propmodule current draw

mctrivia

I was asked today why the propmodule draws so much current. Here is my experimental tests:


S - Switching Regulator
D - No switching regulator

H - test hc.spin
L - test lc.spin

5 - Vin 5V
3 - Vin 3.3V


Over voltage protection connected
SH5: 79.0mA
SH3: 130.0mA
SL5: 19.2mA
SL3: 25.8mA
DH3: 86.2mA
DL3: 17.8mA

Over voltage protection removed:
SH5: 63.7mA
SH3: 101.8mA
SL5: 4.4mA
SL3: 2.9mA
DH3: 77.4mA
DL3: 35.2uA*


As to be expected module draws more current using the switching regulator at lower voltages and less current at higher voltages. I was surprised how much current the over voltage protection draws. if you need really low power and you are careful not to apply voltages higher then 3.9V cut the large black diode on the back of your module off.

*current is average current draw over time. actual current fluctuates between 7.8uA and 86.6uA

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heliboy

This works as advertised. Removing the zener drastically lowers the power draw.

- heliboy

heliboy

This works as advertised. Removing the zener drastically lowers the power draw.

- heliboy

Humanoido

Mctrivia: thanks for these useful tests. When connecting modules together
it would be a good idea to lose the zener.

humanoido

mctrivia

I would keep the zener for testing and cut off when there is no chance you may accidently apply higher voltages. It is a life saver when you accidently hook up to 12v. Though it will burn out if you done notice

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jazzed

@mc this is good to know.

Doesn't the module use a buck-boost converter?
I would like to use 2 AAA's for projects, but if that's the power profile, I'll have to give up that idea.

For now I use a 3AA NiCad on most battery-powered projects without a regulator and even a fully charged pack never exceeds 4.2VDC.

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Short answers?
Not available since you deserve more information than you requested.

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May you create something useful, even if it's just a hack.

mctrivia

I will check the draw on 2 new aa batteries tonight.
My guess is hc will get about 20hours and lc will get 25 days or so.

Not using the buck boost regulator is ideal. It should be pretty easy to hack the regulator to let the prop turn it off and have a wake interrupt from buttons.

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mctrivia

humanoido Ihave decided you are write. I will remove the zener from the US version. If you want voltage protection you can use Vin pin which will safely work between 1.8V and 5.5V and higher voltages will probably not fry the prop just the power supply(I have not tested this theory.) If you want altra low current draw then use the vin pin.

I have also started a test at 10:45PM CDT. I have removed the zener from a propmod-us_ps_sd and the fuse to the power supply. I have connected the unit to a Duracell DL2032 Hearing aid battery. The unit boots up perfectly on the 3V battery. Now to see how long it will run for. I will check that the unit is running 3 times a day(when I wake up, after work, when i go to bed) until it fails. Will get back to you on the possible run time such a tiny battery can provide. My guess is 12-24 months. Anyone want to place bets on the run time?

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