how do I replace MS Access with SQLite in PHP

I am porting a site running PHP with an MS Access DB on a windows machine to a Mac with an SQLite DB.

the original PHP script uses the following code to connect to the database:

$db = 'S:\~myhome\mydata.mdb';
$conn = new COM('ADODB.Connection');
$conn->Open("DRIVER={Microsoft Access Driver (*.mdb)}; DBQ=$db");

What would be the SQLite equivalent?