I have encountered a number of instances now where ICs that supposedly include "thermal overload protection" will still heat up until they fry. Examples: LM338,LM2576.

These devices datasheets provide little details of the thermal limiting (temperature cutoff, reaction time, reset time, etc.) and also provide no power limit. Max power dissipation is simply stated "Internally Limited".

I no longer expect "thermal overload protection" to function at all unless the datasheet has a whole lot more data than the above.

Does anybody have any experience with these or other similar switching and linear regulator ICs actually shutting down non-destructively at a temperature limit, and is there some way I can roughly predict when this happens?

  • \$\begingroup\$ It is quite possible that the chip was damaged in some other way that doesn't involve temperature, for example overvoltage, and as a consequence of this damage it then overheats without the thermal protection being able to do anything about it. \$\endgroup\$ – sh- Feb 10 '19 at 10:38
  • \$\begingroup\$ To truly protect an IC against overheating, the Thermal Measurement needs to be EMBEDDED within the power device. Not just "near", and certainly not located 2,000 microns (2milliMeters) away, across the chip, where a convenient empty region remained. The main reason is not what you expect; the THERMAL timeconstant is the key; without speedy detection and shutdown, the SafeOperatingArea is violated and exciting events occur inside the Power Devices. \$\endgroup\$ – analogsystemsrf Feb 10 '19 at 12:20

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