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AHK1421 EVAL : S2Cwire Controlled, Serial LED Boost Driver EVALUATION BOARD DATASHEET EV-184.2011.05.1.0 www.analogictech.com Introduction The AHK1421 evaluation board demonstrates functionality of the AHK1421 and its application as a white LED backlight driver under AnalogicTech’s S2Cwire serial digital interface control. The AHK1421 is a high frequency, high efficiency, constant-current boost converter driving six white LEDs in series configuration. The input voltage is 2.7V to 5.5V, which is ideal for portable devices powered by single-cell lithium-ion/ polymer (Li-ion) batteries. The maximum LED current is set by an external resistor from 10 to 31mA. The AHK1421 is programmable with the S²Cwire interface, using an onboard microcontroller which is capable of brightening and dim - ming the LEDs in 32 discrete steps. 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. Board Pictures (a) Top (b) Bottom Figure 1: AHK1421 Evaluation Board

AHK1421 EVAL : S2Cwire Controlled, Serial LED Boost Driver EVALUATION BOARD DATASHEET Board Schematic 2.2µF CIN 10µH 2.2µF COUT DS1 DC+ DC- VOUT LX 0.1µF 51k V_MCU EN/SET UP DOWN CYCLE R9 PIC12F675 VDD1 GP52 GP43 GP34 GP2 5GP1 6GP0 7VSS 8 Red LED1 LX 1 OUT 5 330 FB RFB 12.5 VIN EN/SET 3 LED2 Green AHK1421ICA GND 2.7~5.5V AHK1421 White LED Driver S2Cwire Microcontroller Figure 2: AHK1421 Evaluation Board Schematic

AHK1421 EVAL : S2Cwire Controlled, Serial LED Boost Driver EVALUATION BOARD DATASHEET EV-184.2011.05.1.0 www.analogictech.com Getting Started Setup (Figure 3) 1. Connect an input power source (to supply between 2.7V and 5.5V) to the board by placing the jumper, J1 on the left (Connects DC+ power to AHK1421). 2. Connect the DC+ power to the microcontroller VDD by using the jumper V_MCU. 3. Connect the EN/SET jumper to connect the microcontroller GPIOs to the AHK1421 EN/SET pins. 4. After all jumpers are in the correct position, apply power between 2.7V and 5.5V to the DC+ and DC- terminals to power on the AHK1421 (U1) and microcontroller (U2). The red LED (LED1) will illuminate when the microcontroller is powered. The green LED (LED2) will flicker when the three buttons to transfer S²C wire data for AHK1421 are operated. 5. Use the UP, DOWN and CYCLE buttons to vary the brightness of the 6 white LEDs using the EN/SET serial data S2Cwire interface Figure 3: AHK1421 Evaluation Board Measurement Configuration S2Cwire Control Short the EN/SET jumper to receive S2Cwire data generated by the microcontroller according to the status of the three buttons. The AHK1421 records the number of rising edges which control output current in EN/SET pin and change the value of output current from 20mA to 0.4mA when RFB is 12.5Ω

  • UP button: The UP button increments the number of EN/SET rise edges from 1 to 32 each time this button is pushed. By holding down the button for more than 0.6 seconds, the microcontroller enters auto-increment mode. The LED will dim and wrap back after S 2C wire data reaches 32.
  • DOWN button: The DOWN button decrements the number of EN/SET rise edges from 32 to 1 each time this button is pushed. By holding down the button for more than 0.6 seconds, the microcontroller enters auto-decrement mode. The LED will brighten and wrap back after S 2Cwire data reaches 1.
  • CYCLE button: The button increments or decrements the number of EN/SET edges automatically and cyclically after a single push according to the previous EN edges up or down event.
  • UP+DOWN+CYCLE button: EN/SET is set to 0V and the AHK1421 is shut down. All white LEDs are turned off.

AHK1421 EVAL : S2Cwire Controlled, Serial LED Boost Driver EVALUATION BOARD DATASHEET 1234567891 011121314151617181920212223242526272829303132 S2Cwire Data ILED (mA) Figure 4: S2Cwire Dimming Control at Maximum LED Current (20mA max) User Interface Functionality Button(s) Action Effect UP 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. DOWN 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 CYCLE Push/Release once or Push Hold 0.6 sec.+ Auto-cycle in direction last set UP+DOWN+CYCLE Push All Three and Hold Shut down Table 1: User Interface Functionality

AHK1421 EVAL : S2Cwire Controlled, Serial LED Boost Driver EVALUATION BOARD DATASHEET EV-184.2011.05.1.0 www.analogictech.com Functional Testing and Evaluation Operational Waveform Figure 5 shows the waveform controlled by S 2Cwire at 3.6V VIN when the code changes from 32 to 1.The I LED changes from 0.4mA (2% IMAX) to 20mA (IMAX). Figure 5: Operational Waveform under S²Cwire Control. Start up Figure 6 shows the AHK1421 startup waveform after adding rising edge on EN/SET. Soft start control makes the input current rise slowly. Figure 6: Start Up Waveform. Channel Signal

1 VOUT

2 EN/SET

3 ILED

4 IIN

2 VOUT

AHK1421 EVAL : S2Cwire Controlled, Serial LED Boost Driver EVALUATION BOARD DATASHEET Efficiency Curves Figure7 shows that the maximum efficiency is about 85% under 4.2V input voltage. Consult the AHK1421 product datasheet about the external diode selection. 0123456789 10 11 12 13 14 15 16 17 18 19 20 21 VIN = 3.6V VIN = 4.2V Efficiency (%) ILED (mA) Figure 7: Efficiency Curve Waveforms.

AHK1421 EVAL : S2Cwire Controlled, Serial LED Boost Driver EVALUATION BOARD DATASHEET EV-184.2011.05.1.0 www.analogictech.com Printed Circuit Board (a) Top (b) Bottom Figure 8: AHK1421 Evaluation Board (not to Scale) AHK1421 EVAL Board Component Listing Component Part Number Description Manufacturer U1 AHK1421ICA S2C controlled, serial LED boost driver IC, TSOT23-6 AnalogicTech U2 PIC12F675 8-bit CMOS, FLASH-Based uC;SOIC-8 Microchip Chip RES RES 330Ω 1/4W 1% 0603 SMD YageoRFB RES 12.5Ω 1/4W 1% 0603 SMD R5, R7, R8, R9 RES 1KΩ 1/4W 1% 0603 SMD R4 RES 51KΩ 1/4W 1% 0603 SMD CIN GRM188R60J225KE01 Cap 2.2μF 0603 X5R 10V 10% MurataCOUT GRM21BR61H225KA73L Cap 2.2μF 0805 X7R 50V 10% C1 GRM188R71C104K Cap 0.1uF 0603 X7R 16V 10% D1, D2, D3, D4, D5, D6 RS-0805UW 20mA White LED 0805 Realstar DS1 SS14L 1.0AMP.Surface Mount Schottky Barrier Rectifiers TSC L1 CDRH2D14-100 POWER INDUCTOR 10μH SMD Sumida LED1 0805KRCT Red LED 0805 HBLED2 0805KGCT Green LED 0805 CYCLE, UP, DOWN 6*6*5 12V 50mA Push button E-LT Table 2: AHK1421 Evaluation Board Bill of Materials.

AHK1421 EVAL : S2Cwire Controlled, Serial LED Boost Driver EVALUATION BOARD DATASHEET Advanced Analogic Technologies, Inc.

3230 Scott Boulevard, Santa Clara, CA 95054

Phone (408) 737-4600 Fax (408) 737-4611 © Advanced Analogic Technologies, Inc. AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice. Except as provided in AnalogicTech’s terms and conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.