DC/DC CONTROLLER

Dual output synchronous DC/DC controller draws only 80uA quiescent current in an automotive system

Publication date: 05 January 2006

Linear Technology Corporation introduces the LTC3827, a low quiescent current, 2-phase dual output synchronous step-down DC/DC controller. The LTC3827 draws only 80uA when one output is active and only 115uA when both outputs are active, making it ideally suited for automotive applications, such as navigation systems, where one or more supplies remains active while the engine is off.

The LTC3827's input supply range of 4V to 36V is wide enough both to protect against high input voltage transients and to continue to operate during automotive cold crank. The LTC3827 features a +/- 1% internal reference and can provide output voltages from 0.8V up to 10V, making it perfect for the higher voltage supplies typically required for audio systems, analog tuners, and CD/DVD players in many automobiles. Each output can deliver up to 20A of current at efficiencies as high as 95%.

The LTC3827 is rated for operation from -40°C to 85°C, and has a maximum operating junction temperature of 125°C. The LTC3827's constant frequency, current mode architecture provides excellent line and load regulation, and its 2-phase operation reduces input capacitance requirements. The LTC3827 smoothly ramps each output voltage during startup using separate adjustable soft-start and tracking input pins. It operates at a selectable frequency between 250kHz and 550kHz, and can be synchronized to an external clock from 140kHz to 650kHz using its phase-locked loop (PLL). Output overvoltage and overcurrent (short circuit) protection are provided internally.

With both outputs shut down, the LTC3827 draws a mere 8uA. The LTC3827 is offered in two packages: 28-lead SSOP (LTC3827-1) and 32-pin 5mm x 5mm QFN (LTC3827). The pricing for 1000-piece quantities starts at $5.00 each. Summary of Features: LTC3827 Low Quiescent Current of 80uA with One Output Active and 115uA with Both Outputs Active Synchronous Constant Frequency Current Mode Operation Wide Output Voltage Range from 0.8V to 10V Selectable or Phase-Lockable Frequency Adjustable Soft-start/Tracking Input Output Overvoltage and Overcurrent Protection 8uA Shutdown Current

Company Background

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, 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.                                                                                                                                                                                                                                                                                                                                SOURCE : TYCOELECTRONICS.COM