Datasheet LTC3823 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Fast No RSENSE Step-Down Synchronous DC/DC Controller with Differential Output Sensing, Tracking and PLL |
| Pages / Page | 26 / 1 — FEATURES. DESCRIPTION. Wide VIN Range: 4.5V to 36V. ±0.67%, 0.6V … |
| File Format / Size | PDF / 315 Kb |
| Document Language | English |
FEATURES. DESCRIPTION. Wide VIN Range: 4.5V to 36V. ±0.67%, 0.6V Reference Voltage. Output Voltage Tracking Capability
Model Line for this Datasheet
Text Version of Document
LTC3823 Fast No RSENSETM Step-Down Synchronous DC/DC Controller with Differential Output Sensing, Tracking and PLL
FEATURES DESCRIPTION
n
Wide VIN Range: 4.5V to 36V
The LTC®3823 is a synchronous step-down switching regu- n
±0.67%, 0.6V Reference Voltage
lator controller with true remote differential output sensing n
Output Voltage Tracking Capability
and output voltage up/down tracking capability. Its advanced n
True Remote Sensing Differential Amplifi er
functions 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 LTC3823 uses a constant on-time, valley current n
tON(MIN) < 100ns
mode control architecture to deliver very low duty fac- n
Phase-Locked Loop Frequency Synchronization
tors without requiring a sense resistor. The operating n Powerful Dual N-Channel MOSFET Driver frequency is selected by an external resistor and is com- n Adjustable Cycle-by-Cycle Current Limit pensated for variations in input supply voltage. An internal n Adjustable Switching Frequency phase-locked loop allows the IC to be synchronized to an n Programmable Soft-Start external clock. n Current Foldback Protection (Disabled at Start-Up) n Output Overvoltage Protection Fault protection is provided by an overvoltage compara- n Micropower Shutdown: 30μA tor and input undervoltage lockout. The regulator current n Power Good Output Voltage Monitor Tracks the limit is user programmable. A wide supply range allows Reference Input Pin voltages as high as 36V to be stepped down to as low as n Available in (5mm × 5mm) 32-Lead QFN and a 0.6V output. When using remote sense, output voltages 28-Lead SSOP Narrow Packages up to 3.3V can be developed, and up to 90% of VIN without remote sense. Power supply sequencing is accomplished
APPLICATIONS
using an external soft-start timing capacitor. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and n Distributed Power Systems 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, 5847554, n Server Power Supplies 6580258, 6304066, 6476589, 6774611.
TYPICAL APPLICATION Effi ciency and Power Loss High Effi ciency Step-Down Converter vs Load Current
PGOOD I 97 10 ON 68k VIN = 5V VIN 96 0.01 V μF VIN OUT = 2.5V 10k 10μF 5V TO 28V FIGURE 12 CIRCUIT TG Si4884 95 PLLFLTR 35V PLLIN 1.8μH s3 POWER LOSS (W) V 94 OUT 1 EFFICIENCY 0.1μF SW 2.5V TRACK/SS 93 0.22μF 10A BOOST + 180μF I 92 TH 4V POWER LOSS 10k LTC3823 CMDSH-3 1000pF 91 s2 SGND INTV EFFICIENCY (%) CC 0.1 90 RUN DRVCC V V BG Si4874 OUT 89 ON SENSE+ VRNG 88 B340A 10μF VDIFFOUT SENSE– 87 0.01 9.5k PGND 0.1 1 10 V LOAD CURRENT (A) 3823 TA01b FB V + 3k OUTSENSE V – OUTSENSE 3823 TA01a 3823fd 1
FEATURES DESCRIPTION
n
Wide VIN Range: 4.5V to 36V
The LTC®3823 is a synchronous step-down switching regu- n
±0.67%, 0.6V Reference Voltage
lator controller with true remote differential output sensing n
Output Voltage Tracking Capability
and output voltage up/down tracking capability. Its advanced n
True Remote Sensing Differential Amplifi er
functions 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 LTC3823 uses a constant on-time, valley current n
tON(MIN) < 100ns
mode control architecture to deliver very low duty fac- n
Phase-Locked Loop Frequency Synchronization
tors without requiring a sense resistor. The operating n Powerful Dual N-Channel MOSFET Driver frequency is selected by an external resistor and is com- n Adjustable Cycle-by-Cycle Current Limit pensated for variations in input supply voltage. An internal n Adjustable Switching Frequency phase-locked loop allows the IC to be synchronized to an n Programmable Soft-Start external clock. n Current Foldback Protection (Disabled at Start-Up) n Output Overvoltage Protection Fault protection is provided by an overvoltage compara- n Micropower Shutdown: 30μA tor and input undervoltage lockout. The regulator current n Power Good Output Voltage Monitor Tracks the limit is user programmable. A wide supply range allows Reference Input Pin voltages as high as 36V to be stepped down to as low as n Available in (5mm × 5mm) 32-Lead QFN and a 0.6V output. When using remote sense, output voltages 28-Lead SSOP Narrow Packages up to 3.3V can be developed, and up to 90% of VIN without remote sense. Power supply sequencing is accomplished
APPLICATIONS
using an external soft-start timing capacitor. L, LT, LTC, LTM, Linear Technology and the Linear logo are registered trademarks and n Distributed Power Systems 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, 5847554, n Server Power Supplies 6580258, 6304066, 6476589, 6774611.
TYPICAL APPLICATION Effi ciency and Power Loss High Effi ciency Step-Down Converter vs Load Current
PGOOD I 97 10 ON 68k VIN = 5V VIN 96 0.01 V μF VIN OUT = 2.5V 10k 10μF 5V TO 28V FIGURE 12 CIRCUIT TG Si4884 95 PLLFLTR 35V PLLIN 1.8μH s3 POWER LOSS (W) V 94 OUT 1 EFFICIENCY 0.1μF SW 2.5V TRACK/SS 93 0.22μF 10A BOOST + 180μF I 92 TH 4V POWER LOSS 10k LTC3823 CMDSH-3 1000pF 91 s2 SGND INTV EFFICIENCY (%) CC 0.1 90 RUN DRVCC V V BG Si4874 OUT 89 ON SENSE+ VRNG 88 B340A 10μF VDIFFOUT SENSE– 87 0.01 9.5k PGND 0.1 1 10 V LOAD CURRENT (A) 3823 TA01b FB V + 3k OUTSENSE V – OUTSENSE 3823 TA01a 3823fd 1
