LTC1879

` High Efficiency: Up to 95%
` Low Quiescent Current: Only 15A with No Load
` 550kHz Constant Frequency Operation
` 2.65V to 10V Input Voltage Range
` V<sub>OUT</sub> from 0.8V to V<sub>IN</sub>, I<sub>OUT</sub> to 1.2A
` True PLL Frequency Locking from 350kHz to 750kHz
` Power Good Output Voltage Monitor
` Low Dropout Operation: 100% Duty Cycle
` Burst Mode<sup>®</sup> or Pulse Skipping Operation
` Current Mode Operation for Excellent Line and Load Transient Response
` Shutdown Mode Draws <1A Supply Current
` ±2% Output Voltage Accuracy
` Overcurrent and Overtemperature Protected
` Available in 16-Lead SSOP Package

· Cellular Telephones
· Portable Computers
· Wireless Modems

Input Supply Voltage ............................... 0.3V to 11V
I_TH, PLL_LPF Voltages ........................... 0.3V to 2.7V
RUN/SS, V_FB Voltages ............................. 0.3V to V_IN
SYNC/MODE Voltage ................................ 0.3V to V_IN
(V_PVIN V_SWP) Voltage ......................... 0.3V to 11V
V_SWN Voltage ......................................... 0.3V to 11V
P-Channel Switch Source Current (DC) .................... 2A
N-Channel Switch Sink Current (DC) ........................ 2A
Peak Switching Sink and Source Current ................. 3A
Operating Ambient Temperature Range
(Note 2) ............................................. 40°C to 85°C
Junction Temperature (Notes 3, 6) .................... 125°C
Storage Temperature Range .......... 65°C to 150°C
Lead Temperature (Soldering, 10 sec)............... 300°C

The LTC^®1879 is a high efficiency monolithic synchronousbuck regulator using a constant frequency, current mode architecture. Operating supply current is only 15A with no load and drops to <1A 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.