Power Consumption Arduino

[rasberrytoast]

How much current/power does the arduino take when 1. on, but not running any intensive code 2. in power down mode 3. in standby mode 4. idle 5. power save 6. standby

I can't seem to find any datasheets referring to the power intake, other than how much power each output pin takes when on

Thank you!

[graynomad]

The two main active components on the board are the 328 and the FTDI chip, you could look at their specs to get a fair idea.

The FTDI will probably probably always be the same unless it goes into standby when there's no USB activity.

As for the 328 the overview on the spec sheet says

- Active Mode: 0.2 mA
- Power-down Mode: 0.1 [ch956]A
- Power-save Mode: 0.75 [ch956]A

But that's at 1MHz and 1.8v which isn't a lot of use. Maybe a trawl through the rest of the sheet will give more useful numbers.

[RuggedCircuits]

Last time I measured the Arduino was consuming about 25mA while running code.

No insight into the standby/idle numbers.

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[rasberrytoast]

Graynomad

I've read that the voltage regulator takes alot of power too, is it apart of the ftdi chip?

RuggedCircuits

Where/How did you measure the arduino current? When I measure the usb port, I get 18.7mA, but that number didn't change when I had one of the pins light up a mini light for 5s(5000ms), so I'm suspicious that I did it wrong.

Thank You

[RuggedCircuits]

I measured using the DC power input and a bench power supply.

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[graynomad]

I've read that the voltage regulator takes alot of power too, is it apart of the ftdi chip?

In general linear voltage regs do use a lot of power.

If your Arduino is running from the USB there will be no wasted power because the 5v is connected directly through to the PC. The FTDI does regulate the USB 5v down to 3v3 so if you're using that there will be losses.

If you're using the DC jack then the on-board regulator will waste power, more or less according to the level of VIN. In this case the best thing to do is to reduce VIN as much as possible, say to 7v. If it's at 20v then things will get hot and that means a lot of power is being wasted.

Of course no matter what you do power supply-wise the voltage is being reduced by something somewhere?

The most efficient thing to do is bypass all the regs and run the board directly from batteries.

It's interesting that ruggedcircuits measured 25mA, I quote from an email I recently got from an FTDI tech

The device itself requires 25mA.

We were talking about their integrated USB-serial cables, but the electronics would be the same as that implemented on the Arduino. This implies that just about ALL the power consumed is by the FTDI chip.

Therefore if your final product is a stand-alone 328 without the USB then you'll be down in the micro Amps I would think.

[RuggedCircuits]

It's interesting that ruggedcircuits measured 25mA

That was powered from an external DC supply with NO USB! So the FT232 was probably powered down.

Figure 27-2 in the ATmega328P datasheet suggests *TYPICAL* power consumption is 12mA at 5V and 16MHz. Add in a couple of mA for the DC IN regulator and who knows what else and 25mA is conceivable.

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[rasberrytoast]

K Thanks, this all helps

[graynomad]

So the FT232 was probably powered down

Probably, but it does get it's power from the board VCC so maybe not, you'd have to look at the chip specs to see if it goes into standby when there's no signal or whatever. Maybe that accounts for the extra 12-13mA.

The FTDI spec sheet says 15mA in "normal operation", but I can't see any mention of standby etc.

[RuggedCircuits]

OK, my curiosity was sufficiently piqued.

For a Duemilanove (just one...mine...there might be unit-to-unit variations):

With a 9V power supply only (no USB), current consumption is 26mA.

With USB only (no power supply), current consumption is 35 mA. This was measured with a DMM after fuse F1 was removed (the DMM measures in series with the fuse).

With both the 9V power supply and USB plugged in the current consumption is 35mA from the power supply only.

So it looks like the FT232 does enter into a partial shutdown mode when there is no USB data, but still consumes current.

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[graynomad]

Looks like you've pretty much got that sorted.

So raspberrytoast if you really have to save power it looks like you've got to get rid of the FTDI chip, ie do a stand-alone board, because you do have control over the 328's power by going into one of the shutdown modes.

[RuggedCircuits]

Just to add one more measurement....my Duemilanove consumes 9.4mA when powered from an external 9VDC power supply (no USB connection) and running this power-down sketch:

Code: [Select]

#include <avr/sleep.h>
#include <avr/interrupt.h>

void setup()
{
}

void loop()
{
 cli(); // disable interrupts
 set_sleep_mode(SLEEP_MODE_PWR_DOWN);
 sleep_enable();
 sleep_mode(); // never wakes up
}


So it looks like ~9mA is the "price of admission" for powering all the on-board circuitry other than the ATmega328 as that is (in theory) consuming only microamps in power down mode.

I'm not willing to remove the FT232 to see how much of that it's responsible for

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