LTC3811 - High Speed Dual, Multiphase Step-Down DC/DC Controller
Features
- Fixed Frequency, Peak Current Mode Control
- ±0.5% Output Accuracy Over Temperature
- Optimized for Low VOUT Applications (Up to 3.3V)
- Dual or Single Output, Multiphase Operation
- Wide VIN Range: 4.5V to 30V Operation
- High Speed Differential Remote Sense Amplifier
- Inductor DCR or Sense Resistor Capable
- Adjustable Peak Current Sense Voltage: 24mV to 85mV
- Very Low Duty Cycle Operation: tON(MIN) = 65ns (Typ)
- Powerful Internal Gate Drivers
- Output Voltage Soft-Start, Tracking and Sequencing
- Programmable Load Line for Reduced COUT
- Clock Input and Output for Up to 12-Phase Operation
- Fixed Frequency Operation from 250kHz to 750kHz
- PLL Synchronization from 150kHz Up to 900kHz
- Selectable CCM or DCM Operation
- Available in 5mm x 7mm QFN and G36 Packages
Typical Application
Description
The LTC3811 is a dual, PolyPhase synchronous step- down switching regulator controller optimized for output voltages up to 3.3V. The LTC3811 includes high bandwidth error amplifiers as well as a high speed differential remote sense amplifier. The sense voltage range is programmable from 24mV to 85mV, allowing the use of either the inductor DCR or a discrete sense resistor. Multiphase operation is made possible using the MODE/SYNC input, the CLKOUT output and the PHASEMODE control pin, allowing 1-, 2-, 3-, 4-, 6- or 12-phase operation.
Large internal gate drivers minimize switching losses and allow the use of multiple power MOSFETs connected in parallel for high current applications.
The operating frequency of the LTC3811 can be programmed from 250kHz to 750kHz and can also be synchronized to an external clock using the internal PLL.
Tracking and sequencing are possible with the LTC3811, and soft-start is programmed with an external capacitor. Shutdown reduces supply current to 20µA.
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 |
|---|---|---|---|---|---|
| LTC3811EG#PBF | SSOP-36 | G | E | 05-08-1640 (G36) | Yes |
| LTC3811EG#TRPBF | SSOP-36 | G | E | 05-08-1640 (G36) | Yes |
| LTC3811EUHF#PBF | 5x7 QFN-38 | UHF | E | 05-08-1701 | Yes |
| LTC3811EUHF#TRPBF | 5x7 QFN-38 | UHF | E | 05-08-1701 | 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 | |
|---|---|---|---|---|---|---|
| LTC3811EG#PBF | SSOP-36 | E | $5.36 | $3.75 | Yes | |
| LTC3811EG#TRPBF | SSOP-36 | E | $3.81 | Yes | ||
| LTC3811EUHF#PBF | 5x7 QFN-38 | E | $5.36 | $3.75 | Yes | |
| LTC3811EUHF#TRPBF | 5x7 QFN-38 | E | $3.81 | 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.| Part Number | Description | Price | Documentation |
|---|---|---|---|
| DC971A | LTC3811EUHF Demo Board | 4.5V < Vin < 14V, Vout: 2V/15A, 1.5V/15A | $150.00 | |
| Buy Now | |||
Applications
- Network Servers
- High Current ASIC Supplies
- Low Voltage Power Distribution
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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:
LTC3811
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.
