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General => Matemáticas => Mensaje iniciado por: jingwxs04 en Septiembre 17, 2013, 06:43:40 am
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Linear LT3791 of Company step up – step down four switch that move ahead simultaneously LED drive controller, can make VIN higher than, lower than or mean VOUT, efficiency is up to 98.5%, input the voltage 4.7V 60V, the voltage 0V 60V of the output, LED electric current precision 6%, very colored PWM and simulation adjust luminance, each IC input power 100W or greater than 100W. Used mainly in the car headlight / go light and common illumination.
Its continuously invariable frequency and forcing the invariable electric current mode framework, make it can adjust, or the frequency of synchronous 200kHz 700kHz. Do not current sensor (http://www.transducersensor.com/Electrical-Isolation-Transducer/Current-Transducer/Current-Transducer.html) need the switch cycle period of upper MOSFET while stepping down or stepping up and operating. This device is that 60V inputs, 60V exports. The seamless conversion with area of job, make LT3791 become LED driver in more ideal choice of the car, industry, battery electric power system.
LT3791 has input electric current watch-dogs, LED electric current watch-dog while restarting or locking, and the guarantee that LED opens a way or shorts out.
Fig. 1 LT3791 block-diagram
LT3791 main characteristic
? 4 switches of form inductor frameworks allow VIN to be higher than, is lower than or equal VOUT
? Switch over synchronously: Efficiency is up to 98.5%
? 4.7V is the width VIN range of 60V:
? Width VOUT range: 0V~60V 52V LED
? The Voltage transducer (http://www.transducersensor.com/Electrical-Isolation-Transducer/Voltage-Transducer/Voltage-Transducer.html) precision of LED electric current of 6%: 0V is less than or equal to VLED <52V
? True Color PWM and simulation adjust luminance
? LED electric current monitor exported and input the electric current to regulate
? There is not Top MOSFET that break while stepping down or stepping up
? While shut downing, VOUT and VIN disconnection
? Open a way or the short circuit LED trouble is protected
? Every IC 100W or higher one
? 38 pins TSSOP with naked pad
LT3791 application
? Car headlight /drive a vehicle light
? It is lighted that common
Fig. 2 LT3791 efficiency 98% 50W25V2A Rise – depressurization LED drive circuit diagram
Fig. 3 LT3791 efficiency 98.5% 100W 33.3V3A Rise – depressurization LED drive circuit diagram
The intersection of Fig. and 4 DC1666A demonstrate board circuit diagram demonstrate the board DC1666A
DC1666A demonstrates circuit one moves ahead simultaneously four switches step down – stepping up LED driver controller. Its input voltage is 4.7V 60V, drives LED of 2A, 25V at most. Function that DC1666A PWM and simulation with LED bunch adjusts luminance. When it is moved that LED strings together, its OPENLED indicates that reveals; When exporting and shorting out to GND, its SHORTLED indicates that reveals. Under these two kinds of situations, this IC keeps controlling, and there is good protection.
DC1666A has very high efficiency, its frequency of switch is 300kHz, and lead the open mode CCM continuously . Four switches of topological structure that it moves ahead simultaneously, are regulating 50W invariable LED while exporting the electric current step up and step down ,Efficiency is up to 98%. This circuit can be changed, is used in the application over LED of 100W. An available SYNC end son, used for moving ahead simultaneously a external clock and CLKOUT terminal station, and offer another converters and internal clocks LT3791 Synchronous resource. Three were measured the resistor has offered the invariable output electric current to control and monitoring, peak value switch electric current controls and inputs the electric current to limit and control with DC. ISMON its and IVINMON output can tell user have how much electric current flow through output and input into and detect the resistance. The small pottery imports and exports the condenser, in order to save space and cost. LED pressed and protected and adopted IC invariable voltage regulation cycle after opening a way, in order to exercise restraint in exporting about 28.3V, if LED strings together and is opened . As to low to input the voltage into to operate, when inputting the voltage and is lower than 6.5V, CTRL pin voltage reduced, and reduced luminance and restriction peak value switch electric current of LED, in order to limit the size of inductance and switch. When VIN drops to be less than 4.7V, UVLO closes LED. When inputting and rising to and is higher than 57.6V, lock the function and close the switch as protecting in excessive pressure, when VIN drops to 56.2V, open again.
It is very simple for DC1666A PWM to adjust luminance, PWM adjusts luminance MOSFET utilizes PWM to adjust luminance terminal input is led openly and closing LED bunch. PWM on as to the thing that it is supreme adjust luminance than,propose not it is last frequency to use 100Hz as by PWMing. It adjust luminance about PWM than and the informations of performance,it is last information the LT3791 data lists of the parts not to can see. It is very simple too for simulation to adjust luminance, adopt a simple CTRL terminal voltage source.
DC1666A can make the modification, in order to change this board to higher or lower power, or reach an invariable voltage regulator or battery charger with a LED driver.
LT3791 data list provides a intact one, operates and employs the description of information. The data list must be read with the service manual together, in order to understand DC1666A circuit. LT3791 assembles in one and 38 pins plastic TSSOP are encapsulated, and have heat-resisting enhanced ground cushions. The correct circuit board overall arrangement is essential to heat performance.
The details please see:
http://solution.eccn.com/solution_2012092609300138.htm
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