Bridge Rectifier Pd and HS Requirements

[drkidd22]

Hello,

I'm working on a power supply that requires a bridge rectifier of 20A. I've picked the GBPC3508W to get some margin. So I'm new to this and want to be able to calculate if I will be needing a heat sink for the device or not.

The Max ambient temperature is where the rectifier will be used can reach 50C.
The Max Junction temp of the IC is 150C.
Max continuous current load through rectifier is 25A.
Max Powe disipation of the rectifier is 83.3W.

so my Tja = (150C - 50C) / (25A * 1.1V) = 3.63°C/W

So taking that all my above calculations are correct does this mean that the junction temperature can reach (3.63°C/W * (1.1V * 25A)) = 99.83W? which is above the max power disipation of the device so I will need a HS?

Any references to where I can learn more about this will be appreciated.

 

[tronitech]

**broken link removed** article is pretty good.

 

[crutschow]

Note that for a bridge, two diodes carry current at the same time so the dissipation is 25A * 2.2V = 55W. That will definitely require a healthy heat-sink, probably along with a cooling fan.