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Topic: Trying to figure out what is draining my battery (Read 955 times) previous topic - next topic

jerseyguy1996

Ahhhh.....I always manage to miss something.  Well not the end of the world.  I assume that I can't disable the converter without fouling the power supply to the mega328?  I guess I can just keep it plugged into a charger when not in use.
Arduino Uno;
Mega328

vasquo

To OP, see page 13 datasheet.

Device Enable
The device is put into operation when EN is set high. It is put into a shutdown mode when EN is set to GND. In
shutdown mode, the regulator stops switching, all internal control circuitry is switched off, and the load is
disconnected from the input. This also means that the output voltage can drop below the input voltage during
shutdown. During start-up of the converter, the duty cycle and the peak current are limited in order to avoid high
peak currents flowing from the input.

dc42

#5
Feb 10, 2013, 09:54 pm Last Edit: Feb 10, 2013, 09:58 pm by dc42 Reason: 1
How do you calculate the current for the 3.3V converter as 50uA? I can't find that on the datasheet. You have the PS pin tied to +5v, so you're not even using its power save mode.

[EDIT: OK I found the 50uA figure on the datasheet. It's measured at 3.6V input, however it doesn't say whether it is measured with PS tied high or low.]
Formal verification of safety-critical software, software development, and electronic design and prototyping. See http://www.eschertech.com. Please do not ask for unpaid help via PM, use the forum.

vasquo

Quote
I can't believe the converter or charger are sucking up 4.4mA.  This is kind of disappointing to say the least.  The whole thought process was that with everything asleep, the battery drain would be negligible.


DC-DC converters suck power (albeit, very little), even when there's no load.

Quote
According to the datasheet for the converter, the quiescent current is less than 50uA and for the charger it should be less than 5uA.  What could I be missing here?

Maybe the 50uA is when the DC converter is not enabled?

I see an ENABLE pin on the converter hardwired in your schematic. Maybe you should connect this ENABLE pin to your microprocessor and enable/disable it when not needed.

jerseyguy1996


You could quickly find out by using a razor knife.
Cut a power trace, insert the ammeter across the cut, then solder the trace.


Darn.....I was hoping to not have to start cutting into stuff.  I bypassed the 3.3V converter and the battery charging circuit by just applying 5V to Vcc and I get a current draw in sleep mode of 170uA.  I can't believe the converter or charger are sucking up 4.4mA.  This is kind of disappointing to say the least.  The whole thought process was that with everything asleep, the battery drain would be negligible.  According to the datasheet for the converter, the quiescent current is less than 50uA and for the charger it should be less than 5uA.  What could I be missing here?
Arduino Uno;
Mega328

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