Features

• 6A, 42V Combined Power Switch
• Output Short Circuit Protection
• Wide Input Range: 2.5V to 16V Operating, 40V Maximum Transient
• LT3579-1: Dual-Phase Capable
• Master/Slave (3.4A/2.6A) Switch Design
• User Configurable Undervoltage Lockout
• Easily Configurable as a Boost, SEPIC, Inverting, or
• Flyback Converter
• Low V_CESAT Switch: 250mV at 5.5A (Typical)
• Can Be Synchronized to External Clock
• Can Synchronize other Switching Regulators
• High Gain SHDN Pin Accepts Slowly Varying Input Signals
• 20-Lead TSSOP and 20-Pin 4mm × 5mm QFN Packages

Typical Application

Description

The LT®3579 is a PWM DC/DC converter with built-in fault protection features to aid in protecting against output shorts, input/output overvoltage, 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 6A.

The LT3579 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 1.7A, or –12V at 1.2A from a 5V input. In addition, the LT3579’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 LT3579’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 LT3579.

The LT3579 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 LT3579 is available in 20-lead TSSOP and 20-pin 4mm × 5mm QFN packages.