The LTC3614 is a low quiescent current monolithic synchronous buck regulator using a current mode, constant frequency architecture. Because of the low input voltage of 2.25V to 5.5V required ,the LTC3614 is ideally suited for single Li-Ion as well as fixed low voltage input applications. 100% duty cycle capability provides low dropout operation, extending the operating time in battery-powered systems.
The operating frequency is externally programmable up to 4MHz, allowing the use of small surface mount inductors.
For switching-noise-sensitive applications, the LTC3614 can be synchronized to an external clock at up to 4MHz.
During normal operation,the internal top power switch (P-channel MOSFET) is turned on at the beginning of each clock cycle. Current in the inductor increases until the current comparator trips and turns off the top power switch. When the top power switch shuts off, the synchronous power switch (N-channel MOSFET) turns on until either the bottom current limit is reached or the next clock cycle begins. The bottom current limit is typically set at –8A for forced continuous mode and 0A for Burst Mode operation and pulse-skipping mode.
The operating switching frequency can be set from 300kHz to 4MHz.
Main feartures of the LTC3614 are : 4A Output Current , 2.25V to 5.5V Input Voltage Range , Low Output Ripple Burst ModeR Operation: IQ = 75μA , 1% Output Voltage Accuracy , Output Voltage Down to 0.6V , High Effi ciency: Up to 95% , Low Dropout Operation: 100% Duty Cycle , Adjustable Switching Frequency: Up to 4MHz ,Programmable Soft-Start .