基于NCV7680设计的汽车LED照明技术_技术

NCV7680是On Semi公司的线性稳流及控制器，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