LTC3731HG#PBF Linear Technology, LTC3731HG#PBF Datasheet

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... Please refer to the LTC3731 data sheet for 0°C to 70°C and –40°C to 85°C rated versions. L, LT, LTC, LTM, Linear Technology, the Linear logo, Burst Mode, OPTI-LOOP and PolyPhase are registered trademarks and Stage Shedding is a trademark of Linear Technology Corporation. ...

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... PINS 5 AND 6 CAN BE GROUNDED OR NC PIN 7 MUST BE LEFT AS NC orDer inForMaTion LEAD FREE FINISH TAPE AND REEL LTC3731HG#PBF LTC3731HG#TRPBF LTC3731HUH#PBF LTC3731HUH#TRPBF Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based finish parts. ...

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T SYMBOL PARAMETER Main Control Loop V Regulated Voltage at EAIN REGULATED V Maximum Current Sense Threshold SENSEMAX I Maximum Current Threshold Match MATCH V Output Voltage Load Regulation LOADREG V Output ...

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LTC3731H elecTrical characTerisTics temperature range, otherwise specifications are at T SYMBOL PARAMETER Power Good Output Indication V PGOOD Voltage Output Low PGL I PGOOD Output Leakage PGOOD PGOOD Trip Thresholds V V Ramping Negative PGTHNEG EAIN V V Ramping Positive ...

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Typical perForMance characTerisTics Efficiency vs I (Figure 14) OUT 100 V = OPEN 90 FCB FCB FCB 1.5V OUT 0 ...

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LTC3731H Typical perForMance characTerisTics Short-Circuit Arming and Latchoff vs Temperature 5 ARMING 4 LATCHOFF –50 – 100 125 150 TEMPERATURE (°C) 3731H G10 Maximum SENSE RUN/ ...

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Typical perForMance characTerisTics Shed Mode at 1 Amp, Light Load Current (Circuit of Figure 14) V OUT AC, 20mV/DIV V SW1 10V/DIV V SW2 10V/DIV V SW3 10V/DIV V = 12V 4µs/DIV 1.5V OUT ...

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LTC3731H pin FuncTions BG1 to BG3: High Current Gate Drives for Bottom N-Channel MOSFETs. Voltage swing at these pins is from ground BOOST1 to BOOST3: Positive Supply Pins to the Topside Floating Drivers. Bootstrapped capacitors, charged ...

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FuncTional DiagraM PLLIN PHASE DET F IN 50k PLLFLTR CLKOUT CLK1 CLK2 OSCILLATOR PHASMD CLK3 PGOOD – 0.66V + 100µs EAIN DELAY – PROTECTION + 0.54V FCB + FCB 0.6V – R1 EAIN V FB – ...

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LTC3731H operaTion (Refer to Functional Diagram) Main Control Loop The IC uses a constant frequency, current mode step-down architecture. During normal operation, each top MOSFET is turned on each cycle when the oscillator sets the RS latch, and turned off ...

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Functional Diagram) C) Continuous Current Operation Tying the FCB pin to ground will force continuous current operation. This is the least efficient operating mode, but may be desirable in certain applications. The output can source or sink ...

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LTC3731H operaTion (Refer to Functional Diagram) Input Undervoltage Reset The RUN/SS capacitor will be reset if the input voltage ( allowed to fall below approximately 4V. The CC capacitor on the RUN/SS pin will be discharged until the ...

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In a PolyPhase converter, the net ripple current seen by the output capacitor is much smaller than the individual inductor ripple currents due to the ripple cancellation. The details on how to calculate the net output ripple current ...

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LTC3731H applicaTions inForMaTion MOSFET in applications that have an output voltage that is less than 1/3 of the input voltage. In applications where V >> the top MOSFETs’ on-resistance is normally IN OUT less important for overall efficiency ...

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Both MOSFETs have I R losses while the topside N-channel equation includes an additional term for transition losses, which peak at the highest input voltage. For V the high current efficiency generally improves with larger MOSFETs, while ...

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LTC3731H applicaTions inForMaTion reduced by the factor, N, due to the effective increase in the frequency of the current pulses. Ceramic capacitors are becoming very popular for small designs but several cautions should be observed. “X7R”, “X5R” and “Y5V” are ...

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Other capacitor types include Sanyo POS-CAP , Sanyo OS-CON, Nichicon PL series and Sprague 595D series. Consult the manufacturer for other specific recommendations. R Selection for Output Current SENSE ...

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LTC3731H applicaTions inForMaTion An internal 1.5µA current source charges up the C capacitor. When the voltage on RUN/SS reaches 1.5V, the controller is permitted to start operating. As the voltage on RUN/SS increases from 1.5V to 3.5V, the internal current ...

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Current Foldback In certain applications, it may be desirable to defeat the internal current foldback function. A negative impedance is experienced when powering a switching regulator. That is, the input current is higher at a lower V as ...

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LTC3731H applicaTions inForMaTion the PLLFLTR pin. If the external and internal frequencies are the same, but exhibit a phase difference, the current sources turn on for an amount of time corresponding to the phase difference. Thus, the voltage on the ...

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Efficiency Considerations The percent efficiency of a switching regulator is equal to the output power divided by the input power times 100 often useful to analyze individual losses to determine what is limiting the efficiency and ...

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LTC3731H applicaTions inForMaTion Automotive Considerations: Plugging into the Cigarette Lighter As battery-powered devices go mobile, there is a natural interest in plugging into the cigarette lighter in order to conserve or even recharge battery packs during operation. But before you ...

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The power dissipation on the topside MOSFET can be estimated. Using a Fairchild FDS6688 for example 7mΩ 15nC/15V = 1000pF . At maximum input MILLER voltage with T(estimated) = 50° ...

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LTC3731H applicaTions inForMaTion BOLD LINES INDICATE HIGH, SWITCHING CURRENTS. KEEP LINES TO A MINIMUM LENGTH. INDUCTOR LTC3731H + SENSE 1000pF – SENSE OUTPUT CAPACITOR Figure 12. Kelvin Sensing SW1 R ...

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The left half of the circuit gives rise to the “noise” generated by a switching regulator. The ground terminations of the synchronous ...

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LTC3731H applicaTions inForMaTion The worst-case input RMS ripple current for a single stage design peaks at twice the value of the output voltage. The worst-case input RMS ripple current for a two stage design results in peaks at 1/4 and ...

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Total of all three main MOSFETs’ DC loss: 2     OUT MAX =         MAIN ...

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LTC3731H Typical applicaTions 1µF OPTIONAL FILTER FOR SYNCHRONIZATION 1000pF SYNC IN 0.01µF PLLIN 300kHz 10k 3 PLLFLTR 4 FCB 5 100pF NC 6 6.04k 9.09k 300pF 8 EAIN 9 SGND 10 ...

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Typical applicaTions SYNC IN 1k 68pF 8.2k 3.3k 4.64k 14.7k 220pF 330pF EAIN 1000pF – 1000pF – S2 – S3 1000pF + 0.1µF S3 RUN/SS 357k V IN 121k ...

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LTC3731H Typical applicaTions 3-Phase Boost Converter OUT IN C18 C19 R2 LT3010 1µF 1µ 50V 10V SHDN ADJ GND R5 249k OPT OPT ...

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DescripTion 7.8 – 8.2 0.42 ±0.03 RECOMMENDED SOLDER PAD LAYOUT 5.00 – 5.60** (.197 – .221) 0.09 – 0.25 0.55 – 0.95 (.0035 – .010) (.022 – .037) NOTE: 1. CONTROLLING DIMENSION: MILLIMETERS MILLIMETERS 2. DIMENSIONS ARE IN (INCHES) ...

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LTC3731H package DescripTion 5.50 0.05 4.10 0.05 3.45 0.05 3.50 REF (4 SIDES) 3.45 0.05 RECOMMENDED SOLDER PAD LAYOUT APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 5.00 0.10 (4 SIDES) PIN 1 TOP MARK (NOTE 6) NOTE: 1. ...

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... UH package added. Changes reflected throughout the data sheet Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. ...

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... V ≤ 5V, Active Voltage Positioning, Stage OUT ≤ 38V, 0.8V ≤ V ≤ 5V, Active Voltage Positioning, Stage OUT ≤ 12V = 20ns ON(MIN) ≤ 5.25V LT 0510 REV B • PRINTED IN USA  LINEAR TECHNOLOGY CORPORATION 2010 OUT 28V IN 4 ≤ 38V, IN ≤ 24V, IN ≤ ...