Quad Synchronous Step-Down Regulator: 2.25MHz, 300mA, 200mA, 200mA, 100mA

The LTC3544B is a quad, high efficiency, monolithic synchronous buck regulator using a constant frequency, current mode architecture. The four regulators operate independently with separate run pins. The 2.25V to 5.5V input voltage range makes the LTC3544B well suited for single Li-Ion/polymer battery-powered applications. 100% duty cycle provides low dropout operation, extending battery runtime in portable systems. At moderate and low output load levels PWM pulse skip mode operation provides very low output ripple voltage for noise sensitive applications.

Switching frequency is internally set to 2.25MHz, allowing the use of small surface mount inductors and capacitors.

The internal synchronous switches increase efficiency and eliminate the need for external Schottky diodes. Low output voltages are easily supported with the 0.8V feedback reference voltage.

The LTC3544B is available in a low profile (0.75mm) (3mm × 3mm) QFN package.

Light Load Operation

LTC3544

Burst Mode (20mVpp), < 70uA Iq

LTC3544B

Pulse Skip Mode

Applications

* Cellular Telephones

* Personal Information Appliances

* Wireless and DSL Modems

* Digital Still Cameras

* Media Players

* Portable Instruments

* High Efficiency: Up to 95%

* Four Independent Regulators Provide Up to 300mA, 200mA, 200mA and 100mA Output Current

* 2.25V to 5.5V Input Voltage Range

* 2.25MHz Constant Frequency Operation

* No Schottky Diodes Required

* Low Dropout Operation: 100% Duty Cycle