DC/DC Controller draws 170 µA in battery-powered systems.

Press Release Summary:

Housed in 5 x 5 mm QFN package, Model LTC3858/-1 draws 170 µA with one output active and 300 µA when both outputs are active. Input supply range of 4-38 V protects against automotive wide input voltage transients found during load dump and cold crank conditions. Each output can be set from 0.8-24 V at output currents up to 20 A with efficiency as high as 95%. Two-phase, synchronous step-down DC/DC controller is suited for navigation, audio, communications, CD/DVD players, and disk drives.

Original Press Release:

LTC3858/-1: Dual Output Synchronous DC/DC Controller Draws Only 170uA in Battery-Powered Systems

MILPITAS, CA - July 21, 2009 - Linear Technology Corporation introduces the LTC3858/-1, a low quiescent current, 2-phase dual output synchronous step-down DC/DC controller that draws only 170uA with one output active and only 300uA when both outputs are active. With both outputs shut down, the LTC3858/-1 draws a mere 8uA, which is ideal for automotive and notebook PC applications. The LTC3858/-1's wide input supply range of 4V 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 0.8V to 24V at output currents up to 20 amps 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 1.1W 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°C 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 5mm x 5mm QFN package, with the LTC3858-1 in 28-pin SSOP or 4mm x 5mm QFN-28 packages. Pricing starts at $4.47 in 1,000-piece quantities. For more information, visit www.linear.com.


o Low Quiescent Current of 170uA with One Output Active & 300uA with Both Outputs Active

o Draws Only 8uA in Shutdown

o Wide Input Voltage Range: 4V to 38V

o Wide Output Voltage Range: 0.8V to 24V

o On-Board MOSFET Gate Drivers

o Synchronous Rectification for up to 95% Efficiency

o Selectable Burst Mode Operation, Pulse Skipping or Continuous Operation

o Safely Powers Pre-Biased Loads

o Selectable Fixed Operating Frequency from 50kHz to 900kHz

o Synchronizable Operating Frequency from 75kHz to 850kHz with PLL

o Current Mode Control for Easy Loop Compensation & Current Sharing

o Adjustable Soft-Start

o ±1% Voltage Reference Accuracy Over -40°C to 85°C

o Output Over-Voltage & Over-Current Latch-Off Protection

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