Part # Application Notes Lighting Control Factory Automation Home Appliances Control Home Automation L6574 ST7DALIF2 AN2708 datasheet

Part Manufacturer: ST Microelectronics

ST Microelectronics

Part Description: 2X36 W digital dimmable ballast with L6574 and ST7FDALI


Part Details:

AN2708 Application note 2X36 W digital dimmable ballast with L6574 and ST7FDALI Introduction This document describes a high-efficiency, high power factor, low THD and digital dimming electronic ballast designed to drive 2X36 W T8 tube lamps. The system consists of three main blocks: The high-frequency ballast includes an active power factor correction circuit based on the L6562 for universal input voltage as well as a ballast control circuit based on the L6574. The digital dimming is performed by interfacing the ST7FDALI microcontroller with the analog half-bridge driver. The DALI control unit is dedicated to address the slaves, to display the lamp status and to send the dimming commands. This unit is provided with a keyboard which allows setting different dimming scenes over a wide range (5-100%) as well as putting in standby and restarting the ballast. The DALI communication protocol includes single and group mode, as well as broadcast mode to address the slaves. The AC-DC adapter is based on the VIPer12A-E. This is an offline double-output isolated power supply in DCM flyback configuration. The outputs are set for 20 V to supply the communication bus and for 5 V to supply the MASTER microcontroller. The three blocks are described in detail and their performances are shown. In addition some of DALI basics are explained. March 2008 Rev 1 1/42 www.st.com Contents AN2708 Contents 1 Block diagram and system operating conditions . . . . . . . . . . . . . . . . . 5 2 High-frequency ballast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.1 PFC converter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.2 Half-bridge inverter and ballast . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2.2.1 Lamp dimming . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 2.2.2 Supply section . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 2.2.3 Lamp turn-on and lamp turn-off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 2.2.4 Verification of lamp status . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 2.2.5 Ballast performances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 3 DALI master unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 3.1 Master unit schematic and bill of material . . . . . . . . . . . . . . . . . . . . . . . . 26 4 Basics of DALI . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 5 DALI master AC-DC adapter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 5.1 Adapter description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 5.2 Adapter bill of material . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 5.3 Adapter performances . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 5.3.1 Steady state tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 5.3.2 Startup behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 5.3.3


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Application Notes Lighting Control Factory Automation Home Appliances Control Home Automation L6574 ST7DALIF2 AN2708.pdf Datasheet