EVALUATION BOARD DATA SHEET EV193 Evaluation Board for the AAT1278 1.5A Single Flash LED Driver Introduction The AAT1278 evaluation board demonstrates the functionality of the AAT1278 and its application as LED photo flash driver under Skyworks' AS2Cwire serial digital interface control. The AAT1278 is a boost converter with a programmable constant current LED driver with an input voltage range of 2.7V to 5.5V. The single flash LED driver delivers up to 1500mA output current in flash mode. An external resistor is employed to set the flash LED maximum current for flash and movie modes; the movie mode LED current can be easily programmed from 100% to 0% of the maximum current value in 16 steps with a single GPIO output via the AS2Cwire interface; the flash to movie mode ratio can also be easily programmed from 2:1 to OFF in 16 steps with a single GPIO output via the AS2Cwire interface and the fixed flash to movie mode ratio is 7.3:1.The wide input voltage range, small solution size, and high switch frequency is suitable for small battery-powered applications. This document describes the evaluation board and its accompanying user interface. A “Getting Started” section is included to help the user to begin operating the evaluation board. The AAT1278 evaluation board is shown in Figure 1; Figures 2 and 6 depict the board schematic and layout. For additional information, please consult the AAT1278 product datasheet and application note (AN-111) for understanding of the AS2Cwire serial digital interface. Board Pictures (a) Top Side. (b) Bottom Side. Figure 1: AAT1278 Evaluation Board Picture. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 1 EVALUATION BOARD DATA SHEET EV193 Evaluation Board for the AAT1278 1.5A Single Flash LED Driver Board Schematic GND VIN JP1 R3 MCU R5 10K 0 Movie Mode Control Flash/Movie Mode Current Ratio FLEN 0 0 R6 10K R7 10K U2 1 2 3 4 SW1 2 4 1 3 5 SW2 2 4 VDD GP5 GP4 GP3 VSS GP0 GP1 GP2 PIC12F675 1 3 5 8 7 6 5 FLINH 2 4 SW4 1 3 5 JP2 C3 1µF R10 100k R8 330 R9 330 R4 100k (opt) VOUT LED1 RED LED2 GRN SW3 2 4 0 10k D1 1 3 5 U1 JP3 EN/SET A3 A1 C1 A2 R2 100K B2 A4 C4 NA C1 2.2µF AGND EN/SET FL FLEN IN PGND RSET FLGND B1 C2 FLINHIBIT SW SW OUT C3 B3 B4 C4 L1 1µH AAT1278 CSP-12 R1 133k C2 2.2µF Figure 2: AAT1278 Evaluation Board Schematic. Getting Started The board has two terminals labeled VIN and GND for the input power supply connection. Jump the JP1 to connect the VIN power to microcontroller VDD and AAT1278 IN. Jump JP2 to connect the SW4 to AAT1278 FLINHIBIT pin for inhibiting flash current. Jump the JP3 to set the microcontroller to generate AS2C code signal for driving LED. After all jumpers are in the correct positions, apply power between 2.7V and 5.5V to the VIN and GND terminals to power the AAT1278 (U1) and microcontroller (U2); the red LED (LED1) should illuminate when the microcontroller is powered. The green LED (LED2) should flicker when microcontroller sends the AS2C digital signal to AAT1278.Table1 shows the jumps’ function, Figure 3 shows the connection of the AAT1278 board. 2 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 EVALUATION BOARD DATA SHEET EV193 Evaluation Board for the AAT1278 1.5A Single Flash LED Driver Jumper Name JP1 JP2 JP3 Description Jump JP1 MCU ON position to power on the microcontroller and AAT1278, Jump JP1 MCU OFF position to disconnect the power. Connect JP2 to active the Flash Inhibit function by push SW4. Jump JP3 low position to generate AS2C code signal from microcontroller to AAT1278, Jump JP3 high position to cut off the AS2C signal between microcontroller and AAT1278. Table 1: Jumpers’ Function Description Figure 3: AAT1278 Evaluation Board Demonstration Connection. User Interface Functionality The user interface is provided by four push buttons: MMC (SW1), FMM (SW2), FLEN (SW3) and FLINH (SW4). A summary of operational modes for each button is outlined in Table 2. Definition of Each Control • MMC—Movie Mode Control (SW1): Sets movie mode current. Each switch closure will incrementally decrease the movie mode current stating at 100% to 0% (off) in 16 steps. Refer to the AAT1278 datasheet for detailed explanations of movie mode operation. • FMM—Flash/Movie Mode Current Ratio Control (SW2): Sets Flash/Movie Mode Current Ratio. Each switch closure will incrementally decrease the flash/movie mode current ratio stating at 2:1 to 0% (off) in 16 steps. Refer to the AAT1278 datasheet for detailed explanations of Flash to Maximum Movie Mode Current Ratio operation. • FLEN—Manual Flash Enable (SW3): Initiates a flash of maximum flash current. • FLINH—Inhibit Flash (SW4): Inhibit a flash current into default movie-mode current level Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 3 EVALUATION BOARD DATA SHEET EV193 Evaluation Board for the AAT1278 1.5A Single Flash LED Driver Button(s) SW1(MMC) SW2(FMM) SW3(FLEN) SW3(FLEN)+SW4(FLINH) Description [Push/Release once per step] Movie mode LED current dimming control. Each switch closure will issue an AS2C command to increment the data of the movie mode current register bits There are 16 steps in this register to step movie mode current from full scale to off (refer to the AAT1278 product datasheet for additional information). [Push/Release once per step] Flash/Movie Mode Current Ratio Control. Each switch closure will issue an AS2C command to increment the data of the Flash/Movie Mode Current Ratio register bits There are 16 steps in this register to step Flash/Movie Mode Current Ratio from 2:1 to off (refer to the AAT1278 product datasheet for additional information). [Push/Release once] Flash enable. Manually enables the AAT1278 boost converter to get the maximum flash current, initiates a single flash pulse. [Push SW4 and hold, then Push/Release SW3 once] Flash inhibit. Manually inhibit a flash current and enables the AAT1278 boost converter to get the maximum movie mode current, initiates a single flash pulse. Table 2: User Interface Functionality. LED Drive Current Set-Up LED Drive Current The AAT1278 can be set up to provide 1.5A maximum flash mode current. The maximum flash mode current is set by R1 and can be set to 107kΩ for a maximum flash LED drive current of 1.5A. In this AAT1278 manual’s application R1 is set to 133kΩ for 1.2A maximum flash current. Flash current can be calculated using Equation1 by change the value of R1. Refer to the AAT1278 datasheet to program a desired flash current, the default maximum Movie Mode Current can be calculated using Equation2 in this AAT1278 manual. IFL = 162kΩ ∙ A R1 1200mA IMOVIE MODE = IFL(FL to MM Ratio) = 7.3 = 164.4mA AS²Cwire Interface and Control JP3 connects GPIO (U2) and AAT1278 (U1) AS2Cwire interface EN/SET, AS2Cwire interface data is programmed by the microcontroller U2 and its associated push button function switches SW1, SW2. The movie current can be programmed from 100% to 0% of the maximum movie mode current in 16 linear steps controlled by AS2Cwire data signal as shown in Table 3.The flash to movie mode ratio may be varied from 2:1 to OFF in 16 linear steps controlled by AS2Cwire data signal as shown in Table 4, the default ratio between the flash current level and maximum movie mode current level is 7.3:1. 4 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 EVALUATION BOARD DATA SHEET EV193 Evaluation Board for the AAT1278 1.5A Single Flash LED Driver Data Percentage of Maximum MM Current 1* 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 100% 89% 79% 71% 63% 56% 50% 45% 40% 36% 32% 28% 25% 22% 20% 0% Table 3: Movie Mode (MM) Current Programming. Data Flash to Movie Mode Ratio 1 2 3 4* 5 6 7 8 9 10 11 12 13 14 15 16 2:1 3.8:1 5.5:1 7.3:1 8.9:1 10.5:1 12.2:1 13.8:1 14.9:1 16.5:1 18:1 19.6:1 21.1:1 22.6:1 24:1 OFF Table 4: Flash/Movie Mode Current Ratio. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 5 EVALUATION BOARD DATA SHEET EV193 Evaluation Board for the AAT1278 1.5A Single Flash LED Driver Test Waveform Movie Mode Waveform Figure 4 shows the waveform under movie mode controlled by AS2Cwire with data code 5.The IOUT rises to 100mA (63% of maximum movie mode current) as expected. Figure 4: Movie Mode Current Controlled by AS2Cwire Data (Ch1: VOUT; Ch2: EN/SET; Ch3: IIN; Ch4: IOUT). 6 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 EVALUATION BOARD DATA SHEET EV193 Evaluation Board for the AAT1278 1.5A Single Flash LED Driver Maximum Flash Current Waveform Figure 5 shows the AAT1278 Flash Current waveform with a FLEN pulse. IOUT maintains 1.2A when the flash enable pulse is asserted. Figure 5: Flash Current Operation with FLEN Pulse (Ch1: VOUT; Ch2: FLEN; Ch3: IIN; Ch4: IOUT). Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 7 EVALUATION BOARD DATA SHEET EV193 Evaluation Board for the AAT1278 1.5A Single Flash LED Driver Maximum Movie Mode Current Waveform Figure 6 shows the AAT1278 Maximum Movie Mode Current waveform with a FLINH pulse, while FLEN is keeping high. IOUT maintains 164mA when the FLINH pulse is asserted. Figure 6: Complete Flash current operation waveform (Ch1: FLINH pulse; Ch2: FLEN; Ch4: IOUT). 8 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 EVALUATION BOARD DATA SHEET EV193 Evaluation Board for the AAT1278 1.5A Single Flash LED Driver Printed Circuit Board (a) Top Layer. (b) Bottom Layer. Figure 6: AAT1278 Evaluation Board. AAT1278 EVAL Component Listing Component Part Number U1 U2 SW1 – SW4 R1 R2, R4, R10 R3, R5, R6, R7 R8, R9 C1, C2 C3 C4(No Mounted) L1 LED1 LED2 JP1, JP2, JP3 D1 AAT1278 PIC12F675 PTS645TL50 Chip Resistor Chip Resistor Chip Resistor Chip Resistor GRM188R71A225KE15 GRM188R71C105K SD3812-1R0-R 0805KRCT 0805KGCT PRPN401PAEN FCW401Z4 Description 1.5A Step-Up Current Regulator for Flash LED; 8-Pin FLASH-Based 8-Bit CMOS Microcontrollers Switch Tact, SPST, 5mm 133kΩ, 1%, 1/4W,0402 100kΩ, 1%, 1/4W,0603 10kΩ, 5%, 1/4W,0603 330Ω, 5%, 1/4W,0603 2.2μF, 10V, X7R, 0603 1μF, 16V, X7R, 0603 Drum Core, 1μH, 2.69A, 48mΩ Red LED,0805 Green LED,0805 Conn. Header, 2mm zip White Flash LED Manufacturer Skyworks Microchip ITT Industries Vishay MuRata Cooper Bussmann HB Sullins Electronics Seoul Semiconductor Table 5: AAT1278 Evaluation Board Bill of Materials. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 9 EVALUATION BOARD DATA SHEET EV193 Evaluation Board for the AAT1278 1.5A Single Flash LED Driver Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. These materials, including the information contained herein, are provided by Skyworks as a service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Skyworks may change its documentation, products, services, specifications or product descriptions at any time, without notice. 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Additional information, including relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference. 10 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202325A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012