DESCRIPTION

The LX1688 is a fixed frequency, dual current/voltage mode, switching regulator that provides the control function for Cold Cathode Fluorescent Lighting (CCFL). This controller can be used to drive a single lamp, but is specifically designed for multiple lamp LCD panels. The IC can be configured as a master or slave and synchronize up to 12 controllers.

The LX1688 includes highly integrated universal ‘PWM or DC’ dim input that allows either a PWM or DC input to adjust brightness without requiring external conditioning, since a single external capacitor CPWM can be used to integrate a PWM input. Burst mode dimming is possible if the user supplies a low frequency PWM signal on the BRITE input and no CPWM capacitor is used. The controller utilizes Microsemi’s patented direct drive fixed frequency topology and patented resonant lamp strike generation technique.

KEY FEATURES

▪ Provision to Synchronize Lamp Current & Frequency With Other Controllers

▪ Dimming With Analog or Digital (PWM) Methods (>20:1)

▪ Programmable Fixed Frequency

▪ Adjustable Power-up Reset

▪ ENABLE/BRITE Polarity Selection

▪ Voltage Limiting on Step-up Transformer Secondary Winding

▪ Open Lamp Timeout Circuitry

▪ Switched VDD Output (10mA)

▪ Micro-Amp Sleep Mode

▪ Operates With 3.3V to 5V Supply

▪ 100mA Output Drive Capability

APPLICATIONS / BENEFITS

▪ Desktop LCD Monitors

▪ Multiple Lamp Panels

▪ Low Ambient Light Displays

▪ High Efficiency

▪ Lower Cost than Conventional Buck/Royer Inverter Topologies

▪ Improved Lamp Strike Capability

▪ Improved Over-Voltage Control