LED7706TR STMicroelectronics

LED7706 6-rows 30 mA LEDs driver with boost regulator for LCD panels backlight Features Boost section 4.5 V to 36 V input voltage range Internal power MOSFET Internal +5 V LDO for device supply Up to 36 V output voltage Constant frequency peak current-mode VFQFPN-24 4x4 control 250 kHz to 1 MHz adjustable switching frequency Description External synchronization for multi-device application The LED7706 consists of a high efficiency monolithic boost converter and six controlled Pulse-skip power saving mode at light load current generators (rows) specifically designed to Programmable soft-start supply LEDs arrays used in the backlighting of Programmable OVP protection LCD panels. The device can manage an output Stable with ceramic output capacitors voltage up to 36 V (i.e. 10 white LEDs per row). Thermal shutdown The generators can be externally programmed to Backlight driver section sink up to 30 mA and can be dimmed via a PWM Six rows with 30 mA maximum current signal (1 % dimming duty-cycle at 20 kHz can be capability (adjustable) managed). The device allows to detect and Rows disable option manage the open and shorted LED faults and to let unused rows floating. Basic protections (output Less than 500 ns minimum dimming on- over-voltage, internal MOSFET over-current and time (1 % minimum dimming duty-cycle at thermal shutdown) are provided. 20 kHz) 2 % current matching between rows LED failure (open and short-circuit) detection Applications LCD monitors and TV panels PDAs panel backlight GPS panel backlight Table 1. Device summary Order codes Package Packaging LED7706 Tube VFQFPN-24 4x4 (exposed pad) LED7706TR Tape and reel April 2009 Rev 2 1/46 www.st.com 46Contents LED7706 Contents 1 Typical application circuit 4 2 Pin settings 5 2.1 Connections 5 2.2 Pin description 6 3 Electrical data 7 3.1 Maximum rating . 7 3.2 Thermal data . 7 4 Electrical characteristics . 8 5 Operation description . 10 5.1 Boost section 11 5.1.1 Functional description 11 5.1.2 Enable function . 12 5.1.3 Soft-start 13 5.1.4 Overvoltage protection 14 5.1.5 Switching frequency selection and synchronization . 15 5.1.6 Slope compensation . 16 5.1.7 Boost current limit . 18 5.1.8 Thermal protection . 18 5.2 Backlight driver section 19 5.2.1 Current generators . 19 5.2.2 PWM dimming 20 5.3 Fault management 21 5.3.1 FAULT pin . 21 5.3.2 MODE pin . 21 5.3.3 Open LED fault . 22 5.3.4 Shorted LED fault . 23 2/46