Customize the datetime format in Cakephp

When I use the form helper to make a time input,usaually I write code as follows

$options = array(
    'label' => '',
    'type' => 'datetime',
echo $form->input('Service.endtime',$options);

But now I get a problem that I want to make a time input style such as


Then how can do this with setting some parameters in the helper?Suggestions would be appreciated.