+5V to 42V step regulator design

I am looking for a step-up regulator design from +5V  to approx. 42V with an Iout Max of 700mA - 1A. The most important additional factor is the approx. MAX size of the final design. I have a very limited amount of PCB real estate. I probably have no more than 20mm x 20mm but probably even less than this. If I can't find something within this area I might need to go to a lower output voltage (maybe even drop to half of the Voltage output !). What would be good also if this regulator had the option for a negative output as well. Can you help me with this ?