Как у Django в models для поля varchar задать признак binary?

sSectionName_ru = models.CharField(
        max_length=250,
        blank=True,
        unique=False,
        db_index=True,
        verbose_name=u"Название",
        help_text=u"Название раздела (ru)"
    )

class BaseCharField(models.Field):
    def __init__(self, *args, **kwargs):
        super(BaseCharField, self).__init__(*args, **kwargs)
    def db_type(self, connection):
        return 'varchar(%s) binary'

class BaseCharField(models.CharField):
    def __init__(self, *args, **kwargs):
        super(BaseCharField, self).__init__(*args, **kwargs)
    def db_type(self, connection):
        return super(self).db_type(connection) + ' binary'