Datasheet LTC3852 (Analog Devices)
| 制造商 | Analog Devices |
| 描述 | Low Input Voltage, Synchronous Step-Down DC/DC Controller |
| 页数 / 页 | 32 / 1 — FEATURES. DESCRIPTION. Charge Pump Input Range: 2.7V to 5.5V. Controller … |
| 文件格式/大小 | PDF / 429 Kb |
| 文件语言 | 英语 |
FEATURES. DESCRIPTION. Charge Pump Input Range: 2.7V to 5.5V. Controller Input Range: 4V to 38V
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LTC3852 Low Input Voltage, Synchronous Step-Down DC/DC Controller
FEATURES DESCRIPTION
n
Charge Pump Input Range: 2.7V to 5.5V
The LTC®3852 is a constant frequency, current mode n
Controller Input Range: 4V to 38V
step-down DC/DC controller which can be powered by an n
Integrated Charge Pump Provides 5V Gate Drive to
onboard charge pump. Input supplies as low as 2.7V, when
Logic Level MOSFETs
doubled by the charge pump, provide 5V to the LTC3852’s n
RSENSE or DCR Current Sensing
control logic and gate drives, supporting a wide selection n
±1.25% Output Voltage Accuracy Over Temperature
of logic-level N-channel power MOSFETs. n
Phase-Lockable Fixed Frequency: 250kHz to 750kHz
The constant-frequency current mode architecture allows for n Power Good Output Voltage Monitor a phase-lockable fi xed frequency of up to 750kHz. The RUN n Adjustable Soft-Start Voltage Ramping pin provides a precision enable threshold while the TRACK/SS n Current Foldback Disabled During Start-Up pin combines tracking and adjustable soft-start features. n No Reverse Current During Soft-Start n Selectable Constant Frequency, Pulse-Skipping, or The MODE/PLLIN pin selects among Burst Mode® oper- Burst Mode Operation ation, pulse-skipping mode, and continuous current mode. n Output Overvoltage Protection Current foldback limits MOSFET power dissipation during n Very Low Dropout Operation: 99% Duty Cycle short-circuit conditions. Reverse current and current n Available in a 24-Lead (3mm ¥ 5mm) QFN Package foldback functions are disabled during soft-start. A power good output pin indicates when the output is within ±10%
APPLICATIONS
of its designed set point. n General Purpose 3.3V Systems L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks and No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the n Lithium-Ion Powered Devices property of their respective owners. Protected by U.S. Patents including 5408150, 5481178, 5705919, 6498466, 6580258, 6611131. n Distributed DC Power Systems
TYPICAL APPLICATION High Effi ciency Synchronous Step-Down Converter Effi ciency and Power Loss vs Load Current
100k V INTV PGO0D V IN CC IN1 2.7V TO 5.5V 22μF 100 5 MODE/PLLIN TG 0.36μH V 90 OUT 4.5 FREQ/PLLFLTR SW 1.2V EFFICIENCY 80 4 0.1μF 20A 95.3k BOOST + POWER LOSS (W) 470μF 70 3.5 TRACK/SS V 2.1k IN2 ×2 0.1μF 60 3 INTV 1nF CC 50 2.5 4.7μF LTC3852 ITH BG 40 2 EFFICIENCY (%) GND2 12.1k 100pF 30 1.5 POWER LOSS RUN SENSE+ 20k 20 1 0.1μF 1% OFF ON SHDN 10 0.5 SENSE– CHARGE PUMP C+ VFB 0 0 2.2μF 1 10 20 C– V 40.2k PUMP GND1 1% LOAD CURRENT (A) 3852 TA01 3852 TA01a 3852f 1
FEATURES DESCRIPTION
n
Charge Pump Input Range: 2.7V to 5.5V
The LTC®3852 is a constant frequency, current mode n
Controller Input Range: 4V to 38V
step-down DC/DC controller which can be powered by an n
Integrated Charge Pump Provides 5V Gate Drive to
onboard charge pump. Input supplies as low as 2.7V, when
Logic Level MOSFETs
doubled by the charge pump, provide 5V to the LTC3852’s n
RSENSE or DCR Current Sensing
control logic and gate drives, supporting a wide selection n
±1.25% Output Voltage Accuracy Over Temperature
of logic-level N-channel power MOSFETs. n
Phase-Lockable Fixed Frequency: 250kHz to 750kHz
The constant-frequency current mode architecture allows for n Power Good Output Voltage Monitor a phase-lockable fi xed frequency of up to 750kHz. The RUN n Adjustable Soft-Start Voltage Ramping pin provides a precision enable threshold while the TRACK/SS n Current Foldback Disabled During Start-Up pin combines tracking and adjustable soft-start features. n No Reverse Current During Soft-Start n Selectable Constant Frequency, Pulse-Skipping, or The MODE/PLLIN pin selects among Burst Mode® oper- Burst Mode Operation ation, pulse-skipping mode, and continuous current mode. n Output Overvoltage Protection Current foldback limits MOSFET power dissipation during n Very Low Dropout Operation: 99% Duty Cycle short-circuit conditions. Reverse current and current n Available in a 24-Lead (3mm ¥ 5mm) QFN Package foldback functions are disabled during soft-start. A power good output pin indicates when the output is within ±10%
APPLICATIONS
of its designed set point. n General Purpose 3.3V Systems L, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarks and No RSENSE is a trademark of Linear Technology Corporation. All other trademarks are the n Lithium-Ion Powered Devices property of their respective owners. Protected by U.S. Patents including 5408150, 5481178, 5705919, 6498466, 6580258, 6611131. n Distributed DC Power Systems
TYPICAL APPLICATION High Effi ciency Synchronous Step-Down Converter Effi ciency and Power Loss vs Load Current
100k V INTV PGO0D V IN CC IN1 2.7V TO 5.5V 22μF 100 5 MODE/PLLIN TG 0.36μH V 90 OUT 4.5 FREQ/PLLFLTR SW 1.2V EFFICIENCY 80 4 0.1μF 20A 95.3k BOOST + POWER LOSS (W) 470μF 70 3.5 TRACK/SS V 2.1k IN2 ×2 0.1μF 60 3 INTV 1nF CC 50 2.5 4.7μF LTC3852 ITH BG 40 2 EFFICIENCY (%) GND2 12.1k 100pF 30 1.5 POWER LOSS RUN SENSE+ 20k 20 1 0.1μF 1% OFF ON SHDN 10 0.5 SENSE– CHARGE PUMP C+ VFB 0 0 2.2μF 1 10 20 C– V 40.2k PUMP GND1 1% LOAD CURRENT (A) 3852 TA01 3852 TA01a 3852f 1