Features and Benefits
- 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
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.
- Network Servers
- High Current ASIC Supplies
- Low Voltage Power Distribution
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (1)
Demonstration circuit 971 is a high current density supply featuring the dual-output, 2-phase synchronous buck regulator LTC3811. The input voltage of the demo board is designed from 4.5V to 14V. The outputs are 2V/15A and 1.5V/15A. The output voltages can be programmed with different start-up tracking modes. All the critical power and controller IC circuits on the DC971 board are within a 1.45 × 0.9 drop-in PCB layout space. The outputs can be easily configured to have two separated output voltages or a single high current output voltage with two phases in paralleling.
Documentation & Resources
R419 Reliability Data3/22/2018
DC971A - Demo Manual9/24/2009
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.
Models for the following parts are available in LTspice:
LTC3811 Companion Parts
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.
|Part Number||Material Declaration||Reliability Data||Pin/Package Drawing||CAD Symbols, Footprints & 3D Models|
|LTC3811EG#PBF||Material Declaration||Reliability Data||36-Lead SSOP|
|LTC3811EG#TRPBF||Material Declaration||Reliability Data||36-Lead SSOP|
|LTC3811EUHF#PBF||Material Declaration||Reliability Data||38-Lead QFN (5mm x 7mm w/ EP)|
|LTC3811EUHF#TRPBF||Material Declaration||Reliability Data||38-Lead QFN (5mm x 7mm w/ EP)|
|Wafer Fabrication Data||R419 Reliability Data|
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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.