A three terminal bi-directional laterally diffused metal oxide semiconductor (LDMOS) transistor which includes two uni-directional LDMOS transistors in series sharing a common drain node, and configured such that source nodes of the uni-directional LDMOS transistors serve as source and drain terminals of the bi-directional LDMOS transistor. The source is shorted to the backgate of each LDMOS transistor. The gate node of each LDMOS transistor is clamped to its respective source node to prevent source-gate breakdown, and the gate terminal of the bi-directional LDMOS transistor is connected to the gate nodes of the constituent uni-directional LDMOS transistors through blocking diodes. The common drain is a deep n-well which isolates the two p-type backgate regions. The gate node clamp can be a pair of back-to-back zener diodes, or a pair of self biased MOS transistors connected source-to-source in series.