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42V Input with 55V Transient Protection, 2MHz Dual Step-Down Regulator with Power-On Reset & Watchdog Timer with 150°C Maximum Junction Temperature

12th January 2012

Linear Technology (UK) Limited

ES Admin

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Datasheet

Linear Technology announces the H-grade version of the :LT3641, a dual channel, current mode step-down switching regulator with power-on reset and a watchdog timer. Its 4V to 42V input voltage range, with 55V transient capability, makes it ideal for load dump and cold crank conditions commonly found in automotive applications, which require constant output regulation even with input transients as high as 55V. The LT3641 uses a unique dual channel design with a high input voltage (4VIN to 42VIN, 55VIN transient capability) nonsynchronous channel that delivers 1.3A of output current, combined with a lower input voltage (2.5VIN to 5.5VIN) synchronous channel that delivers up to 1.1A of continuous output current. While the device allows separate inputs for each channel, most applications will use the output of the high voltage channel to power the lower voltage channel, offering dual outputs while optimizing efficiency and switching frequency. For example, using a nominal 12V input and a 2MHz switching frequency, the LT3641 can deliver a 3.3V output at 600mA with 85% efficiency via its high voltage channel and a 1.8V output at 800mA with 90% secondary conversion efficiency via its lower voltage channel.

The H-grade version operates up to a junction temperature of 150°C, compared to the E- and I-grade versions’ 125°C maximum junction temperature. All electrical specifications are identical for the E, I and H. H-grade parts are tested and guaranteed to the maximum junction temperature of 150°C, and are ideal for automotive and industrial applications which are subject to high ambient temperatures.

The LT3641HFE is packaged in a 28-lead thermally enhanced TSSOP-28, priced starting at $4.43 each for 1,000 piece quantities. The device is available from stock.

Summary of Features: LT3641H

• High Voltage Buck Regulator:

o 4V to 42V Operating Range, with Transient Protection to 55V

o 1.3A Output Current

• Low Voltage Synchronous Buck Regulator:

o 2.5V to 5.5V Input Voltage Range

o 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: IQ < 290µA

• Short-Circuit Robust

• Programmable Soft-Start

• Low Shutdown Current: IQ < 1µA

• Thermal Shutdown

• Available in Thermally Enhanced

28-Lead TSSOP Package

• Maximum Junction Temperatures to 150°C