| 摘要 |
<p>A high voltage circuit includes a switching device (12) for supplying one of a high voltage (Vpp) and a low voltage (Vcc) to a controlled path including a control p-channel transistor (16) and a protection p-channel transistor (18) in series. A high voltage detector (32) is utilized to determine whether Vpp or Vcc is applied to the controlled path. The high voltage detector establishes a protecting condition for the protection p-channel transistor during Vpp operation and a non-protecting codition during Vcc operation. When the control transistor is off and the protection transistor is in a protecting condition, the voltage drop along the controlled path will cause the protection transistor to turn off, limiting the voltage across the control transistor. A second controlled path, in series with the first, includes one n-channel transistor (46) fixed at Vcc to guard against gate-aided junction breakdown in another n-channel transistor (48).</p> |
