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LT3641 - Dual Monolithic Buck Regulator with Power-On Reset and Watchdog Timer

The LT®3641 is a dual channel, current mode monolithic buck switching regulator with a power-on reset and a watchdog timer. Both regulators are synchronized to a single oscillator with an adjustable frequency (350kHz to 2.5MHz). At light loads, both regulators operate in low ripple Burst Mode® to maintain high effi ciency and low output ripple.

The high voltage channel is a nonsynchronous buck with an internal 2.4A top switch that operates from an input of 4V to 42V and input transient protection to 55V. The low voltage channel operates from an input of 2.5V to 5.5V. Internal synchronous power switches provide high effi ciency without the need of external Schottky diode. Both channels have cycle-by-cycle current limit, providing protection against shorted outputs.

The power-on reset and watchdog timeout periods are both adjustable using external capacitors. The window mode watchdog timer fl ags when the μP pulses group too close together or too far apart.

The LT3641 is available in a 28-pin 4mm × 5mm QFN package and 28-pin TSSOP package. Both packages have an exposed pad for low thermal resistance.

Features High Voltage Buck Regulator: 4V to 42V Operating Range 1.3A Output Current Input Transient Protection to 55V Low Voltage Synchronous Buck Regulator: 2.5V to 5.5V Input Voltage Range 1.1A Output Current Synchronizable, Adjustable 350kHz to 2.5MHz Switching Frequency Programmable Power-On Reset Timer Programmable Window Mode Watchdog Timer Typical Quiescent Current: 290μA Short-Circuit Robust Programmable Soft-Start Low Shutdown Current: IQ < 1μA Thermal Shutdown Available in Thermally Enhanced 28-Lead (4mm × 5mm) QFN and 28-Lead TSSOP Packages Typical Application

Applications Industrial Power Supplies Automotive Electronic Control Units Packaging

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