Semiconductor devices can be surprisingly good at protecting fuses. <humour intended>
Donald.
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On 11-Nov-2019 10:35, Dave wrote:
Hi Harvey,
? In my case I am just using the USB port for handy readily available power to run IR Led's so it is the simplest circuit. They have a .100 mA max spec for amperage and I can run them at 50% and they still work fine so I have plenty of leeway on the design. The USB 2.x ports have 5V and maximum 0.500 mA available. The newer USB 3.x goes up to 0.9 mA but I won't be using a cable that fits that one. So if my PTC kicks out at 0.200 mA or even a little later, it won't be a problem. Now protecting a transistor may be a different story.
Thanks,
Dave
On 11/10/2019 1:58 PM, Harvey White wrote:
Yep, from what I read, the trip current vs time to trip is a lot longer than for fuses, the advantage being only that they reset. From what I can see, they're best used in catastrophic failure cases where the battery (supply/circuit) can stand an overload for a bit of time, then the fuse trips.? They're not the kind of thing I'd think of using to protect an FET unless the trip current were substantially below the rating of the FET.? Just me, of course.
Harvey
[snip]
