The AIC1650 is a high performance inverting DC/DC converter, designed to drive an external power switch to generate programmable negative voltages. In the particularly suitable LCD bias contrast application, maximum efficiency of 90% can be achieved with low cost PNP bipolar transistor drivers. 4V to 20V input operation range allows the AIC1650 to be powered directly by the battery pack in most batteryoperated applications for greater efficiency. 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 range. Quiescent current is about