Abstract: A portable information handling system (IHS) includes an external module which derives its power from the internal unregulated DC power rail of the IHS. An IHS power subsystem includes a multiple threshold current protection circuit which continuously monitors power usage by the external module. The multiple threshold current limit protection circuit dynamically adjusts the current limit depending on whether the IHS is powered by an AC source or a DC battery source.

Abstract: A system and method for selecting a voltage output reference required of a DC-DC converter included in a power supply, the voltage output reference corresponding to an operating state of the power supply load. The method stores data for the voltage output reference required for each of a plurality of operating states of the load in a corresponding register. A control input that identifies an operating state of the load is received. An output of the register is selected in response to the control input. The voltage output reference required for the operating state of the load is generated in response to the selected output from the register. An apparatus for selecting a voltage output reference required by a load with a plurality of operating states includes a plurality of registers. Each of the plurality of registers has a register input and a register output, and is configurable to store data corresponding to a voltage required by the load for each of a plurality of operating states.

Abstract: The speed of a fan motor is controlled by varying a DC voltage to the fan motor. A series pass transistor is used to vary the DC voltage to the fan motor. A power management controller sets the fan motor speed by outputting pulses to a pulse-to-DC voltage converter that changes the pulses to a proportional DC control voltage for controlling the series pass transistor. A tachometer output amplifier circuit is used to remove DC components and amplify to useful logic levels a low level tachometer output signal from the fan motor. The amplified tachometer signal is used by the power management controller in controlling the rotational speed of the fan motor.

Abstract: An information handling system is provided which includes a wired network controller fixedly mounted in the system and an optional wireless network card which is pluggably receivable by a connector in the system. The system includes a first indicator for annunciating network activity and a second indicator for annunciating that the link is good as well as its link rate. Status processing logic is situated between the wireless card connector, the network controller and the first and second indicators to permit the wireless card and the network controller to share the first and second indicators.