How to drop from 6V to 5V a "clean" way?

[flotulopex]

I have made a kind of timer - more or less something like the ones for the chess players but for up to 5 players. My mother just drives me crazy when we play Rami and she wins but she takes almost triple time for reflection....

So to the project, there's a PIC, an LCD display, 5 LEDs, a piezo and a few external pull-up resistors.

On my breadboard, I had no problem to get the timer work properly. I have a lab power supply so no trouble here.

When I made the prototype, my thought went first to the power supply. Due to the boxe size contraints, I choose to go with four UM4-AAA batteries (I didn't want to go with accus and a charger).

After some tests, I had to modify quite a few things such as:
- external 10k pull-ups (the internal ones look to be to weak because both buttons just switch from time to time even if nobody presses them)
- addition of 100nF cap between Vdd and Vss (I never needed before) and another one between LCD and Vss (same)

Actually, the circuit consumes around 50mA when the display is ON and one LED is activated (normal operation). Strangely, when I start the timer, the current drops to 20mA. I'm still invastigating this.

I also used another display for the final version than the one I use on my breadboard and this display is extremely sensible to power fluctuation. If I have 4,8V then the display will dimm a lot and if the power is over 5,4V, the display will just go black (the contrast setting is very sensible).

I think the LDO is effectively the best solution in my case.

Grazie Luciano ;-)