SQLSTATE[08006] [7] invalid connection option "charset"

EDIT : Found the solution :

$db['default'] = array(
'dsn' => 'mysql:host=localhost; dbname=xxx',
'hostname' => '',
'username' => 'root',
'password' => 'root',
'database' => '',
'dbdriver' => 'pdo',
'dbprefix' => '',
'pconnect' => FALSE,
'db_debug' => (ENVIRONMENT !== 'production'),
'cache_on' => FALSE,
'cachedir' => '',
'char_set' => 'utf8',
'dbcollat' => 'utf8_general_ci',
'swap_pre' => '',
'encrypt' => FALSE,
'compress' => FALSE,
'stricton' => FALSE,
'failover' => array(),
'save_queries' => TRUE
);[/php]