What could be possible reasons for Atmega-chip and Xbee heating up?

Other Hardware General Electronics
1

The heating up is slight; temperature of the two parts is maybe a bit less than 40 degrees Celsius. But still trying to diagnose for future reference...

The layout is simple:
--PCB with an Atmega2560V (Arduino bootloader, 3.3V, 8Mhz) and an Series 1 Xbee-Pro (50 mA to 215 mA current draw).
--Made two bad choices, b/c of little experience with PCB design: Used thin traces (8 mil width) throughout the PCB trying to keep it compact. Also did NOT put any copper pours.
--Power comes from Li-ion battery, supplied via TPS63001 Buck-boost regulator with 3.3V output (great and simple regulator; allows up to 1200 mA output current)
--The regulator has the "TI Powerpad" design, i.e., thermal pad under chip soldered onto PCB pad with vias, to allow thermal dissipation.

The heating up is happening on the Atmega chip and the Xbee only. While the part of the PCB around these parts is also heating up slightly, the rest of the PCB and the rest of the parts are cool.

What could be possible culprits that I should check for in a scenario like this?

2

The heating up is happening on the Atmega chip and the Xbee only

It could be that this is perfectly normal and what you would expect from the current it is taking. I assume that is only a rise of 20C.

Is it in a box? Is there any air flow?
The arduino could be getting hot because of current draw from an output pin. The Xbee could be getting hot from a poor impedance match with the antenna.

3

the the xbee is heating up .. in my case because it was short circuited and i had to replace it to a new one since it got burned :frowning:

4

If you're streaming data you're producing around three quarters of a Watt of power. Power = Amps * Voltage.

Add say, 20mA of microcontroller power to your 215mA...

235mA * 3.3V = 775.5 milliWatts

An Xbee Pro even at idle is going to raise temperatures a little running at 55mA, add your microcontroller and you're already at a quarter Watt.

5

giantsfan3:
The heating up is happening on the Atmega chip and the Xbee only. While the part of the PCB around these parts is also heating up slightly, the rest of the PCB and the rest of the parts are cool.

So you are seeing about 40C around the two most active components? Both which are probably rated for at least 85C...