ST公司的L6520/1是用于TL和CFL燈的高度集成鎮(zhèn)流器控制器，能驅(qū)動雙極晶體管（BJT）和MOSFET，具有預(yù)熱起動和即時起動，過流/過壓保護(hù)，扼流圈飽和控制等功能。本文介紹了L6520/1 主要特性，方框圖，驅(qū)動BJT和MOSFET的應(yīng)用案例，以及14 W / 21 W EVAL6520-1421評估板主要特性，電路圖和材料清單。
The L6520/1 is the first highly integrated ballast controller in the market able to drive both BJTs and MOSFETs, providing all the necessary protections to ensure the maximum reliability of the application in compliance with major safety and power consumption regulations.
By adopting BJTs switches in the application, the IC allows to replace more expensive MOSFETs, strongly reducing the system cost without compromises.
The IC represents also the best and cost effective solution to replace self oscillating solutions when the key requirement is the reliability of the ballast. The benefits are an increased MTBF and a reduction of the costs due to the return from the field.
The higher level of flexibility and integration provided allows the possibility to quickly design ballast with any kind of lamp topology/size/power, without limitations. Depending on the power of the lamp, the IC can work without PFC, with passive PFC or with active PFC. In the latter case the L6562A from STMicroelectronics is the suggested IC for the most cost effective solution.
The IC is fully programmable using only resistors and offers over current protections, choke saturation control and hard switching protection thanks to a sophisticated current control circuit (CCC). In ignition, the CCC limits both the maximum lamp voltage in case of old or broken lamp, and also the lamp current in case of inductor saturation.
When the IC is driving bipolar transistors, a variable dead time ensures the correct base discharge time avoiding cross conduction phenomena. Moreover, the IC prevents the failure due to the lamp’s end of life (EOL).
L6520/1 主要特性：
■ Half bridge circuit able to drive both BJT and MOSFET transistors
■ Very accurate oscillator precision in wide operating temperature range
■ BJTs’ storage time compensation
■ Preheated start and instant start
■ Hard switching protection
■ Overcurrent / voltage protection
■ Choke saturation control
■ End-of-life protection
■ Programmable without capacitors
L6520/1 應(yīng)用：
■ Electronic ballasts (TL, Industrial CFL)
■ Integrated CFLs
圖1。L6520/1方框圖
圖2。L6520/1 BJT應(yīng)用案例
圖3。L6520/1 MOSFET應(yīng)用案例
14 W / 21 W EVAL6520-1421評估板
14 W / 21 W T5 miniature ballast driven by L6520 and STT13005D bipolar transistors
The EVAL6520-1421 is a demonstration board able to drive either a 14 W or 21 W linear T5 fluorescent lamp with the L6520 low voltage ballast controller.
The half bridge consists of NPN high voltage power transistors driven by a suitable pulse
transformer.
The L6520 low voltage ballast controller is intended to drive extremely compact applications based on either MOSFETs or bipolar transistors.
The EVAL6520-1421 is capable of driving either a T5-14W-HE or T5-21W-HE lamp, with the same miniatured (16 mm wide) ballast.
The selection of both the resonant components and the bipolar transistors, together with the design of the suitable pulse transformer, and IC power supply is also described.
EVAL6520-1421評估板主要特性：
■ Drives either T5-14W-HE or T5-21W-HE lamps
■ Standard form factor (19 mm x 120 mm)
■ Compliance with IEC61347-2-3, IEC61000-2-3 and EN55022 Class-C
圖4。EVAL6520-1421評估板外形圖
輸入指標(biāo)：
燈指標(biāo)：
圖5。EVAL6520-1421評估板電路圖
圖6。脈沖變壓器（T2）資料圖
圖7。鎮(zhèn)流器扼流圈（L1）資料圖
評估板材料清單（BOM）：
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