Maximum Current?

Question

This is an extremely noobie question, but I have a 5V at 2A power source. This power source is going to be powering 6 Sharp IR distance sensors(20-150cm) and a few other low current consumption sensors(ie Xbee).

My question is if it is safe to simply use that power source without some sort of resistor between the power source and sensors?

also the IR sensors have a analog output. Is that same to plug into the arduino's analog pins?

Answer 1

also the IR sensors have a analog output. Is that same to plug into the arduino's analog pins?

If the sensors won't generate more than 5V, it should be safe. (Generally, they're all less than 5V. However, verify this...)

My question is if it is safe to simply use that power source without some sort of resistor between the power source and sensors?

You probably don't need a resistor*. Current is supplied on demand; if you need 1A but have a 2A supply, only 1A will flow. Voltage, however, is constant.

That being said, some parts will pull more current than they can safely use (like a LED, so then you would use a resistor.

This should all be found on the datasheet (especially with a more trusted brand like Sharp). Just look for example circuits and input voltage/forward voltage. A quick note, make sure to connect the grounds if you're not driving the Arduino directly from the power supply.

_{*There probably is an internal resistor for the LED. Again, datasheets, datasheets, datasheets!}

• Trexter: wow once again you answered my question flawlessly. Thank you so much

Answer 2

A few other points, in addition to Penguin's excellent answer:

Make sure your 5V supply is a REGULATED supply. Unregulated power supplies will exceed their target voltage when unloaded, and "droop" to lower than their target voltage when under heavy load.

Quite a few digital components can be destroyed if their input voltage varies too much from 5V, especially over-voltage. TTL is especially sensitive to over-voltage (which destroys the circuit) and to malfunctioning on under-voltage.

Even a regulated power supply will have some ripple if you switch heavy loads on it. You might want to use separate, isolated supplies for your high power and low power logic systems.

A higher current regulated supply will be "stiffer" and therefore more stable if run at lower loads.

• Trexter: I am using 4 seperate ESC (electronic speed controllers) these give off 5 volts at 2 amps as a BEC (battery eliminating circuit) I assume that they must be regulated to take their 11.1 volt input and turn it into 5 volts.
• Trexter: I also have the IR sensors using their own power supply and my gps and xbee with another. By the way thanks