General description
The UBA2071 and UBA2071A are high voltage ICs intended to drive Cold Cathode Fluorescent Lamps (CCFLs) or External Electrode Fluorescent Lamps (EEFLs) for backlighting applications. They can drive a half bridge circuit made up of two NMOSFETs with a supply voltage of up to 550 V, so the inverter can be supplied directly from a 400 V PFC bus.
The UBA2071 and UBA2071A contain a controller, a level shifter, a bootstrap diode and drivers for the external half bridge power switches. It also contains a low frequency PWM generator, which can be used to control the brightness level of the lamps, using an analog brightness/dimming control voltage. PWM dimming can also be realized, using a digital PWM input signal. PWM dimming can be synchronized with other ICs. The lamp current is controlled by means of a true zero voltage switching resonant control principle, ensuring lowest possible switch losses in the half bridge power structure.
The UBA2071 is designed to be supplied by a ∆V/∆t supply from the half bridge circuit that it drives. The IC itself needs little current and if the IC is off, a clamp protects the supply voltage from getting too high.
The UBA2071A is designed to be supplied by a fixed 12 V supply. It has a lower supply start voltage and no supply clamp.

Features
■ Suitable for operating in a very wide inverter supply voltage range (up to 550 V DC).
■ Integrated level shifter.
■ Integrated bootstrap diode.
■ Lamp current control by means of a true zero voltage switching resonant control
   principle.
■ Sample & Hold circuit, maintaining current control value during PWM lamp-off
   situation.
■ Separately definable time constants for current control loop and PWM dimming
   attack/decay setting.
■ Overvoltage control.
■ Overcurrent protection.
■ Ignition failure detection.
■ Hard switching control.
■ Arcing detection.
■ Open/short pin protections on feedback pins.
■ Integrated, programmable fault timer.
■ Bidirectional pin acting both as fault signaling output and input, allowing external fault
   interfacing to operate via the integrated fault timer.
■ Brightness level adjustment through PWM dimming.
■ Integrated PWM generator.
■ Power-down mode.
■ Communication pin for master / slave operation.
■ DC blocking capacitor pre-charging sequence.
■ Supply clamp (UBA2071 only).

Applications
■ LCD-backlighting, including LCD-TV and LCD-monitor applications. The IC is intended
   to drive and control a half bridge inverter with resonant load circuit for CCFLs, but can
   also drive an array of External Electrode Fluorescent Lamps (EEFLs).