Buying Guide

 

There are three components other than the shield are required to have fully functional power LED setup. Here is a brief explanation and where to get them.

 

High Power RGB LED Shield

The shield name include RGB LED, however it is simple three independent LED driver shield. It is matter of how users want to use the shield. The shield can be connected to single or three strings of white LEDs, RGB strings or any LED strings. Each channel are independent, so any single or two channel can be used.

The shield is designed as an Arduino shield, however it can be used with any variants of Arduino or any microcontroller that support I2C. All functions of the shield are controllable with I2C which require 2 I2C and GND connection only.

When LEDs is operated at high ambient temperature or a small size of heatsink, the shield with temperature sensor can be useful. The current to LED can be dynamically adjustable depending on LED temperature.

You can order the shield from the store.

 

Power LED

Any LEDs that have maximum current rating 350-1000mA would be suitable with the shield.  The lighting-purpose power LEDs have normally higher than 350mA maximum current rating. These are the suitable LEDs for the shield.

It is recommend to have MCPCB (metal core PCB, normally called star-board) mounted LED than FR-4 PCB mounted LED, since MCPCB offer lower heat resistance. For multi-LEDs on single MCPCB, they are connected in series except RGB LED. For RGB LED mounted on single MCPCB, It is required to have all six connectors ( 3x anode and 3x cathode) separated. The shield will not work with common cathode or common anode RGB LEDs.

There are essentially only two different kinds of Power LEDs, 350mA and 700-1000mA LED. 350mA LED are normally un-branded cheap LEDs from Chinese manufactures. These are cost-effective and can be sourced from many places including Chinese website such as DealExtreme. They are cost normally less than $3. With larger quantity, it goes down to less than $1. Their quality is normally good enough for general use. Very long term stability (> 5 year) and exact specifications may be vague.

700mA LEDs are mostly come from reputable manufactures like Cree, Philips, OSRAM, SSC. They are available from big distributers like Digikey, Mouser, and Future Electronics, however only available as LED itself without MCPCB. Since these LEDs are mostly SMD LED, they are hard to mount at home. There are a few places where MCPCB mounted 700mA LEDs are available.

 

There is a post for some power LEDs in here.

 

LED supply

They have MCPCB mounted 700-1000mA Cree (Indus Star) and Philips Luxeon LEDs (Endor Star).

 

Luxeonstar

Varieties of Philips Luxeon LEDs – single, tri-star, 7 LED MCPCB

 

Cutter Electronics

Varieties of Cree LEDs, only place for Cree RGB LED in single MCPCB

 

DealExtreme

DealExtreme have RGB LEDs, Cree Whites, and Cree Color LEDs. They are normally cheaper than other places

Cree XR-E White ( brightness bin : R2 > Q5 > Q2 > P4 )

Cree Red, Green, Blue

 

 

LED Heatsink

It is critical to have proper heatsink for LEDs to maintain the temperature within the specification. Maximum operation temperature of power LED is 150 Celsius degree, however lower is always better. High operation temperature cause reduced life time, reduced brightness and higher voltage drop.

For single starboard, LGA chip heat sink or similar can be used.

http://ledsupply.com/led-heatsink.php

http://www.luxeonstar.com/Thermal-Management-Products-for-High-Power-LEDs-s/84.htm

http://www.cutter.com.au/products.php?cat=Heatsinks

 

For multiple starboard, bigger heatsink is required. computer CPU heatsink is readily available and good. Intel CPU heatsink without fan or Socket 478 CPU heatsink is good, since they have flat CPU-side surface

http://www.newegg.com/Product/Product.aspx?Item=N82E16835150033

http://www.google.com/products/catalog?q=MASSCOOL+9T288B1M3G&oe=utf-8&client=firefox-a&cid=14019147909413548960#p

 

For multiple starboard, a strip of aluminum bar is popular.

http://www.heatsinkusa.com/

To reduce the thermal resistance between LED and heatsink, it is recommend to have thermal material such as thermal adhesive tape or thermal epoxy.

http://www.google.com/products/catalog?q=Arctic+Silver+Alumina+AATA-5G&tbm=shop&cid=8530852200908200294#

 

Power Supply

To power LEDs, it is important to have enough power to the shield. The voltage is really depends on number of LED or output voltage. Each LED has about 2-3.5V forward drop voltage. Supplying voltage to the shield should be higher than total voltage drop of LEDs.

Output Amp is also important. For 350mA LEDs, about >1.2A per shield is good enough. For 700mA LEDs, >2A is required.

For general rule of thumb, please check the manual (Input voltage and operation frequency section).

Most common power adaptors are 12V and 24V. They are typically designed for laptop computer power supplies which have normally have >2A output Amp.

They are available in many different places including local electronic stores. Here are few online places.

As long as adaptor has 5.5mm(outside diameter) and 2.1mm(pole diameter), adaptor will fit with the shield.

http://ledsupply.com/power-supplies.php

http://www.amazon.com/Replacement-Monitor-Adapter-Power-Supply/dp/B0023Y9EQC/

http://www.amazon.com/Universal-Adapter-15V-18-5V-19-5V/dp/B0027BUS0M/

http://www.adafruit.com/products/352

http://www.newegg.com/Product/Product.aspx?Item=N82E16881381030

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