Solar led garden light circuit question

Thread Starter

lordeos

Joined Jun 23, 2015
33
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
 

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Dodgydave

Joined Jun 22, 2012
8,389
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.
 
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Marcus2012

Joined Feb 22, 2015
375
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.
 
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wayneh

Joined Sep 9, 2010
16,102
- 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 .
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.
 

Dodgydave

Joined Jun 22, 2012
8,389
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
 
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