基于NCV7680設(shè)計(jì)的汽車LED照明技術(shù)

NCV7680是On Semi公司的線性穩(wěn)流及控制器，包含8個(gè)線性可編程恒流源，能支持高達(dá)每通道75 mA的發(fā)光二極管(LED)驅(qū)動(dòng)電流。設(shè)計(jì)用于汽車固態(tài)組合尾燈(RCL)的穩(wěn)流和控制，支持兩個(gè)亮度等級(jí)，一個(gè)用于停車，另一個(gè)用于尾部照明。典型應(yīng)用包括組合尾燈、日間行車燈(DRL)、霧燈、中央高位停車燈(CHMSL)陣列、轉(zhuǎn)向信號(hào)燈和液晶顯示器(LCD)背光。本文介紹了NCV7680主要特性，方框圖，升壓模式和多種應(yīng)用電路，以及NCV7680-NCV3163評(píng)估板主要特性，電路圖和材料清單（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優(yōu)勢(shì):

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應(yīng)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

圖1。NCV7680方框圖

圖2。NCV7680帶外接FET鎮(zhèn)流晶體管的應(yīng)用框圖

圖3。NCV7680不帶外接FET鎮(zhèn)流晶體管的應(yīng)用框圖

圖4。NCV7680升壓模式框圖

圖5。NCV7680停車燈應(yīng)用框圖

圖6。NCV7680尾燈應(yīng)用框圖

圖7。NCV7680 PWM工作電路（LCD背光應(yīng)用）

圖8。閉鎖電路

NCV7680-NCV3163評(píng)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評(píng)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



圖9。NCV7680-NCV3163評(píng)估板外形圖

圖10。NCV7680-NCV3163評(píng)估板電路圖

NCV7680-NCV3163評(píng)估板材料清單（BOM）：