Technical Brief 470 Using the ISL97634 White LED Driver Demo Board Introduction Steps for Setting up the Demo Board: The ISL97634 is a white LED driver with high frequency PWM dimming capability. Jumpers JP1 to JP5 can be optionally used to disable five of the seven LEDs. The ISL97634 is guaranteed to drive six LEDs (3.5V/30mA type). It is possible to drive seven LEDs at 20mA if the total VF is lower than the OVP threshold and the input voltage is at nominal rather than low level. 1. Apply a DC power voltage source 2.7V to 5.5V in VIN. Due to the boost function, the input DC voltage must be lower than the output voltage in order to regulate the output LED current. 2. Use R1 or R2 to set the desirable LED peak current. 3. Apply a PWM signal at PWM/EN to achieve the desirable current and LED brightness. Jumper S3 is used to connect the FBSW that must be connected with the center and upper pins. Jumper S4 is used to select the RSet as either a 4.75Ω resistor R1 or a 100Ω potentiometer, R2. If R1 is used, connect S4 with the center and the left most pins. This resistance sets the LED supply current. (EQ. 1) ILED = 95mV/Rset*PWM where PWM is the PWM duty cycle. L1 D1 22µH C0 220n/16V VIN U1 ISL97634 1 GND LX 8 2 VIN VOUT 7 3 PWM/EN FBSW 6 4 NC FB 5 PWM/EN JP1 VOUT D2 1 3 JP2 C1 220nF/50V 2 S3 D3 JP3 1 S4 R2 100 3 2 GND D4 JP4 R1 4.75 D5 D7 JP5 D6 FIGURE 1. SCHEMATIC OF ISL97634 DEMO BOARD September 3, 2013 TB470.1 1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-468-3774 | Copyright Intersil Americas LLC 2007, 2011, 2013. All Rights Reserved Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries. All other trademarks mentioned are the property of their respective owners. Technical Brief 470 FIGURE 2. SCHEMATIC OF ISL97634 DEMO BOARD 2 TB470.1 September 3, 2013 Technical Brief 470 TABLE 1. ISL97634 DEMO BOARD BOM ITEM QTY REF DESCRIPTION VENDOR 1 1 C2 1nF/50V 0603 2 1 R1 4.75 0603 3 1 L1 22µH 4 1 R3 20k 0603 5 1 C3 33nF/50V 0603 6 1 R2 100 0603 7 1 C0 220n/16V 0603 8 1 C1 4.7µF/50V 9 1 R4 698k 0603 10 1 J3 GND POWERPOST 11 1 U1 LED Driver 12 1 JP3 JUMPER JUMPER-2PIN 13 1 JP4 JUMPER JUMPER-2PIN 14 1 JP5 JUMPER JUMPER-2PIN 15 1 JP2 JUMPER JUMPER-2PIN 16 1 JP1 JUMPER JUMPER-2PIN 17 1 J2 SDIN POWERPOST 18 1 J1 VIN POWERPOST 19 1 J4 VOUT POWERPOST 20 7 D1 to D7 LED Sumida Murata Intersil OSRAM PART NO. CDRH3D16NP-220NC GRM32ER71H475KA88 ISL97634 LW Y3SG PACKAGE 4X4X1.8mm 1210 TDFN2X3 0.6mm MircoSIDLED Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that the Application Note or Technical Brief is current before proceeding. For information regarding Intersil Corporation and its products, see www.intersil.com 3 TB470.1 September 3, 2013