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A varistor is an electronic component with a significant non-ohmic current-voltage characteristic. The name is a portmanteau of variable resistor

SMD resistors are manufactured by a number of different companies. Accordingly the specifications vary from one manufacturer to the next. It is therefore necessary to look at the manufacturers rating for a specific SMD resistor before deciding upon exactly what is required. However it is possible to make some generalisations about the ratings that might be anticipated.

Power rating: The power rating needs careful consideration in any design. For designs using SMD’s the levels of power that can be dissipated are smaller than those for circuits using wire ended components. As a guide typical power ratings for some of the more popular SMD resistor sizes are given below. These can only be taken as a guide because they may vary.

• 1206: 1/8 watt
• 0805: 1/10 watt
• 0603: 1/16 watt

Some manufacturers will quote higher power levels than these. The figures given are conservative.

Tolerance: In view of the fact that SMD resistors are manufactured using metal oxide film they available in relative close tolerance values. Normally 5%, 2%, and 1% are widely available. For specialist applications 0.5% and 0.1% values may be obtained.

Temperature coefficient: Again the use of metal oxide film enables these SMD resistors to provide a good temperature coefficient. Values of 25, 50 and 100 ppm / C are available.

Suntan has supply SMD Varistor which called TSVC, TSVC is widely used in Notebook, PDA, Cellular Phone, MP3,Main board, LCM, HUB, Microphone, Wireless LAN, VOIP, Auto electronic and so on. At Suntan website: www.suntan.com.hk ,they have introduced the details about SMD Varistor TSVC by PDF: http://www.suntan.com.hk/pdf/Varistor/TSVC.pdf