I have a canon eos 700D camera and use photoshop CS5. I need to update the camera raw plug in, but I cannot find one on the adobe website site.
New cameras are only supported by new versions of Camera Raw, which in turn means you need a new version of Photoshop.
However, you can download the latest DNG converter and convert your raw files to the digital negative format, and they can be opened with what you have now.
Your camera was first supported by Camera Raw 7.4 which only runs in CS6 or CC, and by Lightroom 4.4.
The other two posters have given you all other necessary details for solutions,