How does negative voltage damage the pins of my PIC16877A microcontroller. Could anyone explain to me? Thanks
This is because there are reverse biased diodes between the most pins and VDD and VSS. If you apply a negative voltage the diode to VSS becomes forward biased and current will flow. The forward drop of the diode before it turns on to conduct is about -0.6 V. Applying a voltage more negative the diode will conduct and the internal structure the chip is very like a SCR and "latch up" - a low resistance path appears between VDD and VSS. Something will heat up and the chip will be damaged.