Features

• PolyPhase® Operation Reduces Required Input and Output Capacitance and Power Supply Induced Noise
• Synchronous Operation for Highest Efficiency and Reduced Heat Dissipation
• Wide V_IN Range: 4.5V to 60V (65V Abs Max); Operates Down to 2.3V After Start-Up
• Output Voltage Up to 60V
• ±1% 1.200V Reference Voltage
• R_SENSE or Inductor DCR Current Sensing
• 100% Duty Cycle Capability for Synchronous MOSFET
• Low Quiescent Current: 28μA
• Phase-Lockable Frequency (75kHz to 850kHz)
• Programmable Fixed Frequency (50kHz to 900kHz)
• Power Good Output Voltage Monitor
• Low Shutdown Current, I_Q < 4μA
• Internal LDO Powers Gate Drive from VBIAS or EXTV_CC
• Thermally Enhanced Low Profile 28-Pin 4mm × 5mm QFN Package and Narrow SSOP Package

Typical Application

Description

The LTC®3784 is a high performance PolyPhase® single output synchronous boost converter controller that drives two N-channel power MOSFET stages out-of-phase. Multiphase operation reduces input and output capacitor requirements and allows the use of smaller inductors than the single-phase equivalent. Synchronous rectification increases efficiency, reduces power losses and eases thermal requirements, simplifying high power boost applications.

A 4.5V to 60V input supply range encompasses a wide range of system architectures and battery chemistries. When biased from the output of the boost converter or another auxiliary supply, the LTC3784 can operate from an input supply as low as 2.3V after start-up. The operating frequency can be set within a 50kHz to 900kHz range or synchronized to an external clock using the internal PLL. PolyPhase operation allows the LTC3784 to be configured for 2-, 3-, 4-, 6- and 12-phase operation.

The SS pin ramps the output voltage during start-up. The PLLIN/MODE pin selects Burst Mode® operation, pulseskipping mode or forced continuous mode at light loads.