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Semiconductor integrated circuit and communication control apparatus

  • US 5,729,722 A
  • Filed: 01/26/1996
  • Issued: 03/17/1998
  • Est. Priority Date: 01/27/1995
  • Status: Expired due to Term
First Claim
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1. A semiconductor integrated circuit comprising:

  • a CPU having a control program which causes said CPU to;

    process data using reference clock pulses from an externally connected oscillator,automatically cut off said reference clock pulses to said CPU when a specified condition is satisfied during the performance of said processing so that said CPU enters a sleep state, andresume said process by applying said reference clock pulses to said CPU upon receiving a start signal so that said CPU exits said sleep state; and

    a timer circuit, coupled to said CPU comprising;

    an oscillation circuit composed of at least a capacity element, a resistance element and a semiconductor element, said oscillation circuit generating second clock pulses without using an externally connected oscillator; and

    sleep time determining means for counting said second clock pulses from a start count value, and generating said start signal when a count value reaches a specified value;

    wherein said CPU includes sleep time calibrating means for correcting said start count value before said CPU enters said sleep state based on a time error contained in said second clock pulses with respect to said reference clock pulses or reference signals externally inputted at a specified time interval.

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