General Description
●The LM3485 is a high efficiency PFET switching regulator controller that can be used to quickly and easily develop a small, low cost, switching buck regulator for a wide range of applications. The hysteretic control architecture provides for simple design without any control loop stability concerns using a wide variety of external components. The PFET architecture also allows for low component count as well as ultra-low dropout, 100% duty cycle operation. Another benefit is high efficiency operation at light loads without an increase in output ripple.
●Current limit protection is provided by measuring the voltage across the PFET’s RDS(ON), thus eliminating the need for a sense resistor. The cycle-by-cycle current limit can be adjusted with a single resistor, ensuring safe operation over a range of output currents.
●Features
●■ Easy to use control methodology
●■ No control loop compensation required
●■ 4.5V to 35V wide input range
●■ 1.242V to VIN adjustable output range
●■ High Efficiency 93%
●■ ±1.3% (±2% over temp) internal reference
●■ 100% duty cycle
●■ Maximum operating frequency > 1MHz
●■ Current limit protection
●■ MSOP-8
●Applications
●■ Set-Top Box
●■ DSL/Cable Modem
●■ PC/IA
●■ Auto PC
●■ TFT Monitor
●■ Battery Powered Portable Applications
●■ Distributed Power Systems
●■ Always On Power
