LTC1700 Linear Technology, LTC1700 Datasheet
LTC1700
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LTC1700 Summary of contents
Page 1
... Burst Mode operation ensures high efficiency at light loads, thus providing high efficiencies over a wide range of load currents. The LTC1700 operates at a minimum input voltage as low as 0.9V. The device boasts a 1.5% output voltage accuracy and consumes only 200 A of quiescent current. In shutdown, it only draws 10 A. ...
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... OUT V = 1.8V 1.8V 1.1V OUT RUN/ Ramping Down from 1.2V SYNC/MODE f = 550kHz OSC V = 1.8V OUT 10mV FB REF ORDER PART NUMBER 10 SW LTC1700EMS 9 PGND OUT 6 TG MS10 PART MARKING = 150 C/W JA LTLC MIN TYP MAX UNITS 0.9 1.8 2.34 2 536 620 179 210 35 45 ...
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... Start-up circuitry of the LTC1700 is shut off. Note 6: Dynamic supply current is higher due to the gate charge being delivered at the switching frequency. and power A Note 7: The LTC1700 is tested in a feedback loop that servos V feedback point for the error amplifier (V Shutdown Current vs Supply Voltage 20 18 ...
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... LTC1700 W U TYPICAL PERFORMANCE CHARACTERISTICS RUN/SS Current vs Temperature 105 – 55 –35 – 125 TEMPERATURE ( C) 1700 G04 Maximum Current Sense Voltage vs Temperature – 55 –35 – 105 25 TEMPERATURE ( C) 1700 G7 3.3V Output Efficiency, Circuit of Figure 1 With Burst Mode ...
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... Burst Mode operation. An external clock between 400kHz and 750kHz applied to this pin forces the LTC1700 to operate at the external clock frequency. Do not attempt to synchronize below 400kHz or above 750kHz. Load Step Transient Response ...
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... Q U OPERATIO (Refer to Functional Diagram) Main Control Loop The LTC1700 is a constant frequency, current mode controller for DC/DC step-up converters. In normal opera- tion, the main external N-channel power MOSFET is turned on when the oscillator sets a latch and turned off either when the V sense amplifier (V ...
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... N-channel MOSFET is only allowed to turn on for a maximum duty cycle of 90%. Burst Mode Operation The LTC1700 can be enabled to go into Burst Mode operation at low load currents simply by connecting the SYNC/MODE pin to a voltage of at least 1.2V. In this mode, the peak current of the inductor is set low duty cycles) even though the voltage at the I actually at a lower value. If the inductor’ ...
Page 8
... Inductor Ripple Current DC = Duty Cycle The peak inductor current is inherently limited in a current mode controller. The maximum V age of the main MOSFET is limited to 78mV. The LTC1700 will not allow peak inductor current to exceed 78mV The following equation is a good DS(ON)(N-CHANNEL) guide for determining the required R ...
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... During synchronization, Burst Mode operation is inhibited. The LTC1700 will lock on at the leading edge of the external clock and the minimum pulse width required is 200ns. Remember just because you can operate at a high switch- ing frequency doesn’ ...
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... U APPLICATIONS INFORMATION To eliminate this subharmonic oscillations, a compensat- ing ramp is added internally to the LTC1700 on the inductor current waveform when the duty cycle exceeds 5%. This scheme, known as slope compensation, makes the loop perceive that there is more inductor current than it actually has result, the maximum current capability of the regulator is reduced ...
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... Sprague 593D and 595D series. Consult the manufacturer for other specific recommendations. Setting Output Voltage and minimum The LTC1700 develops a 1.205V reference voltage be- tween the feedback (Pin 3) terminal and ground (see . Several COUT(RMS) Figure 6). By selecting resistor R1, a constant current is ...
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... Run/Soft Start Function The RUN/SS pin is a dual purpose pin that provides the soft-start function and a means to shut down the LTC1700. Soft-start reduces input surge current from V ally increasing the internal current limit. Power supply sequencing can also be accomplished using this pin. ...
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... IN 2.3V, then t = 0ns. POWERUP Design Example Assume the LTC1700 is used to convert a 3.3V input to 5V output. Load current requirement is a maximum 3A and a minimum of 100mA. Efficiency at both low and high load currents is important. Ambient temperature = 25 C. Since low load current efficiency is important, Burst Mode operation is enabled by connecting pin Duty Cycle = 1 – ...
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... Are all the components connected close to the SW node (Pin 10)? The SW pin is the input to the V amplifier and the current reverse comparator. 2. Connect the V lead directly to the source of the OUT P-channel MOSFET. Besides supplying current to the LTC1700, it also serves as the other input to the current reverse comparator Figure 8 ...
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... U TYPICAL APPLICATIO LTC1700 3.3V/1A Regulator with External Frequency Synchronization 100pF 180pF 2.2k 470pF 30k 53.6k 650kHz C1: AVX TAJB686K006R C2: TAIYO YUDEN CERAMIC JMK316BJ106ML C3: AVX TPSD227M006R0100 PACKAGE DESCRIPTIO 0.007 0 – 6 TYP (0.18) 0.021 0.006 (0.53 0.015) * DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.006" (0.152mm) PER SIDE ** DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.006" ...
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... Synchronous Step-Down Controller SENSE LTC1871 Boost, Flyback and SEPIC Controller LTC1872 SOT-23, 550kHz Step-Up Controller LTC3401/LTC3402 Integrated 1A and 2A Synchronous Step-Up Regulators Linear Technology Corporation 16 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 FAX: (408) 434-0507 LTC1700 2.5V V 3.3V/1.8A Output Regulator SGND SW LTC1700 2 ...