Datasheet LT3509 (Analog Devices)
| Manufacturer | Analog Devices |
| Description | Dual 36V, 700mA Step-Down Regulator |
| Pages / Page | 24 / 1 — FeaTures. DescripTion. Two 700mA Switching Regulators with Internal. … |
| File Format / Size | PDF / 328 Kb |
| Document Language | English |
FeaTures. DescripTion. Two 700mA Switching Regulators with Internal. Power Switches. Wide 3.6V to 36V Operating Range
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LT3509 Dual 36V, 700mA Step-Down Regulator
FeaTures DescripTion
n
Two 700mA Switching Regulators with Internal
The LT®3509 is a dual, current mode, step-down switching
Power Switches
regulator, with internal power switches each capable of n
Wide 3.6V to 36V Operating Range
providing 700mA output current. This regulator provides a n
Overvoltage Lockout Protects Circuit Through 60V
compact and robust solution for multi-rail systems in harsh
Supply Transients
environments. It incorporates several protection features n
Short-Circuit Robust
including overvoltage lockout and cycle-by-cycle current n Low Dropout Voltage: 95% Maximum Duty Cycle limit. Thermal shutdown provides additional protection. n Adjustable 300kHz to 2.2MHz Switching Frequency The loop compensation components and the boost diodes Synchronizable Over the Full Range are integrated on-chip. Switching frequency is set by a n Uses Small Inductors and Ceramic Capacitors single external resistor. External synchronization is also n Integrated Boost Diodes possible. The high maximum switching frequency allows n Internal Compensation the use of small inductors and ceramic capacitors for low n Thermally Enhanced 14-Lead (4mm × 3mm) ripple. Constant frequency operation above the AM band DFN and 16 Lead MSOP Packages avoids interference with radio reception, making the LT3509 well suited for automotive applications. Each regulator
applicaTions
has an independent shutdown and soft-start control pin. When both converters are powered down, the common n Automotive Electronics circuitry enters a low current shutdown state. n Industrial Controls L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective n Wall Transformer Regulation owners. n Networking Devices n CPU, DSP, or FPGA Power
Typical applicaTion 3.3V and 5V Dual Output Step-Down Converter Efficiency
6.5V TO 36V (TRANSIENT TO 60V) 90 2.2µF VIN BD 85 VOUT = 5V BOOST1 BOOST2 80 6.8µH 0.1µF 0.1µF 10µH 3.3V VOUT = 3.3V SW1 SW2 5V 700mA 700mA 75 LT3509 31.6k 53.6k 70 DA1 DA2 MBRM140 MBRM140 EFFICIENCY (%) 65 FB1 FB2 22µF 10µF RUN/SS1 RUN/SS2 60 SYNC RT 1nF 55 VIN = 12V 1nF f 10.2k SW = 700kHz GND 10.2k 60.4k 500.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 LOAD CURRENT (A) 3509 TA01a fSW = 700kHz 3509 TA01b 3509fd For more information www.linear.com/LT3509 1 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Related Parts
FeaTures DescripTion
n
Two 700mA Switching Regulators with Internal
The LT®3509 is a dual, current mode, step-down switching
Power Switches
regulator, with internal power switches each capable of n
Wide 3.6V to 36V Operating Range
providing 700mA output current. This regulator provides a n
Overvoltage Lockout Protects Circuit Through 60V
compact and robust solution for multi-rail systems in harsh
Supply Transients
environments. It incorporates several protection features n
Short-Circuit Robust
including overvoltage lockout and cycle-by-cycle current n Low Dropout Voltage: 95% Maximum Duty Cycle limit. Thermal shutdown provides additional protection. n Adjustable 300kHz to 2.2MHz Switching Frequency The loop compensation components and the boost diodes Synchronizable Over the Full Range are integrated on-chip. Switching frequency is set by a n Uses Small Inductors and Ceramic Capacitors single external resistor. External synchronization is also n Integrated Boost Diodes possible. The high maximum switching frequency allows n Internal Compensation the use of small inductors and ceramic capacitors for low n Thermally Enhanced 14-Lead (4mm × 3mm) ripple. Constant frequency operation above the AM band DFN and 16 Lead MSOP Packages avoids interference with radio reception, making the LT3509 well suited for automotive applications. Each regulator
applicaTions
has an independent shutdown and soft-start control pin. When both converters are powered down, the common n Automotive Electronics circuitry enters a low current shutdown state. n Industrial Controls L, LT, LTC, LTM, Burst Mode, Linear Technology and the Linear logo are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective n Wall Transformer Regulation owners. n Networking Devices n CPU, DSP, or FPGA Power
Typical applicaTion 3.3V and 5V Dual Output Step-Down Converter Efficiency
6.5V TO 36V (TRANSIENT TO 60V) 90 2.2µF VIN BD 85 VOUT = 5V BOOST1 BOOST2 80 6.8µH 0.1µF 0.1µF 10µH 3.3V VOUT = 3.3V SW1 SW2 5V 700mA 700mA 75 LT3509 31.6k 53.6k 70 DA1 DA2 MBRM140 MBRM140 EFFICIENCY (%) 65 FB1 FB2 22µF 10µF RUN/SS1 RUN/SS2 60 SYNC RT 1nF 55 VIN = 12V 1nF f 10.2k SW = 700kHz GND 10.2k 60.4k 500.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 LOAD CURRENT (A) 3509 TA01a fSW = 700kHz 3509 TA01b 3509fd For more information www.linear.com/LT3509 1 Document Outline Features Description Applications Typical Application Absolute Maximum Ratings Electrical Characteristics Typical Performance Characteristics Pin Functions Block Diagram Operation Related Parts
