Hi,

I need to measure current on a board.
This board is running during ~ 6 seconds and sleeps during 10 minutes.
Current while awake is ~ 200 mA, and ~ 17 µA while sleeping.
The manual tells to set the rotary switch to "µA" for currents below 5000 μA (5mA), and to A/mA for currents above 5000 μA.
As I have the two during the time of measure, what would be a good way to do this ?

Thanks for your advice.

 

Hi,

I need to measure current on a board.
This board is running during ~ 6 seconds and sleeps during 10 minutes.
Current while awake is ~ 200 mA, and ~ 17 µA while sleeping.
The manual tells to set the rotary switch to "µA" for currents below 5000 μA (5mA), and to A/mA for currents above 5000 μA.
As I have the two during the time of measure, what would be a good way to do this ?

Thanks for your advice.

Set to microamps and measure current at startup (low current mode).

Set to milliamperes and restart the device, then wait for it to switch to high current state.

 

Or, you can set your meter to uA, but short the two plugs on your meter with another wire and wait until the device goes to sleep. Then undo the short and measure the low current.

 

Meter resistance may impact measurements.

 

Meter resistance may impact measurements.

True for all ammeters. At 17 microamps, that is about 60,000 ohms per volt. The internal resistance of the ammeter shouldn't be a major issue unless the OP needs 4-digits of accuracy.

 

True for all ammeters.

200 uV isn't too shabby for this https://www.atecorp.com/products/keithley/480 but it has a 2 mA max. Some SMU's will work nicely at higher currents.

But then his uP may run on 3V or smaller.

Dave on EEVBlog has created the uCurrent: http://www.eevblog.com/product/ucurrentgold/

With the right scope with math it should be possible to do power measuremnt more precisely.