Linear Tech Adds Dual Output Synchronous DC-DC Controller For Battery-Powered Systems
Linear Technology Corp. introduced the LTC3858/-1, a low quiescent current, 2-phase dual output synchronous step-down dc-dc controller that draws only 170µA with one output active and only 300uA when both outputs are active. With both outputs shut down, the LTC3858/-1 draws a mere 8µA, which is well suited for automotive and notebook PC applications.
The LTC3858/-1’s wide input supply range of 4 to 38V protects against automotive wide input voltage transients commonly found during load dump and cold crank conditions and to cover a broad range of battery chemistries. Each output can be set from 0.8 to 24V at output currents up to 20A with efficiency as high as 95%. The LTC3858/-1 is suitable for powering high performance systems including navigation, audio, communications, CD/DVD players and disk drives.
The LTC3858/-1 has powerful 1.1Ω on-board MOSFET gate drivers and operates with an adjustable fixed frequency between 50kHz and 900kHz, or can be synchronized to an external clock from 75kHz to 850kHz using its phase-locked-loop (PLL). The user can select from continuous operation, pulse skipping and low ripple Burst Mode® operation during light loads. The part safely powers pre-biased loads.
The LTC3858/-1’s 2-phase operation reduces input capacitance requirements, while its current mode architecture provides easy loop compensation and fast transient response. Both outputs have adjustable soft-start to control the turn-on time and the output overload protection feature latches off the converter until the input voltage is recycled. The LTC3858/-1 also features a tight ±1% reference voltage accuracy over the operating temperature range of -40 to 85°C. The LTC3858 is the fully featured part with additional functions beyond the LTC3858-1 including a clock out, clock phase modulation, two separate power good signals and adjustable current limit.
The LTC3858 is offered in a 32-lead 5 x 5mm QFN package, with the LTC3858-1 in 28-pin SSOP or 4 x 5mm QFN-28 packages. Pricing starts at $4.47 in 1,000-piece quantities.
