DESCRIPTION

· Dual, 550kHz, 2-Phase Synchronous Step-Down Switching Regulator

· Drives all N-channel synchronous power MOSFET stages

· Constant-frequency current mode architecture with phase-lockable frequency up to 550kHz

· Minimizes power loss and noise by operating two controller output stages out of phase

· OPTI-LOOP compensation for optimized transient response

· Precision 0.8V reference and power good output indicator

· Wide input supply range: 3.5V to 30V (36V maximum)

· RUN/SS pin for soft-start and optional timed, short-circuit shutdown

· Current foldback limits MOSFET dissipation during short-circuit conditions

· Output overvoltage protection latches on the bottom MOSFET

· FCB mode pin selects Burst Mode, constant-frequency mode, or continuous inductor current mode

FEATURES

· High efficiency dual 5V/3.3V step-down converter

· Dual, 180° phased controllers reduce required input capacitance and power supply induced noise

· ±1% output voltage accuracy

· Power good output voltage indicator

· Phase-lockable fixed frequency: 250kHz to 550kHz

· Dual N-channel MOSFET synchronous drive

· Wide VIN range: 3.5V to 36V operation

· Very low dropout operation: 99% duty cycle

· Adjustable soft-start current ramping

· Foldback output current limiting

· Latched short-circuit shutdown with defeat option

· Output overvoltage protection

· Remote output voltage sense

· Low shutdown IQ: 20μA

· 5V and 3.3V regulators

· 3 selectable operating modes: Constant-Frequency, Burst Mode, and PWM

· Available in 32-Pin 5mm × 5mm QFN and 28-Pin SSOP packages

APPLICATIONS

· Notebook and palmtop computers

· Telecom systems

· Portable instruments

· Battery-operated digital devices

· DC power distribution systems