Power consumption on Arduino Uno and Xbee


I'm working on a project on Arduino Uno and Xbee. I have read on the datasheet for both current consumption.

I know that Xbee consumes about 40-50mA on active state and 30-50uA on cyclic sleep. For Arduino Uno, it consumes about 30-40mA on active state and 150uA on deep sleep mode.

Currently, I did the Arduino Uno on the breadboard and use MCP1702-5002E/TO as my voltage regulator for low Q-current.


For Xbee, I connect up with UartSbee for easy voltage regulation of 5V.

The issue is this...
I checked the current consumption for the Arduino Uno. It is 7mA when asleep and 40mA when awake. (I put the multimeter in series with the 5V power and Vcc pin of the Atmega328p)
For the Xbee, it is also 7mA when asleep and about 50mA when awake.(I put the meter in series with the general ground and ground pin of UartSbee)

I think the current consumption when awake is fine but it is odd for the Xbee and Atmega328 to consume so much during sleep...

Btw, Xbee is on cyclic sleep. Atmega328 is on pin interrupt sleep. (Xbee wakes Atmega328 up through an inverter from Sleep Pin to Pin 2 Interrupt).

Hope someone can help me to unravel the mystery of this sleep power consumption. Now it takes only 6 hours to kill my 9V GP Heavy Duty Battery. Heehee. I need to make it about a week or so.

I checked the current consumption for the Arduino Uno. It is 7mA when asleep and 40mA when awake.

That sounds quite high: I would have expected more like 20ma as the upper limit.

You can do a few things:

  1. slow down the oscillator;
  2. put unused pins to a definitive state;
  3. turn off unused features, like bod, etc.
  4. run at a lower voltage.
  5. use mosfet as output devices.
  6. high value pull-up/down resistors.

10ma @16Mhz is doable.


Thanks for the reply! I just wanna ask about some of the suggestions you made.

  1. How to slow down the oscillator? I’m using 16Mhz currently
  2. I can do that through programming at the setup right?
  3. What are the features such as bod? (sorry, I’m new to this…)
  4. I’m running at 5V step-down from 9V Battery. Can I run at lower voltage…? I bought 5V linear volt reg…
  5. How to use mosfet as output devices? Put them through a resistor to a gate?
  6. I’m using this setup - http://arduino.cc/en/Main/Standalone … What’s the value that will be suitable…?

Sorry for asking these weird questions…

But one thing I think is bothering me more… Isn’t the promised sleep current consumption supposed to be less than 100uA? I’m thinking why I’m getting 7mA… Because I really think that that is the one that is draining my power away since most of the time my setup is sleeping. Btw, I follow this site to build the breadboard arduino with the voltage regulator I mentioned in the first post.