| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor device which is suitable for formation of a circuit for applications using a plurality of supply voltages, and is programmable according to I/O cell allocation and therefore is flexible and can provide protection against ESD/EOS. SOLUTION: The semiconductor device comprises either N type or P type first guard ring and a second guard ring which is formed adjacently to the first guard ring and is N type when the first guard ring is P type or vice versa. The first ring guard is formed as a collection of many insular well regions so divided that each well region may correspond to each I/O cell or to a plurality of I/O cells. At least one of the well regions is connected to a first power line and at least one of the remaining well regions is connected to a second power line.
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