STEVAL-ILL021V1 LCD panels backlight demonstration board based on the LED7707 Data brief Features 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 control 250 kHz to 1 MHz adjustable switching frequency external sync for multi-device application pulse-skip power saving mode at light load STEVAL-ILL021V1 programmable soft-start programmable OVP protection The generators can be externally programmed to single ceramic output capacitor sink up to 85 mA and can be dimmed via a PWM non-latched thermal shutdown signal (1% of minimum dimming duty cycle at Features backlight driver section 1kHz can be managed). six rows with 85 mA maximum current The device allows to detect and manage the open capability (adjustable) and shorted LED faults and to let unused rows up to 10 white LEDs per row floating. rows disable option Basic protections (output overvoltage, internal less than 10 s minimum dimming time MOSFET overcurrent and thermal shutdown) are 2.0% current matching between rows provided. LED failure (open and short circuit) detection RoHS compliant Description This demonstration boards is based on the LED7707 and implements a high efficiency monolithic boost converter and six controlled current generators (rows) specifically designed to supply LEDs arrays used in the backlight of LCD panels. The device can manage an output voltage up to 36 V (i.e. ten white-LEDs per row). May 2009 Doc ID 15677 Rev 1 1/5 For further information contact your local STMicroelectronics sales office. www.st.com 5 Circuit schematic and PCB layout STEVAL-ILL021V1 1 Circuit schematic and PCB layout Figure 1. Schematic diagram 6 ) . , U 3 4 0 3 , - U 6 ) . 2 2 K . - K 39 . 3,/0% 63%, / * 2 K U U . - & 5 2 5 ,% %. K P 6 //34 2 % M 2 . ) ,8 K N . 6 39 63%, / 2 2 3,/0% . 2 U . - . - , / 0 . %. & 5 2 , % . - . - %. 2 / 7 2 / 7 ) - ) - 2 / 7 2 / 7 - / % 2 / 7 2 / 7 / - 0 / - 0 4 ( 0 * 3 7 ( % % 2 33 - - ) ) . ,) , 2 33 37 ) & 2 3 2 K 3 7 - / % K N 2 %3 2 / 7 2 / 7 2 / 7 2 / 7 2 / 7 2 / 7 & 37 N . - N 2 ) , ) - ) , ) - 2 2 2 K 3 7 K K & 37 6 ) . - V Figure 2. Top side component placement 2/5 Doc ID 15677 Rev 1 6 6 ,4 6 ,4 6 6