1.5A Constant Current Linear Regulator for LEDs For
Intro: 1.5A Constant Current Linear Regulator for LEDs For
So there are a ton of instructables covering the use of high brightness leds. Many of them use the commercially available Buckpuck from Luxdrive. Many of them also use linear regulation circuits that top out at 350 mA because they are highly inefficient. This instructable serves to let people know that there are other options out there to drive high power leds. We came upon this project in the work we are doing with a customer for a high power led strobe [www.ohararp.com/blog.html]
The heart of this project is the STCS1 from STM Electronics:
http://www.st.com/stonline/products/literature/ds/13415/stcs1.htm
Warning: Some parts of this project were designed and fabbed using professional software and hardware. However, all aspects of this design could be done using open source products or some perf board and wire wrap.
The heart of this project is the STCS1 from STM Electronics:
http://www.st.com/stonline/products/literature/ds/13415/stcs1.htm
Warning: Some parts of this project were designed and fabbed using professional software and hardware. However, all aspects of this design could be done using open source products or some perf board and wire wrap.
STEP 1: Read the Data Sheet!
First step with any electronics project is to read the data sheet:
http://www.st.com/stonline/products/literature/ds/13415/stcs1.pdf
From this we can easily see some of the key features of this chip:
■ Up to 40 V input voltage
■ Less than 0.5 V voltage overhead
■ Up to 1.5 A output current
■ PWM dimming pin
■ Shutdown pin
■ LED disconnection diagnostic
http://www.st.com/stonline/products/literature/ds/13415/stcs1.pdf
From this we can easily see some of the key features of this chip:
■ Up to 40 V input voltage
■ Less than 0.5 V voltage overhead
■ Up to 1.5 A output current
■ PWM dimming pin
■ Shutdown pin
■ LED disconnection diagnostic
STEP 2: What Else Do We Need? How Bout 5V@20mA
Because I wanted this design to have a nearly identical pinout as the BuckPuck from Luxdrive I decided to add a simple 5V@20 mA
STEP 3: Layout the PCB!
Using the connectivity of the schematic layout your board for the simplest wiring configuration as possible. This might take some time but your patience here will serve you well. This applies to all layout methods. Here you can clearly see we are using 1206 packages for all of our resistors, capacitors, and diodes.
STEP 4: Wired Up!
Here's everything wired up. Unfortunately we had to use the bottom plane and some vias to completely route this board.
Here are the Gerber Files of this board.
Here are the Gerber Files of this board.
STEP 5: Order and Assemble the Board
Using your favorite pcb vendor and assembly method you can put together the board pretty quickly. We prefer http://www.goldphoenixpcb.biz/ for our boards and then we use kapton stencils, kester solderpaste, and a reflow skillet or oven to assemble our boards.
STEP 6: Let the Blinding Begin!
With the .1" spacing on the pinout of this board you can very easily breadboard your project. Here we are powering a string of 3 x K2 Luxeons (140 lumens per led) from a 12V wall wart capable of supplying 3000 mA.
The performance of this chip is pretty amazing. At 1500 mA the driver board is barely warm to the touch when driving leds continuously.
Note: This design is for a strobe light where the leds do not stay on very long. For continuously running the leds you MUST mount them to a heatsink to dissipate the heat that is produced.
All parts for this design can be found at Mouser or Digikey:
Here's the BOM
Driver IC - STCS1
The performance of this chip is pretty amazing. At 1500 mA the driver board is barely warm to the touch when driving leds continuously.
Note: This design is for a strobe light where the leds do not stay on very long. For continuously running the leds you MUST mount them to a heatsink to dissipate the heat that is produced.
All parts for this design can be found at Mouser or Digikey:
Here's the BOM
Driver IC - STCS1
41 Comments
scarittagle 1 year ago
hikira 13 years ago
i can kinda read schematics but im confused is their a way you could post a schematic with pics of the parts in their spots or a pic of the board that is easier to see the traces
additionally i would want to run this at max voltage would i use the same resisters
Remi505 13 years ago
musick7 13 years ago
Simple. If your prototyping one device to see if it works, 99.999% of the IC Manufactures have a sample program. The few that don't you most likely request a few samples... The only thing you agree to when ordering samples is, you can't resale any parts you received for Free. If you make money on something, you have to buy it.
And yes I know it's an old post but thought i'd add my two cents... =)
ohararp 13 years ago
KnH 13 years ago
ohararp 13 years ago
cahillicus 14 years ago
Also, the schematic shows C1 and C3 as 4.7uF and the BOM lists them as10uF and 1uF. Which should I use?
Thanks
conntaxman 14 years ago
I think a 100watt incandescent bulb =1750 Lumens and my 3 watt leds are about 100 Lumens.So I guess I only have a brightness of about 51 watt incandescent right?
oh well its fun anyway. Now I just have to see what different type of cap,I could use that would be smaller the the ceramic .01 cap.All the other parts i got are small and the cap,.now is too big.
well have fun.
Johnny
cahillicus 14 years ago
ohararp 14 years ago
cahillicus 14 years ago
ohararp 14 years ago
conntaxman 14 years ago
TKS
Johnny
ohararp 14 years ago
conntaxman 14 years ago
I connected it in your or the DIY. dia. and it works fine.I didn't disconnect it to see if that would have any effect.
I want to wire up one useing the STCS2.but don't know either to connect it or not.
Tks
Johnny
conntaxman 14 years ago
Is that being used to regulate the voltage? I don't know.First time using these chips.
tks
Johnny
ohararp 14 years ago
RF=VFB/ILEDS=100mV/700ma=142mOhms
conntaxman 14 years ago
I glad the other cir. works very good.
Thank for the reply and have a nice day.
Johnny
conntaxman 14 years ago
TKS
Johnny
reason is ,that it is a little bigger to solder with the pre made pc. board.
tks again.
very nice cir.