This message was posted on behalf of Intel Corporation
Thanks for posting the RealSense community.
The use of a computer connected to the D435 and any other RealSense camera is a must.
The cameras no only use the computer as a storage for the captured images, the computer is also used as the only power source for the camera. Additionally you need the SDK 2.0 to be running in order for the camera to capture images.
In the following link you will find the camera datasheet with detailed technical information.