In described examples, a high-voltage transistor (HVT) structure (140) adapts a low-voltage transistor (LVT) (110) to high-voltage environments. The HVT structure (140) includes a drain node (152), a source node (154), a control gate (156) and a field electrode (162, 164). The drain node (152) and the source node (154) define a conductive channel (163, 165), in which mobilized charges are regulated by the control gate (156). While being isolated from the control gate (156), the field electrode (162, 164) is configured to spread the mobilized charges in response to a field voltage. The field electrode (162, 164) is structured and routed to prevent charge sharing with any one of the drain node (152), source node (154) or control gate (156). Advantageously, the isolated field electrode (162, 164) minimizes the capacitance of the control gate (156) and the drain and source nodes (152, 154), such that the HVT (140) can switch with less power loss and a more robust performance in a high-voltage environment.