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Tolerant input circuit

  • US 20060220686A1
  • Filed: 09/27/2005
  • Published: 10/05/2006
  • Est. Priority Date: 03/29/2005
  • Status: Active Grant
First Claim
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1. A tolerant input circuit for connection to a power supply and an input pad, the tolerant input circuit comprising:

  • an input circuit;

    a step-down device including a first N-channel MOS transistor connected between the input pad and the input circuit, the first N-channel MOS transistor of the step-down device having a gate supplied with voltage from the power supply, wherein voltage of a high voltage signal provided to the input pad is decreased to a value lower than or equal to that of the voltage of the power supply by the step-down device and provided to the input circuit, the first N-channel MOS transistor including a back gate; and

    a back gate voltage control circuit, connected to the back gate of the first N-channel MOS transistor in the step-down device, for increasing back gate voltage of the first N-channel MOS transistor in the step-down device when the input pad is provided with the high voltage signal.

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