Circuitry protection arrangement

A circuit and a method are provided for protecting sensitive circuitry from over voltage and over current during a double fault situation. The circuit may be used in a portable electronic device, and may include an over voltage protection component and an over current protection component. The over voltage protection component may be coupled across power supply inputs of a load of the portable electronic device. The over current protection component is configured in the circuit to provide over current protection to the load of the portable electronic device at least when the over current protection component provides over current protection to the over voltage protection component.

TECHNICAL FIELD

The present invention relates to protection of key circuitry components of an electronic device from over voltage, and more particularly to protection of key circuitry components during two simultaneous faults.

BACKGROUND OF THE INVENTION

In circuitry that includes sensitive components, for example charging circuitry of an electronic device, protection from over voltage may be provided through the use of a transient voltage suppressor. The transient voltage suppressor generally reduces the amount of voltage provided to sensitive circuitry components by diverting an amount of voltage to ground or away from the sensitive circuitry components. However, in a situation where the transient voltage suppressor has become disabled or disconnected from the circuitry, no protection from over voltage is provided to the sensitive components. This may result in damage to the sensitive components due to the increased amount of current flowing through the sensitive components as a result of the increased voltage. In addition, the increased voltage may also result in other unsafe conditions.

Institute of Electrical and Electronics Engineers (IEEE) 1725 standard provides that charging circuitry, in particular charging circuitry related to mobile telephones, must be safe when there are two simultaneous faults. IEEE 1725 establishes criteria for design analysis for qualification, quality, and reliability of rechargeable lithium ion and lithium polymer batteries for cell phone applications. The purpose of IEEE 1725 is to ensure reliable user experience and operation of cell phone batteries.

For example, the voltage of a charging power source provided to the charging circuitry may suddenly increase due to a spike in voltage of an electrical distribution system. In this instance, the voltage provided to the charging circuitry is too high, and the transient voltage suppressor is needed to direct the over voltage away from the charging circuitry. In certain circumstances the transient voltage suppressor may not be able to direct over voltage away from the charging circuitry. For example, the transient voltage suppressor may heat up due to the increased current passing through it, and become disconnected from the charging circuitry. In this case, the transient voltage suppressor will no longer provide protection to the charging circuitry, possibly leading to damage to the charging circuitry or another unsafe condition. Furthermore, the transient voltage suppressor may have been improperly connected to the charging circuitry during manufacture, or not connected at all.

Therefore, if an over voltage condition exists and the transient voltage suppressor is disabled or disconnected due to the over voltage condition or some other fault condition, the charging circuitry may be damaged. In addition, it is difficult to ensure that over voltage protection components, such as transient voltage suppressors, are operating correctly and properly attached to the charging circuitry. If the over voltage protection component is not operating correctly or attached to the charging circuitry effectively during manufacturing, the over voltage protection component will not even provide protection for a first over voltage fault. Accordingly, what is needed is a mechanism to ensure that circuitry is safe during two simultaneous faults, and to ensure that over voltage protection components are functioning properly after manufacture.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention a portable device that includes a circuit is provided. The portable device may be a mobile communication device, for example a cellular telephone. The circuit included in the portable device includes a first component, which may be an overvoltage protection component, configured to be coupled across power supply inputs of a load. The power supply inputs may be configured for receipt of power from an external power source, and the first component may be configured to provide over voltage protection for the load. The circuit may also include a second component coupled to the first component and configured to be coupled to the load. The second component may be configured to provide over current protection for the load and for the first component. The second component is configured to provide over current protection to the load at least when the second component provides over current protection to the first component.

In accordance with the first aspect of the invention, the first component may include a transient voltage suppressor.

In accordance with the first aspect of the invention, the first component may include a zener diode.

In accordance with the first aspect of the invention, the power supply inputs may include a first power supply input and a second power supply input that may each be configured to couple the load to the external power source. The second component includes at least one connecting member configured to be positioned in an electrical path between one power supply input of the load and the external power source, and the first connecting member is responsive to an over current event so as to break the electrical path.

In accordance with the first aspect of the invention, the at least one connecting member includes at least one solder ball.

In accordance with the first aspect of the invention, the at least one connecting member is configured to be positioned in a current path between the external power source and the first component during the over current event.

In accordance with the first aspect of the invention, the at least one connecting member is configured to be positioned in a current path between the external power source and the load during the over current event.

In accordance with the first aspect of the invention, second component includes a first connecting member configured to connect the first component to a first power supply input of the power supply inputs and a first current resisting component. The first connecting member is configured to disconnect the first component from the first power supply input during an over current event, and the second component is configured to alter a signal communicated to a control input of the load when the first component is disconnected from the first power supply input.

In accordance with the first aspect of the invention, the signal is an enable signal with a first state configured to enable the load and a second state configured to disable the load, and the second component is configured to alter the state of the enable signal.

In accordance with the first aspect of the invention, the signal is a not-enable signal with a first state configured to disable the load and a second state configured to enable the load, and the second component is configured to alter the state of the not-enable signal.

In accordance with the first aspect of the invention, the second component further includes a second connecting member configured to connect the first component to a second power supply input of the power supply inputs and a second current resisting component. The second connecting member is configured to disconnect the first component from the second power supply input during the over current event if the first connecting member remains connected to the first component during the over current event. The second component is configured to alter a second signal transmitted to a second control input of the load when the first component is disconnected from the second power supply input.

In accordance with the first aspect of the invention, the second signal is an enable signal with a first state configured to enable the load and a second state configured to disable the load, and the second component is configured to alter the state of the enable signal.

In accordance with the first aspect of the invention, the second signal is a not-enable signal with a first state configured to disable the load and a second state configured to enable the load, and the second component is configured to alter the state of the not-enable signal.

In accordance with the first aspect of the invention, the power supply inputs comprise a first power supply input and a second power supply input each configured to couple the load to the external power source. The first power supply input includes a first section and a second section, and the second component includes at least one connecting member configured to connect the first component to the second section and the first section. The first component is coupled to the second power supply input by at least one more connecting member than the first component is connected to the second section and the first section.

In accordance with the first aspect of the invention, the load includes a charger circuit.

In accordance with the first aspect of the invention, the load includes a battery.

In accordance with the first aspect of the invention, the portable device includes a mobile communication device.

In accordance with a second aspect of the invention, a method is provided that includes providing a first component configured to be coupled across power supply inputs of a load of a portable device. The power supply inputs configured for receipt of power from an external power source, and the first component configured to provide over voltage protection for the load. The method further includes coupling a second component to the first component. The second component is configured to be coupled to the load, and configured to provide over current protection for the load and for the first component. The second component is configured to provide over current protection to the load at least when the second component provides over current protection to the first component.

In accordance with the second aspect of the invention, the first component includes a transient voltage suppressor.

In accordance with the second aspect of the invention, the method further includes providing a first power supply input and a second power supply input of the power supply inputs, each configured to couple the load to the external power source. The method further includes providing at least one connecting member of the second component configured to be positioned in an electrical path between one power supply input of the load and the external power source. The first connecting member is responsive to an over current event so as to break the electrical path.

In accordance with the second aspect of the invention, the at least one connecting member includes at least one solder ball.

In accordance with the second aspect of the invention, the method further includes providing a first connecting member of the second component configured to connect the first component to a first power supply input of the power supply inputs and a first current resisting component. The first connecting member is configured to disconnect the first component from the first power supply input during an over current event. The method further includes altering a signal communicated to a control input of the load when the first component is disconnected from the first power supply input.

In accordance with the second aspect of the invention, the signal is an enable signal with a first state configured to enable the load and a second state configured to disable the load, and the second component is configured to alter the state of the enable signal.

In accordance with the second aspect of the invention, the signal is a not-enable signal with a first state configured to disable the load and a second state configured to enable the load, and the second component is configured to alter the state of the not-enable signal.

In accordance with the second aspect of the invention, the method further includes providing a first power supply input and a second power supply input of the power supply inputs, each configured to couple the load to the external power source. The first power supply input includes a first section and a second section, and the second component includes at least one connecting member configured to connect the first component to the second section and the first section. The first component is coupled to the second power supply input by at least one more connecting member than the first component is connected to the second section and the first section.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1a-1cshow an exemplary embodiment of the invention in which a circuit is provided for coupling a load12to a power source10. The circuit may be included in a portable electronic device, for example a mobile phone, personal data assistant (PDA), laptop computer, or other portable electronic device that contains a rechargeable battery. The circuit shown inFIG. 1aincludes a first power supply input13coupled between the load12and the power source10, and a second power supply input11coupled between the load12and the power source10. The first power supply input13includes the positive line running from the power source10the load12, and the second power supply input11includes the ground or negative line running from the load12to the power source10. While these lines are referred to as first and second power supply inputs it is understood that these names are merely for reference and are not limiting. The load12may include a charger circuitry14and a battery16, but it is understood that the load12may be any electrical load as known in the art. The charger circuitry14and battery16may be those of a portable electronic device. In the exemplary embodiment shown inFIG. 1athe load includes charger circuitry14coupled to a battery16, for example a rechargeable battery whose recharging is regulated or controlled by the charger circuitry14. The power source10may be for example a charger that is configured to connect to an electrical distribution system, or it may be a charger that is cable of producing its own electrical output. It is understood that the first power supply input13and second power supply input11of the load12are included in an electrical path between the power source10and the load12.

In accordance with the exemplary embodiment shown inFIG. 1a, the circuit may also include a over voltage protection component18that is configured to provide over voltage protection for the load12. The over voltage protection component18may be a transient voltage suppressor, for example a zener diode or another equivalent voltage limiter. The over voltage protection component18is configured to be coupled across the first power supply input13and the second power supply input11. The over voltage protection component18may be configured so that when the power source10generates a voltage that is greater than normal for the load12, the resistance of the over voltage protection component18decreases and the over voltage protection component18begins to conduct current, thereby reducing the amount of voltage reaching the load12. It is understood that the voltage at which the over voltage protection component18begins to direct current away from the load12will be dependent upon the application in which the over voltage protection component18is used. The present invention is not limited to any particular voltage or range of voltages at which the over voltage protection component will begin to conduct current away from the load12.

The circuit shown inFIG. 1amay also include a current protection component20. As shown inFIG. 1a, the current protection component20may include solder balls22,24,26,28that connect the over voltage protection component18to the first power supply input13and the second power supply input11. The solder balls26,28on the first power supply input13also connect the sections of the first power supply input13to each other. The solder balls22,24on the second power supply input also connect the sections of the second power supply input11to each other. While two solder balls are shown connecting the sections of the first power supply input13to each other, it is understood that one solder ball may be used. In addition, one solder ball may also be used to connect the sections of the second power supply input11to each other as well. Therefore, as shown inFIG. 1b, when a solder ball is missing the circuit is no longer complete, and no electricity may flow through the circuit. In this manner, both the over voltage protection component18and the load12are protected from over current by the current protection component20.

The embodiments of the invention as shown inFIGS. 1a-1coperate as follows. As current passes through the over voltage protection component18heat may be generated. The current and resulting heat may result in failure of the over voltage protection component18, either due to breakdown of the over voltage protection component18or disconnection between the over voltage protection component and the first power supply input13or second power supply input11. However, as shown inFIGS. 1band1cthe current protection component20is configured to prevent further electrical flow to occur when the over voltage protection component18has become disconnected from the power supply inputs11,13. The over voltage protection component18may be disconnected from the power supply inputs11,13during an over current event due to the heat build up causing any one of the solder balls22,24,26,28of the second component to melt. The melting of the solder balls22,24,26,28disconnects the over voltage protection component18from a section of the circuit causing a break in the electrical path of the circuit.

As shown inFIG. 1b, a solder ball has melted and as a result the circuit is incomplete. Therefore, no current can flow from the power source10, and the load12is protected from damage.FIG. 1cshows another exemplary situation in which a different solder ball has melted, and as a result the circuit is incomplete. Due to discontinuities in the first power supply input13and second power supply input11, the circuit is only complete when all four solder balls of the current protection component20are present, otherwise the circuit is incomplete and no current can flow from the power source10to the load12. It is also possible that the circuit shown inFIGS. 1band1ccan provide preemptive protection to the load, in the sense that if any of the solder balls22,24,26,28are missing or not soldered properly, no current can flow from the power source10to the load12regardless of whether an over voltage situation has occurred. In this manner, current protection component20also protects both the load12and the over current protection component18by ensuring that current cannot pass through the circuit when the over current protection component18will be unable to provide over current protection due because it is missing or improperly connected.

FIGS. 2a-2cshow another exemplary embodiment of the circuit according to the present invention. The circuit shown inFIGS. 2a-2ccontains the same components as the circuit shown inFIGS. 1a-1c, as indicated by like reference numerals. In the embodiment shown inFIG. 2athe current protection component20also includes two current resisting components31,33that may be for example resistors. In the exemplary embodiment shown inFIG. 2a, the first power supply input13and second power supply input11are not discontinuous as shown inFIGS. 1a-1c, instead they form a complete circuit with the power supply10and load12. In addition to the current resisting components31,33, the current protection component20in this embodiment of the invention also includes at least two solder balls35,37, but may also include solder balls32,34as well. As discussed above, when the voltage provided by the power source10is greater than normal for the load12, which will be dependent upon the load12and the type of application the load12is used for, the over voltage protection component18will decrease in resistance and draw current away from the load12to ground. In the event that the heat generated by the excess current flowing through the over voltage protection component18melts one of the solder balls35,37, the current protection component20is configured to disable the charger circuitry14so that the circuit no longer demands electricity from the power source10.

The current protection component20may be configured to sense the change in voltage that occurs when either solder ball35,37or solder balls32,34has been melted and the over voltage protection component18is disconnected from part of the circuit. When the current protection component20senses a change in a voltage it may alter the state an enable or not-enable signal communicated to a control input (not shown) of the charger circuitry14. The enable and inverted not-enable signals may be combined through AND logic, and therefore a change in a state for either signal will result in shutting down of the charger circuitry14so that the load12no longer demands power from the power source10. In this manner, when the over voltage protection component18is no longer capable of providing over voltage protection to the load12, the flow of electricity is prevented so that the load12is not damaged and an unsafe condition is avoided.

Another exemplary embodiment of the invention is shown inFIGS. 3a-3c. The embodiment of the circuit according to the invention shown inFIGS. 3a-3cincludes similar components to the embodiments as shown inFIGS. 1a-1cand2a-2c, as indicated by like reference numerals. The current protection component20shown inFIG. 3aincludes solder balls26,28,37, as well as current resisting component33. The current protection component20may also include solder ball34. The current protection component20is configured to provide current protection to the load12and the over voltage protection component18in the event that the over voltage protection component becomes disconnected from the circuit due to melting of one of the solder balls26,28,37. The current protection component20provides current protection to the over voltage protection component18by disconnecting the over voltage protection component18from the circuit, which has the effect of also protecting the load12due to the configuration of the circuit.

In the event that solder balls26or28melt, the first power supply input13is discontinuous as shown inFIG. 3b, and current flow through the circuit is prevented since the circuit is no longer completed. In the event that solder ball37melts as shown inFIG. 3cby the absence of solder ball37, the current protection component20is configured to sense the change in voltage and alter the state an enable or not-enable signal provided to a control input of the charger circuitry. The enable or not-enable signal will cause the charger circuitry14to be disabled, and thereby stopping the demand for power from the power source10. In this case, no more current will flow into the circuit, because there is no demand for the electricity. The circuit shown inFIGS. 3a-3cwill also protect the load12and over voltage protection component20from over current if any of the solder balls26,28,34or37are disconnected or improperly connected during manufacturing of the circuit. In this instance, no current will be able to flow to the load12from the circuit.

FIGS. 4a-4cshow another exemplary embodiment of the circuit according to the present invention. As shown inFIGS. 4a-4cthe circuit includes components similar to the circuits shown inFIGS. 1a-1c,2a-2cand3a-3c, as shown by like reference numerals. In the circuit shown inFIG. 4athe current protection component includes solder balls51,53connecting the over voltage protection component18to the first power supply input13. As discussed previously, since the first power supply input13is discontinuous, if the solder balls51,53melt the circuit will become incomplete. In order to increase the likelihood that solder balls51,53on the first power supply input13melt the over voltage protection component18is connected to the second power supply input11, i.e. the ground line by at least one more solder ball55,56,57than is used to connect the over voltage protection component18to the first power supply input13. For example, inFIGS. 4a-4cthe over voltage protection component18is connected to the first power supply input13by two solder balls, and connected to the second power supply input13by three solder balls. In this manner, the connection to the ground line will have greater conducting area and better heat resistive properties, thereby decreasing the likelihood that the solder balls55,56,57on the second power supply input11will melt.

The present invention may also be embodied in a method in which the method includes providing a first component configured to be coupled across power supply inputs of a load of a portable device. The first component may be an over voltage protection component such as a transient voltage suppressor. In this exemplary embodiment of the invention, the power supply inputs are configured for receipt of power from an external power source, and the first component is configured to provide over voltage protection for the load. The method further includes coupling a second component to the first component. The second component is configured to provide over current protection for the load and for the first component. The second component is configured to provide over current protection to the load at least when the second component provides over current protection to the first component.

The method according to this exemplary embodiment of the invention may also include providing a first power supply input and a second power supply input of the power supply inputs, each configured to couple the load to the external power source. The method further includes providing at least one connecting member of the second component configured to be positioned in an electrical path between one power supply input of the load and the external power source. The first connecting member is responsive to an over current event so as to break the electrical path.

In another exemplary embodiment of the invention, a method is provided that includes providing a first connecting member of the second component configured to connect the first component to a first power supply input of the power supply inputs and a first current resisting component. The first connecting member is configured to disconnect the first component from the first power supply input during an over current event. The method further includes altering a signal communicated to a control input of the load when the first component is disconnected from the first power supply input. The signal may be an enable signal with a first state configured to enable the load and a second state configured to disable the load, and the second component is configured to alter the state of the enable signal. In the alternative, the signal may be a not-enable signal with a first state configured to disable the load and a second state configured to enable the load, and the second component is configured to alter the state of the not-enable signal.

It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the present invention. Numerous modifications and alternative arrangements may be devised by those skilled in the art without departing from the scope of the present invention.