<input class="form-control" name="dob" type="text"
    datepicker-popup ng-model="user.dateOfBirth"
    is-open="opened" max="maxDate"
    placeholder="Your DOB" required>
  <span class="input-group-btn">
    <button type="button" ng-click="opened = !opened">
      <i class="glyphicon-calendar"></i>
    </button>
  </span>