EVALUATION BOARD DATA SHEET EV172 Evaluation Board for the AAT2869 Fade-In/Fade-Out Four-Channel Backlight Driver with Dual LDOs Introduction The AAT2869 EVAL board demonstrates the functionality of the AAT2869 and its application as backlight driver and dual LDO outputs. The AAT2869 is a low-noise, constant-frequency charge pump DC/DC converter that uses a dual-mode load switch (1x) and fractional (1.5x) conversion to maximize efficiency for white LED applications. The AAT2869 is capable of driving 4 white LEDs at a total 124mA and two 150mA low dropout (LDO) linear regulators from a 2.7V to 5.5V input. The fade-in/fade-out feature makes backlight turn-on/turn-off more visual comfortable. All these functions can be programmed via the AS2Cwire™ interface. Skyworks' AS2Cwire™ serial digital input is used to enable, disable and set the maximum LED current to one of 32 levels for the LEDs. Each LED current ranges from 31mA to 0.4mA. LED current fade in/fade out is also enabled and disabled by writing registers through the interface. Regardless of the backlight setting, LDOs enable, disable and output voltage levels are also programmed through the interface. There are five output voltage levels and sixteen combinations of LDOA and LDOB. This document describes the evaluation board and its accompanying user interface. A brief “Getting Started” section is also included to help the user to begin operating the evaluation board. A real board picture appears in Figure 1. Figures 2 and 5 depict the board schematic and layout. Figure 4 shows the usage of the three buttons on the EVAL board. For additional information, please consult the AAT2869 product datasheet. Board Picture (a) Top Side (b) Bottom Side Figure 1: AAT2869 Evaluation Board Picture. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202290A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 23, 2012 1 EVALUATION BOARD DATA SHEET EV172 Evaluation Board for the AAT2869 Fade-In/Fade-Out Four-Channel Backlight Driver with Dual LDOs Evaluation Board Schematic U1 AAT2869 C1 1µF J1 1 18 7 6 DC+ V_LDO CIN 2.2µF DC- 8 V _MCU 4 AAT2869 White LED Driver R8 50k C2 1µF 16 15 17 VOUT COUT 1µF R1 0 D1 R2 0 R3 0 R4 0 D3 D2 D4 EN/SET GND 9 FCAP 5 AGND EP D1 D2 D3 D4 LDOA LDOB 10 11 12 13 3 LDOA 2 LDOB CLDOB 2.2µF CLDOA 2.2µF EN/SET R10 R11 R12 1k SELECT C2+ C2OUTCP GND 14 CF 1µF C1+ C1IN INLDO 1k 1k 1 2 3 4 U2 VDD GP5 GP4 GP3 PIC12F675 VSS GP0 GP1 GP2 C3 0.1µF 8 7 6 5 R9 1k LED2 Red R6 1k DETAIL LED1 Green SEND AS2Cwire Microcontroller Figure 2: AAT2869 Evaluation Board Schematic. 2 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202290A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 23, 2012 EVALUATION BOARD DATA SHEET EV172 Evaluation Board for the AAT2869 Fade-In/Fade-Out Four-Channel Backlight Driver with Dual LDOs Getting Started The board has two terminals labeled DC+ and DC- for the input power supply connection. Set J1 to the left position, jump the V_MCU, and apply 2.7V to 5.5V power to the DC+ and DC- terminals to power the AAT2869 (U1) and microcontroller (U2); the red LED (LED2) should illuminate when the microcontroller is powered. The EN/SET option provides access to the microcontroller program. Jump EN/SET when using a microcontroller program to generate AS2Cwire data for the AAT2869. Figure 3 shows the connection of the board. Figure 3: AAT2869 Evaluation Board Demonstration Connection. The three buttons on the AAT2869 evaluation board are used to set address and data of the registers and send the selected address and data to the AAT2869 through the EN/SET signal line. The functions of the three buttons are illustrated in Figure 4. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202290A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 23, 2012 3 EVALUATION BOARD DATA SHEET EV172 Evaluation Board for the AAT2869 Fade-In/Fade-Out Four-Channel Backlight Driver with Dual LDOs Button Functions Three buttons are located on the evaluation board: SELECT, DETAIL and SEND. The SELECT button is used to select the register address. Each press of the button selects one register address from 0 to 5 then wraps back to 0. The DETAIL button is used for data select for a particular address register. The SEND button sends the selected address and data to the EN/SET signal line. Figure 4 details the button functions. SELECT Button DETAIL Button Three Button Functions Pressed times Register Addr. 0 Backlight Enable 1 1 Backlight Floor Level 2 2 Backlight MSB 3 3 Backlight LSBs 4 5 4 5 LDO Enable/Disable LDO Output Voltage Selected Register Pressed times Detail selected Addr. 0 0 Backlight On Addr. 1 Addr. 2 Addr.3 Addr. 4 Addr. 5 SEND Button Register Function 0 1 Backlight On 2 Backlight On, Fade Out On 3 Backlight On, Fade In On 4 Backlight Off 0 Backlight Floor: 0.5mA 1 Backlight Floor: 1.0mA 2 Backlight Floor: 2.0mA 3 Backlight Floor: 3.0mA 0 BL[4] = 0 1 BL[4] = 1 0 BL[3~0] = 0000 1 BL[3~0] = 0001 15 BL[3~0] = 1111 0 LDOA off, LDOB off 1 LDOA off, LDOB on 2 LDOA on, LDOB off 3 0 LDOA on, LDOB on LDOA=3.0V LDOB=2.8V 1 LDOA=3.0V LDOB=1.8V 2 LDOA=3.0V LDOB=1.5V 3 LDOA=3.0V LDOB=1.2V 4 LDOA=2.8V LDOB=2.8V 5 LDOA=2.8V LDOB=1.8V 6 LDOA=2.8V LDOB=1.5V 7 LDOA=2.8V LDOB=1.2V 8 9 LDOA=1.8V LDOB=2.8V LDOA=1.8V LDOB=1.8V 10 LDOA=1.8V LDOB=1.5V 11 LDOA=1.8V LDOB=1.2V 12 LDOA=1.5V LDOB=2.8V 13 LDOA=1.5V LDOB=1.8V 14 LDOA=1.5V LDOB=1.5V 15 LDOA=1.5V LDOB=1.2V Send Selected Address and Data through EN/ SET Signal Line Figure 4: Button Functions of the AAT2869 Evaluation Board. 4 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202290A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 23, 2012 EVALUATION BOARD DATA SHEET EV172 Evaluation Board for the AAT2869 Fade-In/Fade-Out Four-Channel Backlight Driver with Dual LDOs LED Current Control AS2Cwire Interface The LED current can be programmed from 0.4mA to 31mA in 32 steps through the AS2Cwire interface. Addresses 3 and 2 with 5 bits from BL[0] to BL[5] are adopted to set the LED current value as shown in Table 1. Addr2 Addr3 LED Current Codes BL4 BL3 BL2 BL1 BL0 LED Current (mA) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0.4 0.9 1.9 2.9 3.9 4.9 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0 20.0 [Default] 21.0 22.0 23.0 24.0 25.0 26.0 27.0 28.0 29.0 30.0 31.0 Table 1: AAT2869 Maximum LED Current Register Settings. The LED current is changed to the programmed value only after the “Backlight LSBs” register is written. For example, to change the LED current setting from the default setting of 20mA to 31mA, the steps are listed as below. 1. 2. 3. 4. 5. 6. Press Press Press Press Press Press the the the the the the SELECT button to select the address 2 “Backlight MSB” register. DETAIL button to set BL[4] to 1. SEND button to send the selected address and data through the EN/SET pin to the AAT2869. SELECT button to the select address 3 “Backlight LSBs” register. DETAIL button to set BL[3~0] to 1111. SEND button to set each LED to 31mA of LED current. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202290A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 23, 2012 5 EVALUATION BOARD DATA SHEET EV172 Evaluation Board for the AAT2869 Fade-In/Fade-Out Four-Channel Backlight Driver with Dual LDOs LED illumination can be turned off directly from the programmed maximum value to zero from the programmed maximum LED current to the set floor gradually using the fade-out function. The default floor is 0.5mA. When using the fade-in or fade-out function, the floor value and LED maximum current value should be set before fade-in or fade-out is enabled. If no LED maximum current and floor value are set, 20mA and 0.5mA are the default LED current maximum and floor level when fade-in or fade-out is enabled. LDO Control The AAT2869 has two LDOs: LDOA and LDOB. The LDOs’ enable, disable, and output voltage values are controlled by writing registers through the AS2Cwire interface. Figure 4 shows how to use the three buttons on the evaluation board to select and send LDO settings. Printed Circuit Board (a) Top Layer (b) Bottom Layer Figure 5: AAT2869 Evaluation Board Layout. 6 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202290A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 23, 2012 EVALUATION BOARD DATA SHEET EV172 Evaluation Board for the AAT2869 Fade-In/Fade-Out Four-Channel Backlight Driver with Dual LDOs AAT2869 EVAL Component List Component Part Number Description Manufacturer U1 U2 R1, R2, R3, R4 R7, R8 R6, R9, R10, R11, R12 C1, C2, COUT CIN, CLA, CLB C3 CF D1, D2, D3, D4 LED1 LED2 CYCLE, UP, DOWN AAT2869IDT-T1 PIC12F675 RC0603FR-070RL RC0603FR-0749K9L RC0603FR-071KL GRM188R71C105K GRM188R61A225K GRM188R71C104K GRM188R71C563K RS-0805UW 0805KGCT 0805KRCT 6*6*5 High Efficiency, 4 Channel Backlight Driver with Dual LDOs 8-Pin Flash-Based 8-Bit CMOS Microcontrollers Res 0Ω 1/10W 1% 0603 SMD Res 49.9KΩ 1/10W 1% 0603 SMD Res 1KΩ 1/10W 1% 0603 SMD Cap Ceramic 1μF 0603 X7R 16V 10% Cap Ceramic 2.2μF 0603 X5R 10V 10% Cap Ceramic 0.1µF 0603 X7R 16V 10% Cap Ceramic 0.056μF 0603 X7R 16V 10% 20mA White LED 0805 Green LED 0805 Red LED 0805 12V 50mA Pushbutton Skyworks Microchip Yageo Murata Realstar HB HB E-LT Table 2: AAT2869 Evaluation Board Component List. 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Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202290A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 23, 2012 7