原标题：ST ALED1262ZT汽车级12路LED驱动解决方案

　　ST公司的ALED1262ZT是汽车级12路输出LED驱动器,具有开路检测,局部调光,总线驱动和单独操作.ALED1262ZT保证有19V输出驱动能力,使用户可串联七个LED.在输出级,12个稳压电流源提供6mA到60mA恒流电流驱动LED,电流可用外接单个电阻进行编程,还可对LED开路误差进行检测.LED亮度每路可单独调整,通过7比特灰度进行控制.慢接通和慢关断时间改善了系统的噪音性能,另外,逐渐的输出延迟降低了浪涌电流,从而进一步降低了EMI.该器件采用内部时钟抖动显示技术,从而获得广谱噪音降低.热管理装载了超温数据简报和输出热关断(170℃).I2C时钟频率高达400kHz,使得器件适合于高数据速率传输,工作电压在5.5V与38V之间,从而不需要外接预稳压器或额外甩负荷对电源进行保护.器件可采用I2C接口工作在总线驱动模式(BDM)或采用内部定制OTP配置工作在单独模式.主要用在汽车内部照明.本文介绍了ALED1262ZT主要特性,内部框图和典型连接方案, 全功能连接方案以及评估板STEVAL-LLL002V1(包括STEVAL-LLL002M1主板和 STEVAL-LLL002D1 USB-UART桥)主要特性,框图,电路图,材料清单和PCB设计图.

　　The ALED1262ZT is a monolithic 12 output LED driver designed for automotiveexterior and interior lighting applications. The ALED1262ZT guarantees 19 V outputdriving capability allowing users to connect several LEDs in series. In the outputstage, twelve regulated current sources provide from 6 mA to 60 mA constant currentto drive LEDs. The current is programmed by a single external resistor. In theALED1262ZT, LED open error detection is available.

　　The brightness can be adjusted separately for each channel through a 7-bitgrayscale control. A slow turn-on and turn-off time improves the system low noisegeneration performance. Moreover the gradual output delay reduces the inrushcurrent. To further increase EMI performance, this device implements an internalclock dithering to have a spread spectrum noise reduction.

　　Thermal management is equipped with overtemperature data alert and the outputthermal shutdown (170℃). The I²C high clock frequency, up to 400 kHz, makes thedevice suitable for high data rate transmissions. The supply voltage range is between5.5 V and 38 V avoiding any external pre-regulation or additional load dumpprotection on the power supply stage.

　　This device can operate in bus-driven mode (BDM) using I²C interface or instandalone mode (SAM) using internal custom configuration by OTP.

　　ALED1262ZT主要特性:

　　• Designed for automotive applications

　　• 12 constant current output channels

　　• 19 V current generator rated voltage

　　• Output current: from 6 mA to 60 mA

　　• Current programmable by a single external resistor

　　• 7-bit PWM local brightness control

　　• Slow turn-on/off time, gradual output delay and dithered clock for EMI reduction

　　• Error detection for open LEDs

　　• Supply voltage: from 5.5 V to 38 V

　　• Thermal shutdown and overtemperature alert

　　• Standalone and bus-driven mode

　　• Custom configuration by OTP with Redundancy and ECC

　　• 400 kHz fast I²C interface with selectable extended Hamming encoding

　　• Wired-OR error flag connection

　　ALED1262ZT应用:

　　• Automotive rear lights

　　• Automotive interior lighting

　　图1.ALED1262ZT简化内部框图

　　图2.ALED1262ZT典型连接方案

　　图3.ALED1262ZT全功能连接方案

　　评估板STEVAL-LLL002V1

　　The STEVAL-LLL002V1 evaluation kit consists of the STEVAL-LLL002M1 main board and the STEVAL-LLL002D1 USB-UARTbridge.It has been designed to test and evaluate ALED1262ZT performance.

　　The STEVAL-LLL002M1 is a LED array driver system evaluation board with local dimming and diagnostics for automotiveapplications. It is based on the ALED1262ZT 12-channel LED driver controlled through the STM8AF6266 microcontroller I²Cinterface.A 48 red LED matrix is driven by four ALED1262ZT LED drivers.

　　The on-board A7986A DC-DC converter, accepting standard adapter input voltages with reverse polarity protection, providesthe voltages and power for the board operation.

　　The STEVAL-LLL002V1 evaluation kit jumpers simulate LED open circuit faults and the 4-pin SWIM connector is used to debugand develop the STM8AF6266 microcontroller firmware.

　　The evaluation kit can operate in bus driven mode (BDM), standalone mode (SAM) and GUI mode.

　　In the bus driven mode, the board is controlled via on-board push buttons andpotentiometers. Commands to the ALED1262ZTdriver are sent by STM8A microcontroller over I²C bus.

　　In the standalone mode, the STEVAL-LLL002V1 evaluation kit is not controlled by the MCU and you can select two possibleoutput configurations using OTP ½ SPDT switch (SW2).

　　In the GUI mode, the board is connected to a PC via USB-UART bridge and you can observe and control various features of thedriver through the graphical user interface.

　　图4.评估板STEVAL-LLL002V1外形图

　　图5.评估板STEVAL-LLL002V1M主板外形图(正面)

　　图6.评估板STEVAL-LLL002V1M主板外形图(背面)

　　图7.评估板STEVAL-LLL002V1D外形图(正面)

　　图8.评估板STEVAL-LLL002V1D外形图(背面)

　　图9.评估板STEVAL-LLL002V1框图

　　评估板STEVAL-LLL002V1M材料清单:

　　评估板STEVAL-LLL002V1M材料清单: