Linear Technology Introduces
High Voltage Step-down DC/DC Controller

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Linear Technology Corporation

MILPITAS, Ca. - Linear Technology Corporation introduces the LTC3890/-1, a high voltage dual output synchronous step-down DC/DC controller that draws only 50µA when one output is active and 60µA when both outputs are enabled. With both outputs shut down, the LTC3890/-1 draws a mere 14µA.

The 4V to 60V input supply range is designed to protect against high voltage transients, continue operation during automotive cold crank and cover a broad range of input sources and battery chemistries. Each output can be set from 0.8V to 24V at output currents up to 20 amps with efficiencies as high as 95%, making it well suited for 12V or 24V automotive, heavy equipment, industrial control, robotics and telecom applications.

The LTC3890/-1 has powerful 1.1Ohm on-chip MOSFET gate drivers. It operates with a selectable fixed frequency between 50kHz and 900kHz, and can be synchronized to an external clock from 75kHz to 850kHz with its phased-locked loop (PLL). The user can select from continuous operation, pulse skipping and low ripple Burst Mode® operation during light loads. The LTC3890/-1's 2-phase operation reduces input filtering and capacitance requirements. Its current mode architecture provides easy loop compensation, fast transient response and excellent line regulation. Output current sensing is accomplished by measuring the voltage drop across the output inductor (DCR) for the highest efficiency or by using an optional sense resistor. Current foldback limits MOSFET heat dissipation during overload conditions. The device is available in two versions; the LTC3890 is the fully featured part with functions including a clock out, clock phase modulation, two separate power good outputs and adjustable current limit.

The LTC3890 is available in a 32-lead 5mm x 5mm QFN package and the LTC3890-1 is housed in a 28-pin SSOP package. Pricing starts at $4.76 each in 1,000-piece quantities. For more information, visit linear.com.

Summary Features LTC3890/-1

Wide Input Voltage Range: 4V to 60V

50µA Quiescent Current with One Output Active & 60µA with Both Outputs Active

14µA Shutdown Current

Wide Output Voltage Range: 0.8V to 24V

Synchronous Rectification for up to 95% Efficiency

DCR or RSENSE Current Sense

Selectable Low Ripple Burst Mode Operation, Pulse Skipping or Continuous Operation

Selectable Fixed Operating Frequency from 50kHz to 900kHz

Synchronizable Operating Frequency from 75kHz to 850kHz with PLL

Current Mode Control for Fast Transient Response & Easy Loop Compensation

Adjustable Soft-Start

±1% Voltage Reference Accuracy Over -40°C to 125°C

Output Overvoltage & Overcurrent Foldback Protection

About Linear Technology

Linear Technology Corporation, a manufacturer of high performance linear integrated circuits, was founded in 1981, became a public company in 1986 and joined the S&P 500 index of major public companies in 2000. Linear Technology products include high performance amplifiers, comparators, voltage references, monolithic filters, linear regulators, DC-DC converters, battery chargers, data converters, communications interface circuits, RF signal conditioning circuits, µModule® products, and many other analog functions. Applications for Linear Technology's high performance circuits include telecommunications, cellular telephones, networking products such as optical switches, notebook and desktop computers, computer peripherals, video/multimedia, industrial instrumentation, security monitoring devices, high-end consumer products such as digital cameras and MP3 players, complex medical devices, automotive electronics, factory automation, process control, and military and space systems.

LT, LTC, LTM, µModule, Burst Mode and are registered trademarks of Linear Technology Corp. All other trademarks are the property of their respective owners.

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