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### Topic: Voltage Regulator Minimum Output Current (Read 982 times)previous topic - next topic

#### Sparked

##### May 28, 2012, 10:04 pm
HI,

I am using an Arduino Uno to build a monitoring system and need to use a voltage regulator to turn a supply voltage of 24Vdc into the 7-12Vdc required by the Arduino Uno.  Originally I was going to use a Pololu step down regulator see here(http://www.pololu.com/catalog/product/2102/specs) but had several of them catch fire.  As an alternative I am planning on using a R-R-6xxxP_D Series regulator see here(http://www.recom-international.com/pdf/Innoline/R-6xxxP_D.pdf)

I noticed that on the specifications page it says there is a minimum output current of .1A or .2A (depending on the model).  I was trying to determine what the minimum current the Uno would draw but have realized that all depends on what your doing.
I know that the 3.3V requires 50mA and that each digital input output uses 40mA.  Does this mean that each input/output always uses 40mA, or they only use that when set to high?

#### majenko

#1
##### May 28, 2012, 10:24 pm
An output provides current to whatever it is connected to - just like a battery - up to a maximum of 40ma.

#### winner10920

#2
##### May 28, 2012, 11:44 pm
Why not supply 5v directly instead of using the onboard regulator? Then just put that to the 5v pin and save a few ma
I believe the atmega328 alone draws like 30ma or. 03amps
so you would need a resistor to draw some amperage
or on ebay they make nice 24v to 5v 3A supplies I think for 4\$

#### terryking228

#3
##### May 29, 2012, 07:34 am
Hi, Another possibility is to use an Arduino Compatible that allows higher voltage input, like this one:

It says "Wide range external input from 7~23V DC"  you have 24?  Plus or minus what??

You could just drop the 24V to 21V with 3 silicon diodes, like: http://goo.gl/VBYY4

Regards, Terry King terry@yourduino.com  - Check great prices, devices and Arduino-related boards at http://YourDuino.com
HOW-TO: http://ArduinoInfo.Info

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