Edit in JSFiddle

angular.module('demo', [
    'revolunet.stepper'
])

.controller('DemoController', function($scope) {
    $scope.rating = 42;     
    $scope.minRating = 40;
    $scope.maxRating = 50;
})



<body ng-app="demo" ng-controller="DemoController">
    <form name="form" >
        Model value : <input type="text" size="3" ng-model="rating"><br>
        Min value: <input type="text" size="3" ng-model="minRating"><br>
        Max value: <input type="text" size="3" ng-model="maxRating"><br>
        Form has been modified : {{ form.$dirty }}<br>
        Form is valid : {{ form.$valid }}
        <hr>
        <div min="minRating" max="maxRating"  ng-model="rating" rn-stepper></div>
    </form>
</body>