Edit in JSFiddle

var app = angular.module('app', []);

function isEmpty(value) {
    return angular.isUndefined(value) || value === '' || value === null || value !== value;
}

app.directive('ngMin', function () {
    return {
        restrict: 'A',
        require: 'ngModel',
        link: function (scope, elem, attr, ctrl) {
            scope.$watch(attr.ngMin, function () {
                ctrl.$setViewValue(ctrl.$viewValue);
            });
            var minValidator = function (value) {
                var min = scope.$eval(attr.ngMin) || 0;
                if (!isEmpty(value) && value < min) {
                    ctrl.$setValidity('ngMin', false);
                    return undefined;
                } else {
                    ctrl.$setValidity('ngMin', true);
                    return value;
                }
            };

            ctrl.$parsers.push(minValidator);
            ctrl.$formatters.push(minValidator);
        }
    };
});

app.directive('ngMax', function () {
    return {
        restrict: 'A',
        require: 'ngModel',
        link: function (scope, elem, attr, ctrl) {
            scope.$watch(attr.ngMax, function () {
                ctrl.$setViewValue(ctrl.$viewValue);
            });
            var maxValidator = function (value) {
                var max = scope.$eval(attr.ngMax) || Infinity;
                if (!isEmpty(value) && value > max) {
                    ctrl.$setValidity('ngMax', false);
                    return undefined;
                } else {
                    ctrl.$setValidity('ngMax', true);
                    return value;
                }
            };

            ctrl.$parsers.push(maxValidator);
            ctrl.$formatters.push(maxValidator);
        }
    };
});

angular.bootstrap(document.body, ['app']);

<form name="myForm">
    Min:
    <input type="date" ng-model="min" />
    <br>
    Max:
    <input type="date" ng-model="max" />
    <br>
    Value:
    <input type="date" ng-model="value" ng-min="min" ng-max="max" name="value" />
    <div class="input-help">
         <h4>The length is outside the current range of acceptable values.</h4>
    </div>
    <br> 
    <tt>value = {{value}}</tt>
    <br>
    <tt>value.$valid = {{myForm.value.$valid}}</tt>
    <br>
    <tt>value.$error = {{myForm.value.$error}}</tt>
</form>

.input-help {
    display: none
}
/* Help should show when invalid */
 .ng-invalid + .input-help {
    display: block;
}