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LTC3869-2 Dataheets PDF



Part Number LTC3869-2
Manufacturers Linear Technology
Logo Linear Technology
Description 2-Phase Synchronous Step-Down DC/DC Controllers
Datasheet LTC3869-2 DatasheetLTC3869-2 Datasheet (PDF)

Features n Dual, 180° Phased Controllers Reduce Required Input Capacitance and Power Supply Induced Noise n Accurate Multiphase Current Matching n RSENSE or DCR Current Sensing n ±0.75% 0.6V Output Voltage Accuracy n Phase-Lockable Fixed Frequency 250kHz to 780kHz n High Efficiency: Up to 95% n Dual N-channel MOSFET Synchronous Drive n Wide VIN Range: 4V to 38V (40V Max) Operation n Wide VOUT Range: 0.6V to 12.5V Operation n Adjustable Soft-Start Current Ramping or Tracking n Foldback Output Cur.

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Features n Dual, 180° Phased Controllers Reduce Required Input Capacitance and Power Supply Induced Noise n Accurate Multiphase Current Matching n RSENSE or DCR Current Sensing n ±0.75% 0.6V Output Voltage Accuracy n Phase-Lockable Fixed Frequency 250kHz to 780kHz n High Efficiency: Up to 95% n Dual N-channel MOSFET Synchronous Drive n Wide VIN Range: 4V to 38V (40V Max) Operation n Wide VOUT Range: 0.6V to 12.5V Operation n Adjustable Soft-Start Current Ramping or Tracking n Foldback Output Current Limiting n Output Overvoltage Protection n Power Good Output Voltage Monitor n 5V Low Dropout Regulator n Small 28-Lead QFN and Narrow SSOP Packages Applications n Server Systems n Telecom Systems n Industrial and Medical Instruments n High Power Battery-Operated Devices n DC Power Distribution Systems LTC3869/LTC3869-2 Dual, 2-Phase Synchronous Step-Down DC/DC Controllers Description The LTC®3869 is a high performance dual synchronous step-down switching regulator controller that drives all N-channel synchronous power MOSFET stages. A constant frequency current mode architecture allows a phaselockable frequency of up to 780kHz. Power loss and noise due to the ESR of the input capacitors are minimized by operating the two controller output stages out-of-phase. OPTI-LOOP® compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. A wide 4V to 38V input supply range encompasses most battery chemistries. Independent TK/ SS pins for each controller ramp the output voltage during start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The MODE/PLLIN pin selects among Burst Mode® operation, pulse-skipping mode, or continuous inductor current mode and allows the IC to be synchronized to an external clock. The LTC3869 is available in low profile 4mm × 4mm and 4mm × 5mm QFN packages. The LTC3869-2 is available in an SSOP-28 package. The LTC3869 is pin-compatible with the LTC3850. L, LT, LTC, LTM, Linear Technology, the Linear logo, µModule, OPTI-LOOP, Burst Mode and PolyPhase are registered trademarks and No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. Protected by U.S. Patents including 5481178, 5705919, 5929620, 6100678, 6144194, 6177787, 6580258, 6498466, 6611131. Typical Application High Efficiency Dual 5V/3.3V Step-Down Converter VIN 7V TO + 4.7µF 24V 22µF VIN INTVCC TG1 TG2 BOOST1 SW1 BG1 LTC3869 BOOST2 SW2 BG2 PGND VOUT1 5V 5A 147k + 47µF SENSE1+ SENSE2+ SENSE1– SENSE2– VFB1 VFB2 ITH1 FREQ 470pF 20k ITH2 TK/SS1 SGND TK/SS2 15k 0.1µF 0.1µF 470pF 122k 15k 90.9k + VOUT2 3.3V 5A 56µF 20k PINS NOT USED IN THIS CIRCUIT: ILIM, MODE/PLLIN, PGOOD, RUN1, RUN2 3869 TA01 For more information www.linear.com/LTC3869 EFFICIENCY (%) POWER LOSS (mW) Efficiency and Power Loss 100 90 80 70 60 50 40 30 20 10 0 0.01 VIN = 12V, VOUT = 3.3V VIN = 12V, VOUT = 5V 1300 1200 1100 EFFICIENCY 1000 900 800 700 600 POWER LOSS 500 0.1 1 LOAD CURRENT (A) 400 10 3869 TA01b 38692fb 1 LTC3869/LTC3869-2 Absolute Maximum Ratings (Note 1) Input Supply Voltage: VIN............................ 40V to –0.3V Top Side Driver Voltages: BOOST1, BOOST2....................................... 46V to –0.3V Switch Voltage: SW1, SW2............................ 40V to –5V INTVCC, RUN1, RUN2, PGOOD, EXTVCC, BOOST1-SW1, BOOST2-SW2........................ 6V to –0.3V SENSE1+, SENSE2+, SENSE1–, SENSE2– Voltages.......................................13V to –0.3V MODE/PLLIN, ILIM, TK/SS1, TK/SS2, FREQ Voltages....................................... INTVCC to –0.3V ITH1, ITH2, VFB1, VFB2 Voltages.............. INTVCC to –0.3V INTVCC Peak Output Current.................................100mA Operating Junction Temperature Range (Note 2)................................................... –40°C to 125°C Junction Temperature (Note 3).............................. 125°C Storage Temperature Range................... –65°C to 150°C Lead Temperature (Soldering, 10 sec) GN Package....................................................... 300°C Pin Configuration TOP VIEW SENSE1+ RUN1 FREQ MODE/PLLIN SW1 TG1 28 27 26 25 24 23 SENSE1– 1 22 BOOST1 TK/SS1 2 21 BG1 ITH1 3 VFB1 4 VFB2 5 ITH2 6 TK/SS2 7 SENSE2– 8 SGND 29 20 VIN 19 INTVCC 18 BG2 17 PGND 16 BOOST2 15 TG2 9 10 11 12 13 14 SENSE2+ RUN2 ILIM EXTVCC PGOOD SW2 UFD PACKAGE 28-LEAD (4mm × 5mm) PLASTIC QFN TJMAX = 125°C, θJA = 34°C/W, EXPOSED PAD (PIN 29) IS SGND, MUST BE SOLDERED TO PCB TOP VIEW RUN1 1 SENSE1+ 2 SENSE1– 3 VFB1 4 TK/SS1 5 ITH1 6 SGND 7 ITH2 8 TK/SS2 9 VFB2 10 SENSE2– 11 SENSE2+ 12 RUN2 13 EXTVCC 14 28 FREQ 27 MODE/PLLIN 26 SW1 25 TG1 24 BOOST1 23 BG1 22 VIN 21 INTVCC 20 BG2 19 PGND 18 BOOST2 17 TG2 16 SW2 15 PGOOD GN PACKAGE 28-LEAD PLASTIC SSOP TJMAX = 125°C, θJA = 80°C/W TOP VIEW SENSE1– SENSE1+ RUN1 FREQ MODE/PLL.


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