38V step-down controller outputs 24V, takes 50 µA in standby

August 25, 2014 // By Graham Prophet
LTC3807 is a low quiescent current synchronous step-down DC/DC controller that draws 50 µA in standby mode with the output voltage in regulation. The 4V to 38V 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.

The output voltage can be set from 0.8V to 24V at output currents up to 25A with efficiencies as high as 95%, suiting it for automotive, heavy equipment, industrial and robotic applications. It has 1.1Ω on-chip MOSFET gate drivers and operates with a selectable fixed frequency between 50 kHz and 900 kHz and is synchronisable to an external clock ranging from 75 kHz to 850 kHz. The user can select from continuous operation, pulse skipping and low ripple Burst Mode operation during light loads. 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. Additional features include a 95 nsec minimum on-time for high step-down ratios, up to 99% duty cycle for low voltage dropout, an internal LDO that powers the gate drivers and a power-good signal.

In 20-pin 3 x 4mm QFN and 20-lead TSSOP thermally enhanced packages, four temperature grades are available, with pricing from $2.30 (1000).

Linear Technology; www.linear.com/product/LTC3807