Overview

Features and Benefits

  • VIN and VOUT Limited Only by External Components
  • Adjustable Slope Compensation
  • Adjustable Overcurrent Protection with Automatic Restart
  • Adjustable Operating Frequency (70kHz to 700kHz) with One External Resistor
  • Synchronizable to an External Clock
  • ±1.5% Reference Accuracy
  • Current Mode Operation for Excellent Line and Load Transient Response
  • RUN Pin with Precision Threshold and Adjustable Hysteresis
  • Programmable Soft-Start with One External Capacitor
  • Low Quiescent Current: 360μA
  • Small 10-Lead MSOP and 3mm × 3mm DFN

Product Details

The LTC3805 is a current mode controller for flyback DC/DC converters designed to drive an N-channel MOSFET in high input and output voltage converter applications. Operating frequency and slope compensation can be programmed by external resistors. Programmable overcurrent sensing protects the converter from short-circuits. Soft-start can be programmed using an external capacitor and the soft-start capacitor also programs an automatic restart feature.

The LTC3805 provides ±1.5% output voltage accuracy and consumes only 360μA of quiescent current during normal operation and only 40μA during micropower startup. Using a 9.5V internal shunt regulator, the LTC3805 can be powered from a high VIN through a resistor or it can be powered directly from a low impedance DC voltage of 9V or less.

The LTC3805 is available in the 10-lead MSOP package and the 3mm × 3mm DFN package.

Turn On Voltage
LTC3805 8.4V
LTC3805-5 4.5V

Applications

  • Telecom Power Supplies
  • 42V and 12V Automotive Power Supplies
  • Isolated Electronic Equipment

Product Lifecycle icon-recommended 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 (2)

Tools & Simulations

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.

To launch ready-to-run LTspice demonstration circuits for this part:

Step 1: Download and install LTspice on your computer.

Step 2: Click on the link in the section below to download a demonstration circuit.

Step 3: If LTspice does not automatically open after clicking the link below, 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.

LTspice

Models for the following parts are available in LTspice:

LTC3805
LTC3805-5

Product Recommendations

LTC3805 Companion Parts

Recommended µModule Regulator

Recommended Suggested Oscillator

Design Resources

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.

Discussions

LTC3805 Discussions

Re: How to use the sync pin of the LTC3805
7 week(s) ago in Power By Linear
How to use the sync pin of the LTC3805
7 week(s) ago in Power By Linear
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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 Analog Devices, Inc. sales office or authorized distributor. Pricing displayed for Evaluation Boards and Kits is based on 1-piece pricing.


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Evaluation Boards Pricing displayed is based on 1-piece.
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.