LT3509 - Dual 36V, 700mA Step-Down Regulator

The LT3509 is a dual, current mode, step-down switching regulator, with internal power switches each capable of providing 700mA output current. This regulator provides a compact and robust solution for multi-rail systems in harsh environments. It incorporates several protection features including overvoltage lockout and cycle-by-cycle current limit. Thermal shutdown provides additional protection. The loop compensation components and the boost diodes are integrated on-chip. Switching frequency is set by a single external resistor. External synchronization is also possible. The high maximum switching frequency allows the use of small inductors and ceramic capacitors for low ripple. Constant frequency operation above the AM band avoids interference with radio reception, making the LT3509 well suited for automotive applications. Each regulator has an independent shutdown and soft-start control pin. When both converters are powered down, the common circuitry enters a low current shutdown state.

Features
  • Two 700mA Switching Regulators with Internal Power Switches
  • Wide 3.6V to 36V Operating Range
  • Overvoltage Lockout Protects Circuit Through 60V Supply Transients
  • Short-Circuit Robust
  • Low Dropout Voltage: 95% Maximum Duty Cycle
  • Adjustable 300kHz to 2.2MHz Switching Frequency Synchronizable Over the Full Range
  • Uses Small Inductors and Ceramic Capacitors
  • Integrated Boost Diodes
  • Internal Compensation
  • Thermally Enhanced 14-Lead (4mm × 3mm) DFN and 16 Lead MSOP Packages
Typical Application
LT3509 Typical Application
LT3509 Typical Application
Applications
  • Automotive Electronics
  • Industrial Controls
  • Wall Transformer Regulation
  • Networking Devices
  • CPU, DSP, or FPGA Power
Packaging
LT3509 Package Drawing
LT3509 Package Drawing
Order Information
Part NumberPackageTempPrice(1-99)Price (1k)*
LT3509EDE#PBF4x3 DFN-14E$4.22$2.95
LT3509EDE#TRPBF4x3 DFN-14E$3.01
LT3509EMSE#PBFMS-16EE$4.36$3.05
LT3509EMSE#TRPBFMS-16EE$3.11
LT3509HMSE#PBFMS-16EH$5.37$3.76
LT3509HMSE#TRPBFMS-16EH$5.37$3.82
LT3509IDE#PBF4x3 DFN-14I$4.84$3.39
LT3509IDE#TRPBF4x3 DFN-14I$3.45
LT3509IMSE#PBFMS-16EI$5.02$3.51
LT3509IMSE#TRPBFMS-16EI$3.57
Demo Boards
Part NumberDescriptionPrice
DC1248ALT3509EDE Demo Board | 6.5V ≤ VIN ≤ 36V (60V Transients), Vout1 = 5V @ 0.7A, Vout2 = 3.3V @ 0.7A$125.00
Datasheet
Reliability Data
LT Journal
Press Release
CAD Symbol
Ad
LTspice
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LT3509 - Dual 36V, 700mA Step-Down Regulator
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R530 - Reliability Data
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LT3509 Footprints and Symbols
36Vin Multichannel Bucks
LT3509 Demo Circuit - Dual 36V, 700mA Step-Down Regulator (12V to 5V @ 700mA)