HTMl :
ng-model, ng-change min-date
<input type="text" uib-datepicker-popup="dd/MM/yyyy" ng-model="personForm.StartDate" name="startDate" ng-change="myStartDateChange()" />
<input type="text" uib-datepicker-popup="dd/MM/yyyy" min-date="endmindate" ng-model="personForm.EndDate" name="endDate" />
:
$scope.myStartDateChange = function () {
$scope.endmindate= $scope.personForm.StartDate;
}