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Power source circuit for an occupant protecting device of motor vehicles

  • US 5,506,775 A
  • Filed: 05/20/1993
  • Issued: 04/09/1996
  • Est. Priority Date: 05/20/1993
  • Status: Expired due to Term
First Claim
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1. A power source circuit for an occupant protecting device of motor vehicles comprising:

  • a DC converter means for boosting a battery voltage subsequently delivered to charge an output capacitor, the charge accumulated in said output capacitor being supplied to a drive circuit for an occupant protecting device;

    a diagnostic voltage source for converting the battery voltage into a predetermined voltage to be supplied to a signal processing circuit for determining a condition of said occupant protecting device;

    a switch regulator means for delivering the charge accumulated in said output capacitor to said diagnostic voltage source immediately after the battery voltage is reduced less than a predetermined level, wherein said switch regulator means comprises a control means for monitoring said battery voltage and for determining when said battery voltage is reduced less than said predetermined level, and wherein said switch regulator means remains in a non-operative condition as long as the battery voltage is applied to said control means, but operates to deliver said charge accumulated in said output capacitor to diagnostic voltage source when said battery voltage is reduced less than said predetermined level; and

    a reverse-current preventing diode electrically connected between said switch regulator means and said diagnostic voltage source to prevent current flow in a direction from said diagnostic voltage source toward said switch regulator means.

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