ltc1628-sync Linear Technology Corporation, ltc1628-sync Datasheet
ltc1628-sync
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ltc1628-sync Summary of contents
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... TH2 C C1 RUN/SS1 SGND RUN/SS2 R1 220pF 220pF 20k SS1 SS2 1% 15k 0.1µF 0.1µF Figure 1. High Efficiency Dual 5V/3.3V Step-Down Converter LTC1628-SYNC U returns to normal. The FCB mode pin OUT V IN 5.2V TO 28V C IN 1µF 22µF CERAMIC 50V CERAMIC 0.1µF B2 6.3µ ...
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... BOOST2 I TH2 12 17 SW2 OSENSE2 – TG2 + 14 15 RUN/SS2 G PACKAGE 28-LEAD PLASTIC SSOP = 125°C, θ 95°C/W JMAX JA *PGOOD ON THE LTC1628-SYNC LTC1628CG-SYNC LTC1628IG-SYNC http://www.linear.com/leadfree/ MIN TYP MAX ● 0.792 0.800 0.808 – 5 – 50 0.002 0.02 ● 0.1 0.5 ● – 0.1 – 0.5 1.3 ...
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... EXTV Ramping Positive 1.2V PLLFLTR PLLFLTR ≥ 2.4V V PLLFLTR f < f PLLIN OSC f > f PLLIN OSC No Load 10mA 3.3 6V < V < 30V 0V 30V RUN/SS1 LTC1628-SYNC MIN TYP MAX UNITS ● 3 ● 0.84 0.86 0.88 V µA – 85 – 99.4 % µA 0.5 1.2 1.0 1.5 1.9 V 4.1 4.5 V µA 0 µ ...
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... P according to the following formulas: D • 95 °C/W) LTC1628-SYNC Note 3: The LTC1628-SYNC is tested in a feedback loop that servos specified voltage and measures the resultant V ITH1 TYPICAL PERFOR A CE CHARACTERISTICS Efficiency vs Output Current and Mode (Figure 14) 100 Burst Mode ...
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... COMMON MODE VOLTAGE ( ITH RUN/SS 2 0.7V OSENSE 2.0 1.5 1.0 0 (V) RUN/SS LTC1628-SYNC Maximum Current Sense Threshold vs Percent of Nominal Output Voltage (Foldback 100 PERCENT ON NOMINAL OUTPUT VOLTAGE (%) 1628 G08 Current Sense Threshold vs I Voltage TH 90 ...
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... LTC1628-SYNC W U TYPICAL PERFOR A CE CHARACTERISTICS Maximum Current Sense Threshold vs Temperature –50 – 100 125 TEMPERATURE (°C) 1628 G17 Soft-Start Up (Figure 14) V OUT 5V/DIV V RUN/SS 5V/DIV I OUT 2A/DIV V = 15V 5ms/DIV IN 1628 G19 OUT Input Source/Capacitor ...
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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 1628 G29 LTC1628-SYNC Oscillator Frequency vs Temperature 350 PLLFLTR 300 250 V = 1.2V PLLFLTR 200 150 PLLFLTR 100 50 0 125 – 50 – TEMPERATURE (°C) 1628 G27 Shutdown Latch Thresholds ...
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... LTC1628-SYNC 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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... U OPERATIO (Refer to Functional Diagram) Main Control Loop The LTC1628-SYNC uses a constant frequency, current 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 LTC1628-SYNC controller functions are shut down, including the 5V and 3.3V regulators. Low Current Operation The FCB pin is a multifunction pin providing two func- ...
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... LTC1628-SYNC THEORY AND BENEFITS OF 2-PHASE OPERATION The LTC1628-SYNC dual high efficiency DC/DC controller brings the considerable benefits of 2-phase operation to portable applications for the first time. Notebook comput- ers, PDAs, handheld terminals and automotive electronics ...
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... 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 LTC1628-SYNC 2-Phase Regulator Allows Less Expensive Input Capacitors, Reduces Shielding Requirements for EMI and Improves Efficiency Of course, the improvement afforded by 2-phase opera- tion is a function of the dual switching regulator’ ...
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... U U APPLICATIO S I FOR ATIO Figure 1 on the first page is a basic LTC1628-SYNC 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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... Selection criteria for the power MOSFETs include the “ON” resistance R input voltage and maximum output current. When the LTC1628-SYNC is operating in continuous mode the duty cycles for the top and bottom MOSFETs are given by: Main Switch Duty Cycle Synchronous Switch Duty Cycle ...
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... Note that capacitor manufacturer’s ripple current ratings are often based on only 2000 hours of life. 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 LTC1628-SYNC [ ( − ...
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... APPLICATIO S I FOR ATIO the design. Always consult the manufacturer if there is any question. The benefit of the LTC1628-SYNC multiphase can be calculated by using the equation above for the higher power controller and then calculating the loss that would have resulted if both controller channels switch on at the same time ...
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... Higher input voltage applications in which large MOSFETs are being driven at high frequencies may cause the maxi- mum junction temperature rating for the LTC1628-SYNC to be exceeded. The system supply current is normally dominated by the gate charge current. Additional external loading of the INTV and 3 ...
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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. Output Voltage The LTC1628-SYNC output voltages are each set by an external feedback resistive divider carefully placed across V IN OPTIONAL EXTV ...
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... Soft-Start/Run Function The RUN/SS1 and RUN/SS2 pins are multipurpose pins that provide a soft-start function and a means to shut down the LTC1628-SYNC. Soft-start reduces the input power source’s surge currents by gradually increasing the controller’s current limit (proportional to V can also be used for power supply sequencing. ...
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... Under short-circuit conditions with very low duty cycles, the LTC1628-SYNC 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 ...
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... W U Minimum On-Time Considerations Minimum on-time t that the LTC1628-SYNC is capable of turning on the top MOSFET determined by internal timing delays and the gate charge required to turn on the top MOSFET. Low duty C: cycle applications may approach this minimum on-time limit and care should be taken to ensure that ...
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... L1, L2, etc. are the individual losses as a percentage of input power. Although all dissipative elements in the circuit produce losses, four main sources usually account for most of the losses in LTC1628-SYNC circuits: 1) LTC1628-SYNC V current (including loading on the 3.3V internal regulator), 2) INTV CC MOSFET transition losses. ...
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... A 25W supply will typically require a mini- switch input mum of 20µF to 40µF of capacitance having a maximum CC current of 20mΩ to 50mΩ of ESR. The LTC1628-SYNC 2-phase IN 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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... 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 LTC1628-SYNC has a maximum input volt- age of 36V, most applications will be limited to 30V by the MOSFET BVDSS regulator can OUT . Thus a 10µ ...
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... C chosen with an ESR of 0.02Ω for low output ripple. The output ripple in continuous mode will be highest at the maximum input voltage. The output voltage ripple due to ESR is approximately: V ORIPPLE = 32 k LTC1628-SYNC = 0.042Ω 100pF. At maximum input RSS ( ) [ ...
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... V OSENSE2 SENSE2 14 SENSE2 Figure 10. LTC1628-SYNC Recommended Printed Circuit Layout Diagram Are the signal and power grounds kept separate? The combined LTC1628-SYNC signal ground pin and the ground return (–) terminals. The path formed by the top N-channel ...
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... All of these nodes have very large and fast moving signals and therefore should be kept on the “output side” of the LTC1628-SYNC and occupy minimum PC trace area. LTC1628-SYNC R ...
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... LTC1628-SYNC U U APPLICATIO S I FOR ATIO 7. Use a modified “star ground” technique: a low imped- ance, large copper area central grounding point on the same side of the PC board as the input and output capacitors with tie-ins for the bottom of the INTV decoupling capacitor, the bottom of the voltage feedback resistive divider and the SGND pin of the IC ...
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... 28V 5V, 3A/3.3V, 6A, 12V, 150mA OUT SWITCHING FREQUENCY = 300kHz MI, M2, M3, M4: NDS8410A L1: SUMIDA CEP123-6R3MC T1: 10µH 1:1.8 — DALE LPE6562-A262 GAPPED E-CORE OR BH ELECTRONICS #501-0657 GAPPED TOROID Figure 12. LTC1628-SYNC High Efficiency Low Noise 5V/3A, 3.3V/5A, 12V/120mA Regulator 1M 100k MBRS1100T3 V PULL-UP (<7V) 28 PGOOD PGOOD 27 ...
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... V OSENSE2 20k 1% 13 SENSE2 63.4k 1000pF 14 1% 27pF SENSE2 0.1µ 5.2V TO 28V SWITCHING FREQUENCY = 300kHz 5V, 4A/3.3V, 4A MI, M2: FDS8936A OUT Figure 13. LTC1628-SYNC 5V/4A, 3.3V/4A Regulator with External Frequency Synchronization 30 V PULL-UP (<7V) 28 PGOOD PGOOD 27 + TG1 26 – SW1 0.1µF 25 BOOST1 BG1 22 CMDSH-3TR ...
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... DWG # 05-08-1640) 1.25 ±0. 5.3 – 5.7 0.65 BSC 0° – 8° 0.65 (.0256) BSC 0.22 – 0.38 (.009 – .015) TYP LTC1628-SYNC 9.90 – 10.50* (.390 – .413 7.40 – 8.20 (.291 – .323 2.0 (.079) MAX 0.05 (.002) MIN ...
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... TYPICAL APPLICATIO 0° OPEN PHASMD TG1 180° TG2 U1 LTC1629 90° CLKOUT 90° TG1 270° TG2 U2 LTC1628-SYNC 90° PLLIN RELATED PARTS PART NUMBER DESCRIPTION LTC1735 High Efficiency Synchronous Step-Down Switching Regulator LTC1778/LTC1778 Current Mode Synchronous Step-Down SENSE Controllers LT1976 LTC3708 ...