Hi all,
I have enjoyed reading this forum, but this is my first post.
I have a circuit I would like to power by plugging it into any USB port I happen to come across. The USB standard specifies output as 5 vdc (+/-.25 vdc) at 1 amp, which is perfect. But many ports are significantly (+/-.5 to .75 vdc) above or below this. I would like to take whatever output I am given from any USB port and then alter that output to be as close to spec as possible.
So, in short, how would I take the power from any USB port and then groom it to 5 vdc (+/-.25 vdc) at 1 amp?
Over-voltage is more of a concern than under-voltage.
I have looked at low-dropout voltage regulators, but I don't think I will always have room for the dropout. Maybe with a pmos voltage regulator? This one:
http://www.datasheetdir.com/TPS7150+LDO-Regulators
has a dropout of only 32 mV at 100 mA, but I think that increases with the current (?), and I have 1 amp of output so that would increase significantly (320 mV?), I'm guessing?
Another (lesser) consideration is efficiency, since many USB ports are on laptops, etc., which rely on battery power.
Thanks for any help you can offer.
I have enjoyed reading this forum, but this is my first post.
I have a circuit I would like to power by plugging it into any USB port I happen to come across. The USB standard specifies output as 5 vdc (+/-.25 vdc) at 1 amp, which is perfect. But many ports are significantly (+/-.5 to .75 vdc) above or below this. I would like to take whatever output I am given from any USB port and then alter that output to be as close to spec as possible.
So, in short, how would I take the power from any USB port and then groom it to 5 vdc (+/-.25 vdc) at 1 amp?
Over-voltage is more of a concern than under-voltage.
I have looked at low-dropout voltage regulators, but I don't think I will always have room for the dropout. Maybe with a pmos voltage regulator? This one:
http://www.datasheetdir.com/TPS7150+LDO-Regulators
has a dropout of only 32 mV at 100 mA, but I think that increases with the current (?), and I have 1 amp of output so that would increase significantly (320 mV?), I'm guessing?
Another (lesser) consideration is efficiency, since many USB ports are on laptops, etc., which rely on battery power.
Thanks for any help you can offer.