The ISL9104， ISL9104A is a 500mA， 4.3MHz step-down regulator， which is ideal for powering low-voltage microprocessors in compact devices such as PDAs and cellular phones. It is optimized for generating low output voltages down to 0.8V. The supply voltage range is from 2.7V to 6V allowing the use of a single Li+ cell， three NiMH cells or a regulated 5V input. It has guaranteed minimum output current of 500mA. A high switching frequency of 4.3MHz pulse-width modulation （PWM） allows using small external components. Under light load condition， the device operates at low IQ skip mode with typical 20μA quiescent current for highest light load efficiency to maximize battery life， and it automatically switches to fixed frequency PWM mode under heavy load condition. The ISL9104， ISL9104A includes a pair of low ON-resistance P-Channel and N-Channel internal MOSFETs to maximize system efficiency and minimize the external component count. 100% duty-cycle operation allows less than 300mV dropout voltage at 500mA. The ISL9104， ISL9104A offers internal digital soft-start， enable for power sequence， overcurrent protection and thermal shutdown functions. In addition， the ISL9104， ISL9104A offers a quick bleeding function that discharges the output capacitor when the IC is disabled. The ISL9104， ISL9104A is offered in a 1.6x1.6mm μTDFN package. The complete converter occupies less than 0.5CM2