LTC3805-5 - Adjustable Frequency Current Mode Flyback/ Boost/SEPIC DC/DC Controller

The LTC3805-5 is a current mode DC/DC controller designed to drive an N-channel MOSFET in flyback, boost and SEPIC converter applications. Operating frequency and slope compensation can be programmed by external resistors. Programmable overcurrent sensing protects the converter from overload and short-circuit conditions. Soft-start can be programmed using an external capacitor and the soft-start capacitor also programs an automatic restart feature.

The LTC3805-5 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 LTC3805-5 can be powered from a high VIN through a resistor or it can be powered directly from a low impedance DC voltage from 4.7V to 8.8V.

The LTC3805-5 is available in the 10-lead MSOP package and the 3mm × 3mm DFN package.

Features
  • VIN and VOUT Limited Only by External Components
  • 4.5V Undervoltage Lockout Threshold
  • 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
  • Only 100mV Current Sense Voltage Drop
  • 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
LTC3805-5 Typical Application
LTC3805-5 Typical Application
Applications
  • Automotive Power Supplies
  • Telecom Power Supplies
  • Isolated Electronic Equipment
  • Auxiliary/Housekeeping Power Supplies
  • Power over Ethernet
Packaging
LTC3805-5 Package Drawing
LTC3805-5 Package Drawing
Order Information
Part NumberPackageTempPrice(1-99)Price (1k)*
LTC3805EDD-5#PBF3x3 DFN-10E$1.99$1.39
LTC3805EDD-5#TRPBF3x3 DFN-10E$1.45
LTC3805EMSE-5#PBFMS-10EE$1.99$1.39
LTC3805EMSE-5#TRPBFMS-10EE$1.45
LTC3805HMSE-5#PBFMS-10EH$2.51$1.76
LTC3805HMSE-5#TRPBFMS-10EH$1.82
LTC3805IDD-5#PBF3x3 DFN-10I$2.10$1.47
LTC3805IDD-5#TRPBF3x3 DFN-10I$1.53
LTC3805IMSE-5#PBFMS-10EI$2.10$1.47
LTC3805IMSE-5#TRPBFMS-10EI$1.53
LTC3805MPMSE-5#PBFMS-10EMP$6.80$4.76
LTC3805MPMSE-5#TRPBFMS-10EMP$4.82
Demo Boards
Part NumberDescriptionPrice
DC1311A-BLTC3805-5 Isolated Demo Board | Flyback Controller, 18V ≤ VIN ≤ 72V, Vout = 3.3V @ 3A$75.00
DC1576ALTC3805IMSE-5 Demo Board | SEPIC, 5V ≤ VIN ≤ 30V, Vout = 12V @ 3A$75.00
Datasheet
Design Note
Reliability Data
Press Release
CAD Symbol
LTspice
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