HP Smart Pin charger explained (blue tip, 4.5mm)
HP's blue-tipped 4.5mm 'Smart Pin' barrel charger has a centre sense pin. Here's what it is, which HP laptops use it, and why brand matters.
What the blue tip means
HP Smart adapters use a 4.5mm × 3.0mm barrel with a blue tip and a centre 'sense' pin used for wattage negotiation. An HP Smart Pin adapter will not correctly power a Dell, even if the tip looks similar.