SC4509
SC4509 is Highly Integrated Step-Up Converter manufactured by SEMTECH.
Description
SC4509 Highly Integrated Step-Up Converter for White LED Applications in MLPD-W8-2x2
Features
VIN range: 2.7V
- 10V Integrated Schottky diode 81% efficiency Requires only 4 external ponents Up to 20V of output voltage 30m A maximum LED current Open LED protection (OVP) 1.2MHz PWM switching frequency Low feedback voltage (20Om V typical) Wide range of PWM dimming Drives up to 5 LEDs 500m A switch current limit 220n F output capacitor Available in 2mm x 2mm x 0.75mm MLPD-W8 and SOT23-6 packages Packages are fully WEEE and Ro HS pliant
The SC4509 is a highly integrated step-up DC/DC converter targeted for white LED backlighting applications. It is designed to drive up to five LEDs with a wide input voltage range of 2.7 to 10 volts. Designed for 20V output voltage, the SC4509 operates with a constant 1.2MHz PWM frequency. To optimize efficiency, the feedback voltage is set to only 199m V, minimizing the power loss in the current setting resistor. The product requires only four external ponents (CIN, COUT, L and RSET), making it ideal for .. applications that require low cost and minimal PCB area. The SC4509 offers current limit and over-voltage protection (OVP) to safeguard the device under extreme operating conditions. If the LEDs bee disconnected or fail in an open state condition, OVP circuitry will be activated to shut down the device. The EN/SS pin allows the device 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 puters
Typical Application Circuit
Vin
L1
Vo
22μH
LED1
LED2
C2 0.22μF LED3 U2 5 VIN
6 VOUT SW 1
EN/SS
4 C1 1μ F EN/SS
LED4 FB 3 R1
March 26, 2007
.semtech.
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