LT1935 Linear Technology, LT1935 Datasheet
LT1935
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LT1935 Summary of contents
Page 1
... Its unprecedented 2A, 40V internal switch allows high output currents to be generated in a small footprint. Intended for space-conscious applica- tions, the LT1935 switches at 1.2MHz, allowing the use of tiny, low profile inductors and capacitors 2mm or less in height. The NPN switch achieves independent of supply voltage, resulting in high efficiency even at maximum power levels from a 3V input ...
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... SHDN Input High Voltage SHDN Input Low Voltage Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LT1935ES5 is guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the – 40°C to 85°C operating 2 U ...
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... SWITCH CURRENT (A) Frequency Foldback 1 25°C A 1.2 1.0 0.8 0.6 0.4 0 0.2 FEEDBACK VOLTAGE (V) 1935 G07 LT1935 Undervoltage Lockout 2.4 2.3 2.2 2.1 2.0 1.9 1.8 125 –50 – TEMPERATURE (°C) 1935 G02 Peak Switch Current vs SHDN Pin Voltage (Soft-Start) 4 50% DUTY CYCLE T = 25° 3 ...
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... FB R2 (EXTERNAL) U OPERATIO The LT1935 uses a constant frequency, current mode control scheme to provide excellent line and load regula- tion. Operation can be best understood by referring to the Block Diagram in Figure 2. At the start of each oscillator cycle, the SR latch is set, turning on the power switch Q1. ...
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... Use a 4.7µF ceramic capacitor to bypass the input of the LT1935. Be aware that the switching regulators require a low impedance input supply. Additional bulk capacitance may be required if the LT1935 circuit is more than a few inches away from the power source. If there are low ESR capacitors nearby, the input bypass capacitor can be reduced to 2.2µ ...
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... W U Soft Start The SHDN pin can be used to soft start the LT1935, reducing the maximum input current during start up. The SHDN pin is driven through an external RC filter to create a ramp at this pin. Figure 6 shows the start-up waveforms with and without the soft start circuit. Without soft start, the input current peaks at ~3A ...
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... JEDEC PACKAGE REFERENCE IS MO-193 Efficiency OUT 3. 2. 200 400 600 800 1000 LOAD CURRENT (mA) V OUT 12V 320mA R1 84.5k C2 22µF R2 10k 1935 TA02 2.90 BSC (NOTE 4) 0.30 – 0.45 TYP 5 PLCS (NOTE 3) 0.01 – 0.10 1.90 BSC S5 TSOT-23 0302 LT1935 1200 1935f 7 ...
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... C3: X5R OR X7R 25V D1: MBRM120 OR EQUIVALENT D2, D3: BAT-54S OR EQUIVALENT L1: SUMIDA CDRH4D28-2R2 5V SEPIC Converter C3 L1 2.2µF 4.7µ 47pF 4.7µF 29.4k LT1935 ON OFF SHDN FB GND R2 10k C1, C3: X5R OR X7R 10V D1: ON SEMI MBRM120 C2: X5R OR X7R 6.3V L1, L2: SUMIDA CDRH4D18-4R7 www.linear.com ● 16V 10mA C3 1µF ...