LTC3891 Datasheet

• Wide V_IN Range: 4V to 60V (65V Abs Max)
• Low Operating I_Q: 50μA
• Wide Output Voltage Range: 0.8V ≤ V_OUT ≤ 24V
• R_SENSE or DCR Current Sensing
• Phase-Lockable Frequency (75kHz to 750kHz)
• Programmable Fixed Frequency (50kHz to 900kHz)
• Selectable Continuous, Pulse-Skipping or Low Ripple Burst Mode^® Operation at Light Load
• Selectable Current Limit
• Very Low Dropout Operation: 99% Duty Cycle
• Adjustable Output Voltage Soft-Start or Tracking
• Power Good Output Voltage Monitor
• Output Overvoltage Protection
• Low Shutdown I_Q: < 14μA
• Internal LDO Powers Gate Drive from V_IN or EXTV_CC
• No Current Foldback During Start-Up
• Small 20-Pin 3mm × 4mm QFN and TSSOP Packages

• Automotive Always-On Systems
• Battery Powered Digital Devices
• Distributed DC Power Systems

The LTC3891 is a high performance step-down switching regulator DC/DC controller that drives an all N-channel synchronous power MOSFET stage. A constant frequency current mode architecture allows a phase-lockable frequency of up to 750kHz.

The 50μA no-load quiescent current extends operating run time in battery-powered systems. OPTI-LOOP^® compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3891 features a precision 0.8V reference and power good output indicator. A wide 4V to 60V input supply range encompasses a wide range of intermediate bus voltages and battery chemistries. The output voltage of the LTC3891 can be programmed between 0.8V to 24V.

The TRACK/SS pin ramps the output voltages during start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The PLLIN/MODE pin selects among Burst Mode operation, pulse-skipping mode, or continuous conduction mode at light loads.