Features and Benefits
- Dual Buck Plus Single Boost Synchronous Controllers
- Outputs Remain in Regulation Through Cold Crank Down to 2.5V
- Low Operating IQ: 55μA (One Channel On)
- Wide Bias Input Voltage Range: 4.5V to 38V
- Buck Output Voltage Range: 0.8V ≤ VOUT ≤ 24V
- Boost Output Voltage Up to 60V
- RSENSE or DCR Current Sensing
- 100% Duty Cycle for Boost Synchronous MOSFET
- Phase-Lockable Frequency (75kHz to 850kHz)
- Programmable Fixed Frequency (50kHz to 900kHz)
- Selectable Continuous, Pulse-Skipping or Low Ripple Burst Mode® Operation at Light Loads
- Very Low Buck Dropout Operation: 99% Duty Cycle
- Adjustable Output Voltage Soft-Start or Tracking
- Low Shutdown IQ: 14μA
- Small 38-Pin 5mm × 7mm QFN and TSSOP Packages
The LTC3859 is a high performance triple output (buck/ buck/boost) synchronous DC/DC switching regulator controller that drives all N-channel power MOSFET stages. Constant frequency current mode architecture allows a phase-lockable switching frequency of up to 850kHz. The LTC3859 operates from a wide 4.5V to 38V input supply range. When biased from the output of the boost converter or another auxiliary supply, the LTC3859 can operate from an input supply as low as 2.5V after start-up.
The 55μA no-load quiescent current extends operating runtime 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 LTC3859 features a precision 0.8V reference for the bucks, 1.2V reference for the boost and a power good output indicator.
Independent TRACK/SS pins for each controller ramp 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 inductor current mode at light loads.
|Quiescent Current (Burst Mode)||Notes|
|LTC3859AL||28μA-One channel on, Buck
38μA-All three channels on
|Internal clamp on the INTVCC pin|
|LTC3859A||55μA-One channel on, Buck
80μA-All three channels on
|Internal clamp on the INTVCC pin. For new designs, we recommend LTC3859AL|
|LTC3859||55μA-One channel on, Buck
80μA-All three channels on
|For new designs, we recommend LTC3859AL|
- Automotive Always-On and Start-Stop Systems
- Battery Operated 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.
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:
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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.
Design tools for the following parts are available in LTpowerCAD:
ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.
Sample & Buy
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