LM2647

LM2647 www.ti.com SNVS210F – JUNE 2003 – REVISED APRIL 2013 LM2647 Dual Synchronous Buck Regulator Controller Check for Samples: LM2647 FEATURES 1 2 Input Voltage Range from 5.5V to 28V Synchronous Dual-channel Interleaved Switching 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 LM2647 is an adjustable 200-500kHz dual channel voltage-mode controlled high-speed synchronous buck regulator controller ideally suited for battery powered applications such as laptop and notebook computers. The LM2647 requires only Nchannel FETs for both the upper and lower positions of each 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 resistors is made possible by sensing the voltage drop across the bottom FET. A unique adaptive duty cycle clamping technique is i...