LTC3805

PRODUCTION

Adjustable Frequency Current Mode Flyback DC/DC Controller

Part Models: 12
1ku List Price: Starting From $1.71

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Part Details

V_IN and V_OUT 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

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 V_IN 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

Part Models: 12
1ku List Price: Starting From $1.71

Documentation

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 Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
LTC3805EDD#PBF	10-Lead DFN (3mm x 3mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3805EDD#TRPBF	10-Lead DFN (3mm x 3mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3805EMSE#PBF	10-Lead MSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3805EMSE#TRPBF	10-Lead MSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3805HMSE#PBF	10-Lead MSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3805HMSE#TRPBF	10-Lead MSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3805IDD#PBF	10-Lead DFN (3mm x 3mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3805IDD#TRPBF	10-Lead DFN (3mm x 3mm w/ EP)	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3805IMSE#PBF	10-Lead MSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3805IMSE#TRPBF	10-Lead MSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3805MPMSE#PBF	10-Lead MSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys
LTC3805MPMSE#TRPBF	10-Lead MSOP w/ EP	Material Declaration Reliablity Data	Ultra Librarian SamacSys

Part Models	Product Lifecycle	PCN

Feb 14, 2025 - 25_0017 Bond Wire Change from Gold to Copper
		PCN25_0017_Form Material_Report Qualification Results Summary
LTC3805EDD#PBF	PRODUCTION
LTC3805EDD#TRPBF	PRODUCTION
LTC3805EMSE#PBF	PRODUCTION
LTC3805EMSE#TRPBF	PRODUCTION
LTC3805HMSE#PBF	PRODUCTION
LTC3805HMSE#TRPBF	PRODUCTION
LTC3805IDD#PBF	PRODUCTION
LTC3805IDD#TRPBF	PRODUCTION
LTC3805IMSE#PBF	PRODUCTION
LTC3805IMSE#TRPBF	PRODUCTION
Oct 11, 2022 - 22_0244 Epoxy Change from Henkel 8290 to 8290A for MSOP Package
		PCN22_0244_Form Material_Report Qualification Results Summary Delta Qualification Matrix
LTC3805EMSE#PBF	PRODUCTION
LTC3805EMSE#TRPBF	PRODUCTION
Jul 12, 2022 - 22_0157 UTAC Thai Limited (UTL) as Alternate Assembly Site for MSOP Packages [With Modification in BOM]
		PCN22_0157_Form Material_Report Qualification Results Summary Delta Qualification Matrix Detailed Parts List
LTC3805EMSE#PBF	PRODUCTION
LTC3805EMSE#TRPBF	PRODUCTION
Jun 21, 2022 - 22_0050 UTAC Thai Limited (UTL) as Alternate Assembly Site for MSOP Packages / Devices
		PCN22_0050_Form Material_Report Qualification Results Summary Delta Qualification Matrix
LTC3805EMSE#PBF	PRODUCTION
LTC3805EMSE#TRPBF	PRODUCTION
Feb 4, 2020 - 20_0130 Laser Top Mark Conversion for 10-Lead MSOP Packages Assembled in ADPG and UTAC
		PCN20_0130_Form Material_Report
LTC3805EMSE#PBF	PRODUCTION
LTC3805EMSE#TRPBF	PRODUCTION
LTC3805HMSE#PBF	PRODUCTION
LTC3805HMSE#TRPBF	PRODUCTION
LTC3805IMSE#PBF	PRODUCTION
LTC3805IMSE#TRPBF	PRODUCTION
LTC3805MPMSE#PBF	PRODUCTION
LTC3805MPMSE#TRPBF	PRODUCTION

This is the most up-to-date revision of the Data Sheet.

Software Resources

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Hardware Ecosystem

Parts	Product Life Cycle	Description
Isolated µModule Converters 2
LTM8047	RECOMMENDED FOR NEW DESIGNS	3.1V_IN to 32V_IN Isolated μModule (Power Module) DC/DC Converter
LTM8048	RECOMMENDED FOR NEW DESIGNS	3.1V_IN to 32V_IN Isolated μModule (Power Module) DC/DC Converter with LDO Post Regulator
Silicon Oscillators 2
LTC6908		Resistor Set SOT-23 Oscillator with Spread Spectrum Modulation
LTC6909	PRODUCTION	1 to 8 Output, Multiphase Silicon Oscillator with Spread Spectrum Modulation

Tools & Simulations

LTspice 1

LTC3805 Demo Circuit - Nonisolated Telecom Flyback Converter (36-72V to 5V @ 2A)

Models for the following parts are available in LTspice:

LTC3805
LTC3805-5

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

LTC3805EMSE Isolated Demo Board | 36V ≤ VIN ≤ 72V, VOUT = 3.3V/3A

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Product Details

Demonstration circuit 1045 is a Telecom isolated DC/DC converter featuring the LTC3805 constant frequency current mode flyback controller. The DC1045 converts 36V to 72V input voltage to an isolated 3A of output current at 3.3V. The 200kHz constant frequency operation is maintained down to very light load to reduce low frequency noise generated over a wide range of load current.