The SC1628 is a high performance step-up DC-DC converter, designed to drive an external power switch to generate programmable positive voltages. In the particularly suitable LCD contrast bias and flash memory programming power supply applications, typical full load efficiencies are 85% to 95%. The 4V to 24V input operation range allows the SC1628 to be powered directly by the battery pack in most batterypowered applications for greater efficiency. The output voltage can be scaled to 40V or greater by two external resistors. A pulse-frequency modulation scheme is employed to maintain high efficiency conversion under wide input voltage ranges. Quiescent current is about 100A and can be reduced down to 8A in shutdown mode. With a switching frequency range of 90kHz to 250kHz, small size switching components may be used, which is ideal for battery powered portable equipment such as notebook and palmtop computers.