LTC1871IMS Linear Technology, LTC1871IMS Datasheet
LTC1871IMS
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LTC1871IMS Summary of contents
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... LTC1871 by connecting the SENSE pin to a resistor in the source of the power MOSFET. The LTC1871 is available in the 10-lead MSOP package. L, 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 ...
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... LEAD BASED FINISH TAPE AND REEL LTC1871EMS LTC1871EMS#TR LTC1871IMS LTC1871IMS#TR LTC1871HMS LTC1871HMS#TR Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. For more information on lead free part marking, go to: For more information on tape and reel specifi cations, go to: ...
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ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T otherwise specifi ed. SYMBOL PARAMETER Main Control Loop V Minimum Input Voltage IN(MIN) I Input Voltage Supply Current Q Continuous Mode Burst Mode Operation, No Load Shutdown Mode + V ...
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LTC1871 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T otherwise specifi ed. SYMBOL PARAMETER D Maximum Duty Cycle MAX f f Recommended Maximum Synchronized SYNC/ OSC Frequency Ratio t MODE/SYNC Minimum Input Pulse Width SYNC(MIN) t MODE/SYNC Maximum ...
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TYPICAL PERFORMANCE CHARACTERISTICS FB Voltage vs Temp 1.25 1.24 1.23 1.22 1. –50 – 100 125 TEMPERATURE (°C) 1871 G01 Shutdown Mode ...
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LTC1871 TYPICAL PERFORMANCE CHARACTERISTICS RUN Thresholds 1.5 1.4 1.3 1 (V) IN 1871 G10 Frequency vs Temperature 325 320 315 310 305 300 295 290 285 280 275 –50 – ...
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PIN FUNCTIONS RUN (Pin 1): The RUN pin provides the user with an accurate means for sensing the input voltage and pro- gramming the start-up threshold for the converter. The falling RUN pin threshold is nominally 1.248V and the comparator ...
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LTC1871 BLOCK DIAGRAM FREQ V-TO-I 4 0.6V MODE/SYNC 5 85mV OV + – 1.230V + FB EA – 1.230V INTV CC 5.2V 8 LDO UV – + 2.00V OPERATION Main Control Loop The ...
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OPERATION SENSE V SW GATE GND GND 2a. SENSE Pin Connection for Maximum Efficiency ( GATE SENSE GND R S GND 2b. SENSE Pin Connection ...
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LTC1871 OPERATION MOSFET the I pin drops below 0.30V, the DS(ON) TH Burst Mode comparator B1 will turn off the power MOSFET and scale back the quiescent current of the IC to 250μA (sleep mode). In this ...
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APPLICATIONS INFORMATION Programming the Operating Frequency The choice of operating frequency and inductor value is a tradeoff between effi ciency and component size. Low frequency operation improves effi ciency by reducing MOSFET and diode switching losses. However, lower frequency operation ...
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LTC1871 APPLICATIONS INFORMATION temperature rating. The junction temperature can be estimated using the following equations: I ≈ • Q Q(TOT • • ...
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APPLICATIONS INFORMATION + INPUT SUPPLY OPTIONAL FILTER CAPACITOR – Figure 8a. Programming the Turn-On and Turn-Off Thresholds Using the RUN Pin RUN 6V EXTERNAL LOGIC CONTROL 1.248V Figure 8b. On/Off Control Using External Logic Boost Converter: Duty Cycle Considerations For ...
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LTC1871 APPLICATIONS INFORMATION Boost Converter: Ripple Current ΔI χ The constant ‘ ’ 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 χ current is chosen, ...
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APPLICATIONS INFORMATION Boost Converter: Inductor Core Selection Once the value for L is known, the type of inductor must be selected. High effi ciency converters generally cannot afford the core loss found in low cost powdered iron cores, forcing the ...
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LTC1871 APPLICATIONS INFORMATION 2.0 1.5 1.0 0.5 0 – JUNCTION TEMPERATURE (°C) Figure 11. Normalized R DS(ON) Another method of choosing which power MOSFET to use is to check what the maximum output current is for a given ...
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APPLICATIONS INFORMATION Remember to keep the diode lead lengths short and to observe proper switch-node layout (see Board Layout Checklist) to avoid excessive ringing and increased dis- sipation. Boost Converter: Output Capacitor Selection Contributions of ESR (equivalent series resistance), ESL ...
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LTC1871 APPLICATIONS INFORMATION OUT 12a. Circuit Diagram I L 12b. Inductor and Input Currents 12c. Switch Current OFF 12d. Diode and Output Currents ΔV COUT V OUT ...
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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 United ...
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LTC1871 APPLICATIONS INFORMATION then off, a packet of gate charge Q INTV to ground. The resulting dQ/ current that CC must be supplied to the INTV CC V pin by an external supply. If the IC is operating ...
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APPLICATIONS INFORMATION A second, more severe transient can occur when con- necting loads with large (> 1μF) supply bypass capacitors. The discharged bypass capacitors are effectively put in parallel with C , causing a nearly instantaneous drop ...
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LTC1871 APPLICATIONS INFORMATION (JMK325BJ226MM) are added for HF noise reduction. Check the output ripple with a single oscilloscope probe connected directly across the output capacitor terminals, where the HF switching currents fl ow. 8. The choice of an input capacitor ...
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APPLICATIONS INFORMATION PIN 1 R2 LTC1871 PSEUDO-KELVIN SIGNAL GROUND CONNECTION VIAS TO GROUND PLANE TRUE REMOTE OUTPUT SENSING BOLD LINES INDICATE HIGH CURRENT PATHS JUMPER ...
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LTC1871 APPLICATIONS INFORMATION that the input fi lter capacitor for the LTC1871 is not shared with other converters. AC input current from another converter could cause substantial input voltage ripple, and this could interfere with the operation of the LTC1871. ...
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APPLICATIONS INFORMATION It is worth noting here that SEPIC converters that operate at high duty cycles (i.e., that develop a high output volt- age from a low input voltage) can have very high input currents, relative to the output current. ...
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LTC1871 APPLICATIONS INFORMATION During the MOSFET’s on-time, the control circuit limits the maximum voltage drop across the power MOSFET to about 150mV (at low duty cycle). The peak inductor current is therefore limited to 150mV/R DS(ON) between the maximum load ...
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APPLICATIONS INFORMATION SEPIC Converter: Output Capacitor Selection Because of the improved performance of today’s electro- lytic, tantalum and ceramic capacitors, engineers need to consider the contributions of ESR (equivalent series resistance), ESL (equivalent series inductance) and the bulk capacitance when ...
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LTC1871 APPLICATIONS INFORMATION The output capacitor in a SEPIC regulator experiences high RMS ripple currents, as shown in Figure 17. The RMS output capacitor ripple current is • RMS(COUT) O(MAX) V IN(MIN) Note that the ripple ...
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APPLICATIONS INFORMATION 3. The operating frequency is chosen to be 300kHz to reduce the size of the inductors; the resistor from the FREQ pin to ground is 80k inductor ripple current of 40% is chosen, so the peak ...
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LTC1871 APPLICATIONS INFORMATION 9. The DC coupling capacitor in a SEPIC converter is cho- sen based on its RMS current requirement and must be rated for a minimum voltage of V voltage. Start with the minimum value which satisfi es ...
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APPLICATIONS INFORMATION 12V OUT V (AC) OUT 200mV/DIV I OUT 0.5A/DIV 50μs/DIV Figure 19. LTC1871 SEPIC Converter Load Step Response TYPICAL APPLICATIONS R C 22k 6.8nF 12. ...
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LTC1871 TYPICAL APPLICATIONS 18V to 27V Input, 28V Output, 400W 2-Phase, Low Ripple, Synchronized RF Base Station Power Supply (Boost 93.1k 8.45k RUN 47pF FREQ 5 R ...
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TYPICAL APPLICATIONS 4.5V to 28V Input, 5V/2A Output SEPIC Converter with Undervoltage Lockout and Soft-Start R1 115k 54.9k 4.7nF 1% 1 RUN 12k FREQ 49.9k 8.2nF ...
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LTC1871 TYPICAL APPLICATIONS 5V to 15V Input, – 5V/5A Output Positive-to-Negative Converter with Undervoltage Lockout and Level-Shifted Feedback R1 R2 154k C1 68.1k 1% 1nF 10k C C2 330pF C C1 10nF C : TDK C5750X5R1C476M IN ...
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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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... OUT 10μF 10BQ060 3.3μF 5 25V 100V X5R • 10BQ060 10μF 6 25V X5R V OUT2 –72V 200mA 10k 196k – LT1783 1871 TA06 ≤ 16V, Miniature Design IN ≤ 0108 REV E • PRINTED IN USA © LINEAR TECHNOLOGY CORPORATION 2001 1871fe ...