Datasheet LTC3770 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Fast No RSENSE Step-Down Synchronous Controller with Margining, Tracking and PLL |
| Pages / Page | 24 / 1 — FEATURES. DESCRIPTION. Wide VIN Range: 4V to 32V. 0.67% 0.6V Reference … |
| File Format / Size | PDF / 273 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. Wide VIN Range: 4V to 32V. 0.67% 0.6V Reference Voltage. Output Voltage Tracking Capability
Model Line for this Datasheet
Text Version of Document
LTC3770 Fast No R TM SENSE Step-Down Synchronous Controller with Margining, Tracking and PLL
FEATURES DESCRIPTION
n
Wide VIN Range: 4V to 32V
The LTC®3770 is a synchronous step-down switching n ±
0.67% 0.6V Reference Voltage
regulator controller with output voltage up/down tracking n
Output Voltage Tracking Capability
capability and voltage margining. Its advanced functions n
Programmable Margining
and high accuracy reference are ideal for powering n
Sense Resistor Optional
high performance server, ASIC and computer memory n
True Current Mode Control
systems. n
2% to 90% Duty Cycle at 200kHz
The LTC3770 uses a constant on-time, valley current n
tON(MIN) ≤ 100ns
mode control architecture to deliver very low duty factors n
Phase-Locked Loop Frequency Synchronization
without requiring a sense resistor. The operating frequency n Powerful Dual N-Channel MOSFET Driver is selected by an external resistor and is compensated for n Adjustable Cycle-by-Cycle Current Limit variations in input supply voltage. An internal phase-locked n Adjustable Switching Frequency loop allows the IC to be synchronized to an external n Programmable Soft-Start clock. n Current Foldback Protection (Disabled at Start-Up) n Output Overvoltage Protection Fault protection is provided by an overvoltage comparator n Micropower Shutdown: I and input undervoltage lockout. The regulator current Q < 30μA n Power Good Output Voltage Monitor limit is user programmable. A wide supply range allows Tracks the Reference Input Pin voltages as high as 32V to be stepped down to as low as n Available in (5mm × 5mm) QFN and 28-Lead a 0.6V output. Power supply sequencing is accomplished SSOP Packages using an external soft-start timing capacitor. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. RSENSE is a registered trademark of Linear Technology Corporation.
APPLICATIONS
All other trademarks are the property of their respective owners. Protected by U.S. Patents including 5481178, 5487554, 6580258, 6304066, 6476589, n Distributed Power Systems 6774611. n Server Power Supply
TYPICAL APPLICATION High Effi ciency Step-Down Converter Effi ciency and Power Loss vs Load Current
100 10 PGOOD ION VIN = 5V 68k 95 V 0.01μF MARGIN V OUT = 2.5V IN 10k VIN 10μF 5V TO 28V 90 EFFICIENCY PLLFLTR TG Si4884 35V PLLIN POWER LOSS (W) x3 85 1.8μH 1 0.1μF SW VOUT TRACK/SS 80 0.22μF 2.5V BOOST 10A I 75 TH + 180μF 10k LTC3770 CMDSH-3 1000pF 4V 70 SGND INTV EFFICIENCY (%) POWER LOSS CC x2 0.1 65 RUN DRVCC V V BG Si4874 B340A OUT ON 60 V SENSE+ RNG 55 95.3k 4.7μF VREFOUT 50 0.01 10k SENSE– 0.01 0.1 1 10 PGND V LOAD CURRENT (A) REFIN 30.1k MPGM 3770 TA01b VFB 82k 3770 TA01 3770fc 1
FEATURES DESCRIPTION
n
Wide VIN Range: 4V to 32V
The LTC®3770 is a synchronous step-down switching n ±
0.67% 0.6V Reference Voltage
regulator controller with output voltage up/down tracking n
Output Voltage Tracking Capability
capability and voltage margining. Its advanced functions n
Programmable Margining
and high accuracy reference are ideal for powering n
Sense Resistor Optional
high performance server, ASIC and computer memory n
True Current Mode Control
systems. n
2% to 90% Duty Cycle at 200kHz
The LTC3770 uses a constant on-time, valley current n
tON(MIN) ≤ 100ns
mode control architecture to deliver very low duty factors n
Phase-Locked Loop Frequency Synchronization
without requiring a sense resistor. The operating frequency n Powerful Dual N-Channel MOSFET Driver is selected by an external resistor and is compensated for n Adjustable Cycle-by-Cycle Current Limit variations in input supply voltage. An internal phase-locked n Adjustable Switching Frequency loop allows the IC to be synchronized to an external n Programmable Soft-Start clock. n Current Foldback Protection (Disabled at Start-Up) n Output Overvoltage Protection Fault protection is provided by an overvoltage comparator n Micropower Shutdown: I and input undervoltage lockout. The regulator current Q < 30μA n Power Good Output Voltage Monitor limit is user programmable. A wide supply range allows Tracks the Reference Input Pin voltages as high as 32V to be stepped down to as low as n Available in (5mm × 5mm) QFN and 28-Lead a 0.6V output. Power supply sequencing is accomplished SSOP Packages using an external soft-start timing capacitor. , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. RSENSE is a registered trademark of Linear Technology Corporation.
APPLICATIONS
All other trademarks are the property of their respective owners. Protected by U.S. Patents including 5481178, 5487554, 6580258, 6304066, 6476589, n Distributed Power Systems 6774611. n Server Power Supply
TYPICAL APPLICATION High Effi ciency Step-Down Converter Effi ciency and Power Loss vs Load Current
100 10 PGOOD ION VIN = 5V 68k 95 V 0.01μF MARGIN V OUT = 2.5V IN 10k VIN 10μF 5V TO 28V 90 EFFICIENCY PLLFLTR TG Si4884 35V PLLIN POWER LOSS (W) x3 85 1.8μH 1 0.1μF SW VOUT TRACK/SS 80 0.22μF 2.5V BOOST 10A I 75 TH + 180μF 10k LTC3770 CMDSH-3 1000pF 4V 70 SGND INTV EFFICIENCY (%) POWER LOSS CC x2 0.1 65 RUN DRVCC V V BG Si4874 B340A OUT ON 60 V SENSE+ RNG 55 95.3k 4.7μF VREFOUT 50 0.01 10k SENSE– 0.01 0.1 1 10 PGND V LOAD CURRENT (A) REFIN 30.1k MPGM 3770 TA01b VFB 82k 3770 TA01 3770fc 1
