SparkFun Forums

[smitty505000]

Hi all,

I am a little confused. Please let me know if I am understanding the spec sheet correctly. Diode on Din allows signal voltages of 3.3vdc or 5vdc. 5v pin can accept an input voltage up to 16vdc?

Smitty

[waltr]

This board has a linear voltage regulator with a 3.3V output. I don't know exactly which regulator SparkFun uses but many would allow a 16V input. Just beware that the regulator will need to dissipate the voltage drop times the current as heat. For one of the 1mW or 2mW XBees this might be ok with 16V but the XBee PRos use a lot more current so the regulator will need to dissipate much more heat.

There is a series diode on the DIN pin. This diode blocks a positive voltage to the XBee Din pin. To get a logic high on the XBee pin the XBee's internal pull-ups must be enabled. For a logic low the external DIN connection, processor UART, sinks current through the diode to pull-down the XBee's Din pin.
The down side is that there will be a voltage drop across the diode of about 0.3 to 0.4V. Therefore the device pulling the DIN inpt low must pull all the way the ground so that on the XBee's DIN the voltage is a valid logic low.

Does this help?

[smitty505000]

Thanks for helping to clear things up. I guess I just want to make sure that I can apply a higher voltage. Because the pad says 5v but the manual says up to 16v. Dont want to fry it if I dont have to.

Smitty

[smitty505000]

I looked up the regulator (stamped KB33) and it turns out to be a micrel mic5205 that will accept up to 16v. But as Waltr stated "will need to dissipate the voltage drop times the current as heat." I am going to be using a 2 cell lipo with a max voltage of 8.4v or nominal 7.2v which should be fine.

Smitty