pic power question

I am new to the whole designing & using pics but want to learn so here I am..

I am building a circuit that will be installed in a car using the PIC 16F690.
I know I need a voltage regulator & have seen many schematics that use the 7805 fixed 5 v regulator TO-220 package. My question is the 7805 is rated at 1A but the PIC maximum input current is around 250mA. In the schematics I've seen there is nothing to drop the current to the minimum current needed. How is this possible... why arent people using the 78L05 in the TO-92 package as it is rated for 100mA? Also there are some that use 2 capacitors 1 on the input one on the output of the 7805 & others that use 3 caps 1 at the input & 2 at the output. Why use three?

Thanks

i think it means the max you can draw is 1A

Datasheet:
https://www.electro-tech-online.com/custompdfs/2008/06/LM7805.pdf

Page 1:
Output Current up to 1A

Wow!! Thanks for the quick response....

The PIC will only draw as much current as it needs, but things like LED's need a resistor to limit the current going through them.

A 7805 is a bad choice for a use in a car. Too much electrical noise.

Some regulators are made for use in cars. For 100mA or less look at the LM2931.

100 mA is enough current for many applications. You did not tell us what you want to do so we have no way to tell.

Cars electrical systems can be very hostile to electronics.

You should put a diode in series to protect against reversal. It is also a good idea to fit a resistor in series with the regulator input, and an 18V zenner diode to ground, as well as a large capacitor.

The resistor should be chosen to give about 3 V drop at maximum power drawn by your circuit. That will give about 8 V on the regulator.

There can be serious spikes on the car supply. Voltage regulators will not like spikes even if very short, and the resistor an the zenner will help to limit those.

You don't say what you are using the PIC for. If you need it to work when the engine in starting, you have a really difficult design problem. The voltage can drop as low as 5 V when the engine in starting, and you won't get anything out of a 7805 at that voltage, and the diode and resistor that I suggest will stop things working, so you have to have alternative protection against spikes and power reversal.

Ok this is way more than I thought I was going to need but this is good learning. 3vO would I have to use a zener & resistor as Diver300 suggested? This circuit is simply a monitoring toy, 3 L.E.D.s & a piezo speaker will trigger when the throttle position is at different positions. I wanted to do a project using the A/D & comparators. For example when the throttle is 90% or higher 1 L.E.D. will trigger as well as the piezo. So the pic is loooking at the throttle position analog 5v to determine which output will trigger. I figured this would be a good way to get familiar with using the A/D & comparators because I know the voltage input has to be stable as it is the ref. for the comparator.

Diver300 do you mean a diode in series on the output of the regulator & the input of the PIC?

I've been using a 7805 and 7833 (3.3v) to power a PIC, accelerometer, and LCD in my car for a while. Despite the massive amount of heat generated by dropping 12V down to 5 and 3.3, everything has been stable.

If you are doing any A/D conversions, I would recommend getting a discrete voltage reference. The 7805 doesn't always put out exactly 5.0V.