Instructions
To generate 3.3V from a 5V supply, use a Low Drop Out regulator
designed for this purpose, such as the Maxim MAX604 (0.5A reg) or
the Linear Technology LT1086 (1.5A reg). If you are more adventurous,
the Maxim MAX767 and MAX710 switching regulators can be significantly
more efficient. If you have lots of stuff at 3.3V, use the integrated
switching regulators from PowerTrends.
The LM317 is NOT a good choice for 3.3V from 5V, as its nominal dropout
voltage is 2V (at 25 deg-C, Load=1A). In fact, its dropout voltage
is quite complex, over temperature, and load, and can be as high as
2.5V.
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