EV-114 AAT2803 EVAL: Six-Channel White LED Backlight Charge Pump with Flash Introduction The AAT2803 EVAL board demonstrates the functionality of the AAT2803 and its application as a white LED backlight driver with flash capability. The backlighting section of the AAT2803 uses a low-noise, constant frequency charge pump DC/DC converter with tri-mode load switch (1X), fractional (1.5X) and doubling (2X) conversion to maximize efficiency and operate over a wide input voltage range. Dedicated to the flash section is a low-noise, constant frequency doubling (2X) charge pump that is capable of delivering 300mA of pulsed current. The backlighting section is programmable with the AS2Cwire™ (Advanced Simple Serial Control™) serial interface and is capable of driving up to six independent LED channels. LED constant current levels are set from a 16-level logarithmic scale and four additional low current settings are available down to 50µA. This document describes the evaluation board and its accompanying user interface. In addition, a brief Getting Started section is included to help the user begin operating the evaluation board. A schematic of the complete circuit is shown in Figure 1, and the actual board layout is given in Figures 2 and 3. For additional information, please consult the AAT2803 product datasheet. Schematic DC+ C3 DC- J1 C2 1µF 1µF C6 1µF D4 D5 D3 D2 D1 13 14 JPx 15 16 17 18 GND VIN GND D1 D2 D3 GND GND N/C EN/FL VIN VOUT_FL C1+ C1- D5 D4 D6 EN/SET N/C GND D6 8 7 C2C3C3+ C2+ VOUT_BL N/C 12 11 10 9 6 5 4 3 C4 1µF 2 1 C1 1µF C5 1µF GND U1 AAT2803 19 20 21 22 23 24 Flash LED D0 GND R4 R5 1Ω 20Ω AAT9513 GND GND EN3 LT MV FL DC+ R3 1kΩ LIGHT 0 2 4 SW3 1 3 5 MOVIE 0 2 4 FLASH 0 2 4 R2 1kΩ R1 1kΩ U3 1 2 3 4 SW2 1 3 5 VDD GP5 GP4 GP3 PIC12F675 VSS GP0 GP1 GP2 U2 C8 10µF 8 GND R6 330Ω 7 6 LED7 RED 5 GND SW1 GND 1 3 5 GND Figure 1: Evaluation Board Schematic. EV-114.2005.06.1.0 1 EV-114 AAT2803 EVAL: Six-Channel White LED Backlight Charge Pump with Flash Getting Started In most cases, the AAT2803 evaluation board ships mounted onto a battery pack. The battery pack holds three AAA size, conventional alkaline batteries. A jumper is inline with the battery supply for connecting/disconnecting power. There are three other jumpers labeled LT, MV, and FL. They provide access to EN/SET, EN_FL, and EN3, respectively. To apply power to the board, connect the supply by jumpering ON, MCU. The red LED7 should illuminate, indicating that power has been connected. Ensure that LT, MV, and FL are jumpered so that the microcontroller can control the parts. The user interface is provided by three buttons. The buttons are LIGHT, MOVIE, and FLASH. The modes of operation are detailed in Table 1. Each button handles a particular function. The LIGHT button controls the backlight section. When the LIGHT button is held down, the MCU will auto-cycle through the available brightness level settings after a short delay. The MOVIE button toggles on/off the movie mode illumination. The FLASH button provides a flash pulse and a red-eye reduction function. When the FLASH button is held down, red-eye reduction mode will be executed after a short delay. Button(s) Pushed1 LIGHT MOVIE FLASH LIGHT + FLASH LIGHT + MOVIE MOVIE + FLASH LIGHT + MOVIE + FLASH Description Increment the number of EN/SET edges. Toggles through the available brightness level settings for the backlighting section. If held down, auto-cycle through the settings. Toggle on/off movie mode illumination. Press once to produce a ~300ms flash pulse. Hold down to produce a sequence of red-eye reduction pulses. Decrement the number of EN/SET edges. Toggles through the available brightness level settings for the backlighting section. If held down, auto-cycle through the settings. Increment the address. Cycles through addresses 1, 2, and 3 (i.e., main/sub, mainonly, sub-only). Switch to the next current level scale. Cycles through the 20mA, 30mA, 15mA, and Low Current scales. Reset. All enable lines are pulled low. Table 1: User Interface Functionality. 1. The + sign indicates that the specified buttons are all pressed and released together. 2 EV-114.2005.06.1.0 EV-114 AAT2803 EVAL: Six-Channel White LED Backlight Charge Pump with Flash Printed Circuit Board Figure 2: Top Layer (not to scale). Figure 3: Bottom Layer (not to scale). EV-114.2005.06.1.0 3 EV-114 AAT2803 EVAL: Six-Channel White LED Backlight Charge Pump with Flash AAT2803 EVAL Component Listing Component Part Number Description U1 AAT2803 U2 AAT9513 U3 PIC12F675 Dual High Efficiency CP for Backlight and Flash; QFN44-24 Package 65mΩ, N-Channel Power MOSFET; SC70JW-8 Package 8-Bit CMOS, FLASH-Based µC; 8-Pin PDIP Package Mini-TOPLED White LED; SMT Package Flash White LED; 4-Chip Package 1kΩ, 5%, 1/4W; 1206 1µF, 10V, X5R, 10%; 0603 10µF, 6.3V, X7R, 10%; 1206 1Ω, 5%, 1/8W; 0805 20Ω, 5%, 1/8W; 0805 330Ω, 5%, 1/4W; 1206 0Ω, 5%; 0805 0Ω, 5%; 0603 Red LED; 1206 Connecting Header, 2mm Switch Tact, SPST, 5mm D1-D6 D0 R1-R3 C1-C6 C8 R4 R5 R6 JP1 JPx LED7 J1, MV, LT, FL SW1-SW3 LW M673 LMFLC4500 Chip Resistor ECJ-1VB1A105K GRM31CR70J106KA01L Chip Resistor Chip Resistor Chip Resistor Chip Resistor Chip Resistor CMD15-21SRC/TR8 PRPN401PAEN PTS645TL50 Manufacturer AnalogicTech AnalogicTech Microchip OSRAM Lumimicro Vishay Panasonic-ECG Murata Vishay Vishay Vishay Vishay Vishay Chicago Miniature Lamp Sullins Electronics ITT Industries Table 2: Component Listing. 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Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed. Advanced Analogic Technologies, Inc. 830 E. Arques Avenue, Sunnyvale, CA 94085 Phone (408) 737-4600 Fax (408) 737-4611 4 EV-114.2005.06.1.0