LTC3775 - High Frequency Synchronous Step-Down Voltage Mode DC/DC Controller

Features

  • Wide VIN Range: 4.5V to 38V
  • Line Feedforward Compensation
  • Low Minimum On-Time: tON(MIN) < 30ns
  • Powerful Onboard MOSFET Drivers
  • Leading Edge Modulation Voltage Mode Control
  • ±0.75%, 0.6V Reference Voltage Accuracy Over Temperature
  • VOUT Range: 0.6V to 0.8VIN
  • Programmable, Cycle-by-Cycle Peak Current Limit
  • Sense Resistor or RDS(ON) Current Sensing
  • Programmable Soft-Start
  • Synchronizable Fixed Frequency from 250kHz to 1MHz
  • Selectable Pulse-Skipping or Forced Continuous Modes of Operation
  • Low Shutdown Current: 14μA Typical
  • Thermally Enhanced 16-Lead MSOP and 3mm × 3mm QFN Packages

Typical Application

LTC3775 Typical Application
LTC3775 Typical Application

Description

The LTC3775 is a high efficiency synchronous step-down switching DC/DC controller that drives an all N-channel power MOSFET stage from a 4.5V to 38V input supply voltage. A patented line feedforward compensation circuit and a high bandwidth error amplifier provide very fast line and load transient response.

High step-down ratios are made possible by a low 30ns minimum on-time, allowing extremely low duty cycles. MOSFET RDS(ON) current sensing maximizes efficiency. Alternatively, a sense resistor can be used for higher current limit accuracy. Continuous monitoring of the voltages across the top and bottom MOSFETs allows cycle-by-cycle control of the inductor current, configurable by external resistors.

The soft-start function controls the duty cycle during start-up, providing a smooth output voltage ramp up. The operating frequency is user programmable from 250kHz to 1MHz and can be synchronized to an external clock.

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
LTC3775EMSE#PBF MS-16E MSE E 05-08-1667 Yes
LTC3775EMSE#TRPBF MS-16E MSE E 05-08-1667 Yes
LTC3775EUD#PBF 3x3 QFN-16 UD E 05-08-1691 Yes
LTC3775EUD#TRPBF 3x3 QFN-16 UD E 05-08-1691 Yes
LTC3775IMSE#PBF MS-16E MSE I 05-08-1667 Yes
LTC3775IMSE#TRPBF MS-16E MSE I 05-08-1667 Yes
LTC3775IUD#PBF 3x3 QFN-16 UD I 05-08-1691 Yes
LTC3775IUD#TRPBF 3x3 QFN-16 UD I 05-08-1691 Yes


LTC3775 Package Drawing
LTC3775 Package Drawing

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
LTC3775EMSE#PBF MS-16E E $2.56 $1.79 Yes
LTC3775EMSE#TRPBF MS-16E E $1.85 Yes
LTC3775EUD#PBF 3x3 QFN-16 E $2.56 $1.79 Yes
LTC3775EUD#TRPBF 3x3 QFN-16 E $1.85 Yes
LTC3775IMSE#PBF MS-16E I $2.99 $2.09 Yes
LTC3775IMSE#TRPBF MS-16E I $2.15 Yes
LTC3775IUD#PBF 3x3 QFN-16 I $2.99 $2.09 Yes
LTC3775IUD#TRPBF 3x3 QFN-16 I $2.15 Yes
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* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

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
DC1290A-A LTC3775EUD Demo Board | 5V ≤ VIN ≤ 26V, VOUT = 1.2V @ 15A $100.00
DC1290A-B LTC3775EUD Demo Board | 5V ≤ VIN ≤ 36V, VOUT = 1.2V @ 10A $100.00
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Click here to view our complete list of demo boards

Applications

  • Automotive Systems
  • Telecom and Industrial Power Supplies
  • Point of Load Applications

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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

To launch a ready to run LTspice demonstration circuit for this part:

  • Step 1: If you have not installed LTspice on this computer, download and install LTspice
  • Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
  • Step 3: If LTspice does not automatically open after clicking the link above, you can instead run the simulation by right clicking on the link and selecting "Save Target As." After saving the file to your computer, start LTspice and open the demonstration circuit by selecting 'Open' from the 'File' menu

To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.

Models for the following parts are available in LTspice:
LTC3775

Technical Support