SERVO CURRENT WITH ARDUINO

Thread Starter

JefferyJames

Joined May 3, 2020
8
Im using a servo thats connected to the 5V pin, D9 and GND on arduino uno rev3.
Each pin supplies a max of 40mA which is not enough for my servo.
The stall current for my servo is 600mA.
Does the 5V pin provide the current I need for the servo.
 

ericgibbs

Joined Jan 29, 2010
10,036
hi JJ,
The Arduino output pin should not be used to drive Servo's directly, usually an external 5V power supply is recommended.
Remember to connect the Arduino 0v and ext +5V PSU 0V lines together.
E
 

danadak

Joined Mar 10, 2018
4,057
When you connect grounds together of servo and Arduino that should be done as
close as possible to the power source/battery ground. Thats to minimize servo current
noise from affecting Arduino, especially when doing A/D operations.


Regards, Dana.
 

MisterBill2

Joined Jan 23, 2018
6,067
Im using a servo thats connected to the 5V pin, D9 and GND on arduino uno rev3.
Each pin supplies a max of 40mA which is not enough for my servo.
The stall current for my servo is 600mA.
Does the 5V pin provide the current I need for the servo.
Why would you expect an output rated at 40 mA to be able to power a load that probably draws at least 200mA running? And why try to power an electromechanical device from a processor board??
Not only is the supply capacity inadequate, but also the servo package may cause noise problems in the processor board.
 

MrSoftware

Joined Oct 29, 2013
1,780
It's a legit question, and the answer is maybe. He's asking about powering the servo from the 5V pin on the Arduino board, not from a processor pin directly.

The Arduino info page for the Uno says the 5V pin is good for 400+mA depending on how the board is powered (excerpt from the page below). I've got an Uno board here that uses the AMS1117 5V regulator, and according to the datasheet (very quick skim) it's good for 1A. (Datasheet here) So my answer would be, in theory the 5v regulator could handle your 600mA for at least a short time, BUT heat is going to be your enemy and you need to read through the datasheet and compare what it says to how the Uno board is constructed to decide whether it has enough heat sink through copper in the board to operate at that level reliably. Also it's a linear LDO, so the higher the supply voltage the more the heat it's going to give off, so read the datasheet and see what effect the input voltage has on its current limit as well.

From the Arduino Uno info page:

http://cactus.io/platform/arduino/arduino-uno

5V: This is a regulated output from the on board voltage regulator. This power will come from either the USB or DC input jack. This is fed into the on board 5V voltage regulator. The output from the regulator is connected to this pin. You use this pin to provide 5V to power components connected to the Arduino board. The maximum current draw is approx 400mA on usb and higher if using the DC power jack.
 

SamR

Joined Mar 19, 2019
2,125
I already told him on his other thread that Yes, it can power a small hobby servo but to look at his total load. He also has a motor shield and several other devices attached to his Arduino board. Also pointed out the current limits on the Arduino and the need for external power supply.
 

jpanhalt

Joined Jan 18, 2008
9,413
Im using a servo thats connected to the 5V pin, D9 and GND on arduino uno rev3.
Each pin supplies a max of 40mA which is not enough for my servo.
The stall current for my servo is 600mA.
Does the 5V pin provide the current I need for the servo.
My interpretation of that is that the servo is powered directly from the power source. Signal is D9, and that requires almost no current. So no problem, except as mentioned in post # 3 , there could be ground noise. Be sure the arduino has its power and ground properly decoupled.

How much power/current your supply can provide, depends on the supply, not the arduino. A lithium battery will probably not be a problem. A USB2 port may be a problem.
 
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