PWM Dimmer

This board will provide I2C intensity control for a Luxeon white LED. Three control options are provided:

analog input of BuckPuck? input of BuckPuck? (not constant current... 12V supply with limit resistor)

PCB Documentation

• ​Layout
• ​Schematic
• ​PCB Design

​ExpressPCB

• Assembly Notes:
  • Buckpuck mounts on bottom side of PCB (oops)
  • Cut trace to U3-6, wire to U3-7

Programming

Digital Pot	50	fb	00-3f	Pot 1 setting
PWM control	60	01	00-ff	PWM 0 blink rate (n+1)/152_Hz?
		02	01-ff	PWM 0 duty cycle n/256?
	60	03	00-ff	PWM 1 blink rate (n+1)/152_Hz?
		04	01-ff	PWM 1 duty cycle n/256?
		05	00-0f	Selector: bits 0-1 = white LED; bits 2-3 = red LED
				00=off 01=on 10=PWM 0 11=PWM 1

Parts Documentation

• Luxeon LXHL-MW1D High-intenisty LED ​Data Sheet
• Philips PCA9530 2-output I2C PWM Dimmer ​Data Sheet ​local copy
• DS3906 digital pot

(​Data Sheet (​Package Drawing

• ​I2CTools.com

​Hardware Manual

• ​LED Dynamics BuckPuck? constant-current driver ​Data Sheet

Bit-Bang I2C Interface

test program

                                         LS05 pin 14 (Vcc) o      -------
                                                           |      |     |
            +--+--+---------------------+--+--+------------+------+-o 1 |
            |  |  |                     |  |  |           ===.1uF | +5V |
  -------- [[R]][[R]][[R]] 3x10K       3x10K [[R]][[R]][[R]]
  |      |  |  |  |                     |  |  |    pin 7 o-+------+-o 2 |
  | 12 o-+--+  |  |   3|\ 4             |  |  |    (Gnd)          | GND |
  | 17 o-+-----|--|----| >o-------------+--|--|--------------+    |     |
  |      |     |  |    |/        8 /|9     |  |     10 /|11  +----+-o 3 |
  | 15 o-+-----+--|--------------o< |------+--|------o< |----+    | SCL |
  |      |        |   1|\ 2        \|         |        \|         |     |
  |  9 o-+--------|----| >o-------------------+--------------+----+-o 4 |
  |      |        |    |/                            6 /|5   |    | SDA |
  | 11 o-+--------+----------------------------------o< |----+    -------
  | 10 o-+-+                                           \|          4-pin
  | 13 o-+-+--oGND                                              Connector
  | 25 o-+-+      ------------------ Part List --------------------------
  --------        | 1 - .1 uF capacitor   | 6 - 10K 5% resistors        |
  25-pin male D   | 1 - 4-pin connector   | 1 - 25-pin male D connector |
  connector to PC | 1 - 74LS05 open collector hex inverter              |
  printer port    -------------------------------------------------------