I am designing an embedded system having following components:
- One arduino uno (~300-500mA 5V=2.5W)
- One nodemcu (esp8266) (~300-500mA 3.3v=~2W)
- One PAM8403 based audio amp board (3W output, so on 5V it should be ~600mA)
- One custom made mic preamp (2n2222A+LM358) (don't know, should be within 200 mA=1W)
- One car door lock actuator (12V, running for 500ms while activated, assuming 1A required so power is 12W).
All of the above systems are connected in a same system. I want to use one PSU that would provide power to all of the modules in the system. I bought a 12V 2A switching power supply, assuming it would be enough to run all systems together.
So I made a regulator board using two 7805 (one for arduino and preamp, another for audio amp), and one lms111733 (for esp8266) (All TO220 package for high power handling), feeding them by the 12V PSU. Problem is while I connect all systems all regulators are running hot, and most hot is the one connected to the audio amp, its so hot it burnt my hand (ran only for a minute or so).
I read through couple of forum posts and found that the 7805 linear would run hot as it would dissipate the power (input power-output power) inside itself. For example if the output is 5V-1A then it would dissipate 12V*1A-5V*1A=7W in itself so the heat.
In such situation I can use one 12V PSU along with 1 5V mobile charger adapter kind of things, but I want to stick to using one PSU. Can anyone suggest how to design the power supply for such system.