Auto Electronics

Linear dual output synchronous dc/dc controller draws 30 µA in automotive systems

Linear Technology Corporation has introduced the LTC3826/-1, an ultralow quiescent current, 2-phase dual-output synchronous step-down dc/dc controller. It draws 30 µA when one output is active and 50 µA when both are active, thus suiting the device for automotive applications such as navigation systems where one or both supplies remain active while the engine is off. With both outputs shut down, the LTC3826/-1 draws just 4 µA.
A 4 V to 36 V input supply range is wide enough both to protect against high-input voltage transients and to continue operation during automotive cold crank. The LTC3826/-1 features a ±1% reference voltage tolerance over the -40 °C to 85 °C operating temperature range and it can provide output voltages from 0.8 V to 10 V for powering audio systems, analog tuners and CD/DVD players. Each output can deliver up to 20 A of current at efficiencies as high as 95%.

The LTC3826/-1's constant frequency, current-mode architecture is said to provide excellent line and load regulation and its 2-phase operation reduces input capacitance requirements, according to Linear. The LTC3826/-1 ramps each output voltage during startup using separate adjustable soft-start and tracking pins. It operates at a selectable frequency between 250 kHz and 550 kHz, and can be synchronized to an external clock from 140 kHz to 650 kHz using its phased-locked loop (PLL).

At light loads a user can select from burst mode operation, pulse skipping and continuous operation. The LTC3826/-1 is available in two versions. The LTC3826 is a fully featured part that also includes a clock out, phase modulation, two separate power good signals, and a current limit foldback disable capability. It comes in a 32-lead 5 mm x 5 mm QFN package. The LTC3826-1 is housed in the 28-pin SSOP. Pricing for both parts in 1,000-piece quantities starts at $5.38 each.
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