I am currently designed a simple instrumentation amplifier "INA125" from Burr-Brown. I am powering with a 7662 charge pump to provide a bi-polar voltage. My design specification is that the amplifier operate from 12-24 VDC. The INA125 operates to a max of +/-18 VDC and the charge pump to +/- 15 VDC. Basically I want to limit the voltage to power the INA and charge pump to 12VDC. I want to be able to operate the INA to produce a 0-10 VDC output. But in order to get a 10 VDC output the INA requires a minimum of at least 11.5 VDC. I tried using an 12 V Zener Diode and Resistor but found the volt drops below the required when I apply the load. If I drop the protection resistor too much, it over heats the Diode, and I don't want to use a high wattage diode. I also tried using a 12V regulator, but that required at least a 13 volt input to generate a 12 volt signal. What would be the best way to take care of this problem. I need to be able to limit the voltage to these chips to prevent damage.