原标题：Infineon BCR450 LED驱动方案

　　infineon 公司的BCR450 特别适合和外接功率晶体管一起驱动大于100mA的LED,有可能达到2.5A. BCR450的电流高达85mA,可以单独使用.工作电压8-27V,具有非常低的待机电流,典型应用在通用照明,建筑物照明,交通工具如火车和飞机照明,通用恒流源,工业应用的LED控制器.本文介绍BCR450主要特性, 方框图, 电测试电路图,”单独使用”模式的应用电路, BCR450评估板电路图, 以及BCR450和OSRAM Platinum Dragon的大功率 LED应用电路与板布局图和材料清单(BOM).

　　The BCR450 is a LED driver IC optimized for usage with an external power transistor for driving LED’s above 100mA. For currents up to 85mA the BCR450 can be used in stand alone operation. The output current level can be adjusted with an external sense resistor.

　　The IC can be switched on and off by an external signal, which is also suitable to regulate brightness of the LEDs by PWM dimming.

　　The precise internal bandgap stabilizes the circuit and provides stable current conditions over temperature range.

　　Additional features are included to protect the LED’s from overload, short circuit events as well as from over voltage. The LED’s can be also protected against thermal overload by thermally coupling the LED’s to the BCR450.

　　BCR450主要特性:

　　•Low voltage drop across sense resistor, 0.15 V typical

　　•High output current precision

　　•Operating voltage fro 8 to 27 V

　　•Over voltage protection

　　•Overtemperature current foldback and Thermal shut down function

　　•Adjustable Constant LED Current up to 85 mA in stand alone operation

　　•Precise Internal bandgap enables High output current accuracy

　　•Up to 2.5 A LED current possible by using external transistor

　　•EN Input for PWM LED brightness control and On/Off control

　　•Very Low Standby Current

　　•Minimum number of external components required, no inductors

　　•Very small SC-74 package: 2.9 mm x 2.5 mm x 1.1 mm

　　Benefits

　　•High level of colour control due to high output current precision

　　•Small space requirement

　　•No electro- magnetic interference

　　•Active thermal monitoring of chip and LED temperature with current fold- back to avoid thermal overstress

　　•Low cost device

　　•Scalable output stage optimizing cost and space

　　BCR450典型应用:

　　•General lighting e.g. retrofits

　　•Architectural lighting, Medical and Dental lighting

　　•Transportation like train and aircraft lighting

　　•Strobe lighting

　　•Universal constant current source

　　•Signal and marker lights for orientation or navigation

　　•LED controller for industrial applications, not qualified to AECQ-100

　　图1.BCR450方框图

　　图2.BCR450电测试电路图

　　图3.BCR450在”单独使用”模式的应用电路

　　BCR450评估板

　　The evaluation board is designed to test the BCR450 as a stand alone device for lower LED current applications and also with additional external “booster“ transistors for high current, high brightness LEDs. Up to three external transistors BCX68 or BC817SU each could be used on the PCB to minimize thermal problems. 3 LEDs in series for high current mode or 3 LEDs for low current applications can be chosen by setting resistors. The particular sense voltage can be derived by jumpers which are provided in the layout for each test case. Additional test circuit is included to measure AC characteristics, and the ENABLE input is designed to connect a PWM signal. The PCB is manufactured in double sided FR4 with substrate thickness of 1.0 mm.

　　图4.带有升压晶体管的BCR450应用电路

　　图5.BCR450评估板电路图

　　材料清单(BOM):