Mitsubishi Denki Kabushiki Kaisha

Masahiko Sayama

Shozo Kanzaki

Kohji Hashimoto

Toshiro Hara

Shouzou Kanzaki

A vehicle-mounted electronic control apparatus can perform a variety of abnormality detections while reducing the control load of a microprocessor in the abnormality detection of a volatile backup memory that is backed up by an on-board battery. The apparatus includes a control CPU which is fed with power from a main power supply circuit upon closure of a power switch, a nonvolatile control memory and a backup memory. Even if the power switch is opened, the backup memory, being a partial area of a RAM memory, is fed with power through an auxiliary power supply circuit connected directly to the battery. When the battery is replaced with a new one and connected again, a power supply interruption monitoring memory is reset. At the start of operation of the control CPU, the backup memory is initialized based on reset information, and the power supply interruption monitoring memory is rewritten into a set state.

Vehicle-mounted electronic control apparatus

The car-mounted electronic control device is constructed to include a main control circuit unit to be powered with a car-mounted battery through a switching element and a main power source circuit, and a starting timer circuit unit powered at all times through an auxiliary power source circuit. The timer circuit unit is provided with a sub CPU for acting in synchronism with a high-speed clock signal, and a timing counter for counting the frequency-divided signal of a low-speed clock signal. When a power source switch is opened to interrupt a switching element, the timer circuit unit measures a target awakening time periodically by contrasting the period of the low-speed clock signal to the period of the high-speed clock signal.

Car-mounted electronic control device

An on-vehicle electronic control device improves safety so as to prevent an unnecessary start by means of an arousal timer circuit section. An on-vehicle electronic control device includes a main control circuit section and an arousal timer circuit section. A switching element is held in a closed-circuit operation with an output permitting signal that a watchdog timer circuit generates when a pulse cycle of a watchdog clear signal that a main CPU generates is normal, and thereafter an arousal output is reset in response to a forced OFF command from the main CPU. In the event that an arousal output is not reset, the arousal timer circuit section self-resets an arousal output after a predetermined time period has passed.

On-vehicle electronic control device

A power circuit of a vehicular electronic control unit is provided with a constant voltage power circuit, an awakening timer circuit, and first and second power supply circuits each of which is supplied with power from a vehicle battery. The constant voltage power circuit is supplied with power from the vehicle battery via the first and second power supply circuits. The awakening timer circuit generates an awakening trigger signal upon a lapse of a prescribed time from a stop of power supply to the microprocessor. The first power supply circuit has an output contact as a first opening/closing element and a coil for closing the output contact. The second power supply circuit has a second opening/closing element that is provided between the vehicle battery and the constant voltage power circuit and is closed at least in response to the awakening trigger signal.

Power circuit of a vehicular electronic control unit

Each channel of an input interface circuit for suppressing noise contained in input signals to a CPU (microcomputer) of an automobile includes: a level determining circuit for shaping the waveform; a clock circuit for generating sampling clock pulses; a sequential memory circuit, clocked by the clock pulses, for sampling the output levels of the level determining circuit and storing at least two successive output levels; and a resetting circuit which is set when all the levels stored in the sequential memory circuit are high, and which is reset when all the levels stored in the sequential memory circuit are low. The noise pulses contained in the output of level determining circuit are thus effectively removed.

Input interface circuit for removing noise components of an input signal

The output of a water temperature sensor is converted into a voltage signal by a first set of resistors. The voltage signal is then converted into a digital signal, which is supplied to a microcomputer for various controls. If the first set of resistors is so set that the voltage change provides optimum representation of temperature variations in a low-temperature range, the measuring accuracy in a high-temperature range becomes degraded. To improve the accuracy in the high-temperature range, the signal from the water temperature sensor is converted into a voltage signal through a second set of resistors--which is optimumly adjusted for the high-temperature range--by turning on a transistor. Thus, the sensor signal-voltage conversion means can be switched between the two conversion characteristics according to whether the temperature being measured is in the low- or high-temperature range, thereby providing high measuring accuracy in a wide range of temperatures.

Growing community of inventors

Hyogo, Japan

Masahiko Sayama