Lightkraken is a PoE++ (802.3bt Type 4) powered LED strip driver.
Fully compatible with switches which support the following PoE standards:
The rectifier uses two Fairchild FDMQ8205A MOSFET bridge ICs. During prototyping it was determined that using Schottky or regular diodes (to reduce cost) for the rectifier section generated too much heat. The use of the FDMQ8205A part is recommended in the Texas Instruments application notes.
There is a 3-position switch on the board which allows the selection of the output voltage. Left position is 5.4V, middle is 12V and right position is 23.5V.
5.4V was selected instead of 5V to slightly extend the physical range of addressable LEDs without color change due to voltage drop. Virtually all LED chips rated for 5V also support 5.4V without any negative effects.
If you drive your LEDs at 25W or higher it is recommended to install a fan as the DC/DC conversion section on the board can become rather hot without one (I measured 100C/212F in open air, this will be much higher in an enclosed space). The board comes with a standard JST XH2.54-2P fan header, readily available 30x30x10mm fans work fine.
The ethernet interface uses a LAN8720A IC which operates in RMII mode only.
The microcontroller is a GigaDevice GD32F107RCT6 Cortex-M3 part. The part was chosen because of physical package size, RAM size and low cost. Unfortunately ST does not provide an equivalent part, 64KB of RAM is way too small for this application. LwIP, the TCP/IP stack used, consumes about 50KB of RAM alone in the latest version which leaves little room for client code. Lightkraken needs about 32KB RAM to be able to drive LED strips using DMA.
Unique MAC addresses are generated by computing a 32-bit hash of the UID of the microcontroller and using a fixed LAA prefix.
There are 4 data lines which can either drive two 1-Wire or two serial data (Clock+Data) signals at 5V TTL.
If the device is configured for Analog RGB mode some of the data lines are hard-rewired to Power MOSFETs instead of to the internal 5V TTL voltage and can drive up to 6A of power.
The data lines are connected to the SPI peripheral pins of the MCU. The MCU does output LED data using DMA+SPI.
The data output pins on the terminals are driven using real 5V TTL through a MOSFET based level shifter. There is a dedicated linear regulator which provides 5V, derived from the voltage the DC/DC converter does output. So even with long cables there should be no signal dropout because of a voltage drop.
All data output lines have a 500 Ohm impedance matching resistor in line. This resistor was chosen to handle the most common LED strip setups. In specific cases this 0603 sized resistor might not be appropriate and has to be customized.
Note: Do not use consume any significant current on the 5V data lines. The linear regulator can only handle a few millamps before it goes into thermal shutdown.
54W@5V and 70W@12V is not a lot in the grand scheme of things. While Lightkraken supports up to 5 universes per output, don't expect to be able to drive LEDs at full brightness using this configuration. Realistically expect 1 universe (~256 LEDs) per Lightkraken device at full brightness. I have tested one of these](https://www.amazon.com/gp/product/B07417BRFN) successfully on a POE-171A-95 switch for several weeks. YMMV will vary of course as all LEDs out there vary in specifications.