Overview
Features and Benefits
- Dual Buck Plus Single Boost Synchronous Controllers
- Wide Bias Input Voltage Range: 4.5V to 60V
- Outputs Remain in Regulation Through Cold Crank Down to a 2.2V Input Supply Voltage
- Buck and Boost Output Voltages Up to 60V
- Adjustable Gate Drive Level 5V to 10V (OPTI-DRIVE)
- No External Bootstrap Diodes Required
- Low Operating IQ: 29μA (One Channel On)
- 100% Duty Cycle for Boost Synchronous MOSFET
- Phase-Lockable Frequency (75kHz to 850kHz)
- Programmable Fixed Frequency (50kHz to 900kHz)
- Very Low Dropout Operation: 99% Duty Cycle (Bucks)
- Low Shutdown IQ: 3.6μA
- Fixed or Adjustable Boost Output Voltage Saves IQ
- Small 38-Lead 5mm × 7mm QFN and TSSOP Packages
Product Details
The LTC3899 is a high performance triple output (buck/ buck/boost) DC/DC switching regulator controller that drives all N-channel synchronous power MOSFET stages. The constant frequency current mode architecture allows a phase-lockable frequency of up to 850kHz. The LTC3899 operates from a wide 4.5V to 60V input supply range. When biased from the output of the boost converter or another auxiliary supply, the LTC3899 can operate from an input supply as low as 2.2V after start-up.
The gate drive for the LTC3899 can be programmed from 5V to 10V to allow the use of logic-level or standard-level FETs and to maximize efficiency. Internal switches in the top gate drivers eliminate the need for external bootstrap diodes. The 29μA 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.
Applications
- Automotive Always-On and Start-Stop Systems
- Distributed DC Power Systems
- Multioutput Buck-Boost Applications
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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 (1)
Documentation
Reliability Data (1)
User Guides (1)
Tools & Simulations
LTspice
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.

Models for the following parts are available in LTspice:
LTpowerCAD
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.

Design tools for the following parts are available in LTpowerCAD:
Reference Designs (1)
Reference Materials
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Design Resources
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PCN-PDN Information
Support & Discussions
LTC3899 Discussions
Sample & Buy
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