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LT3581 - 3.3A Boost/Inverting DC/DC Converter with Fault Protection

The LT®3581 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.

Features 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 Typical Application

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

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