Power Management
Switching Regulator
Step-Down (Buck) Regulators
External Power Switch Buck Controllers
Space & Harsh Environment
Extended Temperature Plastic (H & MP)
Extended Temperature (H & MP) Switching Regulators
LTC3851A - Synchronous Step-Down Switching Regulator Controller
Features
- 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
Typical Application
Description
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.
Packaging
For complete and up to date package information and drawings, please refer to our packaging page
MS-16, SSOP-16, QFN-16
Order Info
- Part numbers ending in PBF are lead free. Please contact LTC marketing for information on lead based finish parts.
- Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
- Please refer to our general ordering information or the product datasheet for more details
Package Variations and Pricing
| Part Number | Package | Pins | Temp | Price (1-99) | Price (1k)* | RoHS Data |
|---|---|---|---|---|---|---|
| LTC3851AEGN#PBF | SSOP | 16 | E | $2.44 | $1.71 | View |
| LTC3851AEGN#TRPBF | SSOP | 16 | E | $1.77 | View | |
| LTC3851AEMSE#PBF | MSOP | 16 | E | $2.44 | $1.71 | View |
| LTC3851AEMSE#TRPBF | MSOP | 16 | E | $1.77 | View | |
| LTC3851AEMSE-1#PBF | MSOP | 16 | E | $2.44 | $1.71 | View |
| LTC3851AEMSE-1#TRPBF | MSOP | 16 | E | $1.77 | View | |
| LTC3851AEUD#PBF | QFN | 16 | E | $2.44 | $1.71 | View |
| LTC3851AEUD#TRPBF | QFN | 16 | E | $1.71 | View | |
| LTC3851AEUD-1#PBF | QFN | 16 | E | $2.44 | $1.71 | View |
| LTC3851AEUD-1#TRPBF | QFN | 16 | E | $1.71 | View | |
| LTC3851AHMSE#PBF | MSOP | 16 | H | $3.20 | $2.24 | View |
| LTC3851AHMSE#TRPBF | MSOP | 16 | H | $2.30 | View | |
| LTC3851AHMSE-1#PBF | MSOP | 16 | H | $3.20 | $2.24 | View |
| LTC3851AHMSE-1#TRPBF | MSOP | 16 | H | $2.30 | View | |
| LTC3851AIGN#PBF | SSOP | 16 | I | $2.77 | $1.94 | View |
| LTC3851AIGN#TRPBF | SSOP | 16 | I | $2.00 | View | |
| LTC3851AIMSE#PBF | MSOP | 16 | I | $2.77 | $1.94 | View |
| LTC3851AIMSE#TRPBF | MSOP | 16 | I | $2.00 | View | |
| LTC3851AIMSE-1#PBF | MSOP | 16 | I | $2.77 | $1.94 | View |
| LTC3851AIMSE-1#TRPBF | MSOP | 16 | I | $2.00 | View | |
| LTC3851AIUD#PBF | QFN | 16 | I | $2.77 | $1.94 | View |
| LTC3851AIUD#TRPBF | QFN | 16 | I | $2.00 | View | |
| LTC3851AIUD-1#PBF | QFN | 16 | I | $2.77 | $1.94 | View |
| LTC3851AIUD-1#TRPBF | QFN | 16 | I | $2.00 | View | |
| LTC3851AMPMSE#PBF | MSOP | 16 | MP | $7.56 | $5.29 | View |
| LTC3851AMPMSE#TRPBF | MSOP | 16 | MP | $5.35 | View | |
| LTC3851AMPMSE-1#PBF | MSOP | 16 | MP | $7.56 | $5.29 | View |
| LTC3851AMPMSE-1#TRPBF | MSOP | 16 | MP | $5.35 | View | |
| LTC3851EGN#PBF | SSOP | 16 | E | $2.44 | $1.71 | View |
| LTC3851EGN#TRPBF | SSOP | 16 | E | $1.77 | View | |
| LTC3851EMSE#PBF | MSOP | 16 | E | $2.44 | $1.71 | View |
| LTC3851EMSE#TRPBF | MSOP | 16 | E | $1.77 | View | |
| LTC3851EMSE-1#PBF | MSOP | 16 | E | $2.44 | $1.71 | View |
| LTC3851EMSE-1#TRPBF | MSOP | 16 | E | $1.77 | View | |
| LTC3851EUD#PBF | QFN | 16 | E | $2.44 | $1.71 | View |
| LTC3851EUD#TRPBF | QFN | 16 | E | $1.77 | View | |
| LTC3851EUD-1#PBF | QFN | 16 | E | $2.44 | $1.71 | View |
| LTC3851EUD-1#TRPBF | QFN | 16 | E | $1.77 | View | |
| LTC3851IGN#PBF | SSOP | 16 | I | $2.77 | $1.94 | View |
| LTC3851IGN#TRPBF | SSOP | 16 | I | $2.00 | View | |
| LTC3851IMSE#PBF | MSOP | 16 | I | $2.77 | $1.94 | View |
| LTC3851IMSE#TRPBF | MSOP | 16 | I | $2.00 | View | |
| LTC3851IMSE-1#PBF | MSOP | 16 | I | $2.77 | $1.94 | View |
| LTC3851IMSE-1#TRPBF | MSOP | 16 | I | $2.00 | View | |
| LTC3851IUD#PBF | QFN | 16 | I | $2.77 | $1.94 | View |
| LTC3851IUD#TRPBF | QFN | 16 | I | $2.00 | View | |
| Buy Now • Request Samples | ||||||
Demo Boards
Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.| Part Number | Description | Price | Documentation |
|---|---|---|---|
| DC1432A-B | LTC3851AEUD-1 Demo Board with PGood Signal u 4.5V | $100.00 | |
| Buy Now | |||
Applications
- Automotive Systems
- Telecom Systems
- Industrial Equipment
- Distributed DC Power Systems
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Simulate
LTspice IV is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. To download LTspice IV and other FREE simulation tools, please visit our Design Simulation page.
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Related models available in LTspice IV
LTC3851-1
LTC3851
LTC3851A-1
LTC3851A
Technical Support
- For immediate technical assistance, contact your local sales office or distributor or call 1-800-4-LINEAR (US customers only) or 408-432-1900.
- For less urgent requests, please complete our Technical Support Request Form. Please allow 2-3 business days for reply.
