淺談On Semi NCV7692汽車LED燈電流控制的解刨

On Semi公司的NCV7692汽車LED燈電流控制器,采用外接NPN雙極器件和反饋電阻來(lái)調(diào)整驅(qū)動(dòng)LED的電流.單個(gè)驅(qū)動(dòng)器使用戶能靈活增加單路到多路系統(tǒng)中.專用的調(diào)光特性通過(guò)PWM輸入引腳來(lái)實(shí)現(xiàn).當(dāng)檢測(cè)到開路或短路時(shí)單路驅(qū)動(dòng)器就開關(guān)斷.LED亮度采用串聯(lián)在雙極晶體管的外接電阻進(jìn)行編程.單個(gè)NCV7692可驅(qū)動(dòng)多個(gè)LED串.NCV7692可采用PWM控制,外接可編電流電阻,可選擇負(fù)溫度系統(tǒng)電流控制,開路LED串和短路LED串診斷,多個(gè)LED串控制,滿足AEC?Q100 規(guī)范和PPAP功能.主要用在汽車后組合燈(RCL),日間燈(DRL),霧燈,中央高位剎車燈(CHMSL)陣列,轉(zhuǎn)向燈和其它外部調(diào)制應(yīng)用,通用汽車線性電流LED驅(qū)動(dòng)器.本文介紹了NCV7692主要特性,框圖和多種應(yīng)用框圖,以及評(píng)估板EVBUM2664主要特性,電路圖和評(píng)估板EVBUM2664應(yīng)用電路與PCB設(shè)計(jì)圖.

The NCV7692 is a device which uses an external NPN bipolar device combined with feedback resistor(s) to regulate a current for use in driving LEDs. The target application for this device is automotive rear combination lamps. A single driver gives the user flexibility to add single channels to multichannel systems. A dedicated dimming feature is included via the PWM input pin. The individual driver is turned off when an open load or short circuit is detected.

LED brightness levels are easily programmed using an external resistor in series with the bipolar transistor. The use of the resistor gives the user the flexibility to use the device over a wide range of currents. Multiple strings of LEDs can be operated with a single NCV7692 device. Set back power limit reduces the drive current during overvoltage conditions.

The device is available in a SOIC?8 package.

NCV7692主要特性:

? Constant Current Output for LED String Drive
? External Bipolar Device for Wide Current Range Flexibility
? With BCP56 Transistor, Can Drive Multiple Strings Concurrently (ref. Datasheet Info)
? External Programming Current Resistor
? Pulse Width Modulation (PWM) Control
? Negative Temperature Coefficient Current Control Option
? Open LED String Diagnostic
? Short?Circuit LED String Diagnostic
? Multiple LED String Control
? Overvoltage Set Back Power Limitation
? SOIC?8 Package
? AEC?Q100 Qualified and PPAP Capable
? These are Pb?Free Devices

NCV7692應(yīng)用:

? Rear Combination Lamps (RCL)
? Daytime Running Lights (DRL)
? Fog Lights
? Center High Mounted Stop Lamps (CHMSL) Arrays
? Turn Signal and Other Externally Modulated Applications
? General Automotive Linear Current LED Driver

圖1.NCV7692框圖

圖2.NCV7692應(yīng)用框圖

圖3.NCV7692微處理器控制應(yīng)用框圖

圖4.NCV7692輸出驅(qū)動(dòng)配置圖

圖5.NCV7692負(fù)溫度補(bǔ)償工作電路圖

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圖6.NCV7692短路檢測(cè)電路圖
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圖7.NCV7692 4或更多路的短路檢測(cè)圖

圖8.NCV7692 短路保護(hù)圖

圖8.NCV7692 SmartFET控制電路圖

圖9.NCV7692剎車燈/尾燈應(yīng)用電路圖

圖10.NCV7692大電流時(shí)剎車燈/尾燈應(yīng)用電路圖

圖11.NCV7692沒有微處理器的應(yīng)用框圖

評(píng)估板EVBUM2664

NCV7692 High-currentDaylight Running LightEvaluation Board

The evaluation board demonstrates high?current daylight running light (DRL) solution. The board regulates constant current of 0.54 A through two on?board white high power LEDs in the wide range of the supply voltage. The current is reduced for the board temperature above 85°C. The cooling is provided through passive heat sink mounted on the bottom side of the board. In case of LEDs short or opening, the current source is disabled and the fault may be detected by the ECU diagnostics.

評(píng)估板EVBUM2664主要特性:

? Wide range of supply voltage: 7 to 40 V (thermally limited)
? Two high?brightness on?board white LEDs
? Nominal LED current of 0.54 A
? Over?temperature current fold?back protection
? LED short?circuit and open?load emulation jumpers
? Positions for optional EMC capacitors
? One?side components assembly
? Passive cooling (heat sink)

圖12.評(píng)估板EVBUM2664外形圖

圖13.評(píng)估板EVBUM2664大電流白天運(yùn)行電路圖

圖14.NCV7692大電流DRL板外形圖

圖15.NCV7692一線驅(qū)動(dòng)器車身電子控制單元(ECU)框圖

圖16.NCV7692 DRL EVB PCB設(shè)計(jì)圖:左:頂層裝配圖;右:頂層綜合圖

圖17.NCV7692 DRL EVB PCB設(shè)計(jì)圖:頂層邊視圖

圖18.NCV7692 DRL EVB PCB設(shè)計(jì)圖:底層邊視圖

圖19.NCV7692DRLV1GEVB評(píng)估板電路圖