How to HTML5 FormData Ajax

How do I use FormData in wordpress ajax ? I am appending files and strings to formdata.

    var formdata = new FormData();
    formdata.append('name', 'This is Name')

    $.ajax({
        url: 'admin-ajax.php',
        type: 'POST',
        data: {'action':'plugin_save', 'data':formdata},
        contentType:false,
        processData:false,
        success: success,
        error: error
    });

   // php
   sends 0 ?

The action should be part of the data object:

var formdata = new FormData();
formdata.append('name', 'This is Name');
formdata.append('action', 'plugin_save');

$.ajax({
    url: 'admin-ajax.php',
    type: 'POST',
    data: formdata,
    contentType:false,
    processData:false,
    success: success,
    error: error
});