LTC3727-1 Linear Technology, LTC3727-1 Datasheet
LTC3727-1
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LTC3727-1 Summary of contents
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... Very Low Dropout Operation: 99% Duty Cycle Adjustable Soft-Start Current Ramping Foldback Output Current Limiting Output Overvoltage Protection Low Shutdown Small 28-Lead SSOP Package LTC3727-1 Also Available in the 5mm 5mm QFN Package Selectable Constant Frequency or Burst Mode Operation U APPLICATIO S Telecom Systems Automotive Systems ...
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... LTC3727/LTC3727 ABSOLUTE AXI U RATI GS Input Supply Voltage (V ).........................36V to – 0.3V IN Top Side Driver Voltages (BOOST1, BOOST2) ...................................42V to – 0.3V Switch Voltage (SW1, SW2) .........................36V to – 5V INTV EXTV , (BOOST1-SW1), CC, CC (BOOST2-SW2) ........................................8.5V to – 0.3V RUN/SS1, RUN/SS2, PGOOD ..................... 7V to – 0. – SENSE1 , SENSE2 , SENSE1 , – SENSE2 Voltages .....................................14V to – ...
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... Lowest Frequency LOW f Highest Frequency HIGH R PLLIN Input Resistance PLLIN I Phase Detector Output Current PLLFLTR Sinking Capability Sourcing Capability LTC3727/LTC3727-1 The denotes the specifications which apply over the full operating = 15V unless otherwise noted RUN/SS1, 2 CONDITIONS I = 1.2V (Note 4) TH1, 2 ...
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... Ramping Negative OSENSE V Ramping Positive OSENSE Note 4: The LTC3727/LTC3727-1 are tested in a feedback loop that servos specified voltage and measures the resultant V ITH1, 2 Note 5: Dynamic supply current is higher due to the gate charge being delivered at the switching frequency. See Applications Information. ...
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... PERCENT ON NOMINAL OUTPUT VOLTAGE (%) 3727 G08 Load Regulation 0.0 FCB = 15V IN FIGURE 1 –0.1 –0.2 –0.3 –0 LOAD CURRENT (A) 3727 G11 LTC3727/LTC3727-1 www.DataSheet4U.com Internal 7.5V LDO Line Regulation 7 1mA LOAD 7.6 7.5 7.4 7.3 7.2 7.1 7.0 6.9 6 INPUT VOLTAGE (V) Maximum Current Sense Threshold ...
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... LTC3727/LTC3727 TYPICAL PERFOR A CE CHARACTERISTICS SENSE Pins Total Source Current 100 50 0 –50 –100 –150 –200 –250 –300 –350 –400 COMMON MODE VOLTAGE (V) SENSE 3727 G13 Soft-Start Up (Figure 13) I OUT 5A/DIV V OUT 5V/DIV V RUN/SS 5V/DIV V = 20V 50ms/DIV 3727 G16 ...
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... Differential Current Comparators. The I controlled offsets between the SENSE in conjunction with R – SENSE1 , SENSE2 Differential Current Comparators OSENSE1 sensed feedback voltage for each controller from an external resistive divider across the output. LTC3727/LTC3727-1 www.DataSheet4U.com Oscillator Frequency vs Temperature 700 600 PLLFLTR 500 V = 1.2V ...
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... LTC3727/LTC3727 CTIO S PLLFLTR (Pin 5): The phase-locked loop’s lowpass filter is tied to this pin. Alternatively, this pin can be driven with voltage source to vary the frequency of the internal oscillator. PLLIN (Pin 6): External Synchronization Input to Phase Detector. This pin is internally terminated to SGND with 50k ...
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... U OPERATIO (Refer to Functional Diagram) Main Control Loop The LTC3727/LTC3727-1 use a constant frequency, cur- rent mode step-down architecture with the two controller channels operating 180 degrees out of phase. During normal operation, each top MOSFET is turned on when the clock for that channel sets the RS latch, and turned off ...
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... I SS gradually released allowing normal, full-current opera- tion. When both RUN/SS1 and RUN/SS2 are low, all LTC3727/LTC3727-1 controller functions are shut down, including the 7.5V and 3.3V regulators. Low Current Operation The FCB pin is a multifunction pin providing two func- ...
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... PART NUMBER FUNCTION LTC3727 With Latchoff Function Available LTC3727-1 Latchoff Always Disabled LTC3727/LTC3727-1 www.DataSheet4U.com THEORY AND BENEFITS OF 2-PHASE OPERATION The LTC3727 dual high efficiency DC/DC controller brings the considerable benefits of 2-phase operation to portable applications. Notebook computers, PDAs, handheld ter- minals and automotive electronics will all benefit from the ...
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... LTC3727/LTC3727-1 U OPERATIO (Refer to Functional Diagram 2.53A IN(MEAS) (a) Figure 3. Input Waveforms Comparing Single-Phase (a) and 2-Phase (b) Operation for Dual Switching Regulators Converting 12V to 5V and 3. Each. The Reduced Input Ripple with the LTC3727 2-Phase Regulator Allows Less Expensive Input Capacitors, Reduces Shielding Requirements for EMI and Improves Efficiency input power path, which could include batteries, switches, trace/connector resistances and protection circuitry ...
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... U U APPLICATIO S I FOR ATIO Figure 1 on the first page is a basic LTC3727/LTC3727-1 application circuit. External component selection is driven by the load requirement, and begins with the selection of R and the inductor value. Next, the power MOSFETs SENSE and D1 are selected. Finally, C ...
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... LTC3727/LTC3727 APPLICATIO S I FOR ATIO The inductor value also has secondary effects. The transi- tion to Burst Mode operation begins when the average inductor current required results in a peak current below 25% of the current limit determined by R inductor values (higher I ) will cause this to occur at ...
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... This makes it advisable to further derate the capacitor choose a capacitor rated at a higher temperature than required. Several capacitors may also be paralleled to meet size or height requirements in the design. Always consult the manufacturer if there is any question. LTC3727/LTC3727 OUT ...
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... LTC3727/LTC3727 APPLICATIO S I FOR ATIO The benefit of the LTC3727 multiphase can be calculated by using the equation above for the higher power control- ler and then calculating the loss that would have resulted if both controller channels switch on at the same time. The ...
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... MOSFET gate drive requirements. 4. EXTV CC work. For 3.3V and other low voltage regulators, efficiency gains can still be realized by connecting EXTV output-derived voltage that has been boosted to greater . IN LTC3727/LTC3727 and INTV CC rises above 7.3V, the CC pin to the INTV pin thereby ...
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... LTC3727/LTC3727 APPLICATIO S I FOR ATIO V IN OPTIONAL EXTV CC CONNECTION + 7.5V < V < 8.5V SEC N-CH LTC3727 TG1 T1 EXTV SW CC 1:N R6 FCB BG1 R5 N-CH SGND PGND Figure 6. Secondary Output Loop & EXTV than 7.5V. This can be done with the inductive boost winding as shown in Figure 6. Topside MOSFET Driver Supply (C ...
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... The RUN/SS pins also provide the ability to latch off the controller(s) when an overcurrent condition is detected 3. *OPTIONAL TO DEFEAT OVERCURRENT LATCHOFF (NOT NEEDED WITH THE LTC3727-1) The RUN/SS capacitor This pin ITH limit the inrush current. After the controller has been started and been given adequate time to charge up the ...
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... After the design is complete, a decision can be made whether to enable the latchoff feature. If latchoff is not required, the LTC3727-1 can be used. The value of the soft-start capacitor C scaled with output voltage, output capacitance and load current characteristics ...
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... Thus, the is 0. FCB input pin removes the requirement that power must LP be drawn from the inductor primary in order to extract LTC3727/LTC3727 the smallest time duration ON(MIN) V OUT ...
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... LTC3727/LTC3727 APPLICATIO S I FOR ATIO power from the auxiliary windings. With the loop in continuous mode, the auxiliary outputs may nominally be loaded without regard to the primary output load. The secondary output voltage V SEC shown in Figure 6a by the turns ratio N of the transformer: ...
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... The DC step, rise time and settling at this test point truly reflects the closed loop response . Assuming a pre- dominantly second order system, phase margin and/or damping factor can be estimated using the percentage of LTC3727/LTC3727 ...
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... LTC3727/LTC3727 APPLICATIO S I FOR ATIO overshoot seen at this pin. The bandwidth can also be estimated by examining the rise time at the pin. The I external components shown in the Figure 1 circuit will provide an adequate starting point for most applications. The I series R -C filter sets the dominant pole-zero ...
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... Are the top N-channel MOSFETs M1 and M3 located within 1cm of each other with a common drain connection A 100 pF 250 kHz not attempt to split the input decoupling for the IN two channels as it can cause a large resonant loop. LTC3727/LTC3727 200 ...
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... LTC3727/LTC3727 APPLICATIO S I FOR ATIO 2. Are the signal and power grounds kept separate? The combined LTC3727 signal ground pin and the ground return of C must return to the combined C INTVCC terminals. The path formed by the top N-channel MOSFET, Schottky diode and the C ...
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... Monitor the output switching node (SW pin) to synchronize the oscilloscope to the internal oscillator and probe the actual output voltage as well. Check for proper performance over the operating voltage and current range expected in the CC LTC3727/LTC3727-1 www.DataSheet4U.com R SENSE1 V OUT1 ...
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... LTC3727/LTC3727 APPLICATIO S I FOR ATIO application. The frequency of operation should be main- tained over the input voltage range down to dropout and until the output load drops below the low current opera- tion threshold—typically 10% to 20% of the maximum designed current level in Burst Mode operation. ...
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... EXTV CC LTC3727 21 INTV 4 10V PGND CMDSH-3TR 19 BG2 OUT 18 BOOST2 0 SW2 16 – TG2 15 + RUN/SS2 SWITCHING FREQUENCY = 250kHz MI, M2: FDS6680A LTC3727/LTC3727-1 www.DataSheet4U.com 0.015 V OUT1 5V 5A; 6A PEAK M1A M1B D1 MBRM 140T3 C OUT1 50V 0.1 F GND C 100 F 16V OUT2 V IN ...
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... LTC3727/LTC3727-1 U TYPICAL APPLICATIO S 1 RUN/SS1 0 SENSE1 27pF 1000pF 105k 3 SENSE1 1% 20k OSENSE1 5 PLLFLTR 6 PLLIN 33pF 7 FCB 8 I TH1 15k 220pF 9 SGND 33pF 10 3.3V 3. TH2 15k 220pF 12 V OSENSE2 20k 1% 13 SENSE2 192.5k 1000pF 14 1% 27pF SENSE2 0 PANASONIC SP SERIES ...
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... M0-220 VARIATION WHHD-(X) (TO BE APPROVED) 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.20mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED LTC3727/LTC3727-1 www.DataSheet4U.com 9.90 – 10.50* (.390 – .413 7.40 – ...
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... LTC3727/LTC3727-1 RELATED PARTS PART NUMBER DESCRIPTION LTC1438/LTC1439 Dual High Efficiency Low Noise Synchronous Step-Down Switching Regulators POR, Auxiliary Regulator LTC1438-ADJ Dual Synchronous Controller with Auxiliary Regulator LTC1538-AUX Dual High Efficiency Low Noise Synchronous Step-Down Switching Regulator LTC1539 Dual High Efficiency Low Noise Synchronous Step-Down Switching Regulator ...