3.3v gps on arduino mega

GPS/GNSS Development Boards
1

Hi

I bought a gps from sparkfun:

http://www.sparkfun.com/commerce/produc … ts_id=8621

it seems to accept only 3.3v power supply @about 75mA

Is it possible to connect this module directly to the arduino mega, using the 3.3v power pin, or do i have to convert the power somehow (because it uses too much mA)?

thanks in advance!

2

Basically, you can connect it to the 3.3V outlet of the Arduino. But be sure to check the maximum current draw of that outlet as it originates from the onboard FT232RL (at least I think so) and I’m quite sure there is an upper limit.

I haven’t checked your provided link, but in case your GPS doesn’t talk to the Arduino via USART, you might also want to make sure that you convert any 3.3V signals 3,3V to 5V and vice versa.

EDIT: I’ve just looked up the maximum current draw on the 3.3V outlet and it’s 50mA. So you’ll probably have to find another solution. And, btw, your GPS does talk “serial”, so you don’t need to worry about that.

3

the 5v output has more amps. is it possible to use a simple resistor (22 ohms in that case) on the 5v pin to get the current down to 3.3v ?

4

No, I wouldn’t do that, since, for example, you cannot be sure about the GPS’ 75mA being constant.

What you need is a low drop voltage regulator like the [TS1085 or the [LD1117.

You could use these at the 5V outlet or also from an external source (in case you need many more amps ;-)).](LD1117 Datasheet pdf - LOW DROP FIXED AND ADJUSTABLE POSITIVE VOLTAGE REGULATORS - SGS Thomson Microelectronics)](TS1085 Datasheet(PDF) - Taiwan Semiconductor Company, Ltd)

5

alright! i got an LD1117 and a 10uF capacitor. I’ll give it a shot when i get home…

thanks for your help

6

You’re welcome. BTW, you might want to use two capacitators, see the datasheet (100nF for Vin and 10uF for Vout).

7

hmm… I thought those were just for correcting the current if it drops…

but the arduino should output a pretty accurate 5v at all the times. is the 100nF really necessary?

(I dont understand the much about electronics :s )

8

I haven’t tried without it, yet I assume it’ll work anyway :smiley: