Xbee Voltage problems while Sleep

Hi, I have a problem with the sleep mode of the Xbee (series2) that I do not understand.

My project is as follows:

I have two Arduino Uno, each of them with an Xbee, one of the modules is set as a coordinator and the other one as an end device.

The end device is programmed to act in pin-sleep mode (hibernate) and wake up after 70 sec and send some data to the coordinator.

The fact is that everything works well as expected. Data is sent from the ED to the Coordinator.

But there is something that intrigues me: I measured the voltage off the DTR pin when it is asserted (HIGH) and I got 4V instead of 3.3V that I expected.

And what is more weird I measured the voltage at the 3.3V output that the Arduino provides and had gone up to 4.1V!

In summary, when you put the Xbee to sleep, the voltage rises to 4.1V in hibernation mode but strangely it does not burn even being above specs.

What’s going on with the voltages?

I am asserting/deasserting by using pinMode(pin, INPUT) / pinMode(pin,OUTPUT)


Jose Ignacio