1.2A Synchronous Step-Down Regulator with 15µA Quiescent Current

The LTC1879 is a high efficiency monolithic synchronous buck regulator using a constant frequency, current mode architecture. Operating supply current is only 15µA with no load and drops to <1µA in shutdown. The input supply voltage range of 2.65V to 10V makes the LTC1879 ideally suited for both single and dual Li-Ion battery-powered applications. 100% duty cycle provides low dropout operation, extending battery life in portable systems.

The switching frequency is internally set to 550kHz, allowing the use of small surface mount inductors and capacitors. For noise sensitive applications, the LTC1879 can be externally synchronized from 350kHz to 750kHz. Burst Mode operation is inhibited during synchronization or when the SYNC/MODE pin is pulled low.

The internal synchronous rectifier switch increases efficiency and eliminates the need for an external Schottky diode. Low output voltages are easily supported with a 0.8V feedback reference voltage. The LTC1879 is available in a 16-lead SSOP package.

Applications

* Cellular Telephones

* Portable Computers

* Wireless Modems

* High Efficiency: Up to 95%

* Low Quiescent Current: Only 15µA with No Load

* 550kHz Constant Frequency Operation

* 2.65V to 10V Input Voltage Range

* VOUT from 0.8V to VIN, IOUT to 1.2A

* True PLL Frequency Locking from 350kHz to 750kHz

* Power Good Output Voltage Monitor

* Low Dropout Operation: 100% Duty Cycle

* Burst Mode® or Pulse Skipping Operation

* Current Mode Operation for Excellent Line and Load Transient Response

* Shutdown Mode Draws <1µA Supply Current

* ±2% Output Voltage Accuracy

* Overcurrent and Overtemperature Protected

* Available in 16-Lead SSOP Package