SEMICONDUCTOR DEVICE PREVENTING LATCH-UP

摘要

A semiconductor device preventing latch-up is provided to prevent switching of a parasitic bipolar transistor by a voltage supplied from the outside by forming a guard ring between MOS transistors. In a semiconductor device preventing latch-up, a first(22) and a second MOS transistor(24) are formed on a semiconductor substrate(20). A guard-ring prevents the parasitic bipolar transistor from being turned on(Q) by an external voltage. A first voltage is supplied to a first MOS transistor and a second voltage lower than the first voltage is supplied to the second MOS transistor and the guard ring. The second voltage is the power voltage or the ground voltage. The switching is enabled by the second voltage and it controls a voltage applied to the guard ring.