The shutdown function of the OPA300 and OPA2300 is referenced to the negative supply voltage of the operational amplifier. A logic level high enables the op amp. A valid logic high is defined as 2.5V greater than the negative supply applied to the enable pin. A valid logic low is defined as < 0.8V greater than the negative supply pin. If dual or split power supplies are used, establish that logic input signals are properly referred to the negative supply voltage. If this pin is not connected to a valid high or low voltage, the internal circuitry pulls the node high and enables the device to function

The logic input is a high-impedance CMOS input. For battery-operated applications, this feature is used to greatly reduce the average current and extend battery life. The enable time is 10µs, and the disable time is 1µs. When disabled, the output assumes a high-impedance state. This state allows the OPA300 to be operated as a gated amplifier, or to have the output multiplexed onto a common analog output bus.