LM3444MM/NOPB National Semiconductor, LM3444MM/NOPB Datasheet
LM3444MM/NOPB
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LM3444MM/NOPB Summary of contents
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... Additional features include thermal shutdown, current limit and V under-voltage lockout. The LM3444 is CC available in a low profile MSOP-10 package. Typical LM3444 LED Driver Application Circuit © 2011 National Semiconductor Corporation LM3444 Features ■ Application voltage range 80V ■ Capable of controlling LED currents greater than 1A ■ ...
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Connection Diagram Ordering Information Order Number Spec. Package Type LM3444MM NOPB MSOP-10 LM3444MMX NOPB MSOP-10 Pin Descriptions MSOP Name Description internal connection. Leave this pin open internal connection. Leave this pin open ...
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... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. V and GATE to GND CC ISNS to GND FILTER and COFF to GND COFF Input Current Continuous Power Dissipation (Note 2) Electrical Characteristics over the full Operating Temperature Range ( T design, or statistical correlation ...
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Note 4: Junction-to-ambient thermal resistance is highly application and board-layout dependent. In applications where high maximum power dissipation exists, special care must be paid to thermal dissipation issues in board design. In applications where high power dissipation and/or poor package ...
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Off Threshold (C11) vs Temperature 1.29 1.28 1.27 OFF Threshold at C11 1.26 1.25 -50 -30 - 110130150 TEMPERATURE (°C) Leading Edge Blanking Variation Over Temperature Normalized Variation in f 30127574 30127572 5 over V ...
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Simplified Internal Block Diagram www.national.com FIGURE 1. Simplified Block Diagram 6 30127511 ...
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Application Information FUNCTIONAL DESCRIPTION The LM3444 contains all the necessary circuitry to build a line- powered (mains powered) constant current LED driver. Theory of Operation Refer to Figure 2 below which shows the LM3444 along with basic external circuitry. FIGURE ...
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VALLEY-FILL CIRCUIT V supplies the power which drives the LED string. Diode BUCK D3 allows V to remain high while V+ cycles on and off. BUCK V has a relatively small hold capacitor C10 which reduces BUCK the voltage ripple ...
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BUCK CONVERTER The LM3444 is a buck controller that uses a proprietary con- stant off-time method to maintain constant current through a string of LEDs. While transistor Q2 is on, current ramps up through the inductor and LED string. A ...
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During the off-period denoted by t OFF continues to flow through the LEDs via D10. THERMAL SHUTDOWN Thermal shutdown limits total power dissipation by turning off the output switch when the IC junction temperature exceeds 165°C. After thermal shutdown occurs, ...
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Worst case scenario for minimum on time is when V its maximum voltage (AC high line) and the LED string voltage ( its minimum value. LED The maximum voltage seen by the Buck Converter is: INDUCTOR SELECTION ...
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FIGURE 10. Inductor Current Waveform in CCM Knowing the desired average LED current, I inal inductor current ripple, Δi , the peak current for an appli- L cation running in continuous conduction mode (CCM) is defined as follows: Or the ...
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FIGURE 12. AC Line Figure 12 shows the AC waveform. One can easily see that the peak voltage (V ) will always be: PEAK The voltage at V with a valley fill stage of two will look BUCK similar to ...
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Calculate nominal line voltage: OFF BUCK 4. Calculate t at high line to ensure that ON(MIN) t > 200 ns: ON(MIN) 5. Calculate C11 and R4: 6. Choose current through R4: (between 50 µA and 100 ...
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LM3444 Design Example 1 Input = 90V to 135V LED String Application @ 400 mA LED 15 30127569 www.national.com ...
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Bill of Materials Qty Ref Des 1 U1 IC, CTRLR, DRVR-LED, MSOP10 1 BR1 Bridge Rectifiier, SMT, 400V, 800 Common mode filter DIP4NS, 900 mA, 700 1 L2 Inductor, SHLD, SMT, 1A, 470 µH 2 L3, L4 ...
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Physical Dimensions inches (millimeters) unless otherwise noted For Ordering, Refer to Ordering Information Table MSOP-10 Pin Package (MM) NS Package Number MUB10A 17 www.national.com ...
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