Datasheet LT3844 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | High Voltage, Current Mode Switching Regulator Controller with Programmable Operating Frequency |
| Pages / Page | 26 / 1 — FeaTures. DescripTion. High Voltage Operation: Up to 60V. Output Voltages … |
| File Format / Size | PDF / 292 Kb |
| Document Language | English |
FeaTures. DescripTion. High Voltage Operation: Up to 60V. Output Voltages Up to 36V (Step Down)
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LT3844 High Voltage, Current Mode Switching Regulator Controller with Programmable Operating Frequency
FeaTures DescripTion
n
High Voltage Operation: Up to 60V
The LT®3844 is a DC/DC controller used for medium power, n
Output Voltages Up to 36V (Step Down)
low part count, high efficiency supplies. It offers a wide n
Programmable Constant Frequency: 100kHz to
4V to 60V input range (7.5V minimum start-up voltage)
500kHz
and can implement step-down, step-up, inverting and n Synchronizable up to 600kHz SEPIC topologies. n Burst Mode® Operation: 120µA Supply Current The LT3844 includes Burst Mode operation, which reduces n 10µA Shutdown Supply Current quiescent current below 120µA and maintains high effi- n ±1.3% Reference Accuracy ciency at light loads. An internal high voltage bias regulator n Drives N-Channel MOSFET allows for simple biasing. n Programmable Soft-Start n Programmable Undervoltage Lockout Additional features include current mode control for fast n Internal High Voltage Regulator for Gate Drive line and load transient response; programmable fixed n Thermal Shutdown operating frequency that can be synchronized to an ex- n Current Limit Unaffected by Duty Cycle ternal clock for noise sensitive applications; a gate driver n 16-Pin Thermally Enhanced TSSOP Package capable of driving large N-channel MOSFETs; a precision undervoltage lockout function; 10µA shutdown current;
applicaTions
short-circuit protection and a programmable soft-start function. n Industrial Power Distribution The LT3844 is available in a 16-lead thermally enhanced n 12V and 42V Automotive and Heavy Equipment TSSOP package. n High Voltage Single Board Systems L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. n Distributed Power Systems Burst Mode is a registered trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. n Avionics Protected by U.S. Patents, including 5731694, 6498466, 6611131 n Telecom Power
Typical applicaTion High Voltage Step-Down Regulator 48V to 12V, 50W Efficiency and Power Loss vs Load Current
VIN 36V TO 60V 68µF 22µF 0.22µF 90 7 VIN = 48V 1M VIN BOOST 88 6 SHDN TG Si7850DP 1000pF 86 5 POWER LOSS (W) 10Ω 82.5k EFFICIENCY CSS SW 84 4 BURST_EN VCC 10µH 0.015Ω VOUT 82 3 LT3844 1µF 12V LOSS VFB PGND 50W EFFICIENCY (%) PDS5100H 68µF 10k 80 2 14.7k 33µF VC SENSE+ 680p 120pF 78 1 SYNC SENSE– 130k 76 0 f 0.1 1 10 SET SGND R7 LOAD CURRENT (A) 49.9k 3844 TA01b 3844 TA01 3844fc For more information www.linear.com/LT3844 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Electrical Characteristics Pin Configuration Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts
FeaTures DescripTion
n
High Voltage Operation: Up to 60V
The LT®3844 is a DC/DC controller used for medium power, n
Output Voltages Up to 36V (Step Down)
low part count, high efficiency supplies. It offers a wide n
Programmable Constant Frequency: 100kHz to
4V to 60V input range (7.5V minimum start-up voltage)
500kHz
and can implement step-down, step-up, inverting and n Synchronizable up to 600kHz SEPIC topologies. n Burst Mode® Operation: 120µA Supply Current The LT3844 includes Burst Mode operation, which reduces n 10µA Shutdown Supply Current quiescent current below 120µA and maintains high effi- n ±1.3% Reference Accuracy ciency at light loads. An internal high voltage bias regulator n Drives N-Channel MOSFET allows for simple biasing. n Programmable Soft-Start n Programmable Undervoltage Lockout Additional features include current mode control for fast n Internal High Voltage Regulator for Gate Drive line and load transient response; programmable fixed n Thermal Shutdown operating frequency that can be synchronized to an ex- n Current Limit Unaffected by Duty Cycle ternal clock for noise sensitive applications; a gate driver n 16-Pin Thermally Enhanced TSSOP Package capable of driving large N-channel MOSFETs; a precision undervoltage lockout function; 10µA shutdown current;
applicaTions
short-circuit protection and a programmable soft-start function. n Industrial Power Distribution The LT3844 is available in a 16-lead thermally enhanced n 12V and 42V Automotive and Heavy Equipment TSSOP package. n High Voltage Single Board Systems L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. n Distributed Power Systems Burst Mode is a registered trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. n Avionics Protected by U.S. Patents, including 5731694, 6498466, 6611131 n Telecom Power
Typical applicaTion High Voltage Step-Down Regulator 48V to 12V, 50W Efficiency and Power Loss vs Load Current
VIN 36V TO 60V 68µF 22µF 0.22µF 90 7 VIN = 48V 1M VIN BOOST 88 6 SHDN TG Si7850DP 1000pF 86 5 POWER LOSS (W) 10Ω 82.5k EFFICIENCY CSS SW 84 4 BURST_EN VCC 10µH 0.015Ω VOUT 82 3 LT3844 1µF 12V LOSS VFB PGND 50W EFFICIENCY (%) PDS5100H 68µF 10k 80 2 14.7k 33µF VC SENSE+ 680p 120pF 78 1 SYNC SENSE– 130k 76 0 f 0.1 1 10 SET SGND R7 LOAD CURRENT (A) 49.9k 3844 TA01b 3844 TA01 3844fc For more information www.linear.com/LT3844 1 Document Outline Features Applications Typical Application Description Absolute Maximum Ratings Order Information Electrical Characteristics Pin Configuration Typical Performance Characteristics Pin Functions Functional Diagram Operation Applications Information Typical Applications Package Description Revision History Typical Application Related Parts
