The LTC ®3731 is a PolyPhase ® synchronous step-down switching regulator controller that drives all N-channel external power MOSFET stages in a phase-lockable fixed frequency architecture. The 3-phase controller drives its output stages with 120° phase separation at frequencies of up to 600kHz per phase to minimize the RMS current losses in both the input and output filter capacitors. The 3-phase technique effectively triples the fundamental frequency, improving transient response while operating each control- ler at an optimal frequency for efficiency and ease of ther- mal design. Light load efficiency is optimized by using a choice of output Stage Shedding or Burst Mode operation. A differential amplifier provides true remote sensing of both the high and low side of the output voltage at the point of load. The precision reference supports output voltages from 0.6V to 6V. Soft-start and a defeatable, timed short-circuit shutdown protect the MOSFETs and the load. Current foldback provides protection for the external MOSFETs under short-circuit or overload conditions.
The LTC3731 is a 3‑Phase PolyPhase® synchronous step‑down switching regulator controller that drives external N‑channel MOSFETs. It operates at frequencies from 250 kHz to 600 kHz per phase and includes features such as adjustable soft‑start, power‑good output indicator, and selectable phase output for up to 12‑phase operation.
The document contains absolute maximum ratings, detailed electrical characteristics, pin descriptions, typical performance graphs, and package information for the 5 mm × 5 mm QFN and 36‑pin narrow SSOP versions. It also lists related part numbers and ordering options.
| Topside Driver Voltage (BOOSTy) Range | 38 V to –0.3 V |
|---|---|
| Peak Output Current (<1 ms) | 5 A |
| Operating Frequency per Phase | 250 kHz to 600 kHz |
| Ambient Temperature Range (LTC3731C) | –40 °C to 70 °C |
| Package Types | 5 mm × 5 mm QFN and 36‑Pin narrow SSOP |
The controller can operate from 250 kHz up to 600 kHz per phase.
It can deliver up to 5 A of peak output current for pulses shorter than 1 ms.
The device is offered in a 5 mm × 5 mm QFN package and a 36‑pin narrow SSOP package.