LED Driver Schematic

I’ve have been searching for LED driver schematic diagram but can’t find it.
Is it available in this forum?
Like for: AMC7135*8+MCU 2800mAh 5-Mode Circuit Board
Appreciate any help.

Rufusbduck pointed his desciption out to me again the other day of this driver but I cant find it. I will get him to link it here.

Great! Thanks. Will watch for it.
Also it would be nice to have a section in the forum where members can post their step by step mods. :beer:

Do you mean like here or something else?


Saw it! Yup! Exactly what I’m looking for, Will review some of the mods. Thanks.

Here is a link to the thread, and here is the photo.

It’s weird that the image disappeared from the original post. I’ll try and put it back. I went back to the thread and the image was there again. I wonder if photobucket was glitchy. It took a while to go that far back in “my album” to get to that image.

Very informative! One more thing, is there a circuit schematic available for this board?

I don’t know but if you google 7135 and search the images you might find one. Post a link if you do and I’ll add it to my Anatomy thread.

I did but can’t find a complete circuit for LED driver with Atmel 1035 and 7135.
I’m hoping somebody here may have one. Will keep looking. Will be a nice addition to your thread.

What part of it are you tracing?

Nothing in particular but it would be nice to understand the whole circuit. :beer:

You know that all of the output pins(left hand pin) of the 7135’s are connected by a trace that runs underneath them and that they are turned on/off by the IC using the Vdd trace that is connected to all of the right hand pins. When turned on, current flows through the 7135’s from the output pins to the ground tabs(large outer tab, also connected to center pin) and back to B-. The only other parts on the boards usually consist of a reverse polarity diode, a capacitor that I think is for mode memory, and 2 resistors that I’m guessing determine low voltage point.

The duck nailed it. Very simple schematic. If I get a chance I’ll draw one and post it.

That would be nice Relic.
Thanks Rufus for the info.

Here is a schematic for the NANJG 105C. Let me know of any errors or omissions and I’ll update the pic or add corrections to this comment.


  • When looking at the battery side of the driver, the stars are number from right to left.
  • +Vin is the spring in the middle, -Vin is the ground ring on the edge of the driver.
  • R1 and R2 form a divider for battery level measurement and power cut detection.
  • D1 provides reverse batrery protection for the MCU, reduces the incoming voltage (driver rated to 6V in, MCU is 5V max), and prevents the capacitor C1 from being discharged by anything other than the MCU.
  • The 7135 chips are controlled my MCU PB1 via their Vdd (Pin3).

I just noticed I didn’t label the MCU; it is the square 8-pin block in the middle, Atmel ATTiny13A.
EDIT: Updated image to correct issues mentioned below by sixty545, Thanks! Original imaged deleted.
Edit: Added rev protection note, thanks texaspyro!

I was going to say “maybe they took it down to correct it”, but just realized you may be saying that’s your image…

No offense intended, but did you notice the labels are wrong? E.g. “Input pad” is actually “LED (+)” and “Output pad” is actually “LED (-)”…

Just sayin’…
(If it’s yours, you could edit that…)

Other than that little niggle, thank you for an awesome effort! That’s what makes BLF so much better than any other possibility of a place.


I found two errors in the battery voltage detector section. R1 should be connected to MCU pin 8, VCC and R2 should be 4K7. The detection level in the MCU is 1.1 V

Good catch, my first draft had it this way, then my clean(er) copy has the error. I misread the value of R2 as well.

Thanks! I will update.

appears to be a linear current sink - there is no duty cycle term in the power dissipation equation.

Your absolutely right and it makes way more sense anyway.
Conventions have changed a bit since I labeled that image. At that time led- was often called the output pad and since led+ feeds the IC and is directly connected to B+ on the other side I labeled it input +.