OBSOLETE
LM27241
www.ti.com
SNVS309 – MAY 2005
LM27241 Synchronous Buck Regulator Controller for Mobile Systems
Chec...
OBSOLETE
LM27241
www.ti.com
SNVS309 – MAY 2005
LM27241 Synchronous Buck Regulator Controller for Mobile Systems
Check for Samples: LM27241
FEATURES
1
2 Input
voltage range from 5.5V to 28V Forced-PWM or Pulse-skip modes Lossless bottom-side FET current sensing Adaptive duty cycle clamping High current N-channel FET drivers Low shutdown supply currents Reference
voltage accurate to within ±1.5% Output
voltage adjustable down to 0.6V Power Good flag and Chip Enable Under-
voltage lockout
Over-
voltage/Under-
voltage protection Soft-start and Soft-shutdown Switching frequency adjustable 200kHz-
500kHz
APPLICATIONS
Notebook Chipset Power Supplies Low Output
Voltage High Efficiency Buck
Regulators
DESCRIPTION
The LM27241 is an adjustable 200kHz-500kHz single channel
voltage-mode controlled high-speed synchronous buck regulator controller. It is ideally suited for battery powered applications such as laptop and notebook computers. 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 high-efficiency 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 re...