Power
Wide Input Voltage Range Synchronous Step-Down DC/DC Controller from Linear Technology
Linear Technology has announced the LTC3851, a wide input range synchronous step-down switching regulator controller that drives all N-channel power MOSFET stages and has coincident or ratiometric tracking. The 4V to 38V input range encompasses a wide variety of applications, including most intermediate bus voltages and battery chemistries.
The A constant-frequency current mode architecture provides a selectable fixed or phase-lockable (PLL) frequency from 250kHz to 750kHz . OPTI-LOOP® compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values, including all ceramic capacitors designs. Output current sensing is accomplished by measuring the voltage drop across the output inductor (DCR) or by using an optional sense resistor; also the current limit threshold voltage is programmable. Current foldback limits MOSFET heat dissipation during short-circuit and over-load conditions.
In addition, the LTC3851 has adjustable soft-start to control the turn-on time and manage inrush current. Selectable Burst Mode® operation, pulse skip mode or continuous current mode is user controlled to optimize light load efficiency vs. output ripple. The LTC3851 features a precision 0.8V reference with an accuracy of ±1% over a -40°C to 85°C operating temperature range. With up to 99% duty cycle, the LTC3851 has a very low drop-out voltage, a useful feature for extending run times in battery powered applications.