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| LT3965八開關(guān)矩陣LED調(diào)光器系統(tǒng)方案 |
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| 文章來源： 更新時間：2016/5/6 15:07:00 |
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Linear公司的LT3965是八開關(guān)矩陣LED調(diào)光器,具有八個單獨控制的17V/330mΩ NMOS開關(guān),八個開關(guān)可并聯(lián)/或串聯(lián),采用I2C串口和MCU通信,每個開關(guān)可單獨開/關(guān)/調(diào)光1-4個LED,數(shù)字可編程256:1 PWM調(diào)光,主要用在汽車LED頭燈,大型LED顯示屏,自動照相機閃光設(shè)備,RGBW彩色混合照明.本文介紹了LT3965主要特性,框圖和幾種應(yīng)用電路,以及演示板DC2218A特性,測試建立圖,電路圖,材料清單和PCB元件布局圖.
The LT®3965 is an LED bypass switching device fordimming individual LEDs in a string using a commoncurrent source. It features eight individually controlledfloating source 17V/330mΩ NMOS switches. The eightswitches can be connected in parallel and/or in series tobypass current around one or more LEDs in a string. TheLT3965 uses the I2C serial interface to communicate withthe microcontroller. Each of the eight channels can beindependently programmed to bypass the LED string inconstant on or off,or PWM dimming with or without fadetransition. Using the fade option provides 11-bit resolution
logarithmic transition between PWM dimming states.
The LT3965 provides an internal clock generator and alsosupports external clock source for PWM dimming. TheLT3965 reports fault conditions for each channel such asopen LED and shorted LED. The four address select pinsallow 16 LT3965 devices to share the I2C bus. The deviceis available in a 28-lead TSSOP package.
LT3965主要特性:
Eight Independent 17V 330mΩ NMOS Switches
Independent On/Off/Dimming Control of 1 to 4 LEDsfor Each Switch
I2C Multidrop Serial Interface with ProgrammableOpen LED and Shorted LED Fault Reporting
16 Unique I2C Addresses
VDD Range: 2.7V to 5.5V and VIN Range: 8V to 60V
Digital Programmable 256:1 PWM Dimming
Fade Transition Between PWM Dimming States
Optional Internal Clock Generator or External ClockSource for PWM Dimming
Open LED Overvoltage Protection
Flicker Free PWM Dimming
LT3965應(yīng)用:
Automotive LED Headlight Clusters
Large LED Displays
Automated Camera Flash Equipment
RGBW Color Mixing Lighting
圖1.LT3965框圖
圖2.LT3965降壓模式LED驅(qū)動器電路
圖3.LT3965雙降壓模式LED驅(qū)動器和升壓預(yù)調(diào)整器電路
演示板DC2218A
Demonstration circuit DC2218A is a matrix LED dimmersystem featuring the LT3965 8-switch matrix LED dimmerIC. There are 16 500mA LEDs that can be individuallyturned on, off, or PWM dimmed with two 8-switch LEDdimmer LT3965 ICs. The two strings of LEDs are drivenwith two buck LED driver outputs of the LT3797 triple LEDcontroller IC. The third channel of the LT3797 serves as a30V pre-boost voltage regulator to provide a proper inputvoltage to the two buck LED driver channels. DC2218Acan be driven from a 9V to 30V input and can survivetransients up to 36V.
A pre-programmed DC2026C Linduino™ One demo circuitis attached to the DC2218A matrix LED dimmer shield tocreate a full matrix LED dimmer system. With the Linduino One attached as an under-shield microcontroller board, theentire system can be powered from either a 9V to 36V labpower supply or battery connected to the EMIVIN bananajacks or from a 12V 4A+ AC/DC converter connected tothe J7 barrel jack connector.
DC2218A can be operated by connecting 12V power to theinput and selecting 7 pre-programmed patterns with rotaryswitch S1. When connected to a PC through a USB cable,an eighth setting of S1 (position 7) allows DC2218A to beoperated with a graphical user interface (GUI).
The LT3965 data sheet gives a complete description ofthe part, operation and applications information. The datasheet must be read in conjunction with this demo manualfor demonstration circuit DC2218A. The LT3965EFE isassembled in a 28-lead plastic TSSOP (FE) package witha thermally enhanced ground pad. Proper board layout is essential for maximum thermal performance.
圖4.演示板DC2218A測試建立圖
圖5.演示板DC2218A電路圖(1)
圖6.演示板DC2218A電路圖(2)
演示板DC2218A材料清單:
圖7.演示板DC2218A PCB元件布局圖(正面)
圖8.演示板DC2218A PCB元件布局圖(背面) |
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