Key advantages of CMOS opamps include extremely small input bias current (on the order of pA) and low power consumption. However, the CMOS process features low withstand voltage, making them suitable for low supply voltage applications. Although bipolar opamps provide higher input bias current and current consumption, they offer higher withstand voltage, low noise, low offset, and wide bandwidth.
In general, a single supply opamp operates by supplying VCC (VDD) to the 0V (ground) reference, while a dual supply opamp is used by supplying a positive voltage to VCC as a reference (ground) and negative voltage to VEE. If the input voltage does not exceed the common mode input voltage range either type can be used. Select a single or dual supply type from the dynamic input/output voltage ranges.
Ground sense opamps can operate up to the ground level of the input signal. I/O full swing types operate from both input/output and ground to the supply voltage, and is also referred to as Rail-to-Rail. Output full swing can provide output from ground to the supply voltage.
When reverse voltage is supplied to the supply and ground pins, current flows through the electrostatic protection diodes between the VCC (VDD) and VEE (VSS) pins, which can lead to current degradation and, ultimately, destruction.
The output and current consumption of unused circuits can be stabilized by short-circuiting the output and inverting input pin (voltage follower), and connecting the non-inverting input pin to a voltage within the common mode input voltage range. In the case of a ground sense type opamp the input can be pulled down to VEE.
When the input terminals are shorted the output is amplified by the input offset voltage multiplied by the open loop gain and the maximum output voltage is High or Low, but if the shorted input is floating the output will become unstable. Therefore, it is recommended that a fixed voltage within the common mode input voltage range be supplied.
The recommendation is to set the inputs to within the common mode input voltage range in a voltage follower configuration, but even if all of the I/O are open there should be no problems such as malfunction or destruction when using these products.