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

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

Applications

* Cellular Telephones

* Personal Information Appliances

* Wireless and DSL Modems

* Digital Still Cameras

* MP3 Players

* Portable Instruments

* 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