Importance

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Abstract

A latching circuit is coupled to the vehicle's power supply and to a trainable transmitter microprocessor such that upon initial training, the latch is set to maintain a logic level signal to the microprocessor for enabling the microprocessor once initially trained. If, however, the power is removed from the latch circuit and reapplied, as may occur if the trainable transmitter is removed from the vehicle, the latch circuit will provide a different logic level signal to the microprocessor either disabling the transmit function for the microprocessor or erasing the code stored in the nonvolatile memory. The trainable transmitter, thus, will not be useful unless retrained utilizing the homeowner's original transmitter. The invention, the latch circuit includes a pair of MOSFETs with a very low current drain coupled in a flip-flop configuration such that their operational state will reverse once set upon removal and reapplication of power.

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First Claim