Dear all,
Can an imperfect power off reset, with the power supply going down to 0.5 V instead of required 0.1 V, damage flash programmable HC08 chips?
I have made a board with a micro and a RS232 line driver amongst other things, and I have been using Metrowerks to download the code. It worked ok for some time, it went to a few dozens of programming/debugging cycles, say 30, and then it become dead (for the Metrowerks).
Later on, trying to see what happened, I have noticed that my power off reset did not bring the power supply for the HC08 down to 0.1V but only down to about 0.5 V (a leak from an overseen pull-up elsewhere on the board
- embarrassing). The chip itself does not seem to have shorted pins neither to the ground nor to the supply, and I haven't been able to find any other electrical fault.
Another thing the chip suffered is that I tried to perform bit set and bit clear using 2 byte addresses. I had detected it while the chip was still ok, and corrected it, went through two or three more programming cycles, and then the chip stopped responding.
I shall try replacing the chip presently, but would anyone care to comment on what could have gone wrong, and why? All comments welcome.