App note from Maxim Integrated about their MAX17291 generating negative voltage from positive input. Link here
Many applications require the power supply to provide a negative voltage, such as LCD displays, gate drivers, embedded applications, op-amp circuits, etc,. This application note explains how to generate a negative output voltage from a positive input voltage using the MAX17291 boost converter IC.
The MAX17291 is a low quiescent current boost (step-up) DC-DC converter with a 1A peak inductor current limit and True Shutdown™. True Shutdown disconnects the output from the input with no forward or reverse current. The output voltage is set with an external resistor-divider. The MAX17291 IC can operate from 1.8V to 5.5V input supply and can output up to 20V.