you sure about the 12.5V limit at the MCLR pin? I just checked the PIC datasheet, and it states that the max voltage is 13.25V. Is the datasheet incorrect?

jspencer · Joined: 22 Dec 2003 Posts: 57 Location: Boise, ID USA

I haven't had any trouble with the ICD-U40, but I did have trouble with the QuickWriter Programmer. I actually called TechTools and they are the ones that told me that the 18F2455 was only capable of handling 12.5V. Check out page 38 of this document: http://ww1.microchip.com/downloads/en/DeviceDoc/39622F.pdf

It says that the max is 12.5V

jspencer

Vroop1 · Joined: 11 Apr 2006 Posts: 2

So the ICD-U40 didn't ruin your PIC. That is comforting to know. Thanks for sharing your experience.