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Thread: YX801 IC - what does it do

  1. #1

    Default YX801 IC - what does it do

    I'm intrigued,

    I bought a very cheap solar garden light for 1.00 today just so I could pull it apart - what I find inside the guts is a solar panel (seems to give about 1.2V) connected to an IC of some sort labelled YX801 - this is connected to a 1.2 V rechargable battery and an LED as below

    I can't find a data sheet for this and the only article I've found is in German and doesn't translate well.

    It has 4 pins -

    Pin 1 attached to the solar panel +ve
    Pin 2 attached to the solar panel -ve
    Pin 3 attached to battery -ve and one leg of the LED
    Pin 4 attahed to battery +ve via the other leg of the LED and a resistor.

    Clearly when Pin 1 and 2 are low (ie not charging), Pin 3 and 4 allow current to flow through the LED - but is that all it's doing ?

    I'd like to know more about what this little chap is doing - is it moderating the voltage ? acting as a switch ? if anyone has come across this little chap I'd like to know as I intend to buy as few for cannibalisation.

  2. #2

    Default Re: YX801 IC - what does it do

    Is that a white LED in there?

    You can't spark up a white LED with 1.2 volts. You need over 3 volts I believe. So that chip is boosting the battery voltage up to drive the LED. I gues it has to handle the switching from day time charge to night time discharge as well.

    Measure the LED output voltage when it lights the LED.

  3. #3

    Default Re: YX801 IC - what does it do

    Yes it is a white LED - I think you could be right. I had thought that the Day/ night issue could be handled with a simple transistor - no power and the battery goes on, but if as you say the LED needs 3V then it's also boosting the voltage. Handy thing that !

    My main reasoning for getting it was I get a white LED, a 1.2 V rechargable battery and a solar panel for a pound - plus some interesting bits of metal and plastic which may come in handy.

    I'm intrigued on the subject of charging batteries - (I'm an electrical dummy ) - what are the rules for charging batteries ?

    I mean if I have, for instance, a 6 V 4A/H battery - can I use any 6V source to charge it? Is there a formula I should use? The batteries I have are mostly lead acid sealed units, but I have NiCd too. I know there are all sorts of dire warning about charging phone and video camera batteries, but wonder about less sophisticated batteries - how universal is a "universal charger" ?

    could I for instance, use a 7806 voltage regulator as a charger ?

  4. #4

    HollyMinkowski's Avatar
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    Default Re: YX801 IC - what does it do

    I made a charger using a 78xx regulator.
    The schematic was very simple and was
    in the datasheet. It gives a constant current
    of 100ma, it's for charging nimh batteries.
    It seems the voltage is unimportant..it's the
    ma. I think 100ma is considered a very low trickle
    charge for the string of nimh cells I charge...they
    never get more than slightly warm as they charge.

    The charger that came with the batteries gets
    them charged quickly but they get really hot!

    The reason I built the charger is because one
    device I use them in takes 3 cells and the charger
    only works on 2 or 4 cells.

    I feed the simple 78xx charger with a wall wart that
    puts out about 15v. I don't think it makes any difference
    what 78xx you use.. 7805, 7809, 7812...
    [The Bug Stops Here]

  5. #5

    Default Re: YX801 IC - what does it do

    While you can use any of the 78xx regulators as a constant current source for battery charging it is better to use the lower output voltage ones since the input voltage has to be the sum of the regulator forward voltage drop, the regulator output voltage, and the voltage of the fully charged batteries.

    The best choice is one of the adjustable regulators that have a 1.2V output such as the LM117.

    The recommended charging rate and time for many lead acid batteries is 1/10th of the amp/hr rating for 14 hours. If you had a 10 amp hour battery that would be 1 amp for 14 hours. A trickle charge for this battery would be 0.1 amp or a bit less. This also seems to work fairly well for NiCd batteries.Attachment 81736

  6. #6

    Default Re: YX801 IC - what does it do

    Quote Originally Posted by Britannicus View Post
    I'm intrigued,

    I bought a very cheap solar garden light for 1.00 today just so I could pull it apart - what I find inside the guts is a solar panel (seems to give about 1.2V) connected to an IC of some sort labelled YX801 - this is connected to a 1.2 V rechargable battery and an LED as below

    I can't find a data sheet for this and the only article I've found is in German and doesn't translate well.

    It has 4 pins -

    Pin 1 attached to the solar panel +ve
    Pin 2 attached to the solar panel -ve
    Pin 3 attached to battery -ve and one leg of the LED
    Pin 4 attahed to battery +ve via the other leg of the LED and a resistor.

    Clearly when Pin 1 and 2 are low (ie not charging), Pin 3 and 4 allow current to flow through the LED - but is that all it's doing ?

    I'd like to know more about what this little chap is doing - is it moderating the voltage ? acting as a switch ? if anyone has come across this little chap I'd like to know as I intend to buy as few for cannibalisation.

    So far as I can make out, this is the operating circuit:

    Click image for larger version

Name:	YX801 solar lamp.jpg
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Size:	36.3 KB
ID:	82444

    The thing that looks a bit like a resistor on my board is actually a 33H inductor. This is switched at about 333kHz and the led is used as a catch/dump diode (lighting it). The high switching frequency means that the human eye cannot perceive that the led is switched. The control scheme seems to be discontinuous conduction mode (the 60-40 on to off ratio suggests that the led current reaches zero before the switch turns on again).

  7. #7

    Default Re: YX801 IC - what does it do

    Probably a knock-off or copy of this:

    PR4401/4402 0.9V White LED driver
    - Rick

  8. #8

  9. #9

    Default Re: YX801 IC - what does it do

    Welcome to the forums CoSt. No apologies required. Your English is much better than my Ukranian.

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