LM10 Negative Regulator
It is possible to build a negative regulator using LM10 comparator and voltage reference IC. A transistor is employed to shift the reference current, increasing the minimum operating voltage to approximately 1.8V. The transistor should has high gain for better thermal stability, for example, gain = 100 will cause 1% drift over -55 to 125 °C temperature range. The gain of the selected transistor shown in the schematic diagram gives only 0.3% drift over that temperature range with supply voltage between -10.5 to -30V.
[Circuit’s schematic diagram source: National Semiconductor Application Note]