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Power Management Switching Regulator Flyback, Forward and Isolated Controllers
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LTC3805 - Adjustable Frequency Current Mode Flyback DC/DC Controller

Features

  • 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

Typical Application

LTC3805 Typical Application
LTC3805 Typical Application

Description

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. Softstart 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.

Packaging

For complete and up to date package information and drawings, please refer to our packaging page

DFN-10, MS-8E

LTC3805 Package Drawing
LTC3805 Package Drawing

Order Info

Package Variations and Pricing

Part Number Package Pins Temp Price (1-99) Price (1k)* RoHS Data
LTC3805EDD#PBF DFN 10 E $2.01 $1.39 View
LTC3805EDD#TRPBF DFN 10 E $1.45 View
LTC3805EDD-5#PBF DFN 10 E $1.99 $1.39 View
LTC3805EDD-5#TRPBF DFN 10 E $1.45 View
LTC3805EMSE#PBF MSOP 10 E $2.01 $1.39 View
LTC3805EMSE#TRPBF MSOP 10 E $1.45 View
LTC3805EMSE-5#PBF MSOP 10 E $1.99 $1.39 View
LTC3805EMSE-5#TRPBF MSOP 10 E $1.45 View
LTC3805HMSE#PBF MSOP 10 H $2.51 $1.76 View
LTC3805HMSE#TRPBF MSOP 10 H $1.82 View
LTC3805HMSE-5#PBF MSOP 10 H $2.51 $1.76 View
LTC3805HMSE-5#TRPBF MSOP 10 H $1.82 View
LTC3805IDD#PBF DFN 10 I $2.10 $1.47 View
LTC3805IDD#TRPBF DFN 10 I $1.53 View
LTC3805IDD-5#PBF DFN 10 I $2.10 $1.47 View
LTC3805IDD-5#TRPBF DFN 10 I $1.53 View
LTC3805IMSE#PBF MSOP 10 I $2.10 $1.47 View
LTC3805IMSE#TRPBF MSOP 10 I $1.53 View
LTC3805IMSE-5#PBF MSOP 10 I $2.10 $1.47 View
LTC3805IMSE-5#TRPBF MSOP 10 I $1.53 View
LTC3805MPMSE#PBF MSOP 10 MP $6.80 $4.76 View
LTC3805MPMSE#TRPBF MSOP 10 MP $4.82 View
LTC3805MPMSE-5#PBF MSOP 10 MP $6.80 $4.76 View
LTC3805MPMSE-5#TRPBF MSOP 10 MP $4.82 View
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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 demo boards are offered free of charge to qualified customers. Contact your local sales office or distributor to request 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
DC1045A LTC3805EMSE Isolated demo board | 36V Vin 72V, Vout: 3.3V/3A $75.00
DC1311A-A LTC3805 Isolated Demo Board, Vin: 18V to 72V, Vout: 3.3V/3A $75.00
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Click here to view our complete list of demo boards

Applications

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

Simulate

LTspice IV is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. To download LTspice IV and other FREE simulation tools, please visit our Design Simulation page.

Related models available in LTspice IV
LTC3805-5
LTC3805

Technical Support