A phase-control loop and half-bridge driver for fluorescent lamps are included in the 600-V IR21592 and IR21593 dimming ballast ICs. Both offer a comprehensive set of protection features, including dimming ignition detection and brownout and overtemperature protection. The IR21592 fits linear lamps, while the IR21593 suits compact lamps. Their phase-control-loop architecture senses and regulates the phase current of the half-bridge. The control method eliminates a separate current-sensing transformer. Pricing is $1.50 each in lots of 50,000, with delivery from stock.