LTC3405A - 1.5MHz, 300mA Synchronous Step-Down Regulator in ThinSOT


  • High Efficiency: Up to 96%
  • Very Low Quiescent Current: Only 20µA During Operation
  • 300mA Output Current at VIN = 3V
  • 2.5V to 5.5V Input Voltage Range
  • 1.5MHz Constant Frequency Operation
  • No Schottky Diode Required
  • Low Dropout Operation: 100% Duty Cycle
  • Stable with Ceramic Capacitors
  • 0.8V Reference Allows Low Output Voltages
  • Shutdown Mode Draws
  • ±2% Output Voltage Accuracy
  • Current Mode Operation for Excellent Line and Load Transient Response
  • Overtemperature Protected
  • Low Profile (1mm) ThinSOT™ Package

Typical Application

LTC3405A Typical Application
LTC3405A Typical Application


The LTC3405A is a high efficiency monolithic synchronous buck regulator using a constant frequency, current mode architecture. Supply current during operation is only 20µA and drops to <1µA in shutdown. The 2.5V to5.5V input voltage range makes the LTC3405A ideally suited for single Li-Ion battery-powered applications. 100%duty cycle provides low dropout operation, extending battery life in portable systems.

Switching frequency is internally set at 1.5MHz, allowing the use of small surface mount inductors and capacitors.The LTC3405A is specifically designed to work well with ceramic output capacitors, achieving very low output voltage ripple and a small PCB footprint.

The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode. Low output voltages are easily supported with the 0.8V feedback reference voltage. The LTC3405A is available in a low profile (1mm) ThinSOT package.

For fixed 1.5V and 1.8V output versions, refer to theLTC3405A-1.5/LTC3405A-1.8 data sheet.

Protected by U.S. Patents, including 6580258, 5481178.

  Vout Features
LTC3405 Adj. -
LTC3405A Adj. Stable With All Ceramic Caps
LTC3405A-1.375 1.375V Stable With All Ceramic Caps
LTC3405A-1.5 1.5V Stable With All Ceramic Caps
LTC3405A-1.8 1.8V Stable With All Ceramic Caps


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


LTC3405A Package Drawing

Order Info

Package Variations and Pricing

Part Number Package Pins Temp Price (1-99) Price (1k)* RoHS Data
LTC3405AES6 SOT 6 E $2.37 View
LTC3405AES6#PBF SOT 6 E $2.37 View
LTC3405AES6#TR SOT 6 E $2.37 $1.67 View
LTC3405AES6#TRM SOT 6 E $2.37 $1.69 View
LTC3405AES6#TRMPBF SOT 6 E $2.37 $1.69 View
LTC3405AES6#TRPBF SOT 6 E $2.37 $1.67 View
LTC3405AES6-1.375 SOT 6 E $2.37 View
LTC3405AES6-1.375#PBF SOT 6 E $2.37 View
LTC3405AES6-1.375#TR SOT 6 E $2.37 $1.67 View
LTC3405AES6-1.375#TRM SOT 6 E $2.37 $1.69 View
LTC3405AES6-1.375#TRMPBF SOT 6 E $2.37 $1.69 View
LTC3405AES6-1.375#TRPBF SOT 6 E $2.37 $1.67 View
LTC3405AES6-1.5 SOT 6 E $2.37 View
LTC3405AES6-1.5#PBF SOT 6 E $2.37 View
LTC3405AES6-1.5#TR SOT 6 E $2.37 $1.67 View
LTC3405AES6-1.5#TRM SOT 6 E $2.37 $1.69 View
LTC3405AES6-1.5#TRMPBF SOT 6 E $2.37 $1.69 View
LTC3405AES6-1.5#TRPBF SOT 6 E $2.37 $1.67 View
LTC3405AES6-1.8 SOT 6 E $2.37 View
LTC3405AES6-1.8#PBF SOT 6 E $2.37 View
LTC3405AES6-1.8#TR SOT 6 E $2.37 $1.67 View
LTC3405AES6-1.8#TRM SOT 6 E $2.37 $1.69 View
LTC3405AES6-1.8#TRMPBF SOT 6 E $2.37 $1.69 View
LTC3405AES6-1.8#TRPBF SOT 6 E $2.37 $1.67 View
LTC3405ES6 SOT 6 E $1.96 View
LTC3405ES6#PBF SOT 6 E $1.96 View
LTC3405ES6#TR SOT 6 E $1.96 $1.67 View
LTC3405ES6#TRM SOT 6 E $1.96 $1.69 View
LTC3405ES6#TRMPBF SOT 6 E $1.96 $1.69 View
LTC3405ES6#TRPBF SOT 6 E $1.96 $1.67 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 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
DC480A-E LTC3405AES6 | Thin SOT Synchronous Buck Regulator, 2.5 to 5.5 Vin, ADJ (1.2V) Vout @ 300mA(3.0 Vin min), (Small size Inductor). $75.00
DC480A-F LTC3405AES6 | Thin SOT Synchronous Buck Regulator, 2.5 to 5.5 Vin, ADJ (1.2V) Vout @ 300mA(3.0 Vin min), (High Efficiency Inductor). $75.00
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Click here to view our complete list of demo boards


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  • Wireless and DSL Modems
  • Digital Still Cameras
  • MP3 Players
  • Portable Instruments

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