原标题：On Semi NCV7680汽车LED照明方案

　　On Semi公司的 NCV7680是线性稳流及控制器，包含8个线性可编程恒流源，能支持高达每通道75 mA的发光二极管(LED)驱动电流。设计用于汽车固态组合尾灯(RCL)的稳流和控制，支持两个亮度等级，一个用于停车，另一个用于尾部照明。典型应用包括组合尾灯、日间行车灯(DRL)、雾灯、中央高位停车灯(CHMSL)阵列、转向信号灯和液晶显示器(LCD)背光。本文介绍了NCV7680主要特性，方框图，升压模式和多种应用电路，以及NCV7680-NCV3163评估板主要特性，电路图和材料清单(BOM)。

　　The NCV7680 consists of eight linear programmable constant current sources. The part is designed for use in the regulation and control of LED based Rear Combination Lamps for automotive applications. System design with the NCV7680 allows for two brightness levels, one for stop and one for tail illumination, or optional PWM control can also be implemented.

　　Discrete LED brightness levels are easily programmed (stop current value, tail duty cycle value) optional external ballast FET allows for power distribution on designs requiring high currents. Set back power limit reduces the drive current during overvoltage conditions. This is most useful for low current applications when no external FET is used.

　　NCV7680主要特性：

　　Constant Current Outputs for LED String Drive

　　LED Drive Current up to 75mA per Channel

　　Open LED String Diagnostic with Open-Drain Output

　　Slew Rate Control

　　Low Dropout Operation

　　External Modulation Capable

　　On-chip 1 kHz Tail PWM Dimming

　　Stop Current Set Point programmability

　　Tail Dimming Set Point programmability

　　Overvoltage Set Back Power Limitation

　　Pb-Free

　　NCV7680优势:

　　LED devices are best controlled with current drive due to their exponential voltage characteristics

　　Sufficient drive for most popular low current LED devices

　　System functionality back to the microprocessor

　　Eliminates EMI concerns

　　Maintains functionality during drops in automotive battery voltage

　　Flexible for many system operation setups

　　Simplifies system design.

　　Easy programmability with one resistor

　　Easy programmability with one resistor

　　Keeps IC temperature lower at extended voltage range.

　　Meets lead free regulations

　　NCV7680应用:

　　Automotive Rear Combination Lamps

　　Daytime Running Lights

　　Fog Lights

　　Center High Mounted Stop Lamps

　　Turn Signal and Other Externally Modulated Applications

　　LCD Backlighting

　　Lighting Module

　　图1。NCV7680方框图

　　图2。NCV7680带外接FET镇流晶体管的应用框图

　　图3。NCV7680不带外接FET镇流晶体管的应用框图

　　图4。NCV7680升压模式框图

　　图5。NCV7680停车灯应用框图

　　图6。NCV7680尾灯应用框图

　　图7。NCV7680 PWM工作电路(LCD背光应用)

　　图8。闭锁电路

　　NCV7680-NCV3163评估板

　　The NCV7680 is an octal LED driver designed for automotive LED rear combination lamps. External programmability of the NCV7680 allows the user to set the tail current and stop currents using a single resistor for each function. An optional external FET is used to help distribute power for high power systems.

　　The NCV7680-NCV3163 Evaluation Board includes both an NCV7680 (octal driver) and NCV3163 (Boost Regulator). The NCV3163 allows for an increased number of LEDs per NCV7680 output by boosting the LED string anode voltage. The DIAG pin is brought out for reporting of open circuit conditions.

　　NCV7680-NCV3163评估板特性 ：

　　STOP Input Switch

　　DIAG Output

　　LED Isolation

　　STOP Programming Current

　　External PWM Input

　　Adjustable Boost Circuit with Internal Switch

　　RoHS Compliant

　　图9。NCV7680-NCV3163评估板外形图

　　NCV7680-NCV3163评估板材料清单(BOM)：