I'm building a replacement power supply for a Twinvision dot matrix LED sign (as would be found on the side of a shuttle bus). The sign requires four unique power supplies: 3x 3v3@4a and 1x 5v@1a. The 5v power rail feeds all of the TTL logic that drives the sign's constant-current LED drivers and the 3v3 supplies each go to a third of the 14x108 LED display.
I've gotten a working design using four RT8298 switching regulators fed from a 12 to 24 volt DC input. I'd like to send all of my PSU's outputs through appropriate fuses that will bust if the sign draws more than the desired 4a/4a/4a/2a for too long.
I'm not sure exactly how long these fuses should stay intact during excess current draw... The sign draws excess current on powerup but I'm not sure how much it draws or for how long. I don't know if there's a way to measure this using only my Rigol DS1054 and my Fluke 87V?
Even if I knew that figure, I don't know how it applies to "fast-blow" and "slow-blow" fuses which are usually rated for a certain amperage at a voltage far above 3v3.
Anyways, how do I go about selecting proper fuses for this system?
I've gotten a working design using four RT8298 switching regulators fed from a 12 to 24 volt DC input. I'd like to send all of my PSU's outputs through appropriate fuses that will bust if the sign draws more than the desired 4a/4a/4a/2a for too long.
I'm not sure exactly how long these fuses should stay intact during excess current draw... The sign draws excess current on powerup but I'm not sure how much it draws or for how long. I don't know if there's a way to measure this using only my Rigol DS1054 and my Fluke 87V?
Even if I knew that figure, I don't know how it applies to "fast-blow" and "slow-blow" fuses which are usually rated for a certain amperage at a voltage far above 3v3.
Anyways, how do I go about selecting proper fuses for this system?