cupoftea
Advanced Member level 6
Hi,
We are doing a offline Two Transistor Forward.
Most of the TO220 heatsinks don't have a "pin" so that they
can be inserted into the PCB and then connected up to a net.
Eg, the lower primary FET heatsink should be connected to primary ground
(The connection should be either "direct" or "capacitive", but if "direct",
then a insulator pad should go between fet and heatsink.)
Why is it that most TO220 heatsinks don't have a PCB pin, when its so
obviously needed?
As you know, switching FETs have switching nodes, and so any heatsink that such fets are on, becomes a radiator , and a nightmare to EMC unless
the heatsink can be tied to a net. (preferably a "EMC quiet" net.
We are doing a offline Two Transistor Forward.
Most of the TO220 heatsinks don't have a "pin" so that they
can be inserted into the PCB and then connected up to a net.
Eg, the lower primary FET heatsink should be connected to primary ground
(The connection should be either "direct" or "capacitive", but if "direct",
then a insulator pad should go between fet and heatsink.)
Why is it that most TO220 heatsinks don't have a PCB pin, when its so
obviously needed?
As you know, switching FETs have switching nodes, and so any heatsink that such fets are on, becomes a radiator , and a nightmare to EMC unless
the heatsink can be tied to a net. (preferably a "EMC quiet" net.
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