The Smart Pin (Hewlett-Packard Smart Pin) or center pin on power supply connectors most commonly found on Hewlett Packard Laptops and some slimline desktop computers has two implications. The existence of the pin is said to help protect the device by preventing excessive loading. Others in the technology industry believe it is a means to prevent customers from purchasing non-OEM power supplies or adapters for their laptop or desktop computer. They believe the pin is used to identify that a genuine HP adapter is being.
- The outer ring is negative
- The inside wall of the ring is the positive full operating voltage (typically 18v DC)
- The pin is a reduced positive voltage (typically 5v DC or variable)
Hewlett-Packard Company is not forthcoming with detailed information about the Smart Pin. What you will find here is some details based on testing and user data.
Equipment Testing
HP Pavilion dv7-4276nr Laptop -w- OEM PPP012A-S AC Power Adapter
The AD Power Adapter is PN: 608428-004. This adapter has the center Smart Pin. The adapter is rating +19VDC 1.6A
- The inner ring (2) voltage tests: 19.40 VDC
- The smart pin (3) voltage tests: 18.81 VDC (unloaded)
Unloaded meaning that the volt meter does not provide the completion of a circuit. With the laptop connected, the "load" becomes present, which will reduce voltage across the smart pin. It is presumed that factors such as a charging battery or processor work on the laptop will increase the load, causing further voltage drop on the smart pin.
HP DC7900 USDT Ultra slim Desktop
Modification of Aftermarket Power Adapter
Chinese made aftermarket AC Adapter for HP DC7900 USDT Ultra slim Desktop. This adapter has no standard part number on the unit. The side has a sticker with YALL-2014-10 , S1135 . The main label on the underside reads: Replacement AC Adapter INPUT 100-240V 1.5A 50/60Hz OUTPUT 19V 7.1A
The vender claims the adapter will work with this computer. Connecting to the computer, system does not power on. This does not work out-of-the-box.