UCC2973

UCC1972/3 UCC2972/3 UCC3972/3 BiCMOS Cold Cathode Fluorescent Lamp Driver Controller FEATURES 1mA Typical Supply Current Accurate Lamp Current Control Analog or Low Frequency Dimming Capability Open Lamp Protection Programmable Startup Delay 4.5V to 25V Operation PWM Frequency Synchronized to External Resonant Tank 8 Pin TSSOP and SOIC Packages Available Internal Voltage Clamp Protects Transformer from Over-voltage (UCC3973) TYPICAL APPLICATION CIRCUIT DESCRIPTION Design goals for a Cold Cathode Fluorescent Lamp (CCFL) converter used in a notebook computer or portable application include small size, high efficiency, and low cost. The UCC3972/3 CCFL controllers provide the necessary circuit blocks to implement a highly efficient CCFL backlight power supply in a small footprint 8 pin TSSOP package. The BiCMOS controllers typically consume less than 1mA of operating current, improving overall system efficiency when compared to bipolar controllers requiring 5mA to 10mA of operating current. External parts count is minimized and system cost is reduced by integrating such features as a feedback controlled PWM driver stage, open lamp protection, startup delay and synchronization circuitry between the buck and push-pull stages. The UCC3972/3 include an internal shunt regulator, allowing the part to operate with input voltages from 4.5V up to 25V. The part supports both analog and externally generated low frequency dimming modes of operation. The UCC3973 adds a pr...