The DC/DC inverting switching regulators project is specifically designed to invert input voltages to negative outputs. It offer input voltage ranges from 4.5V to 6V and output -12V 100mA The MC34063A IC is heart of the project from On semiconductor. The MC33063A is a monolithic control circuit containing the primary functions required for DC-DC converters, This device consist of an internal temperature compensated reference, comparator, controlled duty cycle oscillator with an active current limit circuit, driver and high current output switch. This IC specially designed to be incorporated step-down, step-up, and voltage-inverting applications with minimum number of external components.
5V TO -12V Inverting Switching Regulator – [Link]