安森美CAT4103_3路恒流LED驱动方案.doc

安森美CAT4103 3路恒流LED驱动方案安森美(On Semi)公司的CAT4103是3路恒流LED驱动器,设计用来控制RGB LED,它不需要电感和有低噪音的特性.LED通路电流可通过外接电阻进行编程,高达175mA.高速4线25MHz串口,采用移位寄存器和闭锁配置来控制每个通路.工作电压3V到5.5V,并具有热关断特性. CAT4103可用于多种色彩智能LED建筑物照明,高亮度LED信号和显示以及LCD背景光.本文介绍了CAT4103的主要特性, 功能方框图, 典型应用电路图以及级联电路图, CAT4103EVAL评估板电路图和评估板元件列表.The CAT4103 is a 3-channel, linear based constant-current LED driver designed for RGB LED control, requiring no inductor and provides a low noise operation. LED channel currents up to 175mA are programmed independently via separate external resistors. Low output voltage operation of 0.4V at 175mA allows for more power efficient designs across wider supply voltage range. The three LED pins are compatible with high voltage up to 25V supporting applications with long strings of LEDs.A high-speed 4-wire 25MHz serial interface controls each individual channel using a shift register and latch configuration. Output data pins allow multiple devices to be cascaded and programmed via one serial interface with no need for external drivers or timing considerations. The device also includes a blanking control pin (BIN) that can be used to disable all channels independently of the interface.Thermal shutdown protection is incorporated in the device to disable the LED outputs whenever the die temperature exceeds 150C.The device is available in a 16-lead SOIC package.CAT4103主要特性:3 independent current sinks rated to 25VLED current to 175mA per channel set by separate external resistorsHigh-speed 25MHz 4-wire serial interfaceBuffered output drivers to ensure data integrityCascadable devicesLow dropout current source (0.4V at 175mA)3V to 5.5V logic supplyThermal shutdown protectionRoHS-compliant 16-lead SOIC packageCAT4103应用:Multi-color, intelligent LED, architectural lightingHigh-visual impact LED signs and displaysLCD backlight图1.CAT4103功能方框图图2.CAT4103典型应用电路图图3.三个CAT4103级联电路图CAT4103 LED 驱动器评估板The CAT4103EVAL Evaluation board for the Catalyst SemiconductorCAT4103 three channel RGB LED driver. The functionality and major parameters of the CAT4103 can be evaluated with the CAT4103EVAL board.The CAT4103 is a three channel constant-current LED driver for RGB LEDs. Individual current settings are set by connecting a single resistor from each RSET pin to GND. A four-wire serial interface and output data pins allow for programming one or multiple CAT4103 devices cascaded together.Additional details and electrical characteristics can be found in the CAT4103 data sheet.BOARD HARDWAREThe evaluation board contains one CAT4103 in a typical application circuit driving a RGB LED. The six pin header connector (K1) and receptacle (K2) allows for easy cascading of multiple boards. Simply connect K1 from one board to K2 of another.Jumper J1 sets the VDD supply of the CAT4103. In the right position (pin 2 and pin 3 shunt), VDD is connected to VBUS (K1 pin 1). To power VDD from an external source place J1 in the left position (pin 1 and pin 2 shunt) and connect the external sourcebetween test points T1 and T2.Jumper J2 sets the power supply for the onboard RGB LED. In the left position (pin 1 and pin 2 shunt), the LED anodes are connected to VBUS. To power the RGB LED from an external source place J2 in the right position (pin 2 and pin 3 shunt) and connect the external source between test points T3 and T4.Jumpers J3 to J5 connect the onboard RGB LED cathodes to the CAT4103 while in the left position (pin 1 and pin 2 shunt). To connect external LEDs, place the desired jumper in the right position (pin 2 and pin 3 shunt) and connect the LED cathode to the appropriate test point ( T5, T6, or T7).Trimmer potentiometers R1, R2, R3 control the current setting for each LED channel r