I need to switch off a 20V 60A DC current electronically. I don't want to use a relay, due to the environment (vibrations etc.).
It is not a switching supply, just a switch that turns everything off when given a signal.
I've been trying to design a circuit that basically passes the load current through a MOSFET which can be switched off.
I've been looking at power MOSFETs and IGBTs and am having trouble understanding their specifications. For instance this MOSFET has a Maximum Continuous Current rating of 100A, but when I look at the Safe Operating Area graph, at 20V DC it will only do around 1.5A. Similarly for other FETs and IGBTs.
Is the SOA graph what I need to be designing with, or can I use the Max current specifications?
Are there transistors made specifically for DC applications that can handle a large DC current, or am I using the wrong components/design approach here?
Best Answer
It's not quite that bad - I read about 2.5A at 20V for DC. But it does seem a bit low compared to the 131W max dissipation.
However if you switch in 10us the graph intersects at 400A.
Once the switch is on it will not have 20V across it. Just RDSon * I = 2.8mOhm * 60 = 168mV. This will result in a dissipation of ~10W. Well within the device capability.