Datasheet LTC3775 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | High Frequency Synchronous Step-Down Voltage Mode DC/DC Controller |
| Pages / Page | 34 / 1 — FEATURES. DESCRIPTION. Wide VIN Range: 4.5V to 38V. Line. Feedforward … |
| File Format / Size | PDF / 553 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. Wide VIN Range: 4.5V to 38V. Line. Feedforward Compensation. APPLICATIONS. TYPICAL APPLICATION
Model Line for this Datasheet
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LTC3775 High Frequency Synchronous Step-Down Voltage Mode DC/DC Controller
FEATURES DESCRIPTION
n
Wide VIN Range: 4.5V to 38V
The LTC®3775 is a high effi ciency synchronous step-down n
Line Feedforward Compensation
switching DC/DC controller that drives an all N-channel n Low Minimum On-Time: tON(MIN) < 30ns power MOSFET stage from a 4.5V to 38V input supply n Powerful Onboard MOSFET Drivers voltage. A patented line feedforward compensation circuit n Leading Edge Modulation Voltage Mode Control and a high bandwidth error amplifi er provide very fast line n ±0.75%, 0.6V Reference Voltage Accuracy Over and load transient response. Temperature High step-down ratios are made possible by a low 30ns n VOUT Range: 0.6V to 0.8VIN minimum on-time, allowing extremely low duty cycles. n Programmable, Cycle-by-Cycle Peak Current Limit MOSFET RDS(ON) current sensing maximizes effi ciency. n Sense Resistor or RDS(ON) Current Sensing Alternatively, a sense resistor can be used for higher cur- n Programmable Soft-Start rent limit accuracy. Continuous monitoring of the voltages n Synchronizable Fixed Frequency from 250kHz to 1MHz across the top and bottom MOSFETs allows cycle-by-cycle n Selectable Pulse-Skipping or Forced Continuous control of the inductor current, confi gurable by external Modes of Operation resistors. n Low Shutdown Current: 14μA Typical n Thermally Enhanced 16-Lead MSOP and 3mm × 3mm The soft-start function controls the duty cycle during QFN Packages start-up, providing a smooth output voltage ramp up. The operating frequency is user programmable from 250kHz
APPLICATIONS
to 1MHz and can be synchronized to an external clock. L, LT, LTC, LTM, Linear Technology, the Linear logo are registered trademarks, No R n Automotive Systems SENSE and UltraFast are trademarks of Linear Technology Corporation. All other trademarks are the n Telecom and Industrial Power Supplies property of their respective owners. Protected by U.S. Patents, including 5408150, 5481178, 5705919, 6580258, 5847554, 5055767. n Point of Load Applications
TYPICAL APPLICATION
VIN
Effi ciency and Power Loss vs Load Current
5V TO 28V 330μF 35V 100 5 VIN = 12V 3.16k V 90 IN V I TG OUT = 1.2V LIMT CONTINUOUS MODE 57.6k 80 4 I SENSE SW FREQ = 500kHz LIMB POWER LOSS (W) 4.7μF 0.1μF 70 LTC3775 INTV 60 3 CC BOOST 0.36μH V 0.01μF OUT EFFICIENCY SW 1.2V 50 SS 470μF 15A 39.2k BG 40 2 2.5V FREQ EFFICIENCY (%) ×2 30 PGND FB 20 1 330pF POWER LOSS 10 COMP 3.9nF SGND 0 0 10k 10k 4.7k 0.01 0.1 1 10 100 LOAD CURRENT (A) 3775 TA01a 3775 TA01b 3775fa 1 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION ELECTRICAL CHARACTERISTICS TYPICAL PERFORMANCE CHARACTERISTICS PIN FUNCTIONS BLOCK DIAGRAM APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION REVISION HISTORY TYPICAL APPLICATION RELATED PARTS
FEATURES DESCRIPTION
n
Wide VIN Range: 4.5V to 38V
The LTC®3775 is a high effi ciency synchronous step-down n
Line Feedforward Compensation
switching DC/DC controller that drives an all N-channel n Low Minimum On-Time: tON(MIN) < 30ns power MOSFET stage from a 4.5V to 38V input supply n Powerful Onboard MOSFET Drivers voltage. A patented line feedforward compensation circuit n Leading Edge Modulation Voltage Mode Control and a high bandwidth error amplifi er provide very fast line n ±0.75%, 0.6V Reference Voltage Accuracy Over and load transient response. Temperature High step-down ratios are made possible by a low 30ns n VOUT Range: 0.6V to 0.8VIN minimum on-time, allowing extremely low duty cycles. n Programmable, Cycle-by-Cycle Peak Current Limit MOSFET RDS(ON) current sensing maximizes effi ciency. n Sense Resistor or RDS(ON) Current Sensing Alternatively, a sense resistor can be used for higher cur- n Programmable Soft-Start rent limit accuracy. Continuous monitoring of the voltages n Synchronizable Fixed Frequency from 250kHz to 1MHz across the top and bottom MOSFETs allows cycle-by-cycle n Selectable Pulse-Skipping or Forced Continuous control of the inductor current, confi gurable by external Modes of Operation resistors. n Low Shutdown Current: 14μA Typical n Thermally Enhanced 16-Lead MSOP and 3mm × 3mm The soft-start function controls the duty cycle during QFN Packages start-up, providing a smooth output voltage ramp up. The operating frequency is user programmable from 250kHz
APPLICATIONS
to 1MHz and can be synchronized to an external clock. L, LT, LTC, LTM, Linear Technology, the Linear logo are registered trademarks, No R n Automotive Systems SENSE and UltraFast are trademarks of Linear Technology Corporation. All other trademarks are the n Telecom and Industrial Power Supplies property of their respective owners. Protected by U.S. Patents, including 5408150, 5481178, 5705919, 6580258, 5847554, 5055767. n Point of Load Applications
TYPICAL APPLICATION
VIN
Effi ciency and Power Loss vs Load Current
5V TO 28V 330μF 35V 100 5 VIN = 12V 3.16k V 90 IN V I TG OUT = 1.2V LIMT CONTINUOUS MODE 57.6k 80 4 I SENSE SW FREQ = 500kHz LIMB POWER LOSS (W) 4.7μF 0.1μF 70 LTC3775 INTV 60 3 CC BOOST 0.36μH V 0.01μF OUT EFFICIENCY SW 1.2V 50 SS 470μF 15A 39.2k BG 40 2 2.5V FREQ EFFICIENCY (%) ×2 30 PGND FB 20 1 330pF POWER LOSS 10 COMP 3.9nF SGND 0 0 10k 10k 4.7k 0.01 0.1 1 10 100 LOAD CURRENT (A) 3775 TA01a 3775 TA01b 3775fa 1 Document Outline FEATURES DESCRIPTION APPLICATIONS TYPICAL APPLICATION ABSOLUTE MAXIMUM RATINGS PIN CONFIGURATION ORDER INFORMATION ELECTRICAL CHARACTERISTICS TYPICAL PERFORMANCE CHARACTERISTICS PIN FUNCTIONS BLOCK DIAGRAM APPLICATIONS INFORMATION TYPICAL APPLICATIONS PACKAGE DESCRIPTION REVISION HISTORY TYPICAL APPLICATION RELATED PARTS
