| 摘要 |
A circuit for protecting direct current (DC) powered devices from excessive supply voltage and reverse polarity supply voltage comprises supply voltage coupling circuitry that operably couples a DC powered device to a supply voltage. The circuit also includes a first field effect transistor (FET) having an intrinsic diode operably coupled to the supply voltage coupling circuitry. Further, the circuit includes first current blocking circuitry operably coupled to the first FET for blocking current flow through the intrinsic diode. Still further, the circuit comprises gate supply circuitry operably coupled to the first FET and the supply voltage coupling circuitry to supply gate voltage to the first FET when the supply voltage is less than a predetermined value. Finally, the circuit includes second blocking circuitry operably coupled to the gate supply circuitry to block current flow to the gate supply circuitry when the supply current is reversely coupled to the DC powered device such that the gate supply circuitry does not supply gate voltage to the first FET.
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