Check your notebook model's product support documentation to confirm support. Note: If there is not a setting for the backlight timing in the BIOS, this behavior might not be supported on the notebook. If the blacklight stays on for only a few seconds, the backlight timeout setting might need configuring in the BIOS.
However, I did find this in the HP knowledge base: I've looked at the user guide for your laptop and it only tells you how to turn on and off the backlight but makes no mention of a timeout.
