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Jenalee K.
Could someone please explain how to design a decent input stage for a
power supply?
Let me explain: I have two wires coming in from somewhere with about
24VDC between them. These two wires go to an 8W DC/DC converter (Traco
TEN8-2411) which gives me 5V at its output terminals. I now have to
take care of three things (industrial device):
- overvoltage and reverse voltage protection: I've put a 6A 100V diode
(P600B) and a transil P6KE33A in parallel with the power input through
big fat pcb traces. In case of reverse voltage I assume the PSU's
current protection will kick in before my diode and/or pcb starts
burning.
- EMI filtering. According to the datasheet the DC/DC converter meets
EN55022 class A and FCC class A specs. How does this relate to CE
requirements? Do I have to add anything? I've thought about a common
mode choke with 100n caps between its terminals at both sides and 10n
1kV caps to earth. (as seen somewhere)
- surge protection. How do I handle that? I've seen varistors to earth
but I've also seen pcbs with burned varistors to earth. I found in the
archives that varistors are notorious for starting fires. How do I
choose a varistor? Do I want a varistor?
Thanks,
Jenalee K.
power supply?
Let me explain: I have two wires coming in from somewhere with about
24VDC between them. These two wires go to an 8W DC/DC converter (Traco
TEN8-2411) which gives me 5V at its output terminals. I now have to
take care of three things (industrial device):
- overvoltage and reverse voltage protection: I've put a 6A 100V diode
(P600B) and a transil P6KE33A in parallel with the power input through
big fat pcb traces. In case of reverse voltage I assume the PSU's
current protection will kick in before my diode and/or pcb starts
burning.
- EMI filtering. According to the datasheet the DC/DC converter meets
EN55022 class A and FCC class A specs. How does this relate to CE
requirements? Do I have to add anything? I've thought about a common
mode choke with 100n caps between its terminals at both sides and 10n
1kV caps to earth. (as seen somewhere)
- surge protection. How do I handle that? I've seen varistors to earth
but I've also seen pcbs with burned varistors to earth. I found in the
archives that varistors are notorious for starting fires. How do I
choose a varistor? Do I want a varistor?
Thanks,
Jenalee K.