LTC1775 LINER [Linear Technology], LTC1775 Datasheet
LTC1775
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LTC1775 Summary of contents
Page 1
... Fault protection is provided by foldback current limiting and an output overvoltage comparator. An external ca- pacitor attached to the RUN/SS pin provides soft start capability for supply sequencing. A wide supply range allows operation from 4V (4.3V for LTC1775I) to 36V at the input and 1.19V LTC and LT are registered trademarks of Linear Technology Corporation and Burst Mode are trademarks of Linear Technology Corporation ...
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... Peak Driver Output Current < (TG, BG) ............ 2A INTV Output Current ........................................ 50mA CC Operating Ambient Temperature Range LTC1775C .............................................. LTC1775I (Note 5) .............................. – Junction Temperature (Note 2) ............................. 125 C Storage Temperature Range ................ – 150 C Lead Temperature (Soldering, 10 sec)................. 300 C ELECTRICAL CHARACTERISTICS range, otherwise specifications are at T ...
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... C/ LTC1775CS/LTC1775IS • 110 C/ Note 3: The LTC1775 is tested in a feedback loop that adjusts V achieve a specified error amplifier output voltage (I The denotes specifications which apply over the full operating temperature = 15V unless otherwise noted. IN CONDITIONS (Note 3300pF ...
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... LTC1775 W U TYPICAL PERFOR A CE CHARACTERISTICS Efficiency vs Load Current 100 90 80 CONTINUOUS BURST MODE MODE 10V OUT EXTV = V CC OUT 50 0.001 0.01 0.1 1.0 10 LOAD CURRENT (A) 1775 • G01 Load Regulation 0 FIGURE 1 CIRCUIT – 0.1 – 0.2 – 0.3 – 0.4 – 0 LOAD CURRENT (A) 1775 • ...
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... Transient Response (Burst Mode Operation) V OUT 100mV /DIV I L 5A/DIV V = 20V 200 s/DIV OUT I = 100mA TO 2A LOAD FIGURE 1 CIRCUIT LTC1775 Oscillator Frequency vs Temperature 300 250 SYNC = 1.5V 200 SYNC = 0V 150 100 50 0 110 135 –40 – TEMPERATURE ( C) 1775 • G11 ...
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... LTC1775 CTIO S EXTV (Pin 1): INTV Switch Input. When the EXTV CC CC voltage is above 4.7V, the switch closes and supplies INTV power from EXTV . Do not exceed 7V at this pin SYNC (Pin 2): Synchronization Input for Internal Oscilla- tor. The oscillator will nominally run at 150kHz when open, 225kHz when tied above 1 ...
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... REV TOP – + 0.5V SLEEP B – SWITCH LOGIC/ DROPOUT COUNTER SHUTDOWN OVERVOLTAGE + – FCNT + 1.19V F – INTV FCB EXTV 4 1 OSENSE LTC1775 5.5 – – – BOOST INTV VCC BG 10 PGND 9 1.19V ...
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... This forces continuous operation and can assist second- ary winding regulation. INTV /EXTV CC Power for the top and bottom MOSFET drivers and most . When this of the internal circuitry of the LTC1775 is derived from the SS INTV pin. When the EXTV CC 5.2V low dropout regulator supplies the INTV from V ...
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... U U APPLICATIO S I FOR ATIO The basic LTC1775 application circuit is shown in Figure 1. External component selection is primarily determined by the maximum load current and begins with the selection of the sense resistance for the desired current level. Since the LTC1775 senses current using the on-resistance of the power MOSFET, the maximum application current prima- rily determines the choice of MOSFET ...
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... A JA DS(ON) can operate with a maximum DC current of 10A switching application, the actual power dissipation is increased by the transition losses and is reduced by the switch duty cycle. When the LTC1775 is operating in continuous mode, the duty cycles for the MOSFETs are: V OUT Top Duty Cycle V ...
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... Under short-circuit conditions with very low duty cycle, the LTC1775 will begin skipping cycles in order to limit the short-circuit current. In this situation the bottom MOSFET R valley rather than the top MOSFET controlling the inductor current peak ...
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... It takes about 400ns to commutate a 20A current in this case. This delay reduces efficiency and can also increase the foldback current limit of the LTC1775. The Lead Inductance TO-220 4nH to 12nH ...
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... MOSFET gate drivers. High input voltage applications in which large MOSFETs are being driven at high frequencies may cause the LTC1775 ) to exceed its maximum junction temperature rating. Most of the supply current drives the MOSFET gates unless an ...
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... CC it may be used to power EXTV Figure 6 shows how one can easily generate a suitable EXTV voltage from V CC drive current from V . This is the normal tion from the LTC1775 internal regulator and increases the gate drive voltage SEC 1N4148 + • ...
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... If there is no change in input current, then there is no change in efficiency. External Gate Drive Buffer The LTC1775 drivers are adequate for driving up to about 30nC into MOSFET switches. When using large single, or multiple, MOSFET switches, external buffers may be re- quired to provide additional gate drive capability. Special purpose gate driver circuits such as the LTC1693 are ideal in such cases ...
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... APPLICATIO S I FOR ATIO Run/Soft Start Function The RUN/SS pin is a dual purpose pin that provides a soft start function and a means to shut down the LTC1775. Soft start reduces surge currents from V creasing the controller’s current limit I can also be used for power supply sequencing. ...
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... L to limit the inrush current to the load. LTC1775 2 )(I )(C IN O(MAX) supply current. The V current is the connected to 5V, the LTC1775 will CC and the remaining 520 A will current results in a small and C ESR dissipative IN ...
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... Note that the transient suppressor should not conduct during double-battery operation, but must still clamp the input voltage below breakdown of the converter. Although the LTC1775 has a maximum input voltage of 36V, most applications will be limited to 30V by the MOSFET V . ...
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... SGND INTV OSENSE + VCC V PGND PROG 4 SANYO 6SP680M Figure 11. 5V/10A Fixed Output from Design Example LTC1775 is chosen with an ESR of 0.013 for OUT )(ESR) = (4.3A)(0.013 ) = 56mV L(MAX 22V 30V 4 M1 SUD50N03- OUT 5V ...
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... V 7) For applications with multiple switching power con- verters connected to the same V filter capacitance for the LTC1775 is not shared with the other converters. AC input current from another con- verter will cause substantial input voltage ripple that ...
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... FMMT720 0.47 F FMMT619 12 BOOST D B CMDSH-3 11 INTV VCC FMMT619 4 FMMT720 9 PGND LTC1775 28V 30V 2 M1 Si4412DY OUT 3. MBRS140T3 B 0 OUT + 100 F 10V M2 0.065 Si4412DY 4 1775 TA01 V IN ...
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... R2 PROG 11k 100k C : UNITED CHEMICON THCR70E1H226ZT-CBU SANYO 165A-150M OUT L1: 13 H/11A 22 –5V/2.5A Positive to Negative Converter EXTV SYNC RUN/SS SW LTC1775 4 13 FCB BOOST CMDSH SGND INTV OSENSE + C VCC 4 PGND ...
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... TYP 0.014 – 0.019 (0.355 – 0.483) TYP LTC1775 0.189 – 0.196* (4.801 – 4.978) 0.009 (0.229 REF 0.150 – 0.157** (3.810 – 3.988) 1 ...
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... Dual 2-Phase High Frequency, High Efficiency Voltage Mode Synchronous Step-Down Controller LTC1735 High Efficiency Synchronous Step-Down Controller PolyPhase is a trademark of Linear Technology Corporation. Linear Technology Corporation 24 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 www.linear-tech.com 2.5V/5A Adjustable Output LTC1775 0.1 F EXTV SYNC ...