I'm designing a basic table-top toy based around a dsPIC33 MCU. It'll be battery powered and I'm using a Micrel MIC2940A-3.3 regulator to produce the 3.3v for the chip. (I've fitted a PP3 clip, with the intention that my device can run from a 9v battery or 3x or 4x AA batteries in a cage with a PP3-clip.)
I'm currently using it in the basic configuration with a couple of capacitors to make the MCU happy. (The typical applications from the datasheet just give it used like this.)
That works, but I've read elsewhere that the 3-terminal regulator can be used as a voltage reference in a feedback loop to a power transistor, so that the power current comes from the supply rather than the regulator.
Is it common practise to use these regulators bare in a simple application?
And is the more complex configuration only necessary when a large amount of power is drawn? (And would using it as a reference be more efficient/stable than the regulator by itself?)
Edit - More info: With the MCU running in its 40 MIPS mode and LEDs and other outputs all on this 3.3v output, it comes to 85mA max draw.