Linear Technology has launched the H- and MP-grade versions of the LTC3853, a triple output synchronous step-down switching regulator controller. This device operates over a 4.5V to 24V input voltage range and can produce output currents up to 20A per phase with output voltages ranging from 0.8V to 13.5V at up to 95% efficiency. These H- and MP-grade versions are guaranteed over operating junction temperatures from -40°C to 150°C and -55°C to 150°C, respectively.
The LTC3853 has powerful 1.1 Ohm on-chip MOSFET gate drivers. A constant-frequency current mode architecture allows a selectable fixed or synchronized frequency from 250kHz to 750kHz. Power loss and supply noise have been minimized by operating the three stages 120° out-of-phase. Output current sensing is accomplished by measuring the voltage drop across the output inductor (DCR) or by using an optional sense resistor. Current foldback limits MOSFET heat dissipation during short-circuit and overload conditions. In addition, the LTC3853 has adjustable soft-start or tracking. Selectable Burst Mode operation, pulse skipping or continuous inductor current modes are user controlled to optimize light load efficiency.
The LTC3853 features a precision 0.8V reference with an accuracy of ±1.25% over a -55°C to 150°C operating temperature range. With up to 98% duty cycle, the LTC3853 has a very low dropout voltage, a useful feature for extending run times in battery-powered applications. The LTC3853 is available in a thermally enhanced 6mm x 6mm QFN-40 package.