They most probably have a specific charger just for their laptop like the Mac.
It most probably doesn't have anything to do with wattage or voltage but with patented design or technology.
That way you have to purchase your cords exclusively from them and then when somebody tries to replicate it they will then be charged with patent infringement.
This is a feature I do not like with my Mac because when I lost my cord I ended up having to pay almost $100 for a new one.

You can use a universal and aftermarket chargers for a Sony. Just check to see if the volts and amps are the same. You can get them cheap on ebay.

The voltage (volts, V) and amperage (amps, A) is important, but the other thing is polarity.  Some plugs that fit the socket on the device (like a laptop or a cell phone or a radio, etc.) have a negative (-) center contact and some have a positive (+) center contact.  If you get the wrong polarity of charger and plug it into your device, it could ruin the device in one second.  You can make small errors in A or V and it won't make a lot of difference but there is only one error to make in polarity and it is very serious.  Don't let that happen!!!

The following image shows a charger with a positive (+) center contact.  See the three little figures, looking like O-C-O at the middle of the label.  The "O" on the right (held upside down, with "WARNING:" then above it) has a + in the middle of it, and the line into the "C" touches the center dot in the "C", indicating the positive polarity of the center contact of the male plug that is at the end of the charging cord:



In the worst case, you can check polarity using a multimeter and probes. Whatever you do, DO NOT TAKE A CHANCE and guess when you don't know, because it's either correct or it's incorrect, and you only get one chance.  If you've been sticking different plugs into your laptop and can't find one that charges it, that might be because you have stuck the opposite polarity plug in and you have fried your motherboard, which can cost you $300-$600 to repair, maybe more.  

This charger's input specification (power source) is rated 100-240 V (volts alternating current), 1.8A (amps), 50/60Hz (from 50 to 60 Hertz, or cycles per second). That should work in just about any house wall outlet in North or Latin America or Europe or Australia/New Zealand.  I suspect Singapore and Japan as well.  I don't know about other parts of the world.  Europe has 50 Hz, 230V, while USA has 60 Hz, 115V.  

The output (what this charger delivers) is 19.5V (volts), 3.34A (amps).  That's what the computer will be receiving.  


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