Electronic – the coolest way (using passive cooling only) to step 12V DC down to 5V DC

heatpower

I'm building a project that needs both 5V and 12V rails which will draw about 1A on the 12V and 0.5A on the 5V. I was thinking of using a 7805 to produce the required 5V but this could generate some significant heat. I am not so much asking if it is acceptable to use a 7805 (I just need a mini heatsink), but rather: are there any ways of doing it cooler? Any tips would be great.

Best Answer

Instead of using a linear regulator, which has relatively low efficiency (~50%), use a switching DC-DC converter (efficiency around 80-90%). A decent one to start with is National's "simple switcher." It looks like the LMZ12001 would do the job-- up to 1 A at 5 V, and it accepts input voltages from 0.8-20 V.

http://www.national.com/pf/LM/LMZ12001.html