Easy to kill by backfeeding voltage?

[ligius-]

I had one of these connected to a rPi and it worked fine for about a month. Then I decided to hook it up to an Arduino and did not read the datasheet. I've fed 3.3V into the 3.3V and now it's seemingly dead. I did not put an oscilloscope to it to see if it actually does something, but the leds don't light up anymore and it doesn't draw any current.

I had a second module - hooked it up to an Arduino (just the 3.3V regulated out) and connected the output pin to a buzzer. It buzzed for less then a second and it went dead. Not sure if the buzzer killed it or the 3.3V.

Perhaps it would be useful to have a list of DON'Ts, such as: no voltage on the 3.3V output (without power), no inductive loads, no voltage on OUT... I don't really know what kills these modules. Static?

[ligius-]

Well, it seems that at least the first module was not dead, just sleeping?! Moreover, it doesn't seem to be able to drive a piezo module, which is quite weird. The piezo just has a driver transistor, grounding the base turns it on. I just shorted the base and ground (emitter) together. From the serial out of an Arduino it is still able to make some noise when connected to the collector (because of the pull-up), but somehow it's silent when driven from the microwave sensor. The sensor however can drive the low signal, so the piezo would sound only when there's no movement. Very strange, I will have to scope this.

[LittleFox94]

has the piezo some frequency generation included to work with just a voltage being applied? if you only hear a "click" it might not?