# Help! Learning led driver

#### Joao12300

Joined Jul 3, 2021
6
Hello! I dont work on eletronics professional, but my goal is to learn the working principle of eletronics.

Im starting to study an led driver i took measures values and made the schematic diagram on easyeda now i want to understand what every resistor or any component do on the pcb.

im sorry for my english.

Photos:

#### ci139

Joined Jul 11, 2016
1,815
The YT2201's datasheet - nor the schematic diagram of - nor the pinout of -- will show up when googled in english
You seem to got the model of the chip ? anything ... block diagram

PS! - either your schematic (for the circuit diagram) or the pin-out of the mystery controller is incorrect

#### Joao12300

Joined Jul 3, 2021
6
The YT2201's datasheet - nor the schematic diagram of - nor the pinout of -- will show up when googled in english
You seem to got the model of the chip ? anything ... block diagram

PS! - either your schematic (for the circuit diagram) or the pin-out of the mystery controller is incorrect
sorry i forgot to explain i didnt used the right ic in the easyeda i didnt know how to change and make a custom ic the datasheet its correct

#### ci139

Joined Jul 11, 2016
1,815
? do you got the d/s for the YT2212 (←which might be not the correct or full product type-name)

? do you know the spec.-s for the LED supply/driver it.. (the power converter module) ..comes from // -- such as input voltage , output current or voltage . . . ?anything

#### Joao12300

Joined Jul 3, 2021
6
? do you got the d/s for the YT2212 (←which might be not the correct or full product type-name)

? do you know the spec.-s for the LED supply/driver it.. (the power converter module) ..comes from // -- such as input voltage , output current or voltage . . . ?anything
i got the d/s for the yt2201. about the specs the led driver has in the input 230vac, 78vdc on output and its feedding 96 2835 leds in 24 row of 4 led in series / parallel

#### Joao12300

Joined Jul 3, 2021
6
i guess (not yet digged into your PCB) that what you got is similar to the inverting buck/boost converter - as in
https://www.led-professional.com/te...argeting-100-w-incandescent-bulb-replacements
i guess (not yet digged into your PCB) that what you got is similar to the inverting buck/boost converter - as in
https://www.led-professional.com/te...argeting-100-w-incandescent-bulb-replacements
yup its similiar the diference that my pcb uses a ic that doesnt need auxiliary components to be powered or anything else thats why i picked this pcb so its an "easy" to understand then i will move to harder pcb to learn more.

my problem it is the need of someone that can explain how it works or like the diode close to the inductor what it he doing there.

thank you

#### Joao12300

Joined Jul 3, 2021
6
nope - it's a positive common buck converter ???? with no regulation as it seems
View attachment 264760
the schematic its correct with my pcb yup that is correct.
now i just have to understand everything ahah so i can learn more. any advice to start?

#### ci139

Joined Jul 11, 2016
1,815
there is a theoretical chance that the circuit you got . . . is regulated
if the input is known (can be measured) and the target output voltage is known and the inductance is known - then it is possible to calculate the di/dt ← which can be measured either internally inside the IC or from the voltage drop on the R3||R4 (889mΩ) - so - if you can scope the waveforns - you may be able to get from these how the converter works

#### Joao12300

Joined Jul 3, 2021
6
there is a theoretical chance that the circuit you got . . . is regulated
if the input is known (can be measured) and the target output voltage is known and the inductance is known - then it is possible to calculate the di/dt ← which can be measured either internally inside the IC or from the voltage drop on the R3||R4 (889mΩ) - so - if you can scope the waveforns - you may be able to get from these how the converter works
i never calculated di/dt i will need to learn about that, about the scope i get this one from the inductor

#### ci139

Joined Jul 11, 2016
1,815
interesting "party" with all sorts of relevant figures
(( though it's interesting that the (hi "resolution" figure) 76.0657 does not match some less definitive 12.93 ))
basically i attempted to compile a fast simulation - while i realized that due the requirement for a separate startup control and the precision timings for the regular control the poor performance thingy - such as Falstad - goes too slow (← anyway the "regular control" "waveform generator") - the only option other than differential is to sample output when the mosfet is closed and the inductor has been settled . . .
. . . your waveforms don't hint that particular option ??

? was there a regular (96x .06·3.1≈18W) load on the output

there are some basic formulas at https://www.maximintegrated.com/en/design/technical-documents/tutorials/2/2031.html

basically for $$-\epsilon=L\frac{di}{dt}$$ the $$V_{CHARGE-UP}=400-78V=322$$ and the $$V_{CHARGE-DN}=78V$$ which for a linear time integration (loosely put) defines the difference for $$I=\frac{dq}{dt}=\int{di}$$ , also $$\frac{I_{MAX}}{dI_{IN}}=N·dt$$ and $$\frac{I_{MAX}}{dI_{OUT}}=M·dt$$ . . . as $$di~\epsilon\ or\ V$$ the
${{}\\ \displaystyle{\frac{N}{M}=\frac{V_{OUT}}{V_{IN}}≈\frac1{\frac1{DUTY\ RATIO}-1}}}$
so if we fix the $$I_{MAX}$$ and the I/O voltages differ more then reaching $$I_{MAX}$$ is faster and vice versa - so we have switching times and can measure average input voltage . . . is one way for a robust control

Last edited:

#### Jon Chandler

Joined Jun 12, 2008
191
Please, to get a complete explanation and understanding of LED driver chips, check out Big Clive on YouTube. He has disassembled many LED bulbs and explained their operation in great detsil.