LTC3851A
Synchronous Step-Down Switching Regulator Controller
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Overview
Features and Benefits
- Wide VIN Range: 4V to 38V Operation
- RSENSE or DCR Current Sensing
- ±1% Output Voltage Accuracy
- Phase-Lockable Fixed Frequency: 250kHz to 750kHz
- Dual N-Channel MOSFET Synchronous Drive
- Very Low Dropout Operation: 99% Duty Cycle
- Adjustable Output Voltage Soft-Start or Tracking
- Output Current Foldback Limiting
- Output Overvoltage Protection
- 5V Internal Regulator
- OPTI-LOOP® Compensation Minimizes COUT
- Selectable Continuous, Pulse-Skipping or Burst Mode® Operation at Light Loads
- Low Shutdown IQ: 20μA
- VOUT Range: 0.8V to 5.5V
- Thermally Enhanced 16-Lead MSOP, 16-Lead Narrow SSOP or 3mm × 3mm QFN Package
- AEC-Q100 Qualified for Automotive Applications
Product Details
The LTC3851A is a high performance synchronous step-down switching regulator 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.
OPTI-LOOP compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3851A features a precision 0.8V reference that is compatible with a wide 4V to 38V input supply range.
The TK/SS pin ramps the output voltage during start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The MODE/PLLIN pin selects among Burst Mode operation, pulse-skipping mode or continuous inductor current mode at light loads and allows the IC to be synchronized to an external clock. The LTC3851A contains an improved PLL compared to the LTC3851.
The LTC3851A-1 is a version with a power good output signal instead of adjustable current limit.
| Features | |
| LTC3851 | Not Recommended For New Designs |
| LTC3851-1 | Not Recommended For New Designs |
| LTC3851A | Adjustable Current Limit |
| LTC3851A-1 | PGOOD Output |
APPLICATIONS
- Automotive Systems
- Telecom Systems
- Industrial Equipment
- Distributed DC Power Systems
Product Categories
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 & Resources
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R526 Reliability Data3/26/2018
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DC1432A - Demo Manual12/21/2010
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.
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:
LTC3851
LTC3851-1
LTC3851A
LTC3851A-1
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.
LTpowerCAD Project Files
Design tools for the following parts are available in LTpowerCAD:
LTC3851A
LTC3851A-1
Product Recommendations
LTC3851A Companion Parts
Design Resources
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.View our quality and reliability program and certifications for more information.
PCN-PDN Information
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Sample & Buy
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Buy Now Pricing
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List Pricing
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Sampling
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Evaluation Boards
Pricing displayed is based on 1-piece.
Up to two boards can be purchased through Analog.com. To order more than two, please purchase through one of our listed distributors.
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.