Abstract: An electrical load is supplied with power from a driving power source, and a microprocessor (CPU) controls the opening/closing current supply rate (duty factor) of an opening/closing element in accordance with target current and driving power source voltage so that open loop control is carried out to achieve predetermined target current. The voltage between both the ends of a current detecting resistor connected to the ground side of the opening/closing element is input as a monitoring voltage from a current detecting amplifying circuit portion through a multichannel AD converter to CPU. When the error between the comparison target voltage corresponding to the target current and the monitoring voltage is above a first permissible error, CPU judges that there is an abnormality sign, and if the error is above a larger second permissible error, CPU judges that there is appearing abnormality.

Abstract: A power supply control device for on-vehicle electric loads is proposed, the control device being capable of detecting breakages at a plurality of electrical loads, a positive side wiring thereof, a negative side wiring thereof, and a commutation circuit. Energization of electrical loads from driving power supply is controlled using switching elements. Anode terminals of commutation diodes connected in parallel with the electrical loads are connected to a load ground by an external common negative line or external individual negative lines. A breakage abnormality at the external common negative line or external individual negative lines is detected by negative line breakage abnormality detection circuit. Load currents at the electrical loads are detected by current detection resistors and current detecting differential amplifier circuits, and it is determined that there is an individual abnormality when a detected current is greatly different from a target current.

Abstract: A power supply control device for on-vehicle electric loads is proposed, the control device being capable of detecting breakages at a plurality of electrical loads, a positive side wiring thereof, a negative side wiring thereof, and a commutation circuit. Energization of electrical loads from driving power supply is controlled using switching elements. Anode terminals of commutation diodes connected in parallel with the electrical loads are connected to a load ground by an external common negative line or external individual negative lines. A breakage abnormality at the external common negative line or external individual negative lines is detected by negative line breakage abnormality detection circuit. Load currents at the electrical loads are detected by current detection resistors and current detecting differential amplifier circuits, and it is determined that there is an individual abnormality when a detected current is greatly different from a target current.

Abstract: A current control apparatus for an electric load can prevent burnout at a short-circuit accident with high control precision. A switching element is interrupted by an overcurrent detection circuit upon occurrence of a load short circuit, but is transitionally limited in current by a current detection resistor. A differential amplifier amplifies a difference voltage between voltages at opposite ends of the current detection resistor to generate a monitored voltage Ef corresponding to a load current. A microprocessor controls the energization rate of the switching element so as to make an estimated load current Ime calculated from the monitored voltage Ef coincide with a target load current Is, and it calculates, upon calibration operation, calibration constants and estimates, during actual operation, a load current Ime from the monitored voltage Ef using the calibration constants.

Abstract: An electrical load is supplied with power from a driving power source, and a microprocessor (CPU) controls the opening/closing current supply rate (duty factor) of an opening/closing element in accordance with target current and driving power source voltage so that open loop control is carried out to achieve predetermined target current. The voltage between both the ends of a current detecting resistor connected to the ground side of the opening/closing element is input as a monitoring voltage from a current detecting amplifying circuit portion through a multichannel AD converter to CPU. When the error between the comparison target voltage corresponding to the target current and the monitoring voltage is above a first permissible error, CPU judges that there is an abnormality sign, and if the error is above a larger second permissible error, CPU judges that there is appearing abnormality.

Abstract: A current control apparatus for an electric load can prevent burnout at a short-circuit accident with high control precision. A switching element is interrupted by an overcurrent detection circuit upon occurrence of a load short circuit, but is transitionally limited in current by a current detection resistor. A differential amplifier amplifies a difference voltage between voltages at opposite ends of the current detection resistor to generate a monitored voltage Ef corresponding to a load current. A microprocessor controls the energization rate of the switching element so as to make an estimated load current Ime calculated from the monitored voltage Ef coincide with a target load current Is, and it calculates, upon calibration operation, calibration constants and estimates, during actual operation, a load current Ime from the monitored voltage Ef using the calibration constants.