EVALUATION BOARD DATA SHEET EV176 Evaluation Board for the AAT1409/7/5 Eight/Six/Four-Channel LED Backlight Driver with Integrated Boost and High Frequency Direct PWM Dimming Introduction The AAT1409/07/05 evaluation board provides a platform for evaluating the family of 8-channel / 6-channel / 4-channel LED backlight drivers. The PCB layout has been optimized for portable device applications with a minimum number of external components in a small area. The design operates across an input voltage range of 4.5V to 5.5V (if VIN = VCC) or 5.0V to 26V (if VIN is connected only with VCC open). Schematics VIN 5V - 26V D1 L1 4.7μH MSS1P6 R3 442k JP1 19 C1 10µF 35V 23 24 22 C2 2.2µF 10V C3 15nF 5 JP4 16 R1 4.99k JP3 R2 7.5k 2 1 OVP 17 PWM COMP RSET FSET SYNC C4 2.2µF 50V 0805 R4 12.1k VCC CS1 AAT1409 6 7 CS2 8 CS3 CS4 9 CS5 11 12 CS6 13 CS7 14 CS8 EP 20 PGND 21 GND 18 GND 4 GND 3 GND 10 SGND JP2 15 LX EN IN 10 LEDs in series VOUT U1 TQFN34-24 L1 Sumida, CDRH5D28RHPNP-4R7N, 4.7μH, 3.7A, DCR = 43.1mΩ D1 Vishay, Schottky Barrier Diode, MSS1P6, 1A, 60V C1 Taiyo Yuden, GMK325BJ106KN-T, 10μF, 35V, X5R,1210; OR Murata GRM32ER71H106K, 10μF, 50V, X7R, 1210 C2 2.2μF, 10V, 0603 C3 Cap, 15nF, 10V, 0603 C4 Murata, GRM31CR71H225KA88L, 2.2μF, 50V, X7R, 1206 R1, R2, R3, R4 Carbon Film resistors, 1%, 0603 Figure 1: AAT1409 Evaluation Board Schematic. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202317A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 30, 2012 1 EVALUATION BOARD DATA SHEET EV176 Evaluation Board for the AAT1409/7/5 Eight/Six/Four-Channel LED Backlight Driver with Integrated Boost and High Frequency Direct PWM Dimming VIN 5V - 26V D1 L1 4.7μH JP1 C1 10µF 35V C2 2.2µF 10V C3 15nF 5 JP5 16 R1 4.99k JP3 MSS1P6 R3 442k U1 TQFN34-24 19 23 24 22 R2 7.5k 2 1 OVP 17 R4 12.1k VCC PWM COMP RSET FSET SYNC C4 2.2µF 50V 0805 CS1 AAT1407 6 7 CS2 8 CS3 CS4 9 CS5 11 12 CS6 13 GND 14 GND EP 20 PGND 21 GND 18 GND 4 GND 3 GND 10 SGND JP2 15 LX EN IN 10 LEDs in series VOUT L1 Sumida, CDRH5D28RHPNP-4R7N, 4.7μH, 3.7A, DCR = 43.1mΩ D1 Vishay, Schottky Barrier Diode, MSS1P6, 1A, 60V C1 Taiyo Yuden, GMK325BJ106KN-T, 10μF, 35V, X5R,1210; OR Murata GRM32ER71H106K, 10μF, 50V, X7R, 1210 C2 2.2μF, 10V, 0603 C3 Cap, 15nF, 10V, 0603 C4 Murata, GRM31CR71H225KA88L, 2.2μF, 50V, X7R, 1206 R1, R2, R3, R4 Carbon Film resistors, 1%, 0603 Figure 2: AAT1407 Evaluation Board Schematic. 2 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202317A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 30, 2012 EVALUATION BOARD DATA SHEET EV176 Evaluation Board for the AAT1409/7/5 Eight/Six/Four-Channel LED Backlight Driver with Integrated Boost and High Frequency Direct PWM Dimming VIN 5V - 26V D1 L1 4.7μH MSS1P6 R3 442k JP1 19 C1 10µF 35V 23 24 22 C2 2.2µF 10V C3 15nF 5 JP5 16 R1 4.99k JP3 R2 7.5k 2 1 OVP PWM COMP RSET FSET SYNC 17 C4 2.2µF 50V 0805 R4 12.1k VCC AAT1405 6 CS1 7 CS2 11 CS3 12 CS4 8 GND 9 GND 13 GND 14 GND EP 20 PGND 21 GND 18 GND 4 GND 3 GND 10 SGND JP2 15 LX EN IN 4 LEDs in series VOUT U1 TQFN34-24 L1 Sumida, CDRH5D28RHPNP-4R7N, 4.7μH, 3.7A, DCR = 43.1mΩ D1 Vishay, Schottky Barrier Diode, MSS1P6, 1A, 60V C1 Taiyo Yuden, GMK325BJ106KN-T, 10μF, 35V, X5R,1210; OR Murata GRM32ER71H106K, 10μF, 50V, X7R, 1210 C2 2.2μF, 10V, 0603 C3 15nF, 10V, 0603 C4 Murata, GRM31CR71H225KA88L, 2.2μF, 50V, X7R, 1206 R1, R2, R3, R4 Carbon Film resistors, 1%, 0603 Figure 3: AAT1405 Evaluation Board Schematic. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202317A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 30, 2012 3 EVALUATION BOARD DATA SHEET EV176 Evaluation Board for the AAT1409/7/5 Eight/Six/Four-Channel LED Backlight Driver with Integrated Boost and High Frequency Direct PWM Dimming Test Equipment 1. 2. 3. 4. 5. Unit under test (UUT) is the AAT1409/07/05 Evaluation Board. One (1) XT30-2 Power Supplies or equivalent. One PWM Function Generator. One Fluke 189 multi-meter or equivalent to measure the output voltage. Miscellaneous test leads (banana plug to clip lead type is recommended). Setup and Test Quick Setup Guide 1. Configure and verify the evaluation board as shown in Figure 4 prior to applying any power. 2. Verify the jumper JP1 at ON position; disable the synchronization function using jumper JP2; set the switching frequency either at 675kHz (Lo) or 1.3MHz (Hi) using JP3. 3. Connect a function generator to JP4 with the PWM amplitude from 0V to 5V, the PWM frequency range from 100Hz to 100 kHz, and the PWM duty cycle range from 1% to 99%. 4. Connect a 12V power supply to the input voltage (VIN), and connect an appropriate WLED board to the “to LED Panel” terminal on the board. 5. Turn on the Power Supply; the LED panel should be turn ON. 6. Vary the PWM frequency while monitoring the LED dimming, and vary the dimming of the LED panel by adjusting the PWM duty cycle. 4 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202317A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 30, 2012 EVALUATION BOARD DATA SHEET EV176 Evaluation Board for the AAT1409/7/5 Eight/Six/Four-Channel LED Backlight Driver with Integrated Boost and High Frequency Direct PWM Dimming Setting Over-Voltage Protection (OVP) The resistor divider must be selected so that the voltage at the OVP pin exceeds the OVP rising threshold at VOUT(MAX) and the maximum LX voltage does not exceed its maximum value (50V). Therefore, the value of R3 should be chosen within the range of the following equation: R4 · VCSX + N · VFLED(MAX) - VOVP(MIN) 50V < R3 < R4 · -1 VOVP(MIN) VOVP(MAX) Where: R4 = 12.1kΩ is selected for minimizing losses without degrading noise immunity. N is the number of LEDs in each string. VOVP(MIN) = 1.1V is minimum over-voltage threshold. VOVP(MAX) = 1.3V is maximum over-voltage threshold. VCSX = 0.5V is the current sink voltage. VFLED(MAX) is the maximum forward LED voltage at 20mA. For example, if the number of the white LED in each string is N =11, the resistor divider R3 can be calculated by selecting R4 = 12.1kΩ: 12.1kΩ · 0.5V + 11 · 3.7V - 1.1 1.1 < R3 < 12.1kΩ · 50V -1 1.3V 441.1kΩ < R3 < 453.3kΩ; choose R3 = 442kΩ (closest 1% value) Check the maximum output voltage with the selected values of R4, R3: VOUT(MAX) = VOVP(MAX) · R3 +1 R4 = 1.3V · 442kΩ + 1 = 48.8V < 50V 12.1kΩ Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202317A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 30, 2012 5 EVALUATION BOARD DATA SHEET EV176 Evaluation Board for the AAT1409/7/5 Eight/Six/Four-Channel LED Backlight Driver with Integrated Boost and High Frequency Direct PWM Dimming LED Current Sink Setting The current sink is set by the R2 resistor: R2 = 264 · VRSET 264 · 0.6V = ICSX(MAX) ICSX(MAX) Where VRSET = 0.6V For example, if the maximum current for each string LEDs is 30mA, this corresponds to a minimum resistor of 5.23kΩ. R2 = 264 · 0.6V = 5.23kΩ 30mA Maximum ILED Current (mA) R2 (kΩ) 45 30 25 20 15 10 5 3.48 5.23 6.19 7.87 10.5 15.8 31.6 1 Table 1. Maximum LED Current Sink vs. RSET Resistor (R2) Values. 1. AAT1409 only. 6 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202317A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 30, 2012 EVALUATION BOARD DATA SHEET EV176 Evaluation Board for the AAT1409/7/5 Eight/Six/Four-Channel LED Backlight Driver with Integrated Boost and High Frequency Direct PWM Dimming Figure 4: AAT1409 Evaluation Board Quick Setup Guide Connection Diagram1. 1. Applied the same for both AAT1407 and AAT1405 evaluation boards. Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. 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Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202317A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 30, 2012 7