Abstract: An ambient light sensor produces a current signal that varies linearly with the level of ambient light. The current signal is multiplied by a user dimming preference to generate a brightness control signal that automatically compensates for ambient light variations in visual information display systems. The multiplying function provides noticeable user dimming control at relatively high ambient light levels.

Abstract: A battery charger for an electronic device receives current limited power from an external power source, such as a Universal Serial Bus power interface. The battery charger can linearly regulate a charging current to an internal battery and limit the charging current so as not to demand current in excess of what the external power source can provide. A bi-directional pass element coupled between a system power terminal and the internal battery controls the charging current and effectively isolates the internal battery from a system load during charging of the battery while providing a low impedance path from the internal battery to the system load during discharging of the battery.

Abstract: A battery charger for an electronic device receives current limited power from an external power source, such as a Universal Serial Bus power interface. The battery charger can linearly regulate a charging current to an internal battery and limit the charging current so as not to demand current in excess of what the external power source can provide. A bi-directional pass element coupled between a system power terminal and the internal battery controls the charging current and effectively isolates the internal battery from a system load during charging of the battery while providing a low impedance path from the internal battery to the system load during discharging of the battery.

Abstract: A battery charger for an electronic device receives current limited power from an external power source, such as a Universal Serial Bus power interface. The battery charger can linearly regulate a charging current to an internal battery and limit the charging current so as not to demand current in excess of what the external power source can provide. A bi-directional pass element coupled between a system power terminal and the internal battery controls the charging current and effectively isolates the internal battery from a system load during charging of the battery while providing a low impedance path from the internal battery to the system load during discharging of the battery.

Abstract: A battery charger for an electronic device receives current limited power from an external power source, such as a Universal Serial Bus power interface. The battery charger can linearly regulate a charging current to an internal battery and limit the charging current so as not to demand current in excess of what the external power source can provide. A bi-directional pass element coupled between a system power terminal and the internal battery controls the charging current and effectively isolates the internal battery from a system load during charging of the battery while providing a low impedance path from the internal battery to the system load during discharging of the battery.

Abstract: A backlight intensity for a transflective display increases proportionately with increasing ambient light levels for a first range of ambient light levels and decreases proportionately with increasing ambient levels for a second range of ambient light levels to improve power efficiency. The second range of ambient light levels is higher than the first range of ambient light levels.

Abstract: A battery charger for an electronic device receives current limited power from an external power source, such as a Universal Serial Bus power interface. The battery charger can linearly regulate a charging current to an internal battery and limit the charging current so as not to demand current in excess of what the external power source can provide. A bi-directional pass element coupled between a system power terminal and the internal battery controls the charging current and effectively isolates the internal battery from a system load during charging of the battery while providing a low impedance path from the internal battery to the system load during discharging of the battery.

Abstract: A battery charger for an electronic device receives current limited power from an external power source, such as a Universal Serial Bus power interface. The battery charger can linearly regulate a charging current to an internal battery and limit the charging current so as not to demand current in excess of what the external power source can provide. A bi-directional pass element coupled between a system power terminal and the internal battery controls the charging current and effectively isolates the internal battery from a system load during charging of the battery while providing a low impedance path from the internal battery to the system load during discharging of the battery.

Abstract: A battery charger for an electronic device receives current limited power from an external power source, such as a Universal Serial Bus power interface. The battery charger can linearly regulate a charging current to an internal battery and limit the charging current so as not to demand current in excess of what the external power source can provide. A bi-directional pass element coupled between a system power terminal and the internal battery controls the charging current and effectively isolates the internal battery from a system load during charging of the battery while providing a low impedance path from the internal battery to the system load during discharging of the battery.

Abstract: A battery charger for an electronic device receives current limited power from an external power source, such as a Universal Serial Bus power interface. The battery charger can linearly regulate a charging current to an internal battery and limit the charging current so as not to demand current in excess of what the external power source can provide. A bi-directional pass element coupled between a system power terminal and the internal battery controls the charging current and effectively isolates the internal battery from a system load during charging of the battery while providing a low impedance path from the internal battery to the system load during discharging of the battery.

Abstract: An ambient light sensor produces a current signal that varies linearly with the level of ambient light. The current signal is multiplied by a user dimming preference to generate a brightness control signal that automatically compensates for ambient light variations in visual information display systems. The multiplying function provides noticeable user dimming control at relatively high ambient light levels.

Abstract: An ambient light sensor produces a current signal that varies linearly with the level of ambient light. The current signal is multiplied by a user dimming preference to generate a brightness control signal that automatically compensates for ambient light variations in visual information display systems. The multiplying function provides noticeable user dimming control at relatively high ambient light levels.

Abstract: An illumination control circuit allows a user to set a desired brightness level and maintains the desired brightness level over temperature and life of a light source. The illumination control circuit uses a dual feedback loop with both optical and thermal feedbacks. The optical feedback loop controls power to the light source during normal operations. The thermal feedback loop overrides the optical feedback loop when the temperature of the light source becomes excessive.

Abstract: An illumination control circuit allows a user to set a desired brightness level and maintains the desired brightness level over temperature and life of a light source. The illumination control circuit uses a dual feedback loop with both optical and thermal feedbacks. The optical feedback loop controls power to the light source during normal operations. The thermal feedback loop overrides the optical feedback loop when the temperature of the light source becomes excessive.

Abstract: A dual-mode pulse frequency modulation boost converter operates in a hysteretic mode during light load currents to regulate an output voltage using a substantially fixed peak switching current and operates in a continuous mode during heavy load currents to regulate the output voltage using a variable peak switching current. The boost converter senses load power to automatically switch between the hysteretic mode and the continuous mode.

Abstract: A dual-mode pulse frequency modulation boost converter operates in a hysteretic mode during light load currents to regulate an output voltage using a substantially fixed peak switching current and operates in a continuous mode during heavy load currents to regulate the output voltage using a variable peak switching current. The boost converter senses load power to automatically switch between the hysteretic mode and the continuous mode.

Abstract: The present invention is a method and apparatus of providing EMI filtering through the implementation of a voltage sense circuit that is used in conjunction with a power correction circuit in an electromagnetic (EMI) filter system. The apparatus comprises a filter that receives an alternating current signal, where the filter has an input terminal and an output terminal. The apparatus also comprises a power correction circuit having a voltage reference input terminal and an output terminal. A voltage sense circuit having an input terminal is coupled to the input terminal of the filter. The voltage sense circuit has an output terminal that is coupled to the voltage input terminal.

Abstract: The present invention is a method and apparatus for providing a power supply system having a redundant power supply switchover circuit, which maintains a remotely regulated output voltage when the power supply system switches over from the primary power supply to the secondary power supply. The power supply system comprises a secondary power supply that is connected in parallel to a primary power supply. The two power supplies are OR-connected to a load through two diodes, with the primary power supply connected to the diode via a monitor. During normal operating conditions, the primary power supply delivers most of the current because it operates in a "remote sense" configuration which provides a voltage output that is higher, by a diode voltage drop, than that of the secondary power supply, which operates in a "local sense" configuration.

Abstract: The present invention is a method and apparatus for controlling power supply to aircraft electronic systems based on ambient environmental conditions. The apparatus comprises a monitor for detecting an environmental condition, a power supply for providing power, a circuit which receives power from the power supply, and a switch coupled to the monitor. Upon detection of the environmental condition, the switch connects the power supply to the circuit, otherwise the switch disconnects the circuit from the power supply.

Abstract: A high speed, variable gain video preamplifier circuit disposed on a single IC which can accommodate multiple video input channels supplied by cables of varying length. A multiplexer 34 uses information about the cable length supplied to input pads to selectively connect the outputs of several series connected compensating amplifiers 42(a-b), 44 and 46 to the variable gain amplifier 36. The preamplifier circuit is characterized by a comparative wide common mode input range, as well as being capable of accepting two input channels and providing efficient cable compensation.