LTC1871EMS-7 Linear Technology, LTC1871EMS-7 Datasheet
LTC1871EMS-7
Specifications of LTC1871EMS-7
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LTC1871EMS-7 Summary of contents
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... DS PARAMETER INTV CC + INTV UV CC – INTV LT, LTC, LTM and Burst Mode are registered trademarks of Linear Technology Corporation trademark of Linear Technology Corporation. All other trademarks are the SENSE property of their respective owners. 2.2μF 100k 100V X7R Q1 FMMT625 D1 9.1V 10Ω ...
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LTC1871-7 ABSOLUTE MAXIMUM RATINGS (Note 1) V Voltage ............................................... – 0.3V to 36V IN INTV Voltage ............................................ –0. INTV Output Current .......................................... 50mA CC GATE Voltage ............................ –0. Voltages ....................................... –0.3V to ...
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ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T SYMBOL PARAMETER + V Rising RUN Input Threshold Voltage RUN – V Falling RUN Input Threshold Voltage RUN V RUN Pin Input Threshold Hysteresis RUN(HYST) I RUN Input Current RUN ...
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LTC1871-7 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T SYMBOL PARAMETER UVLO INTVCC Undervoltage Lockout Threshold ΔV INTV Regulator Line Regulation INTVCC CC ΔV IN1 ΔV INTV Regulator Line Regulation INTVCC CC ΔV IN2 V INTV Load Regulation ...
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TYPICAL PERFORMANCE CHARACTERISTICS Shutdown Mode (V) IN 18717 G04 Burst Mode I vs Temperature Q 500 400 300 200 100 0 –50 – ...
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LTC1871-7 TYPICAL PERFORMANCE CHARACTERISTICS Frequency vs Temperature 325 320 315 310 305 300 295 290 285 280 275 –50 50 100 125 150 – TEMPERATURE (°C) 18717 G13 INTV Load Regulation 7.0 ...
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PIN FUNCTIONS MODE/SYNC (Pin 5): This input controls the operating mode of the converter and allows for synchronizing the operating frequency to an external clock. If the MODE/ SYNC pin is connected to ground, Burst Mode operation is enabled. If ...
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LTC1871-7 OPERATION Main Control Loop The LTC1871 constant frequency, current mode controller for DC/DC boost, SEPIC and fl yback converter applications. With the LTC1871-7 the current control loop can be closed by sensing the voltage drop either across ...
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OPERATION In applications where fi xed frequency operation is more critical than low current effi ciency, or where the lowest output ripple is desired, pulse-skip mode operation should be used and the MODE/SYNC pin should be connected to the INTV ...
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LTC1871-7 OPERATION external frequency (above 1.3f ) can result in inadequate O slope compensation and possible subharmonic oscillation (or jitter). The external clock signal must exceed 2V for at least 25ns, and should have a maximum duty cycle of 80%, ...
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OPERATION – 1.230V + R2 Figure 7. Bypassing the LDO Regulator and Gate Driver Supply can cause the LTC1871-7 to exceed its maximum junc- tion temperature rating. The junction temperature can be estimated using the following equations: I ≈ I ...
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LTC1871-7 OPERATION The resistors R1 and R2 are typically chosen so that the error caused by the current fl owing into the FB pin dur- ing normal operation is less than 1% (this translates to a maximum value of R1 ...
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APPLICATIONS INFORMATION Application Circuits A basic LTC1871-7 application circuit is shown in Figure 9. External component selection is driven by the characteris- tics of the load and the input supply. The fi rst topology to be analyzed will be the ...
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LTC1871-7 APPLICATIONS INFORMATION Boost Converter: Ripple Current ΔI The constant ‘ χ ’ in the equation above represents the percentage peak-to-peak ripple current in the inductor, relative to its maximum value. For example, if 30% ripple current is chosen, then ...
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APPLICATIONS INFORMATION Sense Resistor Selection During the switch on-time, the control circuit limits the maximum voltage drop across the sense resistor to about 150mV (at low duty cycle). The peak inductor current is therefore limited to 150mV/R SENSE between the ...
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LTC1871-7 APPLICATIONS INFORMATION 2.0 1.5 1.0 0.5 0 – JUNCTION TEMPERATURE (°C) Figure 12. Normalized R DS(ON) From a known power dissipated in the power MOSFET, its junction temperature can be obtained using the following formula ...
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APPLICATIONS INFORMATION For some designs it may be possible to choose a single capacitor type that satisfi es both the ESR and bulk C require- ments for the design. In certain demanding applications, however, the ripple voltage can be improved ...
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LTC1871-7 APPLICATIONS INFORMATION Table 1. Recommended Component Manufacturers VENDOR AVX BH Electronics Coilcraft Coiltronics Diodes, Inc Fairchild General Semiconductor International Rectifi er IRC Kemet Magnetics Inc Microsemi Murata-Erie Nichicon On Semiconductor Panasonic Sanyo Sumida Taiyo Yuden TDK Thermalloy Tokin Toko ...
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APPLICATIONS INFORMATION During this inductor charging interval, the output capacitor must supply the load current and a signifi cant droop in the output voltage can occur. Generally good idea to choose a value of inductor ΔI between ...
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LTC1871-7 APPLICATIONS INFORMATION Checking Transient Response The regulator loop response can be verifi looking at the load transient response at minimum and maximum V . Switching regulators generally take several cycles to IN respond to an instantaneous step ...
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APPLICATIONS INFORMATION The component chosen is a 6.8μH inductor made by Cooper (part number DR127-6R8) which has a satura- tion current of greater than 13.3A. 5. Because the duty cycle is 81%, the maximum SENSE pin threshold voltage is reduced ...
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LTC1871-7 APPLICATIONS INFORMATION V OUT 1V/DIV I L 1A/DIV MOSFET DRAIN VOLTAGE 20V/DIV V = 28V 1μs/DIV 0.5A OUT V = 42V OUT D = 27% Figure 16. Switching Waveforms for the Converter in Figure 9 at ...
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APPLICATIONS INFORMATION 7. Minimize the capacitance between the SENSE pin trace and any high frequency switching nodes. The LTC1871-7 contains an internal leading edge blanking time of ap- proximately 180ns, which should be adequate for most applications ...
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LTC1871-7 APPLICATIONS INFORMATION 9. For applications with multiple switching power convert- ers connected to the same input supply, make sure that the input fi lter capacitor for the LTC1871-7 is not shared with other converters. AC input current from another ...
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APPLICATIONS INFORMATION The maximum output voltage for a SEPIC converter is MAX = – V O(MAX 1– D MAX The maximum duty cycle of the LTC1871-7 is typically 92%. SEPIC Converter: ...
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LTC1871-7 APPLICATIONS INFORMATION rating for the inductor should be checked at the minimum input voltage (which results in the highest inductor cur- rent) and maximum output current. SEPIC Converter: Power MOSFET Selection Important parameters for the power MOSFET include the ...
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APPLICATIONS INFORMATION From a known power dissipated in the power MOSFET, its junction temperature can be obtained using the following formula • FET TH(JA) The used in this equation normally ...
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LTC1871-7 APPLICATIONS INFORMATION should be verifi dedicated PC board (see Board Layout section for more information on component place- ment). Lab breadboards generally suffer from excessive series inductance (due to inter-component wiring), and these parasitics can make ...
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TYPICAL APPLICATIONS A 48V Input Flyback Converter Confi gurable to 3. Outputs R1 604k 100k 1 RUN 26.7k 1nF 82.5k 4 FREQ 5 MODE/SYNC 12. R2* 21k *R2 = 38.3k FOR V ...
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LTC1871-7 TYPICAL APPLICATIONS 47μF 20V GND ×2 RUN INPUT R8 187k 1% R13 17. DIMMING INPUT L1 10μ 18V TO 33V C6 C5 1μF 22μF 35V 50V R5 150k R7 ...
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... LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX 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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... High Effi ciency, Improves Cross Regulation in Multiple Output Designs, Current Mode, 3mm × 4mm 12-Pin DFN Package www.linear.com ● OUT 12V 0. OUT 47μF (PARALLEL) (SERIES) X5R 0.1μF 0.12Ω X5R 18717 TA05 ≤ 16V, Miniature Design IN ≤ 0108 REV C • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 2002 18717fc ...