First battery powered device

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Working on my first battery powered device. I need some help keeping power usage to very low levels. Here is the situation. The board has three devices on it:

GSM Cell modem (3.4 - 4.0v) 4.0 is recommended
uC (3.0 - 3.6v range) 100mA
Xbee radio (3.0 - 3.6v range) 300mA

Max load with all devices = 1 amp (unsure about GSM modem)

Can I power everything on this board by just hooking it up to a li-ion 1500mAh battery? I'm worried that the voltage may not always be between all the ranges for the devices. Right now I am thinking of using two regulators. 1 reg will power the Uc and xbee (3.3v) and another will power just the cell modem (4.0v).

Obviously I want regs with a very low quiescent current drain. Less than 1mA would be nice. Any other ideas? The cell modem wanting 4.0 volts kinda throws a wrench in things. Also, the datasheet is very unclear about how much current it takes.

Cell modem: https://www.sparkfun.com/product...
Cell datasheet: http://dlnmh9ip6v2uc.cloudfront....

Chief Tinkerer

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The GSM modem will certainly not average 600ma. It might do that transmitting. But 1A is terribly high for battery power. A 1500mA-Hr battery will last 1.5 hours.

The numbers you provide don't seem to match up with the later text.

Separate regulators then mean that you will need voltage translation between the various sections. That adds to the power consumption.

I have no clue how you get 100mA for the UC.

The modem spec sheet says that it works 3.4V to 4.5V. Standby (certainly not transmitting, probably not receiving, either) is 2mA. So, your system will work .over the battery supply range of 3.6V to 3.4V.

Maybe you should look for other devices.

Jim

 

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Switchmode power supply with an output of 3.6V would be perfect..?

The datasheet for the ADH8066 says standby current <2mA, GPRS data typ 350mA...
Did you test it voltages lower than 4V since you say that it's not really that great at lower voltages? I would just run it all at 3.6...

But what MCU and Xbee module are you using? Those values look very high!

Anyway, the trick to long battery life is to turn off the stuff you don't need, when you don't need it!
Ie. you turn off the Xbee and GSM module unless you need it, or at least put them in standby. You put the MCU in standby or power down mode when you don't need it! (Wake up from timer or some other interrupts)

- Brian