SC4509 Highly Integrated Step-Up Converter for White LED Applications in MLPD-W8-2x2 POPOWER MANAWER MANAGEMENTGEMENT Description Features The SC4509 is a highly integrated step-up DC/DC convert- VIN range: 2.7V 10V er targeted for white LED backlighting applications. It is Integrated Schottky diode designed to drive up to ve LEDs with a wide input voltage 81% ef ciency range of 2.7 to 10 volts. Designed for 20V output voltage, Requires only 4 external components the SC4509 operates with a constant 1.2MHz PWM fre- Up to 20V of output voltage quency. To optimize ef ciency, the feedback voltage is set 30mA maximum LED current to only 199mV, minimizing the power loss in the current Open LED protection (OVP) setting resistor. The product requires only four external 1.2MHz PWM switching frequency components (CIN, COUT, L and R ), making it ideal for Low feedback voltage (20OmV typical) SET applications that require low cost and minimal PCB area. Wide range of PWM dimming Drives up to 5 LEDs The SC4509 offers current limit and over-voltage protec- 500mA switch current limit tion (OVP) to safeguard the device under extreme operat- 220nF output capacitor ing conditions. If the LEDs become disconnected or fail in Available in 2mm x 2mm x 0.75mm MLPD-W8 and an open state condition, OVP circuitry will be activated to SOT23-6 packages shut down the device. The EN/SS pin allows the device Packages are fully WEEE and RoHS compliant to be placed in power-down mode, disabling the control circuitry to reduce input current. Applications Digital Video Cameras White LED Backlight Driver OLED Display Driver Portable Media Players GPS Receivers Cellular Phones PDAs and Handheld Computers Typical Application Circuit Vin L1 Vo 22 H LED1 LED2 C2 0.22 F LED3 U2 VIN 5 LED4 SC4509 EN/SS EN/SS FB 4 3 R1 C1 1 F March 26, 2007 www.semtech.com 1 6 SW 2 GND 1 VOUTSC4509 POWER MANAGEMENT PRELIMINARY Absolute Maximum Rating Exceeding the speci cations below may result in permanent damage to the device, or device malfunction. Operation outside of the parameters speci ed in the Electrical Characteristics section is not implied. Exposure to Absolute Maximum rated conditions for extended periods of time may affect device reliability. Parameter Symbol Maximum Units V Input Supply Voltage -0.3 to 20 V IN SW Voltage V -0.3 to 30 V SW Maximum Output Voltage V 30 V OUT Feedback Voltage V -0.3 to 20 V FB EN/SS Voltage V -0.3 to V + 0.3 V EN/SS IN Maximum Junction Temperature T 125 C J Storage Temperature Range T -65 to +150 C STG MLPD-W8 78 Thermal Impedance C/W (1) JA Junction to Ambient SOT23-6 165 Lead Temperature (Soldering), 10s (SOT23-6 package only) T 300 C LEAD Peak IR Flow Temperature, (10-40sec) T 260 C PKG (2) ESD Rating (Human Body Model) V 2kV ESD Note: 1) Calculated from package in still air, mounted to 3x 4.5, 4 layer FR4 PCB with thermal vias under the exposed pad per JESD51 standards. 2) Tested in accordance to JEDEC standard JESD22-A114B. Electrical Characteristics Unless speci ed: V = V = 3.6V C = 1 F C = 0.22 F L = 22 H unless otherwise noted, T = +25C for Typ, -40C to 85C for Min and Max. IN EN/SS IN OUT A Parameter Symbol Conditions Min Typ Max Units Input Voltage V 2.7 10 V IN Quiescent Current I No switching 2.6 3.3 mA Q Feedback Voltage V 182 199 216 mV FB Feedback Pin Bias Current I 35 100 nA QFB Switching Frequency f T =25 C 1.0 1.2 1.4 MHz OSC A Maximum Output Voltage V 20 V OUT Switch Saturation Voltage V I = 85mA T =25 C 160 300 mV CESAT SW A Maximum Duty Cycle D V = GND 90 % MAX FB Switch Current Limit I I = 0 T =25 C 300 500 700 mA cl LOAD A Switch Leakage Current I V = 5V V = Open 0.01 5.0 A LKG SW OUT Shutdown Current I V = GND V = 3V V = Open 3 5 A SHD EN/SS IN OUT (1) PWM Dimming Frequency f 110kHz DIM EN/SS Threshold Low V 50mV IL EN/SS Threshold High V 1.8 V IH 2007 Semtech Corp. www.semtech.com 2