CE9908/CE9909,pdf datasheet (S

The CE9908/9 is a CMOS step-up switching DC/DC converter that mainly
consists of a reference voltage source, an oscillator, and a comparator. The CE9908
allows the duty ratio to be automatically
switched according to the load (light load:
50%, high output current: 75%), enabling
products with a low ripple over a wide
range, high efficiency, and high output
current. With the CE9908/9, a step-up
switching DC/DC converter can be
configured by using an external coil,
capacitor, diode and NMOS or NPN. The
built-in MOSFET is turned off by a
protection circuit when the voltage at the LX pin exceeds the limit to prevent it from being damaged. This feature, along with the mini package and low current consumption, makes the CE9908 ideal for applications such as the power supply unit of portable equipment.