I am building a power supply for my MCU project so I want to turn 12V car battery into 5V. I am looking at Diode’s AP1509 step-down converter. It needs minimal external components and has a current rating of 2A at 5V. The reference design has a Schottky diode on the output side. I wonder why. My logic is that in case the converter fails, the full input voltage will appear on the output side, damaging the output. If I have the Schottky diode, say pick a 5.25V or something, then the output will be protected. But there is no serial resistor (wouldn’t make sense for normal operation to have one) to drop the rest of the voltage though. Any idea whether what I’m thinking is correct?
Here is the diagram: