What is the consequence of having input voltage present at the Vout pin when the device is not powered?
The device can malfunction or incur permanent damage if there is voltage present at the VOUT pin that exceeds the Absolute Maximum Specification when the device is unpowered. The output of the device is intended to drive an input, so having this intended input pin present an output voltage to the device's output pin causes problems. This can result in errors as well as exceed the output current capabilities of the device and cause damage to the device itself.