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Microcomputer reset device for positively resetting microcomputer before starting operation

  • US 6,370,643 B1
  • Filed: 06/11/1999
  • Issued: 04/09/2002
  • Est. Priority Date: 01/20/1999
  • Status: Expired due to Fees
First Claim
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1. A microcomputer reset device comprising:

  • an initializing circuit for placing a microcomputer in a reset state as long as a first divided voltage proportional to a supply voltage is lower than a reference voltage, and for releasing the reset state of the microcomputer when the first divided voltage exceeds the reference voltage;

    an adjusting circuit for adjusting, in response to an operation frequency of the microcomputer, a second divided voltage which is proportional to the supply voltage; and

    a switching circuit for comparing the second divided voltage adjusted by said adjusting circuit with the reference voltage, and for switching, when the second divided voltage exceeds the reference voltage, a clock source of the CPU from an internal clock signal to an external clock signal.

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