EVALUATION BOARD DATA SHEET EV174 Evaluation Board for the AAT1401 Serial LED Driver with Filtered PWM and 32-Step S2C Dimming Control Introduction The AAT1401 evaluation board demonstrates the functionality of the WLCSP-10 packaged AAT1401 and its application as a white LED driver under Skyworks' S2Cwire serial digital interface control or filtered PWM interface control. The AAT1401 is a step-up single current sink LED driver with an input voltage range of 2.7V to 5.5V. The wide input voltage range, small solution size, advanced dimming features and high efficiency is suitable for LED backlight solutions for single cell Li-ion based equipment. A precision, high voltage current sink maintains the maximum LED current set by an external resistor from 10 to 31mA. The high switching frequency supports ultra small, low cost filtering components. This document describes the evaluation board and its accompanying user interface. A brief “Getting Started” section is included to help the user to begin operating the evaluation board. The AAT1401 evaluation board is shown in Figure 1; Figures 2 and 9 depict the board schematic and layout. For additional information, please consult the AAT1401 product datasheet. Board Picture a: Top Side b: Bottom Side Figure 1: AAT1401IUQ Evaluation Board Picture. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202315A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 29, 2012 1 EVALUATION BOARD DATA SHEET EV174 Evaluation Board for the AAT1401 Serial LED Driver with Filtered PWM and 32-Step S2C Dimming Control Schematic DS1 SDM20U40 L1 10µH R1 1M U1 AAT1401IUQ J1 VIN DC+ CIN 4.7µF DC- A2 A1 LX PWM D1 R2 51k D3 OVP D2 A3 EN/SET B3 PWM VIN R3 51k AAT1401 White LED Driver IN J2 D3 C3 COMP D2 RSET CCOM 56nF D4 C1 GND B1 PGND RSET 15k D1 CS D6 D5 R4 51k V_MCU S2Cwire/PWM Microcontroller PWM EN/SET S2C R7 R8 R9 1k 1k 1k U2 1 2 3 4 UP PIC12F675 VDD GP5 GP4 GP3 VSS GP0 GP1 GP2 C1 0.1µF 8 7 R6 51k 6 5 R5 1k LED1 Red VMCU DOWN 3 2 1 J3 CYCLE Figure 2: AAT1401IUQ Evaluation Board Schematic. 2 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202315A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 29, 2012 COUT 0.1μF/50V EVALUATION BOARD DATA SHEET EV174 Evaluation Board for the AAT1401 Serial LED Driver with Filtered PWM and 32-Step S2C Dimming Control Getting Started The board has two terminals labeled DC+ and DC- for the input power supply connection. Set the jumper J1 to the left position to connect the DC+ power to AAT1401 IN. Jump V_MCU to connect the DC+ power to microcontroller VIN. Jump PWM and EN/SET to connect the microcontroller GPIOs to the AAT1401 PWM and EN/SET pins. Jump J3 to the S2C position to set the microcontroller to generate S2Cwire code signal to set the maximum LED current of the AAT1401 by 32 steps of S2C code up to 20mA with 15kΩ RSET. After all jumpers are in the correct positions, apply power between 2.7V and 5.5V to the DC+ and DC- terminals to power the AAT1401 (U1) and microcontroller (U2); the red LED (LED1) should illuminate when the microcontroller is powered. After setting the maximum LED current by pressing the buttons, jump J3 to the PWM position to set the microcontroller to generate PWM signal with varied duty cycle between 5% and 100% in 5% steps to dim the LED current. Figure 3 shows the connection of the AAT1401 board under microcontroller S2Cwire control or both S2Cwire and PWM control. a. Operation Using S2Cwire Control Only b. Operation Using Filtered PWM Control When Finish Max Current Setting. Figure 3: AAT1401 Evaluation Board Demonstration Connection The 6 white LEDs may be dimmed or brightened using the EN/SET serial data S2Cwire interface or both S2Cwire and PWM interface through the three buttons: UP, DOWN and CYCLE. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202315A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 29, 2012 3 EVALUATION BOARD DATA SHEET EV174 Evaluation Board for the AAT1401 Serial LED Driver with Filtered PWM and 32-Step S2C Dimming Control S2Cwire Control Only Set J3 to the S2C position to set the microcontroller to generate S2Cwire data according to the status of the three buttons. The AAT1401 records rising edges of the EN/SET pin and decodes them into 32 maximum individual current level settings from 20mA to 0.4mA with RSET = 15kΩ. • UP button: The UP button increments the number of EN/SET edges from 1 to 32 when the button is pushed once. When the button is held down for more than 0.6 seconds, the microcontroller enters auto-increment mode. The LED will dim and wrap back after S2Cwire data 32. • DOWN button: The DOWN button decrements the number of EN/SET edges from 32 to 1 when the button is pushed once. When the button is held down for more than 0.6 seconds, the microcontroller enters auto-decrement mode. The LED will brighten and wrap back after S2Cwire data 1. • CYCLE button: The button increment or decrements the number of EN edges automatically and cyclically after a single push according to the previous EN edges up or down event. • UP+DOWN+CYCLE button: EN is set to 0V after the three buttons are pressed at the same time and the AAT1401 is shut down. All white LEDs are turned off. 22 20 18 ILED (mA) 16 14 12 10 8 6 4 2 0 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 S2C Code Figure 4: S2Cwire Dimming Control at Maximum LED Current (20mA max). 4 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202315A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 29, 2012 EVALUATION BOARD DATA SHEET EV174 Evaluation Board for the AAT1401 Serial LED Driver with Filtered PWM and 32-Step S2C Dimming Control PWM Dimming with Maximum Current Set by S2Cwire When using both S2Cwire and PWM control, the maximum LED current is set by the EN/SET S2Cwire interface and LED brightness is changed via PWM by varying the duty cycle from the set maximum LED current to almost zero value. PWM control sets the microcontroller to generate a square waveform with duty cycle from 5% to 100% in 5% steps to adjust the LED current according to the status of the three buttons. The operation steps are: 1. 2. 3. 4. Set J3 to the S2C position. Power on and use the UP or DOWN button to set the white LED current value to the desired maximum LED current. Set J3 to the PWM position. Press one of the three buttons to observe the white LED dimming or brightening under PWM control with varied duty cycle. • UP button: The UP button increments the duty cycle from 5% to 100% with 5% steps when the button is pushed once. When the button is held down for more than 0.6 seconds, the microcontroller enters auto-increment mode. The LED will brighten to 100% and wrap back to 5%. • DOWN button: The DOWN button decrements the duty cycle from 100% to 5% with 5% steps when the button is pushed once. When the button is held down for more than 0.6 seconds, the microcontroller enters auto-decrement mode. The LED will dim to 5% and wrap back to 100%. • CYCLE button: The button increments or decrements the duty cycle automatically and cyclically after a single push according to the previous PWM duty cycle up or down event. 20 18 ILED (mA) 16 14 12 10 8 6 4 2 0 100 95 90 85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10 5 PWM Duty Cycle (%) Figure 5: Filtered PWM Dimming Duty Cycle vs. Maximum LED Current (20mA max) on the AAT1401IUQ Evaluation Board. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202315A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 29, 2012 5 EVALUATION BOARD DATA SHEET EV174 Evaluation Board for the AAT1401 Serial LED Driver with Filtered PWM and 32-Step S2C Dimming Control User Interface Functionality Button(s) Control SC 2 UP S2C+PWM S2C DOWN S2C+PWM CYCLE S2C S C+PWM S2C 2 UP+DOWN+CYCLE Description [Push/Release once]: Increment the number of EN/SET edge; Toggles through the available dimming level settings for the backlighting section. [Push Hold 0.6 sec.+ ]: Auto-increment the number of EN/SET edges up to 32 then wrap back to 1. [Push/Release once]: Increment the duty cycle. [Push Hold 0.6 sec.+ ]: Auto-increment the duty cycle from 5% to 100% in 5% steps then wrap back to 5%. [Push/Release once]: Decrement the number of EN/SET edge; Toggles through the available brightness level settings for the backlighting section. [Push Hold 0.6 sec.+ ]: Auto-decrement the number of EN/SET edges down to 1 then wrap back to 32. [Push/Release once]: Decrement the duty cycle. [Push Hold 0.6 sec.+ ]: Auto-decrement the duty cycle from 100% to 5% in 5% steps then wrap back to 100%. Auto-cycling. Auto-cycling. Shut down. Table 1: User Interface Functionality. Test Waveform Operation Waveform Figure 6 shows the operation waveform under code 5 via S2Cwire control at 3.6V VIN; Figure 7 shows the operation waveform under PWM control with 60% duty cycle after setting the 20mA max current by S2Cwire control at 3.6V VIN. Ch1: PWM; Ch2: IIN; Ch3: ILED; Ch4: VOUT Ch1: EN/SET; Ch2: IIN; Ch3: ILED; Ch4: VOUT Figure 6: Waveform Controlled by S2Cwire. 6 Figure 7: Waveform Controlled by Filtered PWM. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202315A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 29, 2012 EVALUATION BOARD DATA SHEET EV174 Evaluation Board for the AAT1401 Serial LED Driver with Filtered PWM and 32-Step S2C Dimming Control Startup Figure 8 shows the AAT1401 startup waveform after adding one rising edge on EN/SET. Soft start control makes the input current rise slowly. Ch1: SW; Ch2: IIN; Ch3: ILED; Ch4: VOUT Figure 8: Startup Waveform at 20mA LED Current. Printed Circuit Board a: Top Layer (not to scale) (b) Bottom Layer (not to scale) Figure 9: AAT1401IUQ Evaluation Board. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202315A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 29, 2012 7 EVALUATION BOARD DATA SHEET EV174 Evaluation Board for the AAT1401 Serial LED Driver with Filtered PWM and 32-Step S2C Dimming Control AAT1401IUQ EVAL Component Listing Component Part Number Description Manufacturer U1 U2 R1 R2, R3, R4, R6 RSET R5, R7, R8, R9 CIN COUT C1 Ccom D1, D2, D3, D4, D5, D6 DS1 L1 LED1 CYCLE, UP, DOWN AAT1401IUQ PIC12F675 RC0603FR-071ML RC0603FR-0751KL RC0603FR-0715KL RC0603FR-071KL GRM188R60J475K GRM18BR71H104K GRM188R71C104K GRM188R71C563K RS-0805UW SDM20U40 CDRH3D18-100NC 0805KRCT 6*6*5 High Efficiency Serial LED Driver for 6 White LEDs 8-Pin Flash-Based 8-Bit CMOS Microcontrollers Res 1MΩ 1/10W 1% 0603 SMD Res 51KΩ 1/10W 1% 0603 SMD Res 15KΩ 1/10W 1% 0603 SMD Res 1KΩ 1/10W 1% 0603 SMD Cap Ceramic 4.7μF 0603 X5R 6.3V 10% Cap Ceramic 0.1μF 0603 X7R 50V 10% Cap Ceramic 0.1µF 0603 X7R 16V 10% Cap Ceramic 0.056µF 0603 X7R 16V 10% 20mA White LED 0805 Surface Mount Schottky Barrier Diode Power Inductor 10μH 0.9A SMD Red LED 0805 12V 50mA Pushbutton Skyworks Microchip Yageo Murata Realstar Diode Sumida HB E-LT Table 4: AAT1401IUQ Evaluation Board Bill of Materials. 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