# What is VDD in this context?

On this page, the two versions of this gyro/accelerometer IC have two different Logic Supply Voltages.

What is the VDD voltage?

Why would one version of the chip also have an option to make the voltage 1.8V?

http://invensense.com/mems/gyro/mpu6000.html

note: not intended to be a dupe of What is the difference between $V_{CC}$, $V_{DD}$, $V_{EE}$, $V_{SS}$.

$V_{DD}$ is the supply voltage (i.e. the main voltage "in" to power the IC).
As for why there's the 1.8V VLOGIC version? I suppose it's for those that want to interface with a 1.8V $I^2C$ bus (as opposed to, say, 3.3V SPI or $I^2C$ as you'd likely use with the non-1.8V version).