The LTC1709-7 is a 2-phase, VID programmable, synchronous step-down switching regulator controller that drives two full n-channel external power MOSFET stages in a fixed-frequency architecture. A 2-phase controller drives its two output stages out of phase at frequencies up to 300kHz to minimize RMS ripple current in input and output capacitors.
Typical application
The 2-phase technique effectively multiplies the fundamental frequency by 2, improving the transient response while running each channel at the optimal frequency to improve efficiency. Thermal design is also simplified. The operating mode selection pin (FCB) can be used to adjust the secondary winding or select among three modes, including the Burst ModeTM operation for maximum efficiency.
Functional block diagram
An internal differential amplifier provides true remote sensing for regulating the positive and negative output terminals required in high current applications. The RUN/SS pin provides soft start and optional timing, short circuit shutdown. Current reversal limits MOSFET losses under short circuit conditions when overcurrent latching is disabled. OPTI-LOOP compensation allows the transient response to be optimized for a wide range of output capacitor and ESR values
Application diagram
