Solar led garden light circuit question

Discussion in 'The Projects Forum' started by lordeos, Mar 29, 2016.

  1. lordeos

    Thread Starter Member

    Jun 23, 2015
    33
    1
    Hi Guys,

    Out of curiosity i demolished one of my solar garden led light and try to analyze to components and the circuit.

    Inside i found a component that i didn't recognize the " YX8018" after some searching on the internet i think it's a solar led driver + it boosts the voltage because it needs to give 3.5V the lit a white LED (3.5). Since the only datasheet i found is chinese and their translation is pretty bad (google translate) i do not fully understand the circuit. I will add the Circuit as an attachment in this post.

    I did some measurements and the solor panel generates 2V in light condition

    if i look at the scheme of the datasheet ... I think as long the VDD input of the YX8018 recieves current (light condition) because the current the solor panel generates flows trough the battery and trough the VDD input it connects output CE and VDD so that the solor led panel is directly connected to ground so it charges up the battery.

    Here is where i'm stuck

    - In light condition the VDD input recieves power from the solor panel. In dark condition it recieves power from the battery. How can the VDD input make the difference ? or does the current from the solor panel flows directly into the battery because the potential of the battery (1.2V) is lower then that of the solar panel 2V, but then again how does the YX8018 know when connect CE en GND

    - What is the use of the inductor ?

    - What is LX output ? i assume it boosts the Voltage up to 3.5 V for the white led .

    Thanks for the help

    Mike
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,998
    745
    Try the PR4403 chip, it uses the solar cell to charge the battery, the inductor is to boost the voltage to 3.5v, and the chip switches off the led when the sense pin has voltage on it from the cell.
     
    Last edited: Mar 29, 2016
  3. Marcus2012

    Member

    Feb 22, 2015
    349
    26
    I've replaced these before and they are really, REALLY badly made ICs. So bad that any electrostatic discharge can destroy them, even just handling them. I replaced about 3 in a year once before I stopped bothering and made a better trickle charger.

    EDIT to answer your question I think it is a boost converter but it looks half baked.
     
    Last edited: Mar 29, 2016
  4. wayneh

    Expert

    Sep 9, 2010
    12,137
    3,054
    I think that circuit drawing on the right has an error - the connection of CE to ground should be open, not closed. Pulling CE low tells the IC to turn on the boost circuit and light the LED. You're right, the inductor is part of the boost circuit. When the LED is lit, you'll see the battery voltage across it. But it's pulsing, and a typical meter reports the time-averaged voltage, not the peaks.
     
  5. lordeos

    Thread Starter Member

    Jun 23, 2015
    33
    1
    What is the use of the LX output pin ?

    thanks for the help
     
  6. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,998
    745
    This will be the fet output to the led, also pulses the inductor, this boosts the battery voltage upto 3v to drive the led.

    datasheet
     
    Last edited: Mar 30, 2016
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