LTC3861-1 - Dual, Multiphase Step-Down Voltage Mode DC/DC Controller with Accurate Current Sharing
Features
- Operates with Power Blocks, DrMOS or External Gate Drivers and MOSFETs
- Constant-Frequency Voltage Mode Control with Accurate Current Sharing
- ±0.75% 0.6V Voltage Reference
- Differential Remote Output Voltage Sense Amplifier
- Multiphase Capability—Up to 12-Phase Operation
- Programmable Current Limit
- Safely Powers a Prebiased Load
- Programmable or PLL-Synchronizable Switching Frequency Up to 2.25MHz
- Lossless Current Sensing Using Inductor DCR or Precision Current Sensing with Sense Resistor
- VCC Range: 3V to 5.5V
- VIN Range: 3V to 24V
- Power Good Output Voltage Monitor
- Output Voltage Tracking Capability
- Programmable Soft-Start
- Available in a 32-Pin 5mm × 5mm QFN Package
AEC-Q100 data available for specific packages
Typical Application
Description
The LTC®3861-1 is a dual PolyPhase® synchronous stepdown switching regulator controller for high current distributed power systems, digital signal processors, and other telecom and industrial DC/DC power supplies. It uses a constant-frequency voltage mode architecture combined with very low offset, high bandwidth error amplifiers and a remote output sense differential amplifier for excellent transient response and output regulation.
The controller incorporates lossless inductor DCR current sensing to maintain current balance between phases and to provide overcurrent protection. The chip operates from a VCC supply between 3V and 5.5V and is designed for stepdown conversion from VIN between 3V and 24V to output voltages between 0.6V and VCC – 0.5V.
Inductor current reversal is disabled during soft-start to safely power prebiased loads. The constant operating frequency can be synchronized to an external clock or linearly programmed from 250kHz to 2.25MHz. Up to six LTC3861-1 controllers can operate in parallel for 1-, 2-, 3-, 4-, 6- or 12-phase operation.
The LTC3861-1 is pin-to-pin compatible with the LTC3860. It is available in a 32-pin 5mm × 5mm QFN package. The LTC3861is a 36-pin QFN version of the LTC3861-1, which has dual differential output voltage sense amplifiers.
| # Diff Amps |
Config Pin | Package | |
| LTC3861 | 2 | Yes | 5 x 6 QFN-36 |
| LTC3861-1 | 1 | No | 5 x 5 QFN-32 |
Packaging
CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.
For complete and up to date package information and drawings, please refer to our packaging page
| Part Number | Package | Code | Temp | Package Drawing |
RoHS |
|---|---|---|---|---|---|
| LTC3861EUH-1#PBF | 5x5 QFN-32 | UH | E | 05-08-1693 | Yes |
| LTC3861EUH-1#TRPBF | 5x5 QFN-32 | UH | E | 05-08-1693 | Yes |
| LTC3861IUH-1#PBF | 5x5 QFN-32 | UH | I | 05-08-1693 | Yes |
| LTC3861IUH-1#TRPBF | 5x5 QFN-32 | UH | I | 05-08-1693 | Yes |
Order Info
- Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
- 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 | Temp | Price (1-99) |
Price (1k)* |
RoHS | |
|---|---|---|---|---|---|---|
| LTC3861EUH-1#PBF | 5x5 QFN-32 | E | $3.94 | $2.76 | Yes | |
| LTC3861EUH-1#TRPBF | 5x5 QFN-32 | E | $2.82 | Yes | ||
| LTC3861IUH-1#PBF | 5x5 QFN-32 | I | $4.37 | $3.06 | Yes | |
| LTC3861IUH-1#TRPBF | 5x5 QFN-32 | I | $3.12 | Yes | ||
| 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.Click here to view our complete list of demo boards
Designed for Automotive and Transportation Applications
AEC-Q100 data is available for these specific part numbers. Please contact your local sales representative for more information regarding reliability reports or to inquire about parts that are not included. For more information, view our Automotive and Transportation page
| Part Number | Package | Temp | Price (1-99) |
Price (1k)* |
RoHS | |
|---|---|---|---|---|---|---|
| LTC3861IUH-1#PBF | 5x5 QFN-32 | I | $4.37 | $3.06 | Yes | |
| LTC3861IUH-1#TRPBF | 5x5 QFN-32 | I | $3.12 | Yes | ||
| Buy Now • Request Samples | ||||||
Applications
- High Current Distributed Power Systems
- DSP, FPGA and ASIC Supplies
- Datacom and Telecom Systems
- Industrial Power Supplies
People Who Viewed This Product Also Viewed
- LTC3861 - Dual, Multiphase Step-Down Voltage Mode DC/DC Controller with Accurate Current Sharing
- LTC3883/LTC3883-1- Single Phase Step-Down DC/DC Controller with Digital Power System Management
- LT8705 - 80V VIN and VOUT Synchronous 4-Switch Buck- Boost DC/DC Controller
- LTC3880 - Dual Output PolyPhase Step-Down DC/DC Controller with Digital Power System Management
- LTC4364 - Surge Stopper with Ideal Diode
- LTC3860 - Dual, Multiphase Step-Down Voltage Mode DC/DC Controller with Current Sharing
- LT4320/LT4320-1 - Ideal Diode Bridge Controller
- LTC3829 - 3-Phase, Single Output Synchronous Step-Down DC/DC Controller with Diffamp
- LT3796/LT3796-1 - 100V Constant-Current and Constant-Voltage Controller with Dual Current Sense
- LTC3789 - High Efficiency, Synchronous, 4-Switch Buck-Boost Controller
Product Notifications
Please login to your MyLinear account for notifications of datasheet updates, new document releases and LTspice model announcements for your favorite products. If you do not have a MyLinear account you may Sign Up Now.
Forgot your password? Click here.
Need help? Email mylinear@linear.com with questions and comments.
Design Tools
LTspice
LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice
Models for the following parts are available in LTspice:
LTC3861
LTC3861-1
LTpowerCAD
The LTpowerCAD design tool is a complete power supply design tool program that can significantly ease the tasks of power supply design. It guides users to a solution, selects power stage components, provides detailed power efficiency, shows quick loop bode plot stability and load transient analysis, and can export a final design to LTspice for simulation. Click here to download LTpowerCAD
Design tools for the following parts are available in LTpowerCAD:
LTC3861
LTC3861 Parallel
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.
