Abstract: Electronic circuits and methods are provided for use in hot-swappable circuit board applications. Circuitry detects an electrical ground connection and signals operation of a hot-swap controller. Detection of stable operating power causes a hierarchical startup of plural voltage regulators. Sensing stable output power from the last of the voltage regulators triggers the configuration of one or more programmable devices. Circuitry and other resources of a hot-swappable circuit board are protected against electrical transient-related damage by virtue of the present teachings.

Abstract: An electronic fuse system includes plural current paths, each operable to be coupled between a power source and a load, and each including a switching element and a current sensing resistor in series with the path such that the path passes current when the switching element is turned on and does not pass current when the switching element is turned off. A controller has two sense inputs and a control output. The control output is coupled to the switching elements in each of the plural current paths and is operable to turn them all on or off simultaneously responsive at least in part to the sense inputs. A summing resistor is connected across the two sense inputs, and coupling circuitry is operable to couple voltages appearing across the current sensing resistors to the summing resistor.

Abstract: Electronic circuits and methods are provided for use in hot-swappable circuit board applications. Circuitry detects an electrical ground connection and signals operation of a hot-swap controller. Detection of stable operating power causes a hierarchical startup of plural voltage regulators. Sensing stable output power from the last of the voltage regulators triggers the configuration of one or more programmable devices. Circuitry and other resources of a hot-swappable circuit board are protected against electrical transient-related damage by virtue of the present teachings.

Abstract: An electronic fuse system includes plural current paths, each operable to be coupled between a power source and a load, and each including a switching element and a current sensing resistor in series with the path such that the path passes current when the switching element is turned on and does not pass current when the switching element is turned off. A controller has two sense inputs and a control output. The control output is coupled to the switching elements in each of the plural current paths and is operable to turn them all on or off simultaneously responsive at least in part to the sense inputs. A summing resistor is connected across the two sense inputs, and coupling circuitry is operable to couple voltages appearing across the current sensing resistors to the summing resistor.

Abstract: A power supply unit according to a preferred embodiment of the invention is self testing. The power supply unit is enabled to function with no external loads applied, and includes a visual indicator of whether or not one or more voltage outputs of the power supply unit is within tolerance. To benefit from the self-test feature, a user in the field may simply unplug the power supply unit from all loads, plug the unit into an A/C source, and observe the visual indicator. If the visual indicator is lit, then the user may reasonably assume that the power supply unit is functioning correctly. But if the visual indicator is not lit, then the user may reasonably assume that the power supply unit is faulty.