LTC1702C LINER [Linear Technology], LTC1702C Datasheet
LTC1702C
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LTC1702C Summary of contents
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Switching Regulator Controller FEATURES Two Independent Controllers in One Package Two Sides Run Out-of-Phase to Minimize C All N-Channel External MOSFET Architecture No External Current Sense Resistors Excellent Output Regulation: 1% Total Output Accuracy 550kHz Switching Frequency Minimizes External ...
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... Input Voltage SW n .......................................................... – All Other Inputs ......................... – 0. Peak Output Current < ............................................................... 5A Operating Temperature Range LTC1702C ............................................... LTC1702I ........................................... – Storage Temperature Range ................. – 150 C Lead Temperature (Soldering, 10 sec).................. 300 C ELECTRICAL CHARACTERISTICS The denotes specifications which apply over the full operating temperature range, otherwise specifications are ...
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... L Relative to Converter 1 (Note 6) V < MAX V > MAX Test Circuit 2000pF (Note 7) L Test Circuit 2000pF (Note 0V, LTC1702C MAX I = 0V, LTC1702I MAX V Relative to Regulated V FB OUT PGOOD = 1mA V < PGOOD (Note 7) FB PGOOD V Relative to Regulated V ...
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LTC1702 W U TYPICAL PERFOR A CE CHARACTERISTICS Efficiency vs Load Current 100 3.3V OUT V = 2.5V OUT 1.6V OUT LOAD CURRENT (A) 1702 ...
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PIN FUNCTIONS PV (Pin 1): Driver Power Supply Input power to the two BG n output drivers. PV connected to a voltage high enough to fully turn on the external MOSFETs QB1 and QB2. PV ...
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LTC1702 PIN FUNCTIONS FB2 (Pin 14): Controller 2 Feedback Input. See FB1. COMP2 (Pin 15): Controller 2 Loop Compensation. See COMP1. RUN/SS2 (Pin 16): Controller 2 Run/Soft-start. See RUN/ SS1. FAULT (Pin 17): Output Overvoltage Fault (Latched). ...
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TEST CIRCUIT f OSC MEASURED 10k V PGOOD1 V FB1 U U APPLICATIONS INFORMATION OVERVIEW The LTC1702 is a dual, step-down (buck), voltage mode feedback switching regulator controller designed to be used in a synchronous ...
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LTC1702 U U APPLICATIONS INFORMATION 2-Step Conversion “2-step” architectures use a primary regulator to convert the input power source (batteries or AC line voltage intermediate supply voltage, often 5V. This intermediate voltage is then converted to the low ...
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U U APPLICATIONS INFORMATION remember that the power losses are proportional to I meaning that the actual power wasted is reduced by a factor of 3.75. The reduced input ripple voltage also means less power is lost in the input ...
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LTC1702 U U APPLICATIONS INFORMATION amp of continuous current with peak currents slew large MOSFET gates quickly. The external MOSFETs are connected with the drain of QT attached to the input supply and the source of ...
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U U APPLICATIONS INFORMATION improves loop phase margin (see Figure 3). The Feedback Loop/Compensation section contains a detailed explana- tion of type 3 feedback loops. + 0.8V COMP FB FB – Figure 3. “Type 3” Feedback Loop ...
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LTC1702 U U APPLICATIONS INFORMATION SHUTDOWN/SOFT-START Each half of the LTC1702 has a RUN/SS pin. The RUN/SS pins perform two functions: when pulled to ground, each shuts down its half of the LTC1702, and each acts as a conventional soft-start ...
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U U APPLICATIONS INFORMATION Any time and the current flowing to the output is reasonably large, the SW node at the drain of QB will be somewhat negative with respect to PGND. The LTC1702 senses this voltage ...
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LTC1702 U U APPLICATIONS INFORMATION ripple voltage and frequency remain constant at all loads, easing filtering requirements. Circuits that take advantage of this behavior can force the LTC1702 to operate in continuous mode at all loads by tying the FCB ...
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U U APPLICATIONS INFORMATION Once again, the LTC1702 switches to a new mode to minimize efficiency loss: Burst Mode operation. As the circuit goes deeper and deeper into discontinuous mode, the total time QT and QB are on reduces. However, ...
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LTC1702 U U APPLICATIONS INFORMATION FAULT mode is used, a Schottky diode should be added with its cathode at the output and its anode at ground to clamp the negative voltage to a safe level and prevent possible damage to ...
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U U APPLICATIONS INFORMATION charge, actual parasitic drain-source capacitance and Miller-multiplied gate-drain capacitance, but can be ap- proximated as a single capacitance from gate to source. Regardless of where the charge is going, the fact remains that it all has ...
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LTC1702 U U APPLICATIONS INFORMATION must be low enough to keep the initial drop as QT turns on within reason (100mV or so); its RMS current capability must be adequate to withstand the 4.6A at the input and the capacitance ...
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U U APPLICATIONS INFORMATION from C (time point A). 50% of the way through, TG2 IN turns on and the total current is 13A (time point B). Shortly thereafter, TG1 turns off and the current drops to 10A (time point ...
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LTC1702 U U APPLICATIONS INFORMATION tantalum capacitors specifically designed for use with switching regulators. When choosing a tantalum input capacitor, make sure that it is rated to carry the RMS current that the LTC1702 will draw. If the data sheet ...
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U U APPLICATIONS INFORMATION feedback amplifier, on the other hand, gives us a handle with which to adjust the AC response. The goal is to have 180 phase shift at DC (so the loop regulates) and some- thing less than ...
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LTC1702 U U APPLICATIONS INFORMATION “Type 3” loops (Figure 11) use two poles and two zeros to obtain a 180 phase boost in the middle of the frequency band. A properly designed type 3 circuit can maintain acceptable loop stability ...
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U U APPLICATIONS INFORMATION nodes don’t corrupt the measurements or damage the analyzer. If breadboard measurement is not practical, a SPICE simulation can be used to generate approximate gain/ phase curves. Plug the expected capacitor, inductor and MOSFET values into ...
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LTC1702 U U APPLICATIONS INFORMATION CURRENT LIMIT PROGRAMMING Programming the current limit on the LTC1702 is straight- forward. The I pin sets the current limit by setting the MAX maximum allowable voltage drop across QB (the bottom MOSFET) before the ...
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U U APPLICATIONS INFORMATION LTC1702 QB BG FCB Figure 13. Regulating an Auxiliary Output with the FCB Pin with 10mV of hysteresis, allowing fairly precise control of the auxiliary voltage. If the LTC1702 ...
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LTC1702 U U APPLICATIONS INFORMATION to an intermediate supply voltage, often 5V. The LTC1702 then converts the intermediate voltage to the low voltage, high current supplies required by the system. Compared to a 1-step converter that converts a high input ...
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U U APPLICATIONS INFORMATION 2-Step Efficiency Calculation Calculating the efficiency of a 2-step converter system involves some subtleties. Simply multiplying the effi- ciency of the primary 5V or 3.3V supply by the efficiency of the 1.8V or 1.5V supply underestimates ...
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LTC1702 U U APPLICATIONS INFORMATION Maximizing Low Load Current Efficiency Low load current efficiency depends strongly on proper operation in discontinuous and Burst Mode operations ideally optimized system, discontinuous mode reduces conduction losses but not switching losses, since ...
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U U APPLICATIONS INFORMATION cycles. Over just a few cycles, however, the external components conspire to limit the speed that the output can move. Consider our typical 5V to 1.6V circuit, sub- jected load transient. ...
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LTC1702 U U APPLICATIONS INFORMATION Making L smaller than this optimum value yields little or no improvement in transient response. As the output voltage recovers, the inductor current will briefly rise above the level of the output current to replenish ...
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U U APPLICATIONS INFORMATION it goes out of spec. Similarly, at full load, the output current can only decrease, causing a positive shift in the output voltage; the initial low value allows it to rise further before the spec is ...
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LTC1702 U U APPLICATIONS INFORMATION FAULT BEHAVIOR Changing the Output Voltage on the Fly Some applications use a switching scheme attached to the feedback resistors to allow the system to adjust the LTC1702 output voltage. The voltage can be changed ...
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U TYPICAL APPLICATIONS LTC1702 33 ...
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LTC1702 U TYPICAL APPLICATIONS 34 ...
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PACKAGE DESCRIPTION 0.007 – 0.0098 (0.178 – 0.249) 0.016 – 0.050 (0.406 – 1.270) * DIMENSION DOES NOT INCLUDE MOLD FLASH. MOLD FLASH SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH. INTERLEAD FLASH SHALL ...
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LTC1702 U TYPICAL APPLICATION 10% + 4.75k 10 F 0.1% 10k 0.1% 330pF 68k 1k QSS1 QSS2 STBY/ON 1k 220pF 20k 56k 1% 16k SANYO 10MV1200GX (6 IN PARALLEL SANYO 6MV1500GX ...