I'd like to start using switching voltage regulators such as the LM2575 in the Arduino-like boards I design, instead of the linear regulators I usually use, such as LM7805 and LM7812, mainly to avoid overheating.
However, I'm finding a little difficult to make the transition, as there are a few more things to worry about when using switching voltage regulators in such designs. The following are a few of the obstacles I've found while studying the LM2575 datasheet:
- Inductor selection based on maximum voltage and current;
- PCB layout issues, such as single-point grounding and ground plane construction;
- Continuous and discontinuous modes of operation (when to select each mode).
Could someone provide some guidelines for beginners like me who would like to transition from linear to switching regulators? Are there any traps or dangerous situations to avoid?
Edit: To be more specific, I have three examples I would like help with:
I have an input of 15 to 18V and want the regulator to output 0.8 to 1.0A @12V. But during operation the load may require less current (when less 7-segment displays will be lit). What inductor should I use for that situation? Should I select the inductor for continuous and discontinuous operation mode?
What would be a good choice of inductor, input and output capacitors if I wanted to replace the LM7805 linear regulator for a LM2575@5V on an Arduino Single Sided Serial board (S3V3 - Severino).
Will I have to worry about EMI to a RF receiver on the same board I use the LM2575?