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I recently shorted out my AMS1117 5 V; it turns out the output is directly connected to input now, that is, I now get direct 12 V supply onboard.
I wanted to know if it is specific to a brand or the if the built-in short-circuit protection doesn't work for anyone.
Edit:
I short-circuited the output of the AMS1117 to ground. The short-circuit protection did not work. Instead, now the input and output of the regulator are internally connected; this is very dangerous for my onboard components.
Well I've just had a similar experience with AMS1117: I have some peripherals that are powered by a Nodemcu ESP32's own 3V3 LDO, I was distracted and connected that to the ESP32, swapping 3V3/GND.
So the peripherals (3x I2C IO expander, and a LCD) got reverse polarity on their power supplies. There were a few electrolytic decoupling caps in there, so they probably limited the voltage to less than a volt.
Everything survived except the AMS1117 which just gave up. It somewhat kinda worked after that, delivering an unstable output, so the ESP32 would still boot, then immediately go into an infinite loop of reboots as soon as the chip tried to start up the power-hungry Wifi.
Here's what the datasheet says:
The AMS1117 series of adjustable and fixed regulators are easy to use and are protected against short circuit and thermal overloads.
Well this chip costs 3 cents, so I guess that's what it's worth. Although the chip could also be a counterfeit, with these super cheap modules, you never know what's on them. Maybe it's not an AMS1117 at all, or it came from the reject pile that somehow "disappears" during night shifts, so it wouldn't be surprising that it doesn't perform as per spec. If you bought chips from aliexpress, wish, etc, just assume they're counterfeit.
Since the thing was powered by a PC USB port, in theory that limits current to 500mA, so it blew way below its rated current.
I replaced it with ST LDL1117 I had lying around, and the ESP32 now works. I would trust the short circuit protection of LDL1117 a lot more. Also I got it from Farnell, so I'd assume it's genuine.
Basically, these super cheap regulators are not a good deal. LDL1117 and many others cost a few cents more but they deliver much better transient response with a much smaller and cheaper ceramic cap, whereas AMS1117 requires a large tantalum cap. So total cost is probably higher with the cheap regulator. Unless the tantalum cap is also counterfeit, of course.
You are dropping a lot of voltage. Maybe the regulator was already hot and having a sudden increase in power dissipation might have caused rapid thermal stress and the protection wasn't fast enough.
I was looking this thread, and today I had the some problem with a 5 V 1117 regulator; pin 2 and 3 are shorted and my Arduino died with 13 V across it.
I put a 5.1 V Zener diode together with a 1 Ω resistor between the "+" and "-" dots. With this scheme, if the regulator fails, the diode and the resistor keep the voltage at 5 V.
