EV-128 AAT3174 EVAL: High Current, High Efficiency Charge Pump Introduction The AAT3174 EVAL board demonstrates the functionality of the AAT3174 and its application as a high current white LED flash driver. The device consists of a tri-mode charge pump with load switch (1X), fractional (1.5X), and doubling (2X) conversion modes to provide excellent efficiency for both flash and movie modes. The LED drive current is programmable in 16 steps through the Simple Serial Control™ (S2Cwire™) interface. An external set resistor determines the maximum LED drive current and it can be set up to 800mA. By default, the evaluation board is set to 600mA maximum LED drive current. 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. The actual board layout is also provided. For additional information, please consult the AAT3174 product datasheet. Schematic DC- DC+ J1 DC+ C4 4.7µF C1 GND 1µF U1 AAT3174 1 2 3 4 5 6 GND VIN VIN C1+ VOUT C1C2+ GND C2F1 N/C RSET EN/SET 12 11 10 9 8 7 C3 2.2µF C2 1µF GND R8 187K D1 R8 = 187K for 600mA GND Uses a single flash LED Lumileds LXCL-PWF1 or Lumimicro LMPTWH556S Not both R6 100K J2 GND DC+ R7 220K R3 R2 R1 1K 1K 1K DATA FLASH MOVIE 0 0 0 2 4 1 3 5 2 4 1 3 5 2 4 1 3 5 SW3 SW2 1 2 3 4 U2 VDD GP5 GP4 GP3 VSS GP0 GP1 GP2 C7 1µF 8 7 6 5 PIC12F675 SW1 GND VR4 POT10K R4 330K GND R5 330 LED7 RED GND LED0 GRN GND Figure 1: Evaluation Board Schematic EV-128.2006.04.1.0 1 EV-128 AAT3174 EVAL: High Current, High Efficiency Charge Pump Getting Started In most cases, the board ships mounted onto a battery pack. The battery pack holds three AAA size, conventional alkaline batteries. When no battery pack is present, external power can be applied to the DC+ and DCterminals. A jumper labeled J1 is inline with the battery supply terminal DC+ for connecting/disconnecting power. To apply power to the board, connect the supply by jumpering ON, MCU. The red LED7 should illuminate, indicating that power has been connected. There is an additional jumper labeled J2 that provides access to the EN/SET pin of the AAT3174. Ensure that ON SRL is also jumpered so that the microcontroller is connected to the EN/SET pin. The user interface is provided by three buttons: DATA, FLASH, and MOVIE. The modes of operation are detailed in Table 1. The FLASH button generates a flash pulse. By default, the FLASH button generates a pulse at full current. The MOVIE button toggles on/off movie mode illumination. The DATA button is used to set different current levels. When the DATA button is held down, the MCU will auto-cycle through the available brightness level settings after a short delay. Some functions require that multiple buttons are pressed and released together. User Interface Functionality Button(s) Pushed1 Description DATA Increments through the 16 data settings. Hold down to auto-cycle (does not turn LED on, just sets data). FLASH2 Generate flash pulse. Current level determined by the DATA setting (defaults to DATA 1). Trim-pot VR4 sets duration. MOVIE Toggle on/off movie mode illumination. Current level determined by the DATA setting. Leave on to see effects of changing DATA. DATA + FLASH + MOVIE Reset, shutdown. Table 1: User Interface Functionality. 1 The '+' sign indicates that these buttons are all pressed and released together 2. Flash pulse duration is adjustable from 10ms to 2 seconds. Rotate trim-pot VR4 clockwise to reduce the duration. 2 EV-128.2006.04.1.0 EV-128 AAT3174 EVAL: High Current, High Efficiency Charge Pump Printed Circuit Board Figure 2: AAT3174 Evaluation Board Top Layer (not to scale). Figure 3: AAT3174 Evaluation Board Bottom Layer (not to scale). EV-128.2006.04.1.0 3 EV-128 AAT3174 EVAL: High Current, High Efficiency Charge Pump AAT3174 EVAL Component Listing Component Part Number Description U1 AAT3174 U2 PIC12F675 Tri-Mode High Efficiency Charge Pump for White LED Flash; TDFN33-12 Package 8-Bit CMOS, FLASH-Based µC; 8-Pin PDIP Package High Brightness Flash LED 1K, 5%, 1/4W; 1206 1µF, 10V, X5R, 10%; 0603 2.2µF, 10V, X5R, 10%; 0603 4.7µF, 6.3V, X5R, 10%; 0603 1µF, 10V, X5R, 10%; 1206 330K, 5%, 1/4W; 1206 100K, 5%, 1/4W; 1206 220K, 5%, 1/4W; 1206 10K POT; 3mm Squared SMD Green LED; 1206 Red LED; 1206 Connecting Header, 2mm Switch Tact, SPST, 5mm D1 R1 - R3 C1 - C2 C3 C4 C7 R4 - R5 R6 R7 VR4 LED0 LED7 J1 - J2 SW1 - SW3 LXCL-PWF1 Chip Resistor GRM18 GRM18 GRM18 GRM31 Chip Resistor Chip Resistor Chip Resistor EVN-5ESX50B14 CMD15-21UGC/TR8 CMD15-21SRC/TR8 PRPN401PAEN PTS645TL50 Manufacturer AnalogicTech Microchip Lumileds Vishay Murata Murata Murata Murata Vishay Vishay Vishay Panasonic-ECG Chicago Miniature Lamp Chicago Miniature Lamp Sullins Electronics ITT Industries Table 2: Component Listing. © Advanced Analogic Technologies, Inc. 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