LTC3811

PRODUCTION

High Speed Dual, Multiphase Step-Down DC/DC Controller

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Overview

  • 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.

Applications

  • Network Servers
  • High Current ASIC Supplies
  • Low Voltage Power Distribution
LTC3811
High Speed Dual, Multiphase Step-Down DC/DC Controller
Dual Output, 2-Phase Tracking Core and I/O Supply Load Step Product Package 1 Product Package 2
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Documentation

Data Sheet 1

Reliability Data 1

User Guide 1

Design Note 1

Data Sheet

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Software Resources

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Hardware Ecosystem

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Tools & Simulations

LTspice

Models for the following parts are available in LTspice:

  • LTC3811
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.

Evaluation Kits

eval board
schematic 1
DC971A

LTC3811EUHF Demo Board | 4.5V < VIN < 14V, VOUT: 2V/15A, 1.5V/15A

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Product Details

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.
DC971A
LTC3811EUHF Demo Board | 4.5V < VIN < 14V, VOUT: 2V/15A, 1.5V/15A
DC971A - Schematic

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