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Topic: Current draw 5V pin arduino uno (Read 571 times) previous topic - next topic

meerweten

for a project i'm working on i draw a lot of current,
momentarily i use my bench power suply but i need to know how much i can draw current from the 5v pin to know if i need to ad an external regulator or not.

Grumpy_Mike

About 600mA due to heat dissipation of the regulator chip. This can move slightly depending on the input voltage to the regulator.

meerweten

good i only need about a 400mA thanks

MAS3

You asked about the 5v pin, not about the controller.
The controller can't handle as much as the regulator can supply.
So if you want to switch that power with your controller, you'll be in for a surprise.
Just to make sure.
Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

Grumpy_Mike

What do you mean by controller? Is it the arduino? That only takes about 30mA.

MAS3

I meant to warn that you can't switch LED's and other "peripherals" with a total of 600 mA with the Arduino.
Although the regulator on the board would allow that, the ATmega chip can't handle this much current.
So there is a difference between the current that can be handled by the on board regulator, and by the ATmega.
Just to let "meerweten" (which translates to "to know more" by the way) or any others that are interested in this info know not to mix up these specs.
Have a look at "blink without delay".
Did you connect the grounds ?
Je kunt hier ook in het Nederlands terecht: http://arduino.cc/forum/index.php/board,77.0.html

Grumpy_Mike

So you mean the ammount of current that can be sourced or sunk by the processor.
There is a limit of 200mA per pin, but the chip used in the Meag has multiple power and ground pins so you can source / sink this ammount of current. There are however other restrictions as to the total of individual ports as well as individual pins.

alnath

I think that OP meant  the 5V pin of the arduino board, the one which is between GND and 3,3V

fungus


good i only need about a 400mA thanks


400mA can be too much if the input voltage is high.

Asking about current is the wrong question. You have to calculate how much power the regulator needs to throw away (ie. convert to heat).

An easy way to do the calculation is to put your finger on the regulator then connect the power. If it you have to remove your finger to avoid a blister, you need an external regulator...
No, I don't answer questions sent in private messages (but I do accept thank-you notes...)

alnath



good i only need about a 400mA thanks


400mA can be too much if the input voltage is high.

Asking about current is the wrong question. You have to calculate how much power the regulator needs to throw away (ie. convert to heat).

An easy way to do the calculation is to put your finger on the regulator then connect the power. If it you have to remove your finger to avoid a blister, you need an external regulator...



it is called "a rule of thumb"  XD

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