Structure to protect against below ground current injection

A protective structure for an integrated circuit having a power transistor integrated on a single chip with control devices, comprising:

• a first epitaxial region, within the substrate, between the power transistor and the control devices;
• a first contact, between the first epitaxial region and the substrate, placed between the first epitaxial region and the power transistor;
• a second contact to the substrate, connected to ground, placed adjacent the power transistor on a side opposite the first contact;
• and
• means for causing current injected into the substrate to flow primarily on the side of the power transistor opposite the first contact.

A protective structure for an integrated circuit having a power transistor integrated on a single chip with control devices, comprising:

• a first contact to the substrate, placed between the control devices and the power transistor;
• a second contact to the substrate, connected to ground, placed adjacent the power transistor on a side opposite the control devices;
• and
• an epitaxial region in the substrate, forming a ring around the power transistor outside the first and second contacts, wherein the epitaxial region is electrically connected to the first contact.