LM3485MMX/NOPB

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 ultralow 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 RDS(ON) of the PFET, thus eliminating the need for a sense resistor. The cycleby-cycle current limit can be adjusted with a single resistor, ensuring safe operation over a range of output currents.

Applications

• Set-Top Box
• DSL or Cable Modem PC/IA
• Auto PC
• TFT Monitor
• Battery-Powered Portable Applications
• Distributed Power Systems Always On Power

Key features

• Easy-to-Use Control Methodology
• No Control-Loop Compensation Required
• 4.5-V to 35-V Wide Input Range
• 1.242-V to VIN Adjustable Output Range
• High Efficiency 93%
• ±1.3% (±2% Over Temp) Internal Reference
• 100% Duty Cycle
• Maximum Operating Frequency >1 MHz
• Current Limit Protection