D2Flex Standby Current

[Alan B]

Today I measured the standby current of my D2Flex based light and was wondering if others had done so. I'm getting about 10mA idle current and my D2Flex light is discharging AA NiMH batteries pretty fast.

Is this typical, or is there some programming mode that controls it??

 

[VidPro]

yup D2flex says
"Draws ~100uA in sleep mode"

this looks like such a tiny tiny ammount, but i calulated one of the other (not this one) parasitic draws on "off" and my battery was going to be mostly depleated in a month :-(

so before designing with that, i made sure that there was a full cutoff.
i use a cheap trick of leaving the normal switch IN things, then tossing in a tiny momentary pushbutton for the control of the board.

i dont know of any way to control the fact that the microcontroller is waiting for your press, sleep modes and such would only ever reduce it so much anyways, not wasting my power, gotta have full disconnect.

 

[Alan B]

I'd be fine if the standby current was only 100 uA, but I'm measuring 100 times that at 10 mA.

 

[Justin Case]

10mA (10^-2 A) is not equal to 100uA (10^-4 A, or 0.1mA).

A 10mA draw looks like active mode, based on the ATMEL Tiny85V specs (actually ranges from 0.3mA to 5mA typical draw, and thus 10mA seems a little high). An 0.1mA draw looks like idle mode.

At 0.1mA draw, if you are using nominally 2000mAh AA NiMH cells, the cells would last for about 20000 hours before running down. That is about 830 days, or over 2 years.

If the AA NiMH cells are draining in about a month, then the parasitic current must be higher than 100uA. To drain a 2000mAh capacity AA NiMH cell in one month takes about 3mA current draw, which is consistent with the Tiny85V specs for active mode.

It looks like that there must be some secret handshake to put the d2Flex into idle mode. Maybe try using the Autosleep function to see if there is a difference in parasitic draw when the light shuts down?

In what light are you using the d2Flex? It would seem that in the popular Maglite mods, this parasitic drain would not be a problem since the switch kills the circuit, cutting off power to the controller.

 

[Alan B]

I'm running this in a 3xAA P7. I wonder if the software is in a funny mode so it is not sleeping. Perhaps I'll try to do a reset to manufacturing default.

The way this driver is used the m@g switch is modified to momentary and the battery plus is routed direct to the board. So there is no disconnect unless the tailcap is loosened.

In this particular light the tailcap doesn't reliably disconnect probably due to the recut threads.

I would like to hear what other folks have measured on their d2flex's standby current.

 

[Justin Case]

The way this driver is used the m@g switch is modified to momentary and the battery plus is routed direct to the board. So there is no disconnect unless the tailcap is loosened.

Thanks, I see that now that I look at the wiring diagram again.

 

[Alan B]

On my other Tiny AVR controllers I'm getting well under 100 uA, even with a battery sensing voltage divider which is drawing more current than the CPU. The D2Flex doesn't have voltage detection so no resistors drawing power. The only standby loads are the FET leakage, CPU and voltage regulator. At 10 mA it has to be the CPU and voltage regulator. I can't tell which voltage regulator is being used.

I'm hoping it is just a software issue not allowing the CPU to sleep. The one button programming is a bit difficult, I'll have to dig out the manual and try. I did reconfigure it once before and perhaps there was some issue from that. It would be nice to hear from other users if they are able to get down to the 100 uA level.

Other than that it is hard to imagine what the drain would be. The assembly was clean and the d2flex is epoxied on the back of the heatsink. The light has not been subjected to abuse or water.

 

[Justin Case]

I think this is the regulator:

http://www.micrel.com/page.do?page=/product-info/products/mic5235.shtml

 

[Alan B]

I think this is the regulator:

http://www.micrel.com/page.do?page=/product-info/products/mic5235.shtml

Nice little regulator. That's not taking much power.

 

[Alan B]

Tonite I reset my d2flex to factory defaults. Still drawing about 10mA.

Anybody else can measure theirs? Remove the tailcap and measure current. When first reconnecting the LED may come back on (this is default), so make sure to turn it off before measuring. Takes almost three hands, not quite. I'm looking to see if it is less than one milliamp or 10, so the measurement doesn't have to be incredibly precise. My board is V1.1 and the software version blinks twice as I recall.

 

[matrixshaman]

You might write to [email protected] and ask him if that is normal. I'll see if I can check mine tomorrow if possible. My only decent DMM is hiding somewhere though for now.

 

[Alan B]

George is on vacation this month, or I'd do that. It would be great if you were able to measure yours.

Thanks,