ISL9109 is 1.6MHz synchronous step-down regulator with integrated power switches capable of delivering 1.5A output for powering RF Power Amplifiers in cellular phones. The ISL9109 features a standby mode which allows for rapid startup while prolonging battery life. The supply voltage range is from 2.7V to 5.5V allowing the use of a single Li+ cell, three NiMH cells, or a regulated 5V input. 1.6MHz pulse-width modulation (PWM) switching frequency allows using small external components. It has a flexible operation mode selection of forced PWM mode and Skip (Low I_Q) mode with typical 22μA quiescent current for highest light load efficiency to maximize battery life.

The ISL9109 integrates a pair of low ON-resistance P-Channel and N-Channel MOSFETs to maximize efficiency and minimize external component count.

When in standby, the ISL9109 band-gap reference is powered. This assists in a rapid power-up when the EN pin is asserted high. Other features include soft-start, overcurrent protection, and thermal shutdown.

The ISL9109 is offered in 8 Ld 2mmx3mm DFN package with 0.9mm typical height. The complete converter can occupy less than 1cm² area.

• Integrated Synchronous Buck Regulator with up to 95% Efficiency
• 2.7V to 5.5V Supply Voltage
• 1.5A Output Current
• 4.3μA Quiescent Supply Current in Standby Mode
• 22μA Quiescent Supply Current in Skip (Low I_Q) Mode
• 3% Output Accuracy Over Temperature/Load/Line
• Selectable Forced PWM Mode or Skip Mode
• Less Than 1μA Logic Controlled Shutdown Current
• 100% Maximum Duty Cycle for Lowest Dropout
• Soft-Start
• Peak Current Limiting, Short Circuit Protection
• Over-Temperature Protection
• 8 Ld 2mmx3mm DFN
• Pb-Free (RoHS Compliant)

• Single Li-Ion Battery-Powered Equipment
• RF Power Amplifier
• CPU Power
• PDAs and Palmtops