Active Record and CURDATE()

[eluser]al404[/eluser]
i'm using active record for a query but i also would like to set a value of a filed to CURDATE() via SQL, it doesn't work eather with or without quote

how can i do that?

$data = array(
'title' => $title,
'datein' => 'CURDATE()',
other fields...
);

$this->db->update('news', $data);