Abstract: There is provided a fit testing method comprising: providing a respirator donned by a wearer; providing a sensor in electrical communication with a sensing element, where the sensor is configured to monitor a particulate concentration parameter of a gas space within the respirator, and a second particulate concentration parameter of a gas space outside the respirator, where the sensor is attached to the respirator such that the respirator such that the weight of the sensor is supported by the respirator; and providing a reader configured to communicate with the sensor, where the reader is configured to provide a respirator fit parameter based on a comparison of the particulate concentration within the respirator to the particulate concentration parameter outside the respirator.

Abstract: In one embodiment, the present invention includes an operational amplifier having a first input to receive a first current formed of an input current and an offset current. A first MOSFET device having a gate terminal may be coupled to an output of the operational amplifier. An output stack including one or more cascoded devices to provide an output current corresponding to a gain of the operational amplifier may be coupled to a first terminal of the first MOSFET device. The operational amplifier may be used in various circuitry, such as a subscriber line interface circuit (SLIC).

Abstract: A powered device includes a first supply terminal, a second supply terminal, and at least one input pin coupled to the first supply terminal. The powered device further includes an external capacitor having a first terminal coupled to the first supply terminal, a switch coupled to the second supply terminal and coupled to a second terminal of the external capacitor, and power surge detection logic coupled to the switch. The external capacitor is charged in response to a detected power surge that exceeds a threshold.

Abstract: In one embodiment, the present invention includes a regulator having a pulse width modulation (PWM) controller to generate a PWM control signal based on a voltage level of a load coupled to the regulator, a driver to provide a drive signal to a switching element of the regulator responsive to the PWM control signal, and a power saver coupled between the PWM controller and the driver to receive the PWM control signal and to output the PWM control signal to the driver at a reduced rate during an idle mode of the load.

Abstract: A powered device includes a power supply input, a diode bridge, and a power loss detector. The power supply input is responsive to an external power source. The diode bridge has an input to receive at least one power supply input. The power loss detector includes an input responsive to the power supply input. The power loss detector is adapted to detect a power loss event and to initiate a power shutdown. In one embodiment, the powered device includes a load circuit to receive a power supply voltage from the diode bridge. The load circuit is responsive to the power loss detector to perform a power shutdown operation.

Abstract: A powered device includes a first supply terminal, a second supply terminal, and at least one input pin coupled to the first supply terminal. The powered device further includes an external capacitor having a first terminal coupled to the first supply terminal, a switch coupled to the second supply terminal and coupled to a second terminal of the external capacitor, and power surge detection logic coupled to the switch. The external capacitor is charged in response to a detected power surge that exceeds a threshold.

Abstract: In one embodiment, the present invention includes an operational amplifier having a first input to receive a first current formed of an input current and an offset current. A first MOSFET device having a gate terminal may be coupled to an output of the operational amplifier. An output stack including one or more cascoded devices to provide an output current corresponding to a gain of the operational amplifier may be coupled to a first terminal of the first MOSFET device. The operational amplifier may be used in various circuitry, such as a subscriber line interface circuit (SLIC).

Abstract: In one embodiment, the present invention includes a regulator having a pulse width modulation (PWM) controller to generate a PWM control signal based on a voltage level of a load coupled to the regulator, a driver to provide a drive signal to a switching element of the regulator responsive to the PWM control signal, and a power saver coupled between the PWM controller and the driver to receive the PWM control signal and to output the PWM control signal to the driver at a reduced rate during an idle mode of the load.

Abstract: A powered device includes a power supply input, a diode bridge, and a power loss detector. The power supply input is responsive to an external power source. The diode bridge has an input to receive at least one power supply input. The power loss detector includes an input responsive to the power supply input. The power loss detector is adapted to detect a power loss event and to initiate a power shutdown. In one embodiment, the powered device includes a load circuit to receive a power supply voltage from the diode bridge. The load circuit is responsive to the power loss detector to perform a power shutdown operation.

Abstract: A sensor capable of being coupled to a transmission line and monitoring a foreign voltage on the transmission line includes a voltage monitoring circuit. The voltage monitoring circuit is adapted to operate in a foreign voltage detection mode in response to receiving a first logic signal and a foreign voltage measurement mode in response to receiving a second logic signal. A method for operating a circuit to detect and measure a foreign voltage on a transmission line includes providing a first logic signal to configure the circuit to detect the foreign voltage. The foreign voltage is detected on the transmission line in the circuit. A second logic signal is provided to configure the circuit to measure the foreign voltage, and the foreign voltage is measured.