I am using an ST Micro L78S12CV to regulate a deep cycle battery to run a nano.
I will put caps in, but do I have to?
Do ripples come from DC power, too?
All I see is reference to rectified AC power so I'm curious.
I assume a 12volt lead/acid battery.
Wrong regulator.
12volt is the upper limit for a Nano,
and with that voltage on the raw (V-in) pin you can draw almost no current from any pin.
Better to use an 7805, and connect it's 5volt output directly to the 5volt pin of the Nano.
Or, better still, use a 5volt buck converter instead of a linear regulator (higher efficiency).
A cigarette lighter type USB car charger is an easy solution.
Just plug the USB lead of the Nano in the USB charger.
And yes, you need decoupling capacitors if you use an 7805, very close to the regulator.
If you omit them then the regulator could oscillate and destroy the Nano.
Leo..
Whether 5v or 12v, the nano will still drive gates and LEDs.
Do ripples come from DC power, too?
The capacitors are not for ripple, they are for "stability". Without the capacitors the regulator can oscillate, go out of regulation, or overheat.
You usually have a "ripple filter" capacitor and that same capacitor can be used for regulator stability.
From the datasheet: [url=http://Note: CI is required if regulator is located an appreciable distance from the power supply filter.
Note: CO improves stability and transient response.[/quote]
Zip_Ferndale:
Whether 5v or 12v, the nano will still drive gates and LEDs.
A Nano always runs internally on 5volt.
If you power it with 6-12volt on the RAW (V-in) pin, then the onboard 5volt regulator turns that first into 5volt.
Turning any difference (12-5= 7volt) into heat.
Leo..
Use a 5V switching regulator.
Lots of efficiency, not wasting (12V - 5V) x current draw (i.e. > 50% of battery capacity) as heat.
The recommended cigarette lighter style USB charger IS a switching regulator.
And hopefully designed for potentially 'dirtier' 12volt car power.
Leo..