> -----Original Message-----
> From: piclist-bounces@mit.edu On Behalf Of John Chung
> Sent: Thursday, August 31, 2006 11:46 AM
>
> I have messing around with LM1117. From my experience it is 
> a good regulator. The thing I like about it is the voltage 
> regulation. When the circuit is open the voltage reads 
> 5.00volts. When I place the load which is a PIC with 
> blinking led the voltage drops only to 4.99 volts*with 
> voltage input ranging from 9v to 18volts!*. This is 
> remarkable to my standards. So my question is, can we build 
> a voltage regulator with such good voltage regulation?

I know I could design and build a voltage regulator circuit that meets the
0.2% combined line/load regulation that you are seeing. However, the circuit
will cost 10+ times more than an LM1117. The high cost to make your own is
why I haven't designed a linear voltage regulator since the late 1980's.

> I have been playing with zeners and diodes and managed to 
> get a +- 0.05 volts with load and varies voltage input*9 
> volts to 18 volts*.

That's pretty good performance (1%) for a simple zener based regulator. To
get significantly better line/load regulation you'll need to start with a
precision voltage reference instead of a zener and use op-amps to provide
the output and isolate the reference from the load.

Paul
 
>
> Thanks,
> John

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