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150V Step-Down DC/DC Controller Draws Only 9µA in Battery-Powered Systems

Analog Devices  announces the Power by Linear™ LTC3894, a high voltage step-down DC/DC controller that draws only 9µA quiescent current with the output enabled in Burst Mode® operation. Its wide 4.5V to 150V input voltage range can effectively eliminate the need for external surge suppression devices. The LTC3894’s 100% duty cycle capability and externally adjustable power good window are ideal for use in battery powered systems that operate continuously in dropout. The LTC3894 is well suited for transportation systems, always-on power, industrial control, robotic and datacom applications.

The LTC3894 drives a P-channel MOSFET power stage and can produce an output voltage from 0.8V to 60V at output currents up to 3 amps with efficiencies as high as 92%. The LTC3894 includes the option for an external N-channel pass FET to supply the PMOS gate driver current in sustained high voltage high power applications.

The LTC3894 operates with a selectable fixed frequency between 50kHz and 850kHz and is synchronizable to an external clock from 75kHz to 800kHz. The user can select between pulse-skipping or Burst Mode operation during light loads. Its current mode architecture provides easy loop compensation, fast transient response and excellent line regulation. Current sensing is accomplished by measuring the voltage drop across the output inductor (DCR) for highest efficiency or by using an optional sense resistor. A low 100ns minimum on-time allows for high step-down ratios at high switching frequency. Current foldback limits MOSFET heat dissipation during overload conditions. Additional protection features include, a power good output signal, adjustable input overvoltage lockout and soft-start.

The LTC3894 is available in a 16-pin thermally enhanced TSSOP with high

voltage pin spacing. Extended and industrial versions are available from –40°C to 125°C.

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