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LTC3543 - 600mA Synchronous Step Down Buck Regulator with PLL, Soft-Start and Spread Spectrum

The switching frequency is internally set at 2.25MHz, allowing the use of small surface mount inductors and capacitors. In PLL mode, the LTC3543 can acquire frequencies between 1MHz and 3MHz. Also, the LTC3543 has spread spectrum capability providing a lower noise regulated output, as well as low noise at the input.

In Burst Mode® 0peration, the supply current is only 45µA, dropping to <1µA in shutdown. The 2.5V to 5.5V input voltage range makes the LTC3543 ideally suited for single Li-Ion battery-powered applications. The 100% duty cycle provides a low dropout operation, extending the battery life in portable systems. Burst Mode operation increases efficiency at light loads, further extending battery life. The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode.

Features 600mA Output Current 2.5V to 5.5V Input Voltage Range 2.25MHz Constant Frequency Operation, Spread Spectrum or Synchronized PLL (1MHz to 3MHz) High Efficiency: Up to 95% 1A Peak Inductor Current Very Low Quiescent Current: Only 45µA During Burst Mode Operation No Schottky Diode Required Low Dropout Operation: 100% Duty Cycle Overtemperature Protected Stable with Ceramic Capacitors Shutdown Mode Draws <1µA Supply Current ±2% Output Voltage Accuracy Current Mode Operation for Excellent Line and Load Transient Response Soft-Start Available in a Low Profi le (0.75mm) 2mm × 3mm 6-Lead DFN Package Typical Application

Applications Portable Instruments Cellular Phones Packaging

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