On 7 April 2013 11:06, veegee wrote: > Over the past couple of weeks, I've randomly noticed on several > occasions that some of my various ICs (MOSFET gate drivers, 74HC595, > opamps) are getting very hot to the touch. > > I'm prototyping on a breadboard, and the power supply is a ~5V NiMH > battery pack. For all ICs, I'm using a linear regulator and several > decoupling capacitors around the regulator and the IC power supply pins, > and making sure that all inputs and outputs stay within the rated > voltage range.... > Any ideas as to what could be causing this? Occam's Razor says that the preferred explanation is that the voltage regulator is oscillating. Whether this is the actual problem is another matter. (Occam only tells you the preferred answer, not necessarily the correct one :-) ). In this case I'd say there is a very high probability that Occam's simplistic reductionist dangerous approach has actually supplied the correct answer :-). What regulator are you using? Be CERTAIN that the regulator capacitor in and out specs are known and met. On some regulators Cout may not have too low or too high ESR. A look at the power rail with an oscilloscope would show what is really happening. Another possibility is that something on board is introducing bad supply rail swings. Oscilloscope finds that too. Then there is possibly excess voltage on a non psu ic-ic path. If you have an external energy source whose voltage is higher than Vpsu it may be externally sourcing energy via some connection to it. This may pump up Vpsu (maybe via body diodes on some IC as a bonus) or inroduce AC energy. As always a circuit would be a really really good idea and a description of intended functionality and connections may help. eg if this is an RFID transmitter that drives an inductor then what you are seeing would not be too unexpected. If this controls and connects to an RF plastic welder then what you are seeing would almost be more expected than not. Russell --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .