The LM2657 is an adjustable 200kHz-500kHz dual channel
voltage-mode controlled high-speed synchronous buck
regulator controller ideally suited for high current applications.
The LM2657 requires only N-channel FETs for both
the upper and lower positions of each 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 resistors 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 two
independently programmable outputs switch 180° out of
phase (interleaved switching) reducing the input capacitor
and filter requirements. The input voltage range is 4.5V to
28V while the output voltages are 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, and chip Enable.