lt3799 Linear Technology Corporation, lt3799 Datasheet
lt3799
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lt3799 Summary of contents
Page 1
... LT3799 typically achieves power factors of 0.97. The FAULT pin provides notification of open and short LED conditions. The LT3799 uses a micropower hysteretic start-up to efficiently operate at offline input voltages, with a third winding to provide power to the part. An internal LDO provides a well regulated supply for the part’s internal circuitry and gate driver ...
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... REF, SENSE ......................................................................0.4V DCM .......................................................................±3mA Maximum Junction Temperature .......................... 125°C Operating Temperature Range (Note 2) LT3799E ............................................ –40°C to 125°C LT3799I ............................................. –40°C to 125°C Storage Temperature Range .................. –65°C to 150°C ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL LT3799EMSE#PBF LT3799EMSE#TRPBF ...
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... Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LT3799E is guaranteed to meet performance specifications from 0°C to 125°C junction temperature. Specifications over the –40°C The denotes the specifications which apply over the full operating l = 25° ...
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... LT3799 TYPICAL PERFORMANCE CHARACTERISTICS V Start-Up Voltage IN vs Temperature 24.0 23.5 23.0 22.5 22.0 – –25 100 TEMPERATURE (°C) 3799 G01 V vs Temperature REF 2.100 2.075 2.050 2.025 2.000 NO LOAD 1.975 200µA LOAD 1.950 1.925 1.900 – 100 –25 TEMPERATURE (°C) 3799 G05 ...
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... TEMPERATURE (°C) Maximum Shunt Current vs Temperature 125 –50 – TEMPERATURE (°C) LT3799 CT Pin Low Threshold vs Temperature 0.4 0.3 0.2 0.1 0 125 100 – –25 TEMPERATURE (°C) 3799 G10 INTV 10.25 10.20 PART ON 10.15 10.10 10.05 10.00 PART OFF 9 ...
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... LT3799 TYPICAL PERFORMANCE CHARACTERISTICS LED Current vs Input Voltage 1.20 PAGE 17 SCHEMATIC: OPTIMIZED FOR 120V 1.15 1.10 1.05 1.00 0.95 0.90 0.85 0.80 90 100 110 120 130 140 3799 G18 Power Factor vs Input Voltage 1.00 0.99 0.98 0.97 0.96 0.95 0.94 0.93 0.92 PAGE 17 SCHEMATIC: 0.91 OPTIMIZED FOR 120V 0.90 90 100 110 120 130 140 3799 G21 Efficiency vs Input Voltage ...
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... Adjustment Pins. These pins control the output current. The lowest value of the three CTRL inputs is compared to the negative input of the operational amplifier. Due to the unique nature of the LT3799 control loop, the maximum current does not directly correspond to the V SENSE (Pin 15): The Current Sense Input for the Control Loop ...
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... LT3799 BLOCK DIAGRAM S&H CT FAULT 6 A3 DETECTION C4 FAULT – + 600mV – + COMP 7 SW1 C6 1M – COMP 8 – CTRL1 + CTRL2 2 CTRL3 REF L1C R10 10 16 DCM V IN_SENSE + 1.22V A8 – ONE SHOT CURRENT COMPARATOR – ...
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... Histori- cally, this has been done with an opto-isolator. The LT3799 uses a novel method of using the external MOSFETs peak current information from the sense resistor to calculate the output current of a flyback converter without the need of an opto-coupler ...
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... F01 a TRIAC dimmer. TRIAC dimmers are not ideal switches when turned off and allow milliamps of current to flow through them. This is an issue if used with a low quiescent part such as the LT3799. Instead of turning the main power + node, thus voltage is connected to a resistor + is held constant ...
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... Start-Up The LT3799 uses a hysteretic start-up to operate from high offline voltages. A resistor connected to the supply voltage protects the part from high voltages. This resis- ...
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... SENSE where R1 is the resistor connected to the V CTRL pin and R2 is the resistor connected to the CTRL pin and ground. When used with an AC input voltage, the LT3799 senses when the V goes below 65mV and above 65mV IN_SENSE for detecting when the TRIAC is off. During this low input voltage time, the output current regulation loop is off but the part still switches ...
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... The minimum volt- age of the switch node during this discontinuous ring is V – V • N. The LT3799 turns the switch back OUT this time, during the discontinuous switch waveform, by sensing when the slope of the switch waveform goes from negative to positive using the dv/dt detector ...
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... The overshoot is proportional to the supply voltage, so again this affects the line regulation. Universal Input The LT3799 operates over the universal input range of 90V to 265V . Output current regulation error may AC ...
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... Linear Technology has worked with several leading magnetic component manufacturers to produce predesigned flyback transformers for use with the LT3799. Table 1 shows the details of several of these transformers. Loop Compensation The current output feedback loop is an integrator con- figuration with the compensation capacitor between the negative input and output of the operational amplifier ...
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... Multiple Zener diodes in series may be needed for higher output power applications to keep the Zener’s temperature within the specification. During a shorted LED condition, the LT3799 operates at the minimum operating frequency. In normal operation, the third winding provides power to the IC, but the third winding voltage is zero during a shorted LED condition. This causes the part’ ...
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... SENSE CTRL2 V CTRL1 INTVCC 100k R10 NTC 24.9k GND + – FAULT CT COMP COMP C7, 0.1µF R10 (Ω) R (Ω) R1 (Ω) S 16.2k 0.05 24.9k 0.075 1.00k 15.4k 0.05 LT3799 4:1 100k Z1 R15 C10 4.99k 560µ × 2 R16 20W Z2 20 LED M1 POWER 0.05 C8 4.7µF 2.2nF 3799 TA02 C2 (µF) C3 (µ ...
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... FAIRCHILD FQU5N60 18 Universal Input TRIAC Dimmable 4W LED Driver 68nF 100k R3 R8 499k C2 R1 100k 4.7pF C5 750 R4 10µ F 499k IN_SENSE R5 LT3799 3.48k V REF R18 CTRL3 R9 100k 40.2k CTRL2 CTRL1 R10 32.4k + FAULT CT COMP FAULT C6 C7, 0.1µF 0.1µ 20:5:1 C4 R13 10k ...
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... DETAIL “A” 1.10 (.043) MAX SEATING PLANE 0.17 – 0.27 (.007 – .011) 0.50 TYP (.0197) BSC LT3799 8 0.35 REF 1.651 ± 0.102 0.12 REF (.065 ± .004) DETAIL “B” CORNER TAIL IS PART OF THE LEADFRAME FEATURE. DETAIL “B” FOR REFERENCE ONLY 9 NO MEASUREMENT PURPOSE 0.280 ± ...
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... 0.22µF 100k 499k 250 100k 4.7pF 10µ F 250 499k D3 V DCM IN_SENSE R5 LT3799 3.48k V REF R9 CTRL3 GATE 40.2k CTRL2 SENSE V CTRL1 INTVCC R17 R10 10k 23.2k GND + – FAULT CT COMP COMP C7, 0.1µF C6 0.1µF COMMENTS V : 4.5V to 40V, V ...