power regulator for Xbee?

hi all,

I am working on a project and I am planning to use Xbee radio modules. However. I need some features that the Xbee shield does not provide, and therefore I decided to have a PCB built that will include several components (Xbee + additional circuitry, AC/DC adapter, MAX232 chip for serial communication...)

I have some doubts regarding the Xbee circuitry required... I have read everywhere that I need a power regulator to supply the Xbee chip with 3.3Volts... But why can´t I simply use the Arduino 3.3V pin?

In case I do need a specific regulator for this, what the requirements would be? Of course I need an output power of 3.3 Volts, but I´m not sure about the minimum/maximum output current... any help?

And also, I have already seen several datasheets and I noticed that I normally need a number of capacitors around the power regulator... I am quite a newbie in electronics and I never liked working with capacitors, can I just assume that the circuit that manufacturers provide will work with my Xbee or do I need something different?

Thanks a lot folks!

I have read everywhere that I need a power regulator to supply the Xbee chip with 3.3Volts... But why can´t I simply use the Arduino 3.3V pin?

Unfortunately, typical current consumption of the Xbee modules is over 200mA when transmitting, an the Arduino 3.3V pin only provides about 50mA.

I have already seen several datasheets and I noticed that I normally need a number of capacitors around the power regulator... I am quite a newbie in electronics and I never liked working with capacitors, can I just assume that the circuit that manufacturers provide will work with my Xbee

Yes. Your requirements are pretty simple. It should accept 5V as an input (or 6-20V on Vin?) and output 3.3V at up to 400mA or so (to be safe.) A lot of people are using (and apparently happy with) the LD1117 type regulators here.

Thanks a lot :D

You really helped me out here!

Mm well now I realize I may have an additional problem with the AC/DC transformer that I am going to use... its max output current is 444mA. Do you think it will be enough for my node? (It consists of the Xbee+regulator, a max232 serial interface and a Arduino Duemilenova board)

its max output current is 444mA. Do you think it will be enough

"444mA"?! that's a lot of significant digits for a power supply! In any case, it sounds OK. The Arduino itself is well under 100mA, and the max232 is "small" (~10mA, probably depending on loading of the signal lines.) So it sounds pretty much "just right."

Ook, thanks a lot again :slight_smile:

I make a board that integrates an Arduino compatible design with an XBee. I use an 800mA 3.3V regulator (MC33269) to power everything. This gives plenty of current for most applications. The schematic is in the datasheet at http://wiblocks.luciani.org/ZB1/index.html

(* jcl *)

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