Step Down (Buck) Regulator Voltage Spike Protection
Step down regulators work with feedback. For example if you set the output of LM2596 at 3.3V. There will be +5V voltage at the output for a while (if the input voltage is more than 3.3V). It may burn out some sensitive circuits working with 3.3V over time. A 2.8 or 2.7V zener diode and a 3V relay (coil resistance must be minimum 60 or 45ohm) are required for the circuit to work. It is a little difficult to find in the market. If the input voltage is 3.3V, the LED turns on. But if it is more than +3.3V, the LED turns off.
