A high voltage device for use as an up-side switch of a power stage circuit includes: at least one lateral diffused metal oxide semiconductor (LDMOS) device, a second conductivity type isolation region and at least one Schottky barrier diode (SBD). The LDMOS device includes: a well formed in a semiconductor layer, a body region, a gate, a source and a drain. The second conductivity type isolation region is formed in the semiconductor layer and is electrically connected to the body region. The SBD includes: a Schottky metal layer formed on the semiconductor layer and a Schottky semiconductor layer formed in the semiconductor layer. The Schottky semiconductor layer and the Schottky metal layer form a Schottky contact. In the semiconductor layer, the Schottky semiconductor layer is adjacent to and in contact with the second conductivity type isolation region.