LT3477 LINER [Linear Technology], LT3477 Datasheet
LT3477
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LT3477 Summary of contents
Page 1
... Flyback). The switching frequency is programmable from 200kHz to 3.5MHz through an external resistor. Available in thermally enhanced 20-pin (4mm × 4mm) QFN and 20-pin TSSOP packages, the LT3477 provides a complete solution for both constant-voltage and con- stant-current applications. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. ...
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... Out of Pin REF 2 U RATINGS (Note 1) Junction Temperature .......................................... 125°C Operating Temperature Range (Note 2) LT3477E ............................................. – 40°C to 85°C LT3477I ............................................ – 40°C to 125°C Storage Temperature Range ................. – 65°C to 125°C Lead Temperature (Soldering, 10 sec) TSSOP .............................................................. 300° SP1 ...
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... Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: The LT3477E is guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the – 40°C to 85°C operating W U ...
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... LT3477 W U TYPICAL PERFOR A CE CHARACTERISTICS SHDN Pin Turn-On Threshold 1.6 1.4 1.2 1.0 – 100 125 –25 0 TEMPERATURE (°C) 3477 G04 Soft-Start Pin Current –50 – 100 125 150 TEMPERATURE (°C) 3477 G07 FBP Pin Bias Current 50 “+” INDICATES THE CURRENT ...
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... First Current Sense Adjustment. ADJ1 Setting I ADJ1 the sensed voltage of the first current sense amplifier linearly current sense voltage is 100mV. If current sense ampli- fier 1 is not used, always tie I LT3477 Current Sense Voltage vs I ADJ V = 10V CM 100 200 ...
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... Exposed Pad (Pin 21/Pin 21): Power Ground. Must be soldered to PCB ground for electrical contact and rated thermal performance – A4 SLOPE + Σ Figure 1. LT3477 Block Diagram – OSCILLATOR R T 3477 F01 3477fb ...
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... U OPERATIO The LT3477 uses a fixed frequency, current mode control scheme to provide excellent line and load regulation. Operation can be best understood by referring to the Block Diagram in Figure 1. The start of each oscillator cycle sets the SR latch and turns on power switch Q1. The signal at the noninverting input of the PWM comparator (A4 SLOPE) is proportional to the sum of the switch current and oscillator ramp ...
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... TDK (847) 803-6100 Inductor Selection Several inductors that work well with the LT3477 are listed in Table 2. However, there are many other manufacturers and devices that can be used. Consult each manufacturer for more detailed information and their entire range of parts. Ferrite core inductors should be used to obtain the best efficiency ...
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... Considerations When Sensing Input Current In addition to regulating the DC output current for current- source applications, the constant-current loop of the LT3477 can also be used to provide an accurate input current limit. Boost converters cannot provide output short-circuit protection, but the surge turn-on current can R3 be drastically reduced using the LT3477 current sense at the input ...
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... A typical value for the soft-start capaci- tor is 10nF. and C com- Switching Frequency C C The switching frequency of the LT3477 is set by an external resistor attached to the R pin open. A resistor must always be connected for proper ), which C operation. See Table 4 and Figure 4 for resistor values and corresponding frequencies. ...
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... Another advantage of PWM dimming over analog dimming is that a wider dimming range is possible. The LT3477 is a DC/DC converter that is ideally suited for LED applications. For the LT3477, analog dimming offers a dimming ratio of about 10:1; whereas, PWM dimming with the addition of a few external components results in a wider dimming range of 500:1 ...
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... IN 4 LEDs BOOST 300mA Figure 7b. PWM Dimming Waveforms 2.0µ 3.3µ SP1 SN1 V FBN IN I ADJ1 FBP I ADJ2 SHDN LT3477 V REF I SS SP2 C SS 33nF I SN2 V C GND D2 NMOS1 10nF 3477 F07b D1 OUT C2 10µF 1M 75k ...
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... GND D2 3477 F08a NMOS1 C C 0.1µF PWM 5V/DIV I L 500mA/DIV I LED 500mA/DIV 2ms/DIV PV = 32V PWM FREQUENCY = 100Hz IN 6 LEDs BUCK MODE 300mA Figure 8b. PWM Dimming Waveforms LED1 LED6 1k 1k PWM NMOS2 C2 1µF D1 280k 10k R T 6.81k 3477 F08b LT3477 3477fb 13 ...
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... Figure 9a. 10V to 2 White LEDs: Buck-Boost Mode with PWM Dimming 500mA/DIV PMOS L1 4.7µ 10V C1 3.3µ SP1 SN1 ADJ1 I ADJ2 SHDN LT3477 33nF V C GND D2 PWM NMOS1 R C 100k 1. 10nF PWM 10V/DIV I L 1A/DIV I LED 2ms/DIV ...
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... FBN SP2 SN2 33nF 10µF 10k 18.2k 3477 TA02a D1 12V 0. 200k C2 FBN 10µ SP2 23.2k I SN2 10nF 17.8k 3477 TA04a LT3477 Efficiency 0.1 0.2 0.3 0.4 0.5 0.6 0.7 I (A) OUT 3477 TA02b Efficiency ...
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... LED4 SP1 SN1 3. ADJ1 3.3µF I ADJ2 SHDN SHDN LT3477 REF R C FBP GND 4.7nF C1: NIPPON UNITED CHEMICON NTS40X5R1H225M C2: TAIYO YUDEN GMK316BJ105ML C3: TAIYO YUDEN LMK316BJ475 L1: TOKO A814AY-330M D1: DIODES INC DFLS140 3.3µ ...
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... SN2 V R REF T FBP GND 33nF 10nF C1: TAIYO YUDEN LMK316BJ335ML C2: MURATA GRM31CR71E475KA88L D1: DIODES, INC. B320A L1: TOKO FDV0630-4R7M Efficiency 4.2V IN 0.2 0.4 0.8 0.6 1.0 I (A) OUT 3477 TA06b LT3477 R1 D1 0.1Ω R3 200k 4.7µF 10k 18k 3477 TA06a V (V) I (A) IN OUT 2.7 0.57 3.6 0.74 4.2 0.83 5 0.93 8 1.0 3477fb 17 ...
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... LT3477 PACKAGE DESCRIPTIO 4.50 ± 0.05 3.10 ± 0.05 2.45 ± 0.05 (4 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 4.00 ± 0.10 PIN 1 TOP MARK (NOTE 6) NOTE: 1. DRAWING IS PROPOSED TO BE MADE A JEDEC PACKAGE OUTLINE MO-220 VARIATION (WGGD-1)—TO BE APPROVED 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH ...
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... BSC 0.195 – 0.30 (.0077 – .0118) 4. RECOMMENDED MINIMUM PCB METAL SIZE FOR EXPOSED PAD ATTACHMENT MILLIMETERS (INCHES) *DIMENSIONS DO NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.150mm (.006") PER SIDE LT3477 6.40 – 6.60* (.252 – .260) 3.86 (.152 6.40 2.74 (.252) ( ...
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... LED4 L1 33µ SP1 SN1 FBN IN 3. ADJ1 3.3µF I ADJ2 LT3477 SHDN SHDN REF R C FBP GND 4.7nF C1: NIPPON UNITED CHEMICON NTS40X5R1H225M C2: TAIYO YUDEN GMK316BJ105ML C3: TAIYO YUDEN LMK316BJ475 L1: TOKO A814AY-330M D1: DIODES INC DFLS140 ...