The three elements that must be considered when purchasing.
Interface: interface is required, or can be connected to the corresponding conversion interface, but this is a bit superfluous.
Output voltage: The best output voltage is the same, if we can not find exactly the same, and the original charger output voltage difference within 5%, basically no problem, but if the two output voltage difference is too large, the device can not charge, no boot work, or even burned.
Current: Many people think that the current should be completely consistent, otherwise too large current into our digital devices, will cause damage to digital equipment. In fact, this kind of understanding is wrong, we can explain this problem according to the physics knowledge that we study.
According to Ohm's law, in the same circuit, the electric current in the conductor is proportional to the voltage at both ends of the conductor, which is proportional to the resistance of the conductor, i.e. i=u/r. When the voltage is constant, the current size of the line depends on the resistance of the load, which means that the digital device itself determines the current of the line, rather than the maximum output current of the charger itself.
However, it should be noted that although the same voltage with a large current charger to replace the small current charger no problem, but with a small current charger to replace the large current charger is not the current is too small, the response of the digital device may be unable to boot or display power shortage, frequent restart.