Abstract: Methods, systems, and circuits are provided that allow temporary power management of a telematics control unit (TCU). Employing the aspects disclosed herein, a TCU may handle temporary losses of power from a main battery of a vehicle, without overly drawing power from a backup battery (BUB) system. The aspects disclosed herein may be implemented through the addition of circuit elements as well as logic changes to existing TCU systems.

Abstract: To protect the class II integrated circuit bus from negative transients, the present invention uses a clamp circuit which is biased from the battery and referenced to ground as opposed to being biased and referenced to ground. Thus, the current path is not from ground to the bus pin. Instead, it is from the battery through a blocking diode, a transistor, a resistor and a plurality of diodes to the bus pin yet referenced to ground. In a preferred embodiment, the present invention consists of a transient protection circuit including a reference diode with its cathode connected to ground, a transistor biased as a current source having its output terminal operably connected to an anode of the reference diode, and at least a second diode operably connected between the anode of the reference diode and a bus pin, whereby the transistor supplies current when a module ground is intact.

Abstract: To protect the class II integrated circuit bus from negative transients, the present invention uses a clamp circuit which is biased from the battery and referenced to ground as opposed to being biased and referenced to ground. Thus, the current path is not from ground to the bus pin. Instead, it is from the battery through a blocking diode, a transistor, a resistor and a plurality of diodes to the bus pin yet referenced to ground. In a preferred embodiment, the present invention consists of a transient protection circuit including a reference diode with its cathode connected to ground, a transistor biased as a current source having its output terminal operably connected to an anode of the reference diode, and at least a second diode operably connected between the anode of the reference diode and a bus pin, whereby the transistor supplies current when a module ground is intact.

Abstract: A DC power supply 44 for providing a desired filament voltage to a static filament in a vacuum fluorescent display 16 includes a voltage regulator 46 with an input and an output. The input couples to a source of ignition voltage 10 while the output couples to the base of a transistor 50. A first dropping resistor 52 connects between the source of ignition voltage 10 and the collector of the transistor 50. A second dropping resistor 54 connects between the emitter of the transistor 50 and the filament 20 of the VF display 16. Accordingly, a first current path to the filament 20 is defined through the first dropping resistor 52, the collector-emitter junction of the transistor 50, and the second dropping resistor 54. A second current path to the filament 20 is defined through the voltage regulator 46, the base-emitter junction of the transistor 50, and the second dropping resistor 54.

Abstract: In two embodiments of the present invention, the speed of a DC motor is determined by examining the signal at the negative terminal of the motor. The signal is high-pass-filtered to extract the AC component of the signal. The frequency of this signal is, in almost all cases, proportional to the speed of the motor. This signal is then fed into a comparator, which converts the signal into a square wave, which is then input into a microprocessor. The microprocessor determines the frequency of the square wave. If the frequency of the square wave is below a threshold of acceptable motor speed, the microprocessor can turn off the motor and provide a malfunction indication. If the frequency of the square wave is above a second threshold of acceptable motor speed, the microprocessor can likewise turn off the motor and provide a malfunction indication.

Abstract: An automatic headlamp dimmer system for switching a vehicle's headlamps from high beam to low beam when lights from another vehicle are detected in front of the vehicle. To prevent spurious responses to reflected light from signs and other sources, the dimmer system includes a light detector which is responsive only to infrared light. Also, unwanted responses to flashing lights are avoided by detecting the presence of a periodically varying light signal, and inhibiting switching between high and low beams in response thereto. The system is also capable of sensing the activation of windshield wipers and preventing headlamp switching caused by interruption of light to the system's light sensor by action of the wiper blades.

Abstract: A low voltage inhibiting circuit for use with a microcomputer in which a reset signal is applied during power-up or whenever the voltage of an unregulated source to a regulated supply drops below a predetermined threshold level. The reset signal is removed whenever the voltage from the unregulated source is restored to a value which is above a second predetermined threshold value defined as being above the first threshold value and after a predetermined period of time.

Abstract: An automatic headlamp dimmer system for switching a vehicle's headlamps from high beam to low beam when lights from another vehicle are detected in front of the vehicle. To prevent spurious responses to reflected light from signs and other sources, the dimmer system includes a light detector which is responsive only to infrared light. Also, unwanted responses to flashing lights are avoided by detecting the presence of a periodically varying light signal, and inhibiting switching between high and low beams in response thereto. The system is also capable of sensing the activation of windshield wipers and preventing headlamp switching caused by interruption of light to the system's light sensor by action of the wiper blades.

Abstract: A vehicle light sensor for controlling light responsive systems such as an automatic headlamp dimmer. The sensor includes an enclosure containing a lens and a photo responsive detector. An optical chamber within the enclosure permits unwanted light from reaching the detector. A series of baffles within the chamber prevent light from outside a desired entrance angle from reaching the detector. A thin-film aperture is attached to the detector for controlling the size and shape of the detector's field of view. Gray scale shading may also be incorporated into the aperture to reduce the intensity of incoming light in selected portions of the field of view. An adjustment mechanism provides very fine angular view adjustments, beyond what is practical by simple assembly of molded parts.

Abstract: A vehicle lamp control sensor for switching a lamp on or off depending on ambient levels. The device employs a silicon photodetector in combination with a filter chosen to give the detector a response curve that peaks at about 550 nanometers. This gives the control sensor the same proximate spectral response as the human eye. The photo detector transmits an electrical signal in response to the ambient light. The electrical signal is sensed by a lamp switching circuit to switch the vehicle lamp at predetermined light levels. The vehicle lamp control sensor will thus respond to changes in the ambient light levels in a manner which matches the perceived light levels of a human observer.