Power Consumption for Battery use (sleep at 33µA

Using Arduino General Electronics
#1

Hi,

Not sure if this should be here or in "programming" but I'll start here.

Like many I'm trying to reduce power for battery operation.

My setup:

Pro Mini Clone with 3.3v regulator in circuit. Power LED disconnected. No I/Os connected to anything. I changed the fuses so the Brownout function is disabled.

Using Nick Gammon's Sketch J on the Pro mini with nothing connected the current is ~ 30 - 33 µA. Nick's website states the current should be in the 1µA area. Now looking at a typical low dropout regulator it seems the quiescent current is in the 50µA area so I think I'm doing pretty well.

Question: Has anyone had similar results? Would like to know if I was really missing something.

Thanks

John

#2

Remove the regulator. Most of that 33 uA is probably the quiescent current.

There is no need for a regulator, unless some peripheral requires 3.3V.

#3

The need for 3.3 volts for my RFN69 radion requires me to keep the regulator.

#4

You should try to use 3.3V 8MHz version of ProMini and avoid regulator.

#5

Hi,

I guess the regulator is the limiting factor in this case. I cannot however remove it because the RFM69 is limited to 3.3 volts.

#6

Then don't use that radio. The NRF24L01+ runs on as little as 1.9V.

See this solar powered/supercap remote sensor project.

#7

JohnRob:
I cannot however remove it because the RFM69 is limited to 3.3 volts.

So why does the datasheet say it will run on 1.8v ?

#8

The voltage limitation for the RFM69 is not the low end but the high end. If I start with a battery voltage of 4.5 or so I must regulate it down to be below the max RFM69. Hence the regulator.

#9

If you power your project using 2xAA batteries (NiMH or alkaline), you don't need a regulator at all.

Another possibility is to use a lithium battery, with a series diode to drop the voltage below 3.6V.

Or, you can do much better than the regulator you have. The MCP1700 Low Quiescent Current LDO 3.3V reg has a quiescent current of 1.6 uA.

#10

JohnRob:
If I start with a battery voltage of 4.5 or so I must regulate it down to be below the max RFM69.

So don't start with 4.5v ..........................

#11