Features and Benefits
- Wide VIN Range: 4V to 60V (65V Abs Max)
- Low Operating IQ: 50μA
- Wide Output Voltage Range: 0.8V ≤ VOUT ≤ 24V
- RSENSE 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 IQ: < 14μA
- Internal LDO Powers Gate Drive from VIN or EXTVCC
- No Current Foldback During Start-Up
- Small 20-Pin 3mm × 4mm QFN and TSSOP Packages
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.
- Automotive Always-On Systems
- Battery Powered Digital Devices
- Distributed DC Power Systems
Product Lifecycle Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Evaluation Kits (2)
Demonstration circuit 1695 is a Low Quiescent Current, Synchronous Buck Converter featuring the LTC3891EFE. DC1695 converts a 4.5V-60V voltage source to 3.3V at 5.0A. The main features of the board include an internal LDO for power gate driver from VIN or EXTVCC, RUN and PGOOD pins and a Mode selector that allows converter to run in CCM, Pulse Skipping or Burst Mode operation, selectable current limit. DC1695 supports also adjustable output voltage, Soft-Start and Tracking. Synchronization to an external clock is possible as well. The wide input voltage range of 4.5V to 60V is suitable for automotive or other battery fed application and Distributed DC Power Systems where low quiescent current is important.
Demonstration circuit 1940A is a low quiescent current, synchronous buck converter featuring the LTC3891EUDC. This demo board converts a 16V to 60V voltage to a 12V at 15A output. The main features of this board include an internal LDO for gate drive power from VIN or EXTVCC, RUN and PGOOD pins, a mode selector that allows the converter to run in constant current mode (CCM), pulse-skipping or Burst Mode® operation, and selectable current limit. The DC1940A supports an adjustable output voltage, soft-start and tracking. The wide input voltage range of 16V to 60V is suitable for double battery automotive and distributed DC power systems where low quiescent current is important.
Documentation & Resources
R526 Reliability Data3/26/2018
Overcoming Constraints: Design a Precision Bipolar Power Supply on a Simple Buck Controller12/3/2018 Analog Dialogue
Data Backup Solution for 1mm, Low Profile Industrial Applications8/25/2015
Step-Down Converter Delivers 25A at 12V Output from Inputs Up to 60V7/1/2012 LT Journal
Tools & Simulations
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.
Models for the following parts are available in LTspice:
LTpowerCAD® is a power supply design program which selects power stage components, provides detailed power efficiency, shows quick loop Bode plot stability and load transient analysis, and can export to LTspice for simulation.
To open the project file for this circuit:
Step 1: Download and install LTpowerCAD on your computer.
Step 2: Click on the link(s) in the section below to download part-specific project files.
Step 3: If the project file doesn't run, right-click the link and select "Save Target As." Then start the LTpowerCAD tool and open the project file by selecing "Open Project" from the "File" menu.
LTpowerCAD Project Files
Design tools for the following parts are available in LTpowerCAD:
LTC3891 Companion Parts
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Sample & Buy
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.