LTC3707 Linear Technology, LTC3707 Datasheet
LTC3707
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LTC3707 Summary of contents
Page 1
... OSENSE2 I I TH1 TH2 C C1 RUN/SS1 RUN/SS2 R1 220pF 20k SS1 SS2 1% 15k 0.1 F 0.1 F Figure 1. High Efficiency Dual 5V/3.3V Step-Down Converter LTC3707 U returns to normal. The FCB mode pin OUT V IN 5.2V TO 28V CERAMIC D4 50V CERAMIC 0 6 ...
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... Peak Output Current <10 s (TG1, TG2, BG1, BG2) ... 3A INTV Peak Output Current ................................ 40mA CC Operating Temperature Range LTC3707EG (Note 2) .......................... – Junction Temperature (Note 3) ............................. 125 C Storage Temperature Range ................. – 150 C Lead Temperature (Soldering, 10 sec).................. 300 C ELECTRICAL CHARACTERISTICS temperature range, otherwise specifications are at T ...
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... FREQSET FREQSET V = 2.4V FREQSET FREQSET No Load 10mA 3.3 6V < V < 30V 2mA PGOOD PGOOD V Respect to Set Output Voltage OSENSE V Ramping Negative OSENSE V Ramping Positive OSENSE LTC3707 MIN TYP MAX UNITS 1 99.4 % 0.5 1.2 A 1.0 1.5 2.0 V 4.1 4. ...
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... T J dissipation P according to the following formula: D LTC3707EGN = • Note 4: The LTC3707 is tested in a feedback loop that servos V specified voltage and measures the resultant TYPICAL PERFOR A CE CHARACTERISTICS Efficiency vs Output Current and Mode (Figure 13) 100 Burst Mode 90 OPERATION 80 ...
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... COMMON MODE VOLTAGE ( ITH RUN/SS 2 0.7V OSENSE 2.0 1.5 1.0 0 (V) RUN/SS LTC3707 Maximum Current Sense Threshold vs Percent of Nominal Output Voltage (Foldback 100 PERCENT ON NOMINAL OUTPUT VOLTAGE (%) 3707 G08 Current Sense Threshold vs I Voltage TH 90 ...
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... LTC3707 W U TYPICAL PERFOR A CE CHARACTERISTICS Maximum Current Sense Threshold vs Temperature –50 – 100 125 TEMPERATURE ( C) 3707 G17 Soft-Start Up (Figure 13) V OUT 5V/DIV V RUN/SS 5V/DIV I OUT 2A/DIV V = 15V 5ms/DIV IN 3707 G19 OUT Input Source/Capacitor Instantaneous Current (Figure 13) ...
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... TEMPERATURE ( C) 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0 100 125 –50 3707 G29 LTC3707 Oscillator Frequency vs Temperature 350 FREQSET 300 250 V = OPEN FREQSET 200 150 FREQSET 100 50 0 125 – 50 – TEMPERATURE ( C) 3707 G27 Shutdown Latch Thresholds ...
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... LTC3707 CTIO S RUN/SS1, RUN/SS2 (Pins 1, 15): Combination of soft- start, run control inputs and short-circuit detection timers. A capacitor to ground at each of these pins sets the ramp time to full output current. Forcing either of these pins back below 1.0V causes the IC to shut down the circuitry required for that particular controller ...
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... FB SLOPE 45k 45k COMP 2.4V – – 1.2 A SHDN RUN RST SOFT- 6V 4(V ) START FB Figure 2 LTC3707 INTV BOOST TOP INTV CC BG BOT PGND R SENSE INTV CC + SENSE D C 30k SEC SEC – SENSE 30k ...
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... As C continues to charge, the I SS gradually released allowing normal, full-current opera- tion. When both RUN/SS1 and RUN/SS2 are low, all LTC3707 controller functions are shut down, and the STBYMD pin determines if the standby 5V and 3.3V regulators are kept alive. 10 Low Current Operation ...
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... RUN/SS capacitor(s) during an overcurrent and/or short-circuit condition. Foldback current limiting is also activated when the output voltage falls below 70% of its nominal level whether or not the short-circuit latchoff LTC3707 3707f 11 ...
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... THEORY AND BENEFITS OF 2-PHASE OPERATION The LTC1628 and the LTC3707 are the first dual high efficiency DC/DC controllers to bring the considerable benefits of 2-phase operation to portable applications. Notebook computers, PDAs, handheld terminals and au- ...
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... In addition, isolation between the two channels U U APPLICATIO S I FOR ATIO Figure 1 on the first page is a basic LTC3707 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 and D1 are selected ...
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... However, designs for surface mount are available that do not increase the height significantly. Power MOSFET and D1 Selection Two external power MOSFETs must be selected for each controller with the LTC3707: One N-channel MOSFET for ). Remember, the the top (main) switch, and one N-channel MOSFET for the MAX bottom (synchronous) switch ...
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... Selection criteria for the power MOSFETs include the “ON” resistance R , reverse transfer capacitance C DS(ON) input voltage and maximum output current. When the LTC3707 is operating in continuous mode the duty cycles for the top and bottom MOSFETs are given by: V OUT Main Switch Duty Cycle ...
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... Always consult the manufacturer if there is any question. The benefit of the LTC3707 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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... An internal P-channel low dropout regulator produces 5V at the INTV pin from the V supply pin. INTV CC IN the drivers and internal circuitry within the LTC3707. The INTV pin regulator can supply a peak current of 40mA CC and must be bypassed to ground with a minimum of 4.7 F tantalum special polymer, or low ESR type electrolytic capacitor ...
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... If a change is made and the input current decreases, then the efficiency has improved. If there is no change in input current, then there is no change in efficiency SEC + LTC3707 SENSE V OUT T1 EXTV CC ...
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... U U APPLICATIO S I FOR ATIO Output Voltage The LTC3707 output voltages are each set by an external feedback resistive divider carefully placed across the output capacitor. The resultant feedback signal is com- pared with the internal precision 0.800V voltage reference by the error amplifier. The output voltage is given by the ...
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... SS 75mV to 25mV. Under short-circuit conditions with very low duty cycles, the LTC3707 will begin cycle skipping in order to limit the short-circuit current. In this situation the bottom MOSFET will be dissipating most of the power but less than in normal operation. The short-circuit ripple current is determined by the minimum on-time t ...
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... INTV oscillator frequency as shown in Figure 5. Minimum On-Time Considerations Minimum on-time t that the LTC3707 is capable of turning on the top MOSFET. returns to a safe level determined by internal timing delays and the gate charge required to turn on the top MOSFET. Low duty cycle ...
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... V again above its minimum. In order to prevent erratic operation if no external connec- tions are made to the FCB pin, the FCB pin has a 0.18 A Figure 8. Active Voltage Positioning Applied to the LTC3707 internal current source pulling the pin high. Include this current when choosing resistor values R5 and R6 ...
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... CC current IN minimum capacitance having a maxi- mum of 20m to 50m of ESR. The LTC3707 2-phase architecture typically halves this input capacitance re- quirement over competing solutions. Other losses includ- ing Schottky conduction losses during dead-time and inductor core losses generally account for less than 2% total additional loss ...
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... LTC3707 U U APPLICATIO S I FOR ATIO Checking Transient Response The regulator loop response can be checked by looking at the load current transient response. Switching regulators take several cycles to respond to a step in DC (resistive) load current. When a load step occurs, V amount equal to I (ESR), where ESR is the effective ...
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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 LTC3707 has a maximum input voltage of 30V, most applications will be limited to 28V by the MOSFET BVDSS. 50A I ...
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... LTC3707 U U APPLICATIO S I FOR ATIO Design Example As a design example for one channel, assume V 12V(nominal 22V(max OUT and f = 300kHz. The inductance value is chosen first based on a 30% ripple current assumption. The highest value of ripple current occurs at the maximum input voltage. Tie the FREQSET pin to the INTV pin for 300kHz operation ...
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... PC Board Layout Checklist When laying out the printed circuit board, the following checklist should be used to ensure proper operation of the LTC3707. These items are also illustrated graphically in the layout diagram of Figure 10. The Figure 11 illustrates the current waveforms present in the various branches of the 2-phase synchronous regulators operating in the continuous mode ...
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... HIGH, SWITCHING CURRENT LINES. KEEP LINES TO A MINIMUM LENGTH. signal ground and a small V OSENSE should be as close as possible to the LTC3707 SGND pin. The R2 and R4 connections should not be along the high current input feeds from the input capacitor(s). – Are the SENSE ...
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... Compensation of the voltage loop will be much more sensitive to component selection. This behavior can be investigated by temporarily shorting out the current sensing resistor—don’t worry, the regulator will still maintain control of the output voltage. LTC3707 to prevent the short-circuit IN from its nominal level to verify operation of the IN ...
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... 28V 5V, 3A/3.3V, 6A/12V, 120mA OUT SWITCHING FREQUENCY = 300kHz MI, M2, M3, M4: NDS8410A L1: SUMIDA CEP123-6R3MC T1 1:1.8 — DALE LPE6562-A262 GAPPED E-CORE OR BH ELECTRONICS #501-0657 GAPPED TOROID Figure 12. LTC3707 High Efficiency Low Noise 5V/3A, 3.3V/5A, 12/120mA Regulator 30 1M 100k MBRS1100T3 V PULL-UP (<7V) 28 PGOOD PGOOD 27 ...
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... LTC DWG # 05-08-1641 0.229 – 0.244 (5.817 – 6.198 0.015 0.004 0.053 – 0.069 45 (0.38 0.10) (1.351 – 1.748) 0 – 8 TYP 0.008 – 0.012 (0.203 – 0.305) LTC3707 0.386 – 0.393* 0.033 (9.804 – 9.982) (0.838 1615 REF 0.150 – ...
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... I BOOST2 TH2 0 SW2 OSENSE2 13 16 – SENSE2 TG2 SENSE2 RUN/SS2 L1, L2 SUMIDA CEP1238R0MC OUTPUT CAPACITORS: PANASONIC SP SERIES Figure 13. LTC3707 5V/4A, 3.3V/4A Regulator TM Synchronous Controller www.linear.com 0.015 V OUT1 5V 3A; 4A PEAK M1A M1B 50V 0.1 F GND ...