An apparatus and methods are provided that more accurately detect the onset of thermal runaway in a device and timely control it. According to one embodiment, changes in stand-by current and temperature of a transistor device are measured and are used to be compared to some thresholds to trigger the device to respond before the onset thermal runaway. According to another embodiment, stand-by current is measured and is compared to some thresholds to trigger the device to respond before the onset thermal runaway.