The MAX4289 micropower, operational amplifier is optimized for ultra-low supply voltage operation. The amplifier consumes only 9A of quiescent supply current and is fully specified for operation from a single 1.0V to 5.5V power supply. This ultra-low voltage operation together with the low quiescent current consumption make the MAX4289 ideal for use in battery-powered systems operated from as little as a single alkaline cell. The MAX4289 also features a wide input common-mode range that includes the ground, and an output voltage swing that is virtually Rail-to-Rail, allowing almost all of the power supply to be used for signal voltage. The low input offset voltage and low input bias current specifications along with the high open-loop gain make the MAX4289 well-suited to applications requiring a high degree of precision.