Would these voltage regulators work for my project?

Andrey Demenev

I am working on a project where electronics include Propeller, SD card, GSM module and GPS module. Everything is powered from a Li-ion battery. GSM and GPS can be powered directly from the battery, and for card and propeller I need a voltage regulator, since battery produces up to 4.2 volts when fully charged. Obviously, the regulator is to be LDO. Unfortunately, I cannot purchase suitable regulators locally, and ordering them would take too much time. What I have by hand are a couple of LP2980, which are rated up to 50 mA. I am thinking about using two such regulators - one for the propeller, another for SD card. SD card will be used for reading only, propeller will run at 80 MHz, I think up to 5 cogs would be used.

Would these 2 LP2980 regulators be enough for this project?

kwinn

Page 27 of the propeller data sheet shows a current consumption of about 10mA for a cog running a spin repeat loop at 80MHz. That is with no pins drawing current, so I think 5 cogs on a 50mA regulator might be marginal at best. You might try a pnp transistor and a 4V zener (or several diodes in series) as a substitute.

max72

Marginally off topic.. do you have a low voltage control/shut down? Draining the Li ions batteries too low will kill them.
They tend to explode if they are charged too much, and will die if the voltage goes too low...

Andrey Demenev

kwinn wrote: »

I think 5 cogs on a 50mA regulator might be marginal at best.

Thanks, understood

max72 wrote: »

Marginally off topic.. do you have a low voltage control/shut down?

The battery has built-in protection

Andrey Demenev

I decided to use a non-LDO regulator (1.3 volts dropout) and an additional 6 volt battery to power the Prop and SD card. Weight and space are not big issues in this project