Part # Application Notes Lighting Control Access Control Accessories Audio Body And Convenience Computer Power Supply Corded Terminals datasheet

Part Manufacturer: ST Microelectronics

ST Microelectronics

Part Description: ntelligent multipower digital ballast for fluorescent lamps


Part Details:

AN2640 Application note Intelligent multipower digital ballast for fluorescent lamps Introduction Fluorescent lamps are highly popular due to their luminous efficiency, long life and color rendering. These lamps need external circuitry to compensate for their negative resistance characteristic. This circuitry is called "ballast". The simplest ballast is a magnetic inductor connected in series at the lamp. The electronic ballast with respect to the magnetic one offers the following advantages: Better efficiency Increased lamp life Lightweight with smaller dimensions Better lamp power control For these reasons, in the last years there has been a shift in the market towards the use of electronic ballasts with dedicated drivers and controllers. Today, thanks to microcontrollers, it is possible to add intelligence into the circuit. Instead of having a dedicated circuit for each lamp with a single ballast it is possible to drive many different lamp groups. This application note describes an electronic ballast that is able to recognize lamps within the T5 fluorescent family such as 24 W, 39 W, 54 W and 80 W. It consists of two main blocks: A boost converter (Power Factor Controller PFC) working in transition mode (fixed TON and variable frequency) An inverter in half-bridge configuration working in zero voltage switching Both ballast and PFC stages are controlled by the ST7FLIT19B that offers its entire signal to the L6382D5 which provides the right voltage and current levels for the Power MOSFET. This system after tube recognition sets the right parameter and drives the lamp correctly. Figure 1 shows the ballast block diagram. Figure 1. Ballast block diagram January 2008 Rev 1 1/36 www.st.com Contents AN2640 Contents 1 PFC section design criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2 Boost inductor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.3 PFC devices selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.3.1 Power switch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 1.3.2 Rectifier . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2 Half-bridge design criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 3 ST7LIT19BF1 - 8-bit MCU . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 3.2 Use of the pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 4 L6382D5 - power management units for microcontrolled ballast . . . . 18 4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 4.2 Use of the pins . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 5 Recognition technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 5.1 Code implementation on microcontroller . . . . . . . . . . . . . . . . . . . . . . . . . 23


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Application Notes Lighting Control Access Control Accessories Audio Body And Convenience Computer Power Supply Corded Terminals.pdf Datasheet