LT3581

RECOMMENDED FOR NEW DESIGNS

3.3A Boost/Inverting DC/DC Converter with Fault Protection

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Overview

  • 3.3A, 42V Combined Power Switch
  • Master/Slave (1.9A/1.4A) Switch Design
  • Output Short Circuit Protection
  • Wide Input Range: 2.5V to 22V Operating, 40V Maximum Transient
  • Switching Frequency Up to 2.5MHz
  • Easily Configurable as a Boost, SEPIC, Inverting or Flyback Converter
  • User Configurable Undervoltage Lockout
  • Low VCESAT Switch: 250mV at 2.75A (Typical)
  • Can be Synchronized to External Clock
  • Can Be Synchronized to other Switching Regulators
  • High Gain SHDN Pin Accepts Slowly Varying Input Signals
  • 14-Pin 4mm × 3mm DFN and 16-Lead MSE Packages

The LT3581 is a PWM DC/DC converter with built-in fault protection features to aid in protecting against output shorts, input/output overvoltages, and overtemperature conditions. The part consists of a 42V master switch, and a 42V slave switch that can be tied together for a total current limit of 3.3A.

The LT3581 is ideal for many local power supply designs. It can be easily configured in Boost, SEPIC, Inverting or Flyback configurations, and is capable of generating 12V at 830mA, or –12V at 625mA from a 5V input. In addition, the LT3581’s slave switch allows the part to be configured in high voltage, high power charge pump topologies that are very efficient and require fewer components than traditional circuits.

The LT3581’s switching frequency range can be set between 200kHz and 2.5MHz. The part may be clocked internally at a frequency set by the resistor from the RT pin to ground, or it may be synchronized to an external clock. A buffered version of the clock signal is driven out of the CLKOUT pin, and may be used to synchronize other compatible switching regulator ICs to the LT3581.

The LT3581 also features innovative SHDN pin circuitry that allows for slowly varying input signals and an adjustable undervoltage lockout function. Additional features such as frequency foldback and soft-start are integrated. The LT3581 is available in 14-Pin 4mm × 3mm DFN and 16-Lead MSE packages.

Applications

  • Local Power Supply
  • Vacuum Fluorescent Display (VFD) Bias Supplies
  • TFT-LCD Bias Supplies
  • Automotive Engine Control Unit (ECU) Power

LT3581
3.3A Boost/Inverting DC/DC Converter with Fault Protection
Output Short Protected, 5V to 12V Boost Converter Operating at 2MHz Efficiency and Power Loss vs Load Current Product Package 1 Product Package 2
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Documentation

Data Sheet

This is the most up-to-date revision of the Data Sheet.

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Software Resources

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Hardware Ecosystem

Parts Product Life Cycle Description
Protection Switches & Controllers 1
LTC4365 RECOMMENDED FOR NEW DESIGNS Overvoltage, Undervoltage and Reverse Supply Protection Controller
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Tools & Simulations

LTspice 1


Models for the following parts are available in LTspice:

  • LT3581
LTspice

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.


Evaluation Kits

eval board
DC1424A-A

LT3581EMSE Demo Board | VIN = 5V to 10V, VOUT1 = 12V @ 900mA

Product Details

Demonstration circuits 1424A-A and 1424A-B feature the LT3581 in Boost and Inverting Regulator configurations, respectively. The Boost is designed to convert a 5V to 10V input source to 12V at 900mA, and the Inverter a 5V to 12V to -12V at 750mA. DC1424A-A is designed to survive output short circuit events with the external MOSFET installed at the output as default. The demo board includes an option to install the MOSFET at the input side. Install Q1 and R1 on the back of the board and refer to Figure 4 for other instructions. DC1424A-B can easily be converted into a SEPIC Converter by swapping L2 and D2 from their respective locations as shown in Figure 5. The LT3581 includes a 42V Master and Slave switch combination with 3.3A total current and can be used in many configurations such as Boost, SEPIC, CUK and Flyback.

eval board
DC1424A-B

LT3581EMSE Demo Board | VIN = 5V to 12V, VOUT1 = –12V @ 750mA

Product Details

Demonstration circuits 1424A-A and 1424A-B feature the LT3581 in Boost and Inverting Regulator configurations, respectively. The Boost is designed to convert a 5V to 10V input source to 12V at 900mA, and the Inverter a 5V to 12V to -12V at 750mA. DC1424A-A is designed to survive output short circuit events with the external MOSFET installed at the output as default. The demo board includes an option to install the MOSFET at the input side. Install Q1 and R1 on the back of the board and refer to Figure 4 for other instructions. DC1424A-B can easily be converted into a SEPIC Converter by swapping L2 and D2 from their respective locations as shown in Figure 5. The LT3581 includes a 42V Master and Slave switch combination with 3.3A total current and can be used in many configurations such as Boost, SEPIC, CUK and Flyback. It has a 2.5V to 22V operating input range, UVLO, soft-start, programmable switching frequency and many other popular features.

DC1424A-A
LT3581EMSE Demo Board | VIN = 5V to 10V, VOUT1 = 12V @ 900mA
DC1424A-A - Schematic
DC1424A-B
LT3581EMSE Demo Board | VIN = 5V to 12V, VOUT1 = –12V @ 750mA
DC1424A-A - Schematic

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