How to buy HP/Compaq power adapter:
check your current AC adapter to find out the required specification of your
laptop, and then follow the step below.
1) The required output power (W)--which shown in the back of your original power adapter and notebook computer-- is the minimum power that will turn on your notebook computer. So in choosing a replacement adapter, the provided power (W) has to be equal or greater than the required power. Power (W) =Voltage (V) x Current (A), Example: 90 W =18 V x 5A
2) When comparing the required output voltage (V) for the replacement power adapter, exact number is required. Example: Original adapter=18V, you will need exact 18V adapter, the wrong voltage will cause a malfunction of the device.
3) The current (A) indicated on the replacement adapter is the maximum current (A) that the adapter able to output, not necessarily the operating current (A).
the operating current (A) is controlled by the device requirement, not the
4) Additionally the jack dimensions must match with this model's specification to ensure that this power adapter will work for you.