EVALUATION BOARD DATA SHEET EV155 Evaluation Board for the AAT1239-1 40 V Step-Up Converter Introduction The AAT1239-1 is a high frequency, high efficiency regulated current boost converter driving up to ten white LEDs in a series connected configuration. The input voltage is 2.7V to 5.5V, which is ideal for portable devices powered by singlecell lithium-ion/polymer (Li-ion) batteries. With over-voltage protection and dynamically-programmable voltage control via Skyworks' patented Simple Serial Control™ (S2Cwire™) interface, the AAT1239-1 is an ideal choice for wider diagonal monochrome or color TFT-LCD displays. The AAT1239-1 evaluation board provides a platform for test and evaluation of the AAT1239-1 for white LED backlight applications driving up to ten LEDs. The AAT1239-1 is programmable with the S2Cwire interface, using an onboard microcontroller which is capable of brightening and dimming the LEDs in 16 discrete steps. The SELECT logic signal from the microcontroller provides a stepped load from 1.5x to 3.0x of nominal output current, depending on the S2Cwire data register (default = 3.0x). 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 2. The board layout is also provided. For additional information, please refer to the AAT1239-1 product datasheet. Board Picture Figure 1: AAT1239-1 Evaluation Board. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202278A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 17, 2012 1 EVALUATION BOARD DATA SHEET EV155 Evaluation Board for the AAT1239-1 40 V Step-Up Converter Schematic S2Cwire Microcontroller VCC R7 1k R8 330 D12 Red Select Down Up R6 1k R5 1k 1 2 S1 3 4 S2 U2 PIC12F675 VDD VSS GP5 GP0 GP4 GP1 GP3 GP2 8 C3 0.1µF 7 6 R9 330 5 S3 D11 Green JP2 JP3 R4 10k DCC 10µF DC+ VCC 1 2 3 1 JP1 2 3 4 C1* 2.2µF 5 6 L1* 2.2µH U1 AAT1239-1 PVIN EN SEL VIN N/C SW LIN OVP FB AGND PGND SW DS1 Schottky VOUT R2 374k 12 11 10 R3 12k 9 8 AAT1239-1 White LED Driver JP4 D1 WLED C2 2.2µF D2 WLED D3 WLED 7 D4 WLED D5 WLED R1 30.1 D10 WLED D9 WLED D8 WLED D7 D6 WLED WLED *: C1 and L1 can choose bigger value, such as C1=4.7µF, L1=10µH or 4.7µH, to enhance the efficiency. Please refer to the AAT1239-1 datasheet. Figure 2: AAT1239-1 Evaluation Board Schematic for Driving 10 WLEDs in Series. Table 1 illustrates R2 value to set the over-voltage protection point when AAT1239-1 is used to drive 4~9 WLEDs. LED Num R2 (kΩ) Over-Voltage Protection Point (V) 4 5 6 7 8 9 158 182 215 255 287 324 17 19.4 22.7 26.7 29.9 33.6 Table 1: AAT1239-1 R2 Value in 4~9 WLEDs Application. 2 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202278A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 17, 2012 EVALUATION BOARD DATA SHEET EV155 Evaluation Board for the AAT1239-1 40 V Step-Up Converter Getting Started The LED forward current is set by the resistor R1. The ballast resistor (R1) is preset to 30.1Ω on the evaluation board for a maximum LED current to 20mA. ILED = VFB R1 LED current accuracy is determined by VFB and R1. A 1% tolerance resistor is recommended to achieve optimum accuracy. Over-voltage protection is set to the maximum operation voltage (38.6V) to protect the IC from damage and is a function of the number of series-connected WLEDs used in the application. There are three (3) press buttons on the evaluation board (S1-S3). The modes of operation are detailed in Table 2. Each button controls a particular function. · S1 (Up) button: The S1 (Up) button increments the number of EN edges and decrease the FB pin voltage according to Table 2. By holding down the Up button for more than 1.5 seconds, the microcontroller enters auto-increment mode. · S2 (Down) button: The S2 (Down) button decrements the number of EN edges and increases the FB pin voltage according to Table 2. By holding down the Down button for more than 1.5 seconds, the microcontroller enters autodecrement mode. · S3 (Select) button: The S3 (Select) button toggles High/Low on the SEL pin. A green LED (D11) indicates the status on the SEL pin. If the green LED turns ON, the SEL pin is set to High. If the green LED turns off, the SEL pin is set to Low. Figure 3 details the LED nominal current levels for SEL=High and SEL=Low settings with R1=30.1Ω. 25 LED Current (mA) 20 SEL=HIGH Default 15 10 SEL=LOW 5 0 1 4 7 10 13 16 S2Cwire Data Register Figure 3: Programming the AAT1239-1’s LED Current with RBALLAST = 30.1Ω. Upon initial power-up and prior to S2Cwire programming, the default FB pin voltage is set at 0.6V/0.4V depending on the SEL pin logic level. The illumination of the green LED (D11) signifies that the SEL pin is high. The red LED (D12) should illuminate, indicating that power has been connected to the evaluation board. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202278A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 17, 2012 3 EVALUATION BOARD DATA SHEET EV155 Evaluation Board for the AAT1239-1 40 V Step-Up Converter User Interface Functionality Button(s) Pushed S1 (Up) S2 (Down) S3 (Select) Description [Push/Release once] Increment the number of EN edges. Toggles through the available brightness level settings for the backlighting section. [Holding 1.5 sec.+] Auto-increment one voltage level per second. [Push/Release once] Decrement the number of EN/SET edges. Toggles through the available dimming level settings for the backlighting section. [Holding 1.5 sec.+] Auto-decrement one voltage level per second. [Push/Release once] Toggles the SEL logic pin High/Low. Table 2: AAT1239-1 User Interface Functionality. SEL = High SEL = Low Rising Clock Edges/Data Register Reference Voltage VFB (V) LED Current (mA) RBALLAST = 30.1Ω Reference Voltage VFB (V) LED Current (mA) RBALLAST = 30.1Ω 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 0.60 0.58 0.56 0.54 0.52 0.50 0.48 0.46 0.44 0.42 0.40 0.38 0.36 0.34 0.32 0.30 19.80 19.14 18.48 17.82 17.16 16.50 15.84 15.18 14.52 13.86 13.20 12.54 11.88 11.22 10.56 9.90 0.40 0.38 0.36 0.34 0.32 0.30 0.28 0.26 0.24 0.22 0.20 0.18 0.16 0.14 0.12 0.10 13.20 12.54 11.88 11.22 10.56 9.90 9.24 8.58 7.92 7.26 6.60 5.94 5.28 4.62 3.96 3.30 Table 3: AAT1239-1 S2Cwire Reference Feedback Voltage Control Settings with RBALLAST = 30.1Ω (Assume Nominal Values). 4 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202278A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 17, 2012 EVALUATION BOARD DATA SHEET EV155 Evaluation Board for the AAT1239-1 40 V Step-Up Converter Layout 1. The power traces, including the GND trace, the SW trace and the VIN trace should be kept short, direct and wide to accommodate high current flow. 2. Connect the input capacitor C1 to the VIN pin as closely as possible to optimize power filtering effects. 3. Keep the switching node, SW, away from the sensitive FB node. Figure 4: AAT1239-1 Evaluation Board Top Layer. Figure 5: AAT1239-1 Evaluation Board Bottom Layer. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202278A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 17, 2012 5 EVALUATION BOARD DATA SHEET EV155 Evaluation Board for the AAT1239-1 40 V Step-Up Converter AAT1239-1 EVAL Component Listing Component Part Number U1 U2 L1 C C1 C2 C3 R1 R2 R3 R4 R5,R6,R7 R8,R9 DS1 D1- D10 D11 D12 S1,S2,S3 AAT1239-1 PIC12F675 SD3814-2R2 T494B106M010AS GRM188R61A225K GRM31CR71H225K GRM21BR71E104K RC0603FR-0730R1L RC0603FR-07390KL RC0603FR-0712K1L RC0603FR-0710KL RC0603FR-071KL RC0603FR-07330RL SS16L RS--0805UW Description 40V Step-up Converter White LED Driver IC 8-Pin Flash-Based 8-Bit CMOS Microcontrollers INDUCTOR 2.2μH 1.9A SMD Cap Ceramic 10μF 10V Tan B Cap Ceramic 2.2μF 10V X5R 0603 10% Cap Ceramic 2.2μF 50V X7R 1206 10% Cap Ceramic 0.1μF 25V X7R 0805 10% Res 30Ω 1/10W 1% 0603 SMD Res 390kΩ 1/10W 1% 0603 SMD Res 12.1kΩ 1/10W 1% 0603 SMD Res 10kΩ 1/10W 1% 0603 SMD Res 1kΩ1/10W 1% 0603 SMD Res 330Ω 1/10W 1% 0603 SMD 1A, 60V Schottky Diode White LED Green LED Red LED 6*6*4.3 press-button Manufacturer Skyworks Microchip Cooper Kemet Murata Murata Murata Yageo Yageo Yageo Yageo Yageo Yageo Taiwan Semiconductor Readystar Electronics Table 4: AAT1239-1 Evaluation Board Component List. 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Additional information, including relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference. 6 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202278A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 17, 2012