PHP - Unix timestamp to DateTime string, maintaining milliseconds precision

Question

I have a timestamp

1457459333506 (Tue, 08 Mar 2016 17:48:53 GMT)

This should be Unix timestamp with milliseconds. I want to write this as a string, so I'm using

$dt = new DateTime("@$unixTimestamp");
echo date('Y-m-d H:i:s.u', $unixTimestamp) . "<br>";

But the output is 2016-06-08 22:09:22.000000

This is obviously wrong, and has no milisecond precision. So I've tried

echo date('Y-m-d H:i:s.u', $unixTimestamp / 1000) . "<br>";

Which outputs as 2016-03-08 17:48:53.000000 (correct, but also has no milisecond precision).

How can I get this to output correctly as: 2016-03-08 17:48:53.506 ?

Answer 1

As simple as

$unixTimestamp = 1457459333506;
$dt = DateTime::createFromFormat("U.u", $unixTimestamp / 1000);
var_dump($dt);

with a DateTime object

Demo