I have a 555 timer set up in a standard monostable oscillator configuration. Nothing fancy, no modifications whatsoever. I'm driving it with about 12V. If I trigger the 555 with the ground directly, everything works as planned. However. if I connect the collector of a transistor to pin 2, the emitter of that transistor to ground, and the base to a positive pulse, the 555 triggers, but then it quickly overheats and dies.
Of note, the circuit triggered by the number 3 pin is an RC circuit where C=940uf and R=10k, and when the timer switches off, pin 3 drains this fairly large capacitor. However, with a 9V battery, there's no overheating, and no dead chip. The overheating only happens with 12V, which I'm getting from a hobby power supply normally used for a train. My meter reads ~11.5V on the supply.
Why is my 555 chip overheating and burning out? Everything looks within specs, and it doesn't happen if I use a 9V battery.