Nippondenso Co., Ltd.

Takahiko Hasegawa

Takayoshi Honda

Shigeru Takeuchi

Taketoshi Sato

An A/D-converter for a knock determination of an engine performs A/D-conversion with respect to a knock signal having a reference voltage and to another sensor signal having a reference voltage that differs therefrom. When the engine rotation is less than 1000 rpm, since the knock signal is too small to perform malfunction determination, integration of '0' point data (reference voltage: 2.5V) of an integrating circuit is performed within a knock determination time period. The resulting data is A/D-converted by the A/D-converter to thereby update the '0' point value stored in a RAM. On the other hand, in a range of greater than 1000 rpm where malfunction determination can be performed of the knock sensors, within the knock determination time period, the knock signal is integrated using the integrating circuit.

Signal processing circuit with offset compensation

In a pump control circuit, if a battery voltage declines to a voltage level lower than that required to insure a constant voltage, a low-voltage detection circuit outputs a low voltage detection signal. In the case of the decline in the battery voltage, an NOR circuit outputs the conversion signal from an internal logic section, and a pump control signal bypassing the internal logic section, giving priority to the latter signal. A motor drive circuit turns FET ON and OFF in accordance with the output signal of the NOR circuit. According to ON/OFF of the FET, the intermittent control of the current from the battery to the pump drive motor is performed.

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Nukata-gun, Japan

Takahiko Hasegawa