LM27241 Datasheet | National Semiconductor

LM27241 Synchronous Buck Regulator Controller for Mobile Systems May 2005 Synchronous Buck Regulator Controller for Mobile Systems General Description The LM27241 is an adjustable 200k Hz-500k Hz single channel voltage-mode controlled high-speed synchronous buck regulator controller. It is ideally suited for battery powered applications such as laptop and notebook puters. The LM27241 requires only N-channel FETs for both the upper and lower positions of the synchronous stage. It Features line feedforward to improve the response to input transients. At very light loads, the user can choose between the highefficiency Pulse-skip mode or the constant frequency Forced-PWM mode. Lossless current limiting without the use of external sense resistor is made possible by sensing the voltage drop across the bottom FET. A unique adaptive duty cycle clamping technique is incorporated to significantly reduce peak currents under abnormal load conditions. The input voltage range is 5.5V to 28V while the output voltage is adjustable down to 0.6V. Standard supervisory and control Features include soft-start, power good, output under-voltage and over-voltage protection, under-voltage lockout, soft-shutdown and enable. Features n Input voltage range from 5.5V to 28V n Forced-PWM or Pulse-skip modes n Lossless bottom-side FET current sensing n Adaptive duty cycle clamping n High current N-channel FET drivers n Low shutdown supply currents n Reference voltage accurate to within ±1.5% n Output voltage adjustable down to 0.6V n Power Good flag and Chip Enable n Under-voltage lockout n Over-voltage/Under-voltage protection n Soft-start and Soft-shutdown n Switching frequency adjustable 200k Hz-500k Hz Applications n Notebook Chipset Power Supplies n Low Output Voltage High Efficiency Buck Regulators Typical Application See Figure 17 for Expanded View © 2005 National Semiconductor Corporation DS201201 .national. Connection Diagram Top View...