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Moteur de recherche de fiches techniques de composants électroniques |
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Moteur de recherche de fiches techniques de composants électroniques |
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LC5210D Fiches technique(PDF) 10 Page - Sanken electric |
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LC5210D Fiches technique(HTML) 10 Page - Sanken electric |
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10 / 16 page  10 SANKEN ELECTRIC CO., LTD. LC5200-DS, Rev. 6.0 Off-Line LED Driver ICs LC5200 Series Functional Description PMW Current Control (Buck Converter) • The polarity value for current specifies a sink as "+ ," and a source as “−,” referencing the IC. • All of the parameter values used in these descriptions are typical values, unless they are specified as minimum or maximum. PWM On-Time Period At startup, or during normal operation before the output cur- rent through the LED string reaches the target current level, the internal power MOSFET turns on and the output current flows through the ION path shown in figure 2. Turning-Off Period The output current through the LED string is equivalent to the current through the detection resistor, RS, and thus the LED cur- rent is detected at the SEN pin as a voltage. When the SEN pin voltage, VSEN, is equal to the REF pin voltage, VREF, the internal power MOSFET turns off. PWM Off-Time Period When the internal power MOSFET turns off, the current recir- culation diode, D1, is forward biased by the back electromotive force (BEMF) in the inductor, L1, and D1 turns on. Then the energy stored in L1 during PWM on-time flows through the recir- culation path shown as IOFF in figure 2. Turning-On Period After the fixed off-time, tOFF, the internal power MOSFET turns on again, and the PWM on-time period repeats. The cycle is shown in figure 2 panel B. Internal PWM Control Circuit Figure 3 shows the internal PWM control circuit, and figure 4 shows the timing diagram of that circuit. When the power MOSFET turns on, both the load current and VSEN across the cur- rent detection resistor RS increase. + - + - Logic OUT To LED load SEN GND REG LC5200 PWM REF RPWM CPWM RS VREF 6V 2V 3V Comp1 Comp2 Gate Driver R Q S Blank Pulse I O Figure 3. Current Control Circuit Figure 4. Current Control Circuit Timing Chart Figure 2. Current Control of Buck Converter IOFF GND ION OUT SEN GND RS D1 L1 LC5200 VIN VLED VSEN MOSFET VSEN VREF LED current ILED ION IOFF OFF ON tOFF OFF ION IOFF ON MOSFET (A) (B) VPWM Comp1 Negative IN Comp2 Comp2 OUT A B EN VSEN VREF LED Current ILED ION IOFF tOFF ION IOFF MOSFET DS DS EN DS OT Comp OUT ON OFF ON tBLK tBLK |
Numéro de pièce similaire - LC5210D |
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Description similaire - LC5210D |
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