Please consider this device

The TC53 is a low power voltage detector. Typical supply current consumption is only 1µA at an input voltage of 2V. The voltage detection threshold setting is factory-programmed and guaranteed to ±2% accuracy. Threshold settings are available over a range of 1.6V to 6.0V. The TC53 has both complementary (CMOS) and open drain (NMOS) output configuration options. TC53 is the ideal voltage detector for precision applications in which small size, low installed cost, high accuracy, and low supply current consumption are critical.

HighlyAccurate....+/-2%
Low Power Consumption.............1.0µA, Typ.
Detect Voltage Range................1.6V to 6.0V in 0.1V Steps
Operating Voltage....................1.5V to 10.0V 
Output Configuration................Open Drain or CMOS