Features

• High Efficiency: Up to 96%
• High Peak Switch Current: 1000mA
• Low Output Ripple (<20mVP-P Typical) Burst Mode Operation: Only 26µA
• Very Low Quiescent Current: Only 26µA
• 2.5V to 5.5V Input Voltage Range
• 2.25MHz Constant Frequency Operation
• 1MHz to 3MHz External Frequency Synchronization
• Low Dropout Operation: 100% Duty Cycle
• No Schottky Diode Required
• Internal Soft-Start Limits Inrush Current
• 0.6V Reference Allows Low Output Voltages
• Shutdown Mode Draws <1µA Supply Current
• ±2% Output Voltage Accuracy
• Current Mode Operation for Excellent Line and Load Transient Response
• Overtemperature Protected
• Available in 6-Lead 2mm × 2mm DFN and Small TSOT

Typical Application

Description

The LTC3542 is a high efficiency monolithic synchronous buck converter using a constant frequency, current mode architecture. Supply current during operation is only 26µA, dropping to <1µA in shutdown. The 2.5V to 5.5V input voltage range makes the LTC3542 ideally suited for single Li-Ion battery-powered applications. 100% duty cycle provides low dropout operation, extending battery life in portable systems. The output voltage is adjustable from 0.6V to VIN. Internal power switches are optimized to provide high efficiency and eliminate the need for an external Schottky diode.

Switching frequency is internally set at 2.25MHz, allowing the use of small surface mount inductors and capacitors, and it can synchronize to an external clock signal with a frequency range of 1MHz to 3MHz through the MODE/ SYNC pin. The LTC3542 is specifically designed to work well with ceramic output capacitors, achieving very low output voltage ripple and a small PCB footprint.

The LTC3542 can be configured for the power saving Burst Mode Operation. For reduced noise and RF interference, the MODE/SYNC pin can be configured for pulse skipping operation.