Integrated current fault controller
A fault monitoring and management system integrates a fault controller with the power load functions within the power management device of a battery operated system. Multiple input load lines allow the fault controller to diagnose and disable defective or faulty power load functions that draw current from the system supply or battery. In addition, the fault monitor allows the system to stay operational if the fault is non-catastrophic to the critical functions.
1. A fault monitoring and management system comprising:
a portable battery-operated device having a plurality of functional subassemblies that are selectively activated in different operational states of the device that are selected according to user control;
a power management device having a plurality of power load functions, each of the plurality of power load functions having at least two states;
a fault controller integrated on the power management device;
a plurality of input load lines each having a first connection to one of the plurality of power load functions and a second connection to the fault controller for transmitting an input load signal from each of the plurality of power load functions to the fault controller; and,
wherein the fault controller is programmed to assess load conditions from changes in the input load signal from said power load functions during one of the operational states, and the fault controller is programmed for switching at least a subset of the power load functions from a first load state to a second load state within said states of the power load functions, thereby switching to another of the operational states upon occurrence of a fault, and wherein switching to said another of the operational states is predetermined according to programming of the fault controller to preserve at least one of the power load functions while protecting the device from the fault.
2. The fault monitoring and management system of claim 1 , wherein the fault controller is configured to at least reduce power supplied to a power load function associated with the fault, and while activating and deactivating others of the power load functions according to priority of the power load functions in view of the fault.
3. The fault monitoring and management system of claim 2 , comprising a fault status detector with an on-chip temperature monitor, and wherein the fault status controller reacts to a fault status signal that varies due to temperature.
4. The fault monitoring and management system of claim 3 , wherein the fault status detector comprises a thermal shutdown circuit.
5. The fault monitoring and management system of claim 1 , wherein said at least two states comprise an on-state and an off-state.
6. The fault monitoring and management system of claim 5 , wherein said at least two states further comprise a partially powered state.
7. The fault monitoring and management system of claim 1 , wherein the load functions are chosen from the group consisting of cellular telephone communication functions, network data communications, data storage and retrieval functions, display, clock and alarm functions, vibration and ringer, camera photo record, camera flash, picture display, audio record and audio output.
8. The fault monitoring and managing system of claim 1 , wherein the power loads comprise at least one of a supply regulator, a battery charger, an accessory switch control, a switched mode power supply and a display.
9. A method of monitoring and managing device faults comprising the steps of:
providing a power management device for a portable battery-powered device and preprogramming the cower management device to define responses to fault conditions associated with one or more of a plurality of power load functions, by which the power management device at least partly disables programmably selected ones of the power load functions;
operating the portable battery-powered device according to user inputs wherein a plurality of power load functions are activated in combinations to achieve operation in states selected by the user inputs;
monitoring a plurality of the power load functions via the power management device, wherein each of the plurality of power load functions is electrically coupled to an over-current fault controller;
receiving an over-current indication from at least one of the plurality of power load functions for alerting the fault controller that a fault has occurred;
evaluating a state of operations in view of the fault according to said preprogramming of the power management device, and determining a course of action wherein selected ones of the power load functions can be enabled and disabled so as to protect the device from the fault while preserving at least one of the power load functions; and
managing the system according to the course of action determined.
10. The method of monitoring and managing device faults of claim 9 , further comprising the step of monitoring an on-chip temperature monitor.
11. The method of monitoring and managing device faults of claim 9 , further comprising the steps of:
monitoring a thermal shutdown circuit; and
receiving a thermal shutdown signal from the thermal shutdown circuit.
12. The method of monitoring and managing device fault of claim 10 , wherein the step of evaluating the system to determine a course of action includes gauging the severity of the fault with the assistance of the on-chip temperature monitor.
13. The method of monitoring and managing device faults of claim 9 , wherein a course of action is selected from the group consisting of: shutting down an offending function, shutting down a source regulator, generating an interrupt, and setting an appropriate status indication in the status register.