LTC1709 - 2-Phase, 5-Bit Adjustable,High Efficiency, Synchronous Step-Down Switching Regulator

The LTC1709 is a 2-phase, VID programmable, synchronous step-down switching regulator controller that drives all N-channel external power MOSFET stages in a fixed frequency architecture. The 2-phase controller drives its two output stages out of phase at frequencies up to 300kHz to minimize the RMS ripple currents in both input and output capacitors. The 2-phase technique effectively multiplies the fundamental frequency by two, improving transient response while operating each channel at a optimum frequency for efficiency. Thermal design is also simplified. An internal differential amplifier provides true remote sensing of the regulated supply’s positive and negative output terminals as required in high current applications. The RUN/SS pin provides soft-start and optional timed, short-circuit shutdown. Current foldback limits MOSFET dissipaton during short-circuit conditions when overcurrent latchoff is disabled. OPTI-LOOP compensation allows the transient response to be optimized for a wide range of output capacitors and ESR values.

Features

Two Ouput Stages Operate Antiphase Reducing Input Capacitance and Power Supply Noise
5-Bit VID Control (VRM 8.4 Compliant) VOUT: 1.3V to 3.5V in 50mV/100mV Steps
Current Mode Control Ensures Current Sharing
True Remote Sensing Differential Amplifier
OPTI-LOOP™ Compensation Minimizes COUT
Programmable Fixed Frequency: 150kHz to 300kHz—Effective 300kHz to 600kHz Switching Frequency
±1% Output Voltage Accuracy
Wide VIN Range: 4V to 36V Operation
Adjustable Soft-Start Current Ramping
Internal Current Foldback
Short-Circuit Shutdown Timer with Defeat Option
Overvoltage Soft-Latch Eliminates Nuisance Trips
Low Shutdown Current: 20µA
Small 36-Lead Narrow (0.209") SSOP Package