LTC3868IUFD-1#TRPBF Linear Technology, LTC3868IUFD-1#TRPBF Datasheet
LTC3868IUFD-1#TRPBF
Specifications of LTC3868IUFD-1#TRPBF
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LTC3868IUFD-1#TRPBF Summary of contents
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... PGOOD outputs, see the LTC3868 data sheet. L, LT, LTC, LTM, Burst Mode, OPTI-LOOP , μModule, Linear Technology and the Linear logo are registered trademarks and No R Corporation. All other trademarks are the property of their respective owners. Protected by U.S. ...
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... ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL LTC3868EUFD-1#PBF LTC3868EUFD-1#TRPBF LTC3868IUFD-1#PBF LTC3868IUFD-1#TRPBF LTC3868EGN-1#PBF LTC3868EGN-1#TRPBF LTC3868IGN-1#PBF LTC3868IGN-1#TRPBF Consult LTC Marketing for parts specifi ed with wider operating temperature ranges. *The temperature grade is identifi label on the shipping container.Consult LTC Marketing for information on non-standard lead based fi nish parts. ...
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ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T SYMBOL PARAMETER V Input Supply Operating Voltage Range IN V Regulated Feedback Voltage FB1,2 I Feedback Current FB1,2 V Reference Voltage Line Regulation REFLNREG V Output Voltage Load Regulation LOADREG ...
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LTC3868-1 ELECTRICAL CHARACTERISTICS temperature range, otherwise specifi cations are at T SYMBOL PARAMETER BG Transition Time: BG1,2 t Rise Time r BG1,2 t Fall Time f TG/BG t Top Gate Off to Bottom Gate On Delay 1D Synchronous Switch-On Delay ...
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TYPICAL PERFORMANCE CHARACTERISTICS Effi ciency and Power Loss vs Output Current 100 FIGURE 12 CIRCUIT 12V 3.3V OUT 0.0001 0.001 0.01 0.1 OUTPUT CURRENT (A) ...
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LTC3868-1 TYPICAL PERFORMANCE CHARACTERISTICS Total Input Supply Current vs Input Voltage 400 FIGURE 12 CIRCUIT V = 3.3V 350 OUT ONE CHANNEL ON 300 300μA LOAD 250 200 NO LOAD 150 100 INPUT ...
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TYPICAL PERFORMANCE CHARACTERISTICS Soft-Start Pull-Up Current vs Temperature 1.20 1.15 1.10 1.05 1.00 0.95 0.90 0.85 0.80 –45 – 105 TEMPERATURE (°C) 38681 G19 – SENSE Pin Input Current vs Temperature 3.3V ...
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LTC3868-1 TYPICAL PERFORMANCE CHARACTERISTICS INTV vs Load Current CC 5. 12V IN 5.15 5.10 5.05 5.00 4. 100 120 140 LOAD CURRENT (mA) PIN FUNCTIONS (QFN/SSOP) – – SENSE1 , SENSE2 (Pin 2, ...
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PIN FUNCTIONS (QFN/SSOP) INTV (Pin 17/Pin 19): Output of the Internal Linear Low CC Dropout Regulator. The driver and control circuits are powered from this voltage source. Must be decoupled to power ground with a minimum of 4.7μF ceramic or ...
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LTC3868-1 FUNCTIONAL DIAGRAM PGOOD1 + 0.88V – V FB1 + – 0.72V 20μA FREQ VCO SYNC DET PLLIN/MODE 100k V IN EXTV CC 5.1V 5.1V LDO LDO – 4.7V SGND INTV CC 10 DUPLICATE FOR SECOND CONTROLLER ...
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OPERATION (Refer to the Functional Diagram) Main Control Loop The LTC3868-1 uses a constant frequency, current mode step-down architecture with the two controller channels operating 180 degrees out of phase. During normal op- eration, each external top MOSFET is turned ...
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LTC3868-1 OPERATION (Refer to the Functional Diagram) INTV CC SS VOLTAGE 2V 0.8V LATCHOFF COMMAND 0V SS PIN 1μA CURRENT –9μA OUTPUT VOLTAGE LATCHOFF ARMING ENABLE SOFT-START INTERVAL Figure 1. Latchoff Timing Diagram The delay time from when a short-circuit ...
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OPERATION (Refer to the Functional Diagram) current comparator, IR, turns off the bottom external MOSFET just before the inductor current reaches zero, preventing it from reversing and going negative. Thus, the controller is in discontinuous operation. In forced continuous operation ...
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LTC3868-1 OPERATION (Refer to the Functional Diagram) Power Good (PGOOD) Pin The PGOOD1 pin is connected to an open drain of an internal N-channel MOSFET. The MOSFET turns on and pulls the PGOOD1 pin low when the corresponding V voltage ...
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OPERATION (Refer to the Functional Diagram) 2 proportional meaning that the actual power wasted RMS is reduced by a factor of 2.66. The reduced input ripple voltage also means less power is lost in the input power ...
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LTC3868-1 APPLICATIONS INFORMATION The Typical Application on the fi rst page is a basic LTC3868-1 application circuit. LTC3868-1 can be confi gured to use either DCR (inductor resistance) sensing or low value resistor sensing. The choice between the two cur- ...
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APPLICATIONS INFORMATION Low Value Resistor Current Sensing A typical sensing circuit using a discrete resistor is shown in Figure 5a chosen based on the required SENSE output current. The current comparator has a maximum threshold V of 50mV. ...
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LTC3868-1 APPLICATIONS INFORMATION The maximum power loss related to duty cycle, and will occur in continuous mode at the maximum input voltage – V • V IN(MAX) OUT P R1= LOSS R1 Ensure that ...
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APPLICATIONS INFORMATION Selection criteria for the power MOSFETs include the on-resistance Miller capacitance, C DS(ON) voltage and maximum output current. Miller capacitance can be approximated from the gate charge curve MILLER usually provided on the MOSFET ...
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LTC3868-1 APPLICATIONS INFORMATION Equation 1 has a maximum /2. This simple worst-case condition is commonly OUT used for design because even signifi cant deviations do not offer much relief. Note that capacitor manufacturers’ ripple current ...
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APPLICATIONS INFORMATION linear ramping voltage at the SS pin. The LTC3868-1 will regulate the V pin (and hence V FB voltage on the SS pin, allowing V OUT 0V to its fi nal regulated value. The total soft-start time will ...
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LTC3868-1 APPLICATIONS INFORMATION The following list summarizes the four possible connec- tions for EXTV : CC 1. EXTV Left Open (or Grounded). This will cause INTV powered from the internal 5.1V regulator result- ing in an effi ...
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APPLICATIONS INFORMATION above the nominal output voltage. When this condition is sensed, the top MOSFET is turned off and the bottom MOSFET is turned on until the overvoltage condition is cleared. The bottom MOSFET remains on continuously for as long ...
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LTC3868-1 APPLICATIONS INFORMATION Minimum On-Time Considerations Minimum on-time the smallest time dura- ON(MIN) tion that the LTC3868-1 is capable of turning on the top MOSFET determined by internal timing delays and the gate charge required ...
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APPLICATIONS INFORMATION 4. Transition losses apply only to the topside MOSFET(s), and become signifi cant only when operating at high input voltages (typically 15V or greater). Transition losses can be estimated from: Transition Loss = (1.7) • V • 2 ...
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LTC3868-1 APPLICATIONS INFORMATION greater than 1:50, the switch rise time LOAD OUT should be controlled so that the load rise time is limited to approximately 25 • Thus a 10μF capacitor would LOAD require ...
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APPLICATIONS INFORMATION PC Board Layout Checklist When laying out the printed circuit board, the following checklist should be used to ensure proper operation of the IC. These items are also illustrated graphically in the layout diagram of Figure 10. Figure ...
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LTC3868-1 APPLICATIONS INFORMATION Reduce V from its nominal level to verify operation IN of the regulator in dropout. Check the operation of the undervoltage lockout circuit by further lowering V monitoring the outputs to verify operation. Investigate whether any problems ...
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APPLICATIONS INFORMATION BOLD LINES INDICATE HIGH SWITCHING CURRENT. KEEP LINES TO A MINIMUM LENGTH. SW1 L1 R SENSE1 D1 C OUT1 SW2 L2 R SENSE2 D2 C OUT2 Figure 11. Branch Current Waveforms LTC3868-1 ...
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LTC3868-1 TYPICAL APPLICATIONS R B1 215k 15pF 1nF R A1 68.1k C 150pF ITH1A R 15k ITH1 C 820pF ITH1 C 0.1μF SS1 C 0.1μF SS2 C 680pF ITH2 R 27k ITH2 C 100pF ITH2A R A2 ...
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TYPICAL APPLICATIONS R B1 143k 22pF 1nF R A1 68.1k C 100pF ITH1A R 22k ITH1 C 820pF ITH1 C 0.01μF SS1 C 0.01μF SS2 C 820pF ITH2 R 15k ITH2 C 150pF ITH2A R A2 68.1k ...
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LTC3868-1 TYPICAL APPLICATIONS R B1 422k 33pF 1nF R A1 34k C 100pF ITH1A R 33k ITH1 C 0.01μF SS1 C 680pF ITH1 R FREQ 60k C 0.01μF SS2 C 680pF ITH2 R 17k ITH2 C 100pF ...
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TYPICAL APPLICATIONS R B1 28. 56pF 1nF R A1 115k C 220pF ITH1A R 3.93k ITH1 C 1000pF ITH1 C 0.01μF SS1 R FREQ 60k C 0.01μF SS2 C 1000pF ITH2 R 3.43k ITH2 C 220pF ITH2A ...
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LTC3868-1 TYPICAL APPLICATIONS High Effi ciency Dual 1V/1.2V Step-Down Converter with Inductor DCR Current Sensing R B1 28. 56pF 0.1μ 115k C 200pF ITH1A R 3.93k ITH1 C 1000pF ITH1 C 0.01μF SS1 R FREQ ...
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PACKAGE DESCRIPTION 4.50 0.05 3.10 0.05 2.50 REF 2.65 0.05 0.25 0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED PIN 1 TOP MARK (NOTE 6) 5.00 0.10 (2 SIDES) NOTE: ...
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LTC3868-1 PACKAGE DESCRIPTION .254 MIN .0165 .0015 RECOMMENDED SOLDER PAD LAYOUT .0075 – .0098 (0.19 – 0.25) .016 – .050 (0.406 – 1.270) NOTE: 1. CONTROLLING DIMENSION: INCHES INCHES 2. DIMENSIONS ARE IN (MILLIMETERS) 3. DRAWING NOT TO SCALE * ...
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... Changes to Functional Diagram Changes to Typical Applications Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representa- tion that the interconnection of its circuits as described herein will not infringe on existing patent rights. LTC3868-1 ...
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... I = 170μA OUT Q ≤ 24V 50μA OUT Q ≤ 10V 30μA OUT Q ≤ 10V 80μA OUT Q = 120μA, TSSOP- 40μA, MSOP-10E Q LT 1210 REV D • PRINTED IN USA © LINEAR TECHNOLOGY CORPORA TION 2009 ≤ 38V, IN ≤ 60V, IN ≤ 60V, IN 38681fd ...