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Topic: Constant current power supplies (Read 6 times) previous topic - next topic

retrolefty

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Let's see a show of hands how many of you have used cel phone charger even like the iphone charger  or any of the newer smart phone chargers. Well how may hands are up in the air Guess what there constant current supply that do to things one
there output is fixed at 5 volts till you over load them then it drops off to a point that they shut down.


Not sure what you are trying to say here exactly. However as far as cell phone charger modules most are indeed just fixed DC voltage regulators, typically rated at 5.1 or 5.2 vdc output and at some maximum current rating. The chip that handles how much constant current to allow to charge the phones Li battery and when to shutdown charging current when the cell is fully charged is inside the phone itself. I find these power modules at second hand stores for usually $1-2 and they work fine for powering small digital projects drawing an amp or less.

Lefty

westfw

I believe that the root of the question is essentially: "look!  Cheap switchmode power supplies being produced in the millions for the LED lighting market!  While they're supposed to be "constant current", don't they have a practical limit on output voltage that falls in the range needed at the input of an Arduino?"

Answer: maybe.  But the cheap switchmode power supplies being produced by the millions for the cellphone/etc market are more appropriate and not that different in price.  (although, the price goals of the supply for a $10 lightbulb are probably lower than the goals for the supply for a $100 cellphone/videogame/whatever.)

be80be

Cel phone charger are a constant current supply fixed at 5 volts. That's the newer one's like the iphone use's and most smart phones use

What part don't you understand I'm talking about the charger that plugs in the wall
not how it disconnects the battery from it.  

retrolefty

#18
Dec 01, 2012, 09:09 am Last Edit: Dec 01, 2012, 09:11 am by retrolefty Reason: 1

Cel phone charger are a constant current supply fixed at 5 volts. That's the newer one's like the iphone use's and most smart phones use

What part don't you understand I'm talking about the charger that plugs in the wall
not how it disconnects the battery from it.  


No, you are giving these cell phone charger modules more functionality then they actually have. I've used many in my projects, they put out a constant regulated +5vdc voltage only, and not at a constant current. I have wired one up to power my arduino board via It's 5V and ground shield pins and the board draws about 80ma and the voltage is fixed at 5.1vdc. The constant current part is performed by a chip inside the cell phone that handles the chore of properly charging the battery at a proper constant current, using the regulated voltage supplied by the external cell phone charger module.

Again a typical 'cell phone charger module' is simply a switch mode DC voltage regulator outputting a regulated nominal +5vdc (most are rated at 5.1 or 5.2vdc) and can supply any current demand from 0 to typically 1 amp.

Lefty

be80be

#19
Dec 01, 2012, 09:15 am Last Edit: Dec 01, 2012, 09:47 am by be80be Reason: 1
I not giving them any thing there I just tested about 100 of them as to there rating
and did a lot of digging on the net

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TND329
5 W Cellular Phone CCCV
(Constant Current Constant
Voltage) AC-DC Adapter

better charger like the smart phones and iphone use these in them and there
Not this same chip but one like it.
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This reference document describes a built-and-tested,
GreenPoint solution for a cellular phone Constant Current
Constant Voltage (CCCV) AC-DC adapter. This design is
intended for isolated, low power, universal input off-line
applications where a constant current/constant voltage
output (CCCV) is required for charging NiCd, NiMH,
Lithium-ion or similar batteries. Typical applications would
include cell phone chargers or cordless phone chargers.


Back to the Op you may be able to use the supply you posted if like I said they fit the happy spot of 7 to 12 volts but may need to add a regulator and filtering  

See I have a bunch of these old ones and new ones and got to wondering why some of the old one where no way near there rated voltage and the newer one where dead on 5 volts and I got my kids two new phones so we had 4 of the same
chargers that open the door to cut one open and have a look and as I figured
they have CCCV
So draythomp test it for output voltage and see what it is you may be able to use
the E-Bay supply but I have to say one thing if the output is 350mA and it's 2 watts it's only good for about 5.7 volts at that load

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