Features: Synchronizable To Display Video Frequency
High Voltage Feedback Loop Directly Controls Maximum Open Lamp And Minimum Strike Voltages
Transformer Protected From Over-Heating During Lamp Striking
Micro-Amp Sleep Mode
User-Programmable Fixed Frequency Operation
Under-Voltage Lockout Feature With Power- Up Reset
Built-In Soft-Start Feature
Operates With 3.3V or 5V Power Supplies
100mA Output Drive Capability
Application Notebooks
Instrumentation Displays
Desktop Computer Monitors
Low Ambient Light Displays (usedAircraft, Automobiles, and Hand-held Equipment)Pinout
SpecificationsSupply Voltage (VDD, VDD_P) ............................................................................. 6.5V
Digital Inputs .................................................................................. -0.3 to VDD+0.5V
Analog Inputs .................................................................................. -0.3 to VDD+0.5V
Digital Outputs ................................................................................ -0.3 to VDD+0.5V
Analog Outputs ............................................................................... -0.3 to VDD+0.5V
Operating Junction Temperature
Plastic (DB, PW Packages) .......................................................................... .....150°C
Storage Temperature Range .............................................................-65°C to 150°C
Lead Temperature (Soldering, 10 seconds) .................................................... ..300°C
The LX1686 Backlight Controller IC provides all the control functions needed to implement Linfinity's direct drive inverters used to operate cold cathode fluorescent lamps (CCFL's). This IC can be used to control single or multiple-lamp configurations. CCFL's are used for back or edge lighting of liquid crystal flat panel displays (LCD s) and typically find application in notebook computers, web browsers, automotive and industrial instrumentation, and entertainment systems.
The LX1686 includes a PWM controlled amp current burst circuit that can provide a >100:1 dimming range from
a simple zero to 2.5V potentiometer input. The PWM dimming burst rate is easily synchronized to the LCD panel s frame rate to prevent interference from optical beat frequencies.
LX1686 Safety and reliability features include a new dual feedback contol loop that permits regulation of maximum lamp strike voltage as well as lamp current. Regulating maximum lamp voltage permits the designer to provide for ample worst case lamp strike voltage while at the same time conservatively limit maximum open circuit voltage.
An innovative new strike voltage generation technique enables the module designer to optimize high voltage
transformer design for maximum operating efficiency with no power dissipating overhead to guarantee strike capability. Direct drive topology is a non-resonant, oscillator-controlled PWM regulation method. The LX1686 allows a wide choice of fixed operating frequencies to match lamp current frequency to the lamp's most efficient operating point, and to minimize high frequency interference.
LX1686 Data Sheet
