3-Terminal Regulator question

3073 Views 16 Replies 4 Participants Last post by micromind, May 21, 2009

Robertw55

Discussion Starter · May 20, 2009 (Edited)

i have a charger that I use for my PSP that is 300mA and 4.5v.

The PSP is 5v 2A

this charger isn't the real charger for the PSP, it just happens to fit and it works fine (just takes longer).

im making a charger out of small 1 watt solar panels and using a +5v 1A 3T regulator. So would it be ok to use a +5v 1A charger for the 5v 2A? That wont damage my PSP right? charging under the specs?

also, will it damage a 5v 1a 3 terminal regulator putting 2.5 amps into it from the solar panels? Or is it specifically made to reduce amperage as well?

many thanks

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Yoyizit

· #2 · May 20, 2009 (Edited)

Robertw55 said:
i have a charger that I use for my PSP that is 300mA and 4.5v.

The PSP is 5v 2A

this charger isn't the real charger for the PSP, it just happens to fit and it works fine (just takes longer).

im making a charger out of small 1 watt solar panels and using a +5v 1A 3T regulator. So would it be ok to use a +5v 1A charger for the 5v 2A? That wont damage my PSP right? charging under the specs?

Charging protocols are different for each battery technology: nicad, nickel-metal-hydride, lithium. I wouldn't use a constant voltage regulator unless you have inside info that you can get away with it.
http://www.maxim-ic.com/appnotes.cfm/an_pk/680

also, will it damage a 5v 1a 3 terminal regulator putting 2.5 amps into it from the solar panels? Or is it specifically made to reduce amperage as well?

many thanks

An IC regulator may protect itself as to current, but you may need a heatsink if the power into the regulator exceeds a watt or so. There's usually a 2v drop through the regulator. Post a datasheet.
(5+2)v x 2.5A = 18w = 2 sq. ft. panel
To get max power from a solar panel is pretty tricky. Check out the equiv. circuit in this link
http://en.wikipedia.org/wiki/Solar_cell

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