SS6577

SS6577 External NMOS Step-Down PWM Controller FEATURES N-Channel MOSFET Drive Operating input voltage from 4.5V to 24V Wide output Range : 0.8V to 20V Reference: ±1.5% 0.8V Reference Low dropout operation : 95% duty cycle Fixed constant frequency - 500kHz Low standby current, I Q typically 720µA Logic-control micropower shutdown Output overvoltage protection Internal diode for bootstrapped gate drive Current-mode operation for excellent line and load transient response Available in 8-lead SO or MSOP packages DESCRIPTION The SS6577 is a current-mode switching regulator controller that drives an external N-channel power MOSFET using a fixed frequency architecture. It uses an external divider to adjust the output voltage from 0.8V to 20V with excellent line and load regulation. A maximum high duty-cycle limit of 95% provides low dropout operation which extends operating time in battery-operated systems. A constant switching frequency of 500KHz is used thus allowing smaller sized filter components. The operating current level is user-programmable via an external current sense resistor. It also provides output overvoltage protection under fault conditions. A multifunction pin (ITH/RUN) allows external compensation for optimum load step response plus shutdown. Soft start can also be implemented with this pin to properly sequence supplies. Packages available are SOP-8 and MSOP-8 for SMD. APPLICATIONS LCD Monitor Palmtop Computers, PDAs Wireless Modems On-Card Switching Regulators...