Datasheet Texas Instruments UCC3973PWTR — Datenblatt

UCC1972/3
UCC2972/3
UCC3972/3 BiCMOS Cold Cathode Fluorescent Lamp Driver Controller
FEATURES DESCRIPTION 1mA Typical Supply Current 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. Accurate Lamp Current Control Analog or Low Frequency Dimming
Capability Open Lamp Protection Programmable Startup Delay 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. 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) The UCC3973 adds a programmable voltage clamp at the BUCK pin. This
feature can be used to protect the transformer from overvoltage during
startup or when an open lamp occurs. Transformer voltage is controlled by
reducing duty cycle when an over-voltage is detected. TYPICAL APPLICATION CIRCUIT C6 27pF UCC3972 NO INTERNAL VOLTAGE CLAMP
UCC3973 T1 INTERNAL VOLTAGE CLAMP LIMITS TRANS FORMER
VOLTAGE AT S TART-UP OR DURING FAULT S YS TEM VOLTAGE …