I purchased several fixed output LDO regulators, specifically LM2936Z-5.0/NOPB.
I connected this LDO with a 100nF capacitor on input and a 100uF cap on the output as the datasheet shows. With a 12-20V input the output is at 5.0V until I place a load on the output. Then the output voltage equals the input voltage and destroys the MCU. At first I thought the MCU was pulling to much current, even though I had measured it at 7 mA beforehand. So I set up a test circuit and simply placed a 475k resistor to ground as the load on a second regulator. Same thing happened. But there should have only been 10.5 uA of output current according to V=IR, and the LM2936Z-5.0 is rated for 50 mA of output current. I then tried a 3.3M resistor and had the same problem with a third regulator. After removing the load, the output voltage remains equal to the input voltage, almost as though the LM2936 has blown. If I discharge the 100uF capacitor and start again, the output voltage slowly builds to 5V, but eventually, quickly jumps to the same value as the input voltage.
Any ideas? I do not want to continue destroying the units if that is what is happening. Thank you.