I'm working on a battery powered circuit that is using a 1N4001 diode to bring the 6V from 4xAA closer to 5V, as well as for protection in case the batteries are put in backwards. The total circuit draws around 0.6A when driving some LEDs and, when doing so, the diode gets pretty toasty. Definitely uncomfortable for prolonged contact. Probably in the high 100's (F).
I'm really more of a software guy so a lot of this is new to me. I tried looking at the diode datasheet but it was mostly a bunch of stuff I didn't quite understand. Since it's dropping 0.7V @ 0.6A I realize that it's dissipating 0.42W of power, but it doesn't seem that that would be all that much.
Should I be worried about it being too hot or is this sound like it would be in normal operating conditions.
>Since it's dropping 0.7V @ 0.6A I realize that it's dissipating 0.42W
>of power, but it doesn't seem that that would be all that much.
The spec you're looking for is "thermal resistance, junction-to-ambient". This will tell you the temperature rise (above ambient temperature) of the semiconductor junction, expressed typically in degrees C per watt of dissipation.
Looking at a typical spec sheet for the 1N4001 in an epoxy case, this is 50 degrees C per watt, so in your case, 21 degrees C *above ambient*.
However, looking at typical voltage drop curves for the device, I think you may get a forward voltage drop closer to 0.85 V, for a dissipation of closer to half a watt (resulting in 25 deg temp rise). This could get uncomfortable for you, but the spec sheet I saw indicated a max operating junction temp of 150 degrees C, so the diode itself may still be happy.