2.25MHz, 600mA Synchronous Step-Down Regulator in ThinSOT

The LTC3406B-2 is a high efficiency monolithic synchronous buck regulator using a constant frequency, current mode architecture. Supply current with no load is 350µA, dropping to <1µA in shutdown. The 2.5V to 5.5V input voltage range makes the LTC3406B-2 ideally suited for single Li-Ion battery-powered applications. 100% duty cycle capability provides low dropout operation, extending battery life in portable systems. PWM pulse skipping mode operation provides very low output ripple voltage for noise sensitive applications.

The switching frequency is internally set at 2.25MHz, allowing the use of tiny surface mount inductors and capacitors. The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode. Low output voltages are easily supported with the 0.6V feedback reference voltage. The LTC3406B-2 is available in a low profile (1mm) SOT-23 package. Refer to LTC3406 for applications that require Burst Mode® operation.

Vout

Fsw

Features

LTC3406

Adj.

1.5MHz

Burst Mode

LTC3406-1.2

1.2V

1.5MHz

Burst Mode

LTC3406-1.5

1.5V

1.5MHz

Burst Mode

LTC3406-1.8

1.8V

1.5MHz

Burst Mode

LTC3406B

Adj.

1.5MHz

Burst Mode Disabled

LTC3406B-1.2

1.2V

1.5MHz

Burst Mode Disabled

LTC3406B-2

Adj.

2.25MHz

Burst Mode Disabled

LTC3406A

Adj.

1.5MHz

Low Ripple Burst Mode

LTC3406AB

Adj.

1.5MHz

Burst Mode Disabled

LTC3406AB-2

Adj.

2.25MHz

Burst Mode Disabled

Applications

* Cellular Telephones

* Personal Information Appliances

* Wireless and DSL Modems

* Digital Still Cameras

* MP3 Players

* Portable Instruments

* High Efficiency: Up to 96%

* 600mA Output Current at VIN = 3V

* 2.5V to 5.5V Input Voltage Range

* 2.25MHz Constant Frequency Operation

* No Schottky Diode Required

* Low Dropout Operation: 100% Duty Cycle

* Low Quiescent Current: 350µA

* 0.6V Reference Allows Low Output Voltages

* Shutdown Mode Draws < 1µA Supply Current

* Current Mode Operation for Excellent Line and Load Transient Response

* Overtemperature Protected

* Low Profile (1mm) SOT-23 Package