Increased robustness of components with regard to overvoltage transients

Abstract

A process that has: selectively activating a switch (10) by means of control logic (12, 13) and based on a control signal; Activating the switch (10) by means of the control logic (12, 13) and regardless of the control signal in response to the determination that an electrical characteristic of a signal supplied to the switch (10) has reached a threshold value, while the switch (10) is deactivated until it is determined that a potential of the signal supplied to the switch (10) has reached a threshold potential; and Deactivating the switch (10) in response to determining that the potential of the signal supplied to the switch (10) has reached the threshold potential; wherein the determination that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold value comprises: Determining that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold in response to determining that a current level of the signal (I) has reached a current threshold.

Description

TECHNICAL FIELD

[0001] This description concerns the overstress detection of semiconductor devices. BACKGROUND

[0002] Semiconductor devices such as metal-oxide-semiconductor field-effect transistors (MOSFETs), insulated-gate bipolar transistors (IGBTs), and other such devices such as diodes are sometimes exposed to stressful operating environments. A stressful operating environment can destroy or degrade the device, ultimately leading to permanent component failure. If a device fails, the failed device can be subjected to failure analysis.

[0003] To perform an adequate analysis of the failed or damaged component, it may be desirable to understand the operating conditions of the component in the time prior to the failure as well as during the failure. For example, electrical transients (e.g., voltage spikes) along the supply lines are one of the most common stress conditions that can lead to a faulty semiconductor device. These transients, sometimes referred to as ISO pulses, can cause unprotected devices to exceed their specified maximum values and become stressed. Publication US 2016 / 0 049 786 A1 deals with overvoltage protection of semiconductor switches. Publication US 2007 / 0 153 589 A1 deals with a voltage regulation device. Publication US 8 847 656 B1 deals with a system for controlling transistors.

[0004] While some components can often withstand the high power dissipation that may occur as a result of such a transient for a short period of time, continued or repeated exposure to transients can eventually cause permanent damage (e.g., according to the Wunsch-Bell breakdown characteristic of the device). When a device is subjected to failure analysis, it may not always be clear from visual inspection and / or other indications of failure whether such a transient has occurred, which can lead to an inaccurate or misdiagnosed failure. One object of the present invention is to protect a switch from electrical transients. SUMMARY

[0005] The mentioned object is achieved by the methods according to claims 1 and 2, the systems according to claims 10 and 11, and the devices according to claims 18 and 19. Various embodiments and further developments are subject to the dependent claims. In one example, a method comprises selectively activating a switch by means of control logic and based on a control signal; activating the switch by means of the control logic and regardless of the control signal in response to determining that an electrical characteristic of a signal supplied to the switch reaches a threshold value, while the switch is deactivated until determining that a potential of the signal supplied to the switch reaches a threshold potential; and deactivating the switch in response to determining that the potential of the signal supplied to the switch reaches the threshold potential.

[0006] In another example, a system includes a switch configured to receive a signal; and control logic configured to: selectively activate the switch based on a control signal; activate the switch regardless of the control signal responsive to determining that an electrical characteristic of a signal applied to the switch reaches a threshold while the switch is deactivated until determining that a potential of the signal applied to the switch reaches a threshold potential; and deactivate the switch responsive to determining that a potential of the signal applied to the switch reaches the threshold potential.

[0007] In another example, a device comprises means for selectively activating a switch based on a control signal; means for activating the switch regardless of the control signal in response to determining that an electrical characteristic of a signal applied to the switch reaches a threshold value while the switch is deactivated until determining that a potential of the signal applied to the switch reaches a threshold potential; and means for deactivating the switch in response to determining that the potential of the signal applied to the switch reaches the threshold potential. BRIEF DESCRIPTION OF THE ILLUSTRATIONS Fig. 1 is a schematic diagram illustrating an exemplary system in accordance with one or more of the techniques described herein, including one or more components configured to protect a switch from electrical transients. Fig. 2 is a schematic diagram illustrating an exemplary system in accordance with one or more of the techniques described herein, including one or more components configured to protect a switch from electrical transients. Fig. 3 is a schematic diagram illustrating an exemplary system in accordance with one or more of the techniques described herein, including one or more components configured to protect a switch from electrical transients. Fig. 4A-4C are schematic diagrams each illustrating examples of protection logic configured to activate a switch based on the detection of an electrical transient in accordance with one or more of the techniques described herein. Fig. Figure 5 is a graph illustrating an exemplary Wunsch-Bell characteristic of a switch according to one or more of the techniques described herein. Fig. Figure 6 is a graph illustrating an exemplary Wunsch-Bell characteristic of a switch according to one or more of the techniques described herein. Fig. Figure 7 is a graph illustrating, by way of example, the effect of loading a component according to one or more of the techniques described herein. Fig. 8 is a flowchart illustrating an exemplary technique for protecting a switch from damage in accordance with one or more of the techniques described herein. DETAILED DESCRIPTION

[0008] Fig. 1 is a schematic diagram illustrating an exemplary system having one or more components configured to protect a switch from electrical transients in accordance with one or more of the techniques described herein. As shown in Fig. 1, the system 2A comprises a power supply 4, a switch driver 6A and a load 8.

[0009] In some examples, system 2A may include power supply 4, which may be configured to power one or more other components of system 2A. For example, power supply 4 may power load switch driver 6A. Examples of power supply 4 include, but are not necessarily limited to, batteries, electrical outlets, AC / DC converters, and DC / DC converters.

[0010] In some examples, the system 2A may include a load 8, which may be configured to receive power from one or more components of the system 2A, such as the switch driver 6A. Examples of the load 8 include, but are not necessarily limited to, resistive loads (e.g., incandescent bulbs and electric heaters), capacitive loads (e.g., camera flashes), and inductive loads (e.g., motors and transformers).

[0011] In some examples, the system 2A may include a switch driver 6A that may be configured to control the amount of energy provided to one or more components of the system 2A, such as the load 8. As in Fig. 1, the switch driver 6A may include a switch 10, a control logic 12, a current sensor 14, and a temperature sensor 16.

[0012] The switch driver 6A may include a switch 10, which may be configured to control the amount of energy provided to one or more components of the system 2A, such as the load 8, based on a control signal received from the switch control logic 12. Examples of a switch include, but are not necessarily limited to, power metal-oxide-semiconductor field-effect transistors (MOSFETs), double-diffused MOS (DMOS), bipolar transistors, insulated-gate bipolar transistors (IGBTs), and other such devices, such as silicon-controlled rectifiers (SCR / GTO). In some examples, the switch 10 may include a plurality of switches. In the example of Fig. 1, switch 10 is illustrated as a high-side switch with respect to load 8. In other examples, switch 10 may be a low-side switch with respect to load 8 or may be a discrete component.

[0013] The switch driver 6A may include control logic 12 that may be configured to control the operation of the switch 10. The control logic 12 may be configured to communicate with one or more external components, such as via communication channels 20. In some examples, the communication channels 20 may include one or more connectors configured to receive an activation signal for one or more of the switches included in the switch 10. In some examples, the communication channels 20 may include one or more connectors configured to couple the control logic 12 to a communication bus, such as a Serial Peripheral Interface (SPI) bus. As shown in Fig. 1, the control logic 12 may include a switch control 15 that may be configured to control the operation of the switch 10 based on one or more control signals received via the communication channels 20.

[0014] The switch driver 6A may include a current sensor 14 that may be configured to measure a current level of a signal supplied to one or more components of the switch driver 6A. As shown in Fig. As shown in Figure 1, the current sensor 14 can measure a current level of the supply signal supplied to the switch 10 from the power supply 4. The current sensor 14 can output an indication of the measured current to one or more components of the switch driver 6A, such as the control logic 12.

[0015] The switch driver 6A may include a temperature sensor 16 that may be configured to measure a temperature of one or more components of the switch driver 6A. As shown in Fig. 1, the temperature sensor 16 can measure a temperature of the switch 10. The temperature sensor 16 can output an indication of the measured temperature to one or more components of the switch driver 6A, such as the control logic 12.

[0016] The system 2A may include a fuse 18 that may be configured to provide overcurrent protection to one or more components of the system 2A. For example, the fuse 18 may provide overcurrent protection for the switch driver 6A and / or the load 8.

[0017] As discussed above, it may be desirable to protect switches and drivers from electrical transients. In the example from Fig. 1, the system 2A includes a clamping diode 22, which may be configured to protect the switch 10 and the control logic 12 from electrical transients on the supply line, such as the electrical transient 26. However, since clamping diodes 22 may be positioned far from the switch 10 and the control logic 12 in some examples, the system 2A may also include clamping diodes 24 and a resistor 25 to protect the control logic from electrical transients on the supply line, such as the electrical transient 26.

[0018] Fig. 2 is a schematic diagram illustrating an exemplary system according to one or more of the techniques described herein, including one or more components configured to protect a switch from electrical transients. As shown in Fig. 2, system 2B includes a power supply 4, a switch driver 6B, and a load 8. Similar to system 2A, system 2B also includes clamp diodes 22, clamp diodes 24, and a resistor 25 to protect control logic 12 from electrical transients on the supply lines, such as electrical transient 26.

[0019] In some examples, such as when the switch 10 comprises a DMOS or an IGBT switch, the switch 10 may not be functional while in avalanche breakdown and may fail or degrade while in avalanche breakdown. Thus, in some examples, it may be desirable to protect the switch 10 from entering breakdown. As in Fig. As shown in Figure 2, a gate clamping technique can be implemented, in which the switch 6B includes one or more diodes 30 electrically positioned between the gate / base and a drain / collector of the switch 10 (the terminology depends on a technology of the switch 10). According to the gate clamping technique, the diodes 30 can open the gate of the switch 10 in response to an overvoltage at the drain / collector or the gate / base. In this way, the diodes can protect the switch 10 from entering avalanche breakdown.

[0020] However, the gate clamp technique has one or more disadvantages. For example, when using the gate clamp technique, the switch will not operate at the lowest Rds-ON / Rce-ON value during supply line transients, such as transient 26, causing high power dissipation, wear, and degradation, even damaging switch 10. Thus, the gate clamp technique may not guarantee reliable protection. In examples where switch driver 6B has multiple switches and a separate set of clamp diodes for each switch, the forward voltage threshold for each of the clamp diodes may be similar, but not the same. The switch with the lower Rds-ON / Rce-ON value will dissipate the most supply voltage transient energy when activated by the gate clamp and will be more likely to be damaged during a supply voltage transient.

[0021] In some examples, where, for example, the switch 10 includes a FET switch, the switch 10 may be functional during an avalanche. However, allowing the switch 10 to operate in avalanche mode introduces one or more disadvantages. For example, depending on the dissipated energy, the switch 10 may degrade or fail over time. An example showing how an avalanche mode may cause it to degrade and fail over time is discussed below with reference to Fig. 4. In examples where the switch driver 6B includes multiple switches, the avalanche threshold may be similar, but not the same, for each switch, and may also depend on the respective loads. One or more of the switches may conduct before others in avalanche, and the switch(es) conducting in avalanche will dissipate the most energy of the power line transient. Furthermore, the load affects the amount of energy dissipated by the switches, making some switches more prone to failure than others.

[0022] Fig. 3 is a schematic diagram illustrating an exemplary system according to one or more of the techniques described herein, including one or more components configured to protect a switch from electrical transients. As shown in Fig. 3, system 2C includes a power supply 4, a switch driver 6C, and a load 8. Similar to systems 2A and 2C, system 2C may include clamp diodes 22, clamp diodes 24, and a resistor 25 to protect control logic 12 from electrical transients on the supply line, such as transient 26

[0023] System 2C, in some examples, includes control logic 13 that may be configured to perform operations similar to control logic 12. For example, control logic 13 may be configured to control the operation of switch 10. As shown in Fig. 3, the control logic 13 may include a switch controller 15 that may be configured to control the operation of the switch 10 based on one or more control signals received via the communication channels 20. As shown in Fig. 3, the control logic 13 may additionally comprise a protection logic 32, a memory 34 and an OR gate 36.

[0024] According to one or more of the techniques described herein, control logic 13 may include protection logic 32, which may be configured to activate a switch, such as switch 10, based on the detection of an incoming power line transient. In one example, the control logic may activate the switch immediately in response to detection of the incoming power line transient. In another example, the control logic may briefly delay activation of the switch to tolerate a limited avalanche breakdown while still avoiding destruction of the switch. By activating a switch in this manner, the control logic may reduce the amount of power dissipated by the switch, which may improve robustness and extend the lifetime of the switch.

[0025] In some examples, protection logic 32 may detect the incoming transient based on one or more electrical characteristics of the power signal supplied to switch 10. Some exemplary electrical characteristics include, but are not limited to, a voltage level (i.e., potential) of the signal (V) and a current level of the signal (I). In some examples, protection logic 32 may detect the incoming transient based on parameters calculated based on one or more electrical characteristics of the power signal supplied to the switch. For example, protection logic 32 may detect the incoming transient based on the amount of energy dissipated in switch 10, which was calculated based on a current of the power signal.In some examples, protection logic 32 may determine when to activate switch 10 based on a temperature (T) of switch 10 received from temperature sensor 16. In any case, protection logic 32 may output a signal (Out) to one or more components of switch driver 6C, such as OR gate 36, based on the detection of an incoming power line transient.

[0026] In some examples, control logic 13 may include a memory that may be configured to store an indication that an electrical transient event has occurred. For example, in response to receiving a signal from protection logic 32 to activate switch 10, memory 34 may increment a counter indicating how many electrical transient events have occurred. In this way, memory 34 may store information that may be used to monitor the performance and / or fault analysis of switch driver 6C.

[0027] In some examples, control logic 13 may include an OR gate 36 that may be configured to activate switch 10 in response to a signal from protection logic 32 or switch controller 15. For example, OR gate 36 may activate switch 10 in response to receiving a signal from protection logic 32, even if switch controller 15 does not output a signal requesting activation of switch 10.

[0028] Although in Fig. 3, in some examples, the switch driver 6C may include one or more components configured to implement the above-mentioned "gate clamping" technique. For example, the switch driver 6C may include one or more diodes 30 electrically positioned between a drain and a gate, or a collector and a base (the terminology depends on a technology of the switch 10).

[0029] Fig. 4A-4C are schematic diagrams each illustrating examples of protection logic 32A-32C configured to activate a switch based on the detection of an electrical transient in accordance with one or more of the techniques described herein. Fig. 4A illustrates protection logic 32A that may be configured to activate a switch in response to determining that a voltage level of the signal supplied to the switch reaches a voltage threshold, until determining that the voltage level of the signal supplied to the switch reaches a threshold potential. As in Fig. 4A, the protection logic 32A may include a comparator 40, a comparator 42, and a flip-flop 44.

[0030] The protection logic 32A may include a comparator 40 configured to output a signal indicating which input signal is greater. In the example of Fig. 4A, the comparator 40 may output a signal indicating whether or not the voltage level of the supply line (V) is greater than a first threshold (V_Thres1). For example, the comparator 40 may output a logic high level to the flip-flop 44 when the voltage level of the supply line (V) is greater than the first threshold (V_Thres1), or output a logic low level to the flip-flop 44 when the voltage level of the supply line (V) is less than the first threshold (V_Thres1).

[0031] The protection logic 32A may include a comparator 42 that may be configured to output a signal indicating which input signal is greater. Fig. 4A, the comparator 42 may output a signal indicating whether or not the voltage level of the supply line (V) is greater than a second threshold (V_Thres2). For example, the comparator 42 may output a logic low level to the flip-flop 44 when the voltage level of the supply line (V) is greater than the second threshold (V_Thres2) or a logic high level to the flip-flop 44 when the voltage level of the supply line (V) is less than the second threshold (V_Thres2).

[0032] The protection logic 32A may include a flip-flop 44 that may be configured to store state information. In the example of Fig. 4A, flip-flop 44 may be an SR latch. When flip-flop 44 receives a logic high signal from comparator 40 at the Set terminal (S), flip-flop 44 may set the logic level of output terminal (Q) to a high level. When flip-flop 44 receives a logic high signal from comparator 42 at the Reset terminal (R), flip-flop 44 may reset the logic level of output terminal Q to a low level.

[0033] In some examples, protection logic 32A may include a comparator with hysteresis instead of comparator 40, comparator 42, and flip-flop 44. In this way, the implementation cost of this technique may be reduced.

[0034] Referring to Fig. 3 and Fig. 4A, a transient may occur on the supply line while switch 10 is off (deactivated). The transient may cause the voltage level of the supply line to rise. Comparator 40 may detect that the voltage level of the supply line has reached the first voltage threshold (i.e., is greater than the first voltage threshold) and output a logic high signal to the Set input of flip-flop 44. The first voltage threshold may be set to be greater than an absolute maximum rating for switch 10, but less than a breakdown voltage of switch 10.

[0035] In response to receiving the signal indicating that the supply line voltage level has reached the first voltage threshold, flip-flop 44 at output terminal Q may output a logic high signal to OR gate 36, which may activate switch 10. Activation of switch 10 may allow the transient to flow through switch 10 without causing damage.

[0036] As a result of the activation of switch 10, the voltage level of the supply line may drop. Once the voltage level of the supply line reaches the second voltage threshold (V_Thres2) (i.e., is less than the second voltage threshold), comparator 42 may output a logic high signal to flip-flop 44. The second voltage threshold may be set to be less than the first voltage threshold. In response to receiving the signal indicating that the voltage level of the supply line has reached the second voltage threshold, flip-flop 44 may output a logic low signal at output terminal Q to OR gate 36, which may deactivate switch 10 (provided switch controller 15 outputs a signal to activate switch 10).

[0037] Fig. 4B illustrates protection logic 32B, which may be configured to activate a switch in response to determining that a current level of a signal supplied to the switch has reached a current threshold, until it is determined that a voltage level of the signal supplied to the switch has reached a threshold potential. As in Fig. 4B, the protection logic 32B may include a comparator 42 and a flip-flop 44, both of which may be configured to perform similar operations as comparator 42 and flip-flop 44 of Fig. 4A.

[0038] As in Fig. 4B, the protection logic 32B may include a comparator 46 configured to output a signal indicating which input signal is greater. In the example of Fig. 4B, comparator 46 may output an output signal indicating whether or not the current level of the supply line (I) is greater than a first threshold (I_Thres1). For example, comparator 46 may output a logic high signal to flip-flop 44 if the current level of the supply line (I) is greater than the first threshold (I_Thres1), or output a logic low signal to flip-flop 44 if the current level of the supply line (I) is less than the first threshold (I_Thres1).

[0039] Referring to Fig. 3 and Fig. 4B, in operation, a transient may occur on the supply line while switch 10 is off (deactivated). Normally, the current measured by current sensor 14 is zero while switch 10 is off. However, the transient may cause the supply line current level to rise above zero (e.g., the transient voltage may exceed the avalanche breakdown voltage of switch 10, which may cause current to flow through switch 10). Comparator 46 may monitor the current level measured by current sensor 14 while switch 10 is off and output a logic high signal to the Set terminal of flip-flop 44 in response to determining that the supply line current level has reached a current threshold (i.e., is greater than the current threshold). The current threshold may be set greater than zero.

[0040] In response to receiving a signal indicating that the supply line current level has reached the threshold, flip-flop 44 at output terminal Q may output a high signal to OR gate 36, which may activate switch 10. Activation of switch 10 may allow the transient to flow through switch 10 without causing damage.

[0041] As a result of the activation of switch 10, the voltage level of the supply line may drop. Once the voltage level of the supply line reaches the second voltage threshold (V_Thres2) (i.e., is less than the second voltage threshold), comparator 42 may output a logic high signal to flip-flop 44. The second voltage threshold may be set to be less than the avalanche breakdown voltage threshold of switch 10. In response to receiving the signal indicating that the voltage level of the supply line has reached the second voltage threshold, flip-flop 44 may output a logic low signal at output terminal Q to OR gate 36, which may deactivate switch 10 (provided switch controller 15 outputs a signal to activate switch 10).

[0042] Fig. 4C illustrates protection logic 32C, which may be configured to activate a switch in response to determining that the amount of power dissipated by the switch is close to destroying the switch, until it is determined that a voltage level of the signal supplied to the switch has reached a threshold potential. As in Fig. 4C, the protection logic 32C may include a comparator 42 and a flip-flop 44, both of which may be configured to perform similar operations as comparator 42 and flip-flop 44 of Fig. 4A.

[0043] The protection logic 32C may include a standby module 52, which may be configured to bring the protection logic 32C out of a standby module in response to determining that the voltage level (V) of a signal supplied to the switch 10 is greater than a voltage threshold or the current level of the signal supplied to the switch 10 is greater than a current threshold, or both. In some examples, the standby module 52 may include a comparator similar to the comparator 40 of Fig. 4A to determine whether the voltage level (V) of the signal supplied to the switch 10 is greater than the voltage threshold and / or a comparator similar to the comparator 46 of Fig. 4B, to determine whether the current level of the signal supplied to switch 10 is greater than the current threshold. The voltage threshold may be less than a breakdown voltage of switch 10 and greater than an absolute maximum voltage rating of the switch (V_breakdown_AMR). In some examples, standby module 52 may output a signal to one or more components of protection logic 32C, such as Wunsch-Bell module 50, to bring protection logic 32C out of standby mode.

[0044] The protection logic 32C may include a power dissipation module 58, which may be configured to determine an amount of power dissipated by a switch. For example, the power dissipation module 58 may determine an amount of power dissipated by the switch 10 based on an avalanche breakdown voltage of the switch 10 (i.e., V Avalan) and a current level flowing through the switch 10 (i.e., I ). The power dissipation module 58 may output a value for the amount of power dissipated by the switch 10 to one or more components of the protection logic 32C, such as the Wunsch-Bell module 50 and / or the comparator 54.

[0045] The protection logic 32C may include a Wunsch-Bell module 50, which may be configured to determine whether the switch has sustained or will sustain damage based on a Wunsch-Bell characteristic of a switch, a temperature of the switch, an amount of power dissipated by the switch, and a duration of time for which the switch has dissipated the amount of power. The Wunsch-Bell characteristics are based on the theory that high-amplitude, short-duration transient pulses can cause the destruction of an electronic component; and the amount of damage inflicted on a semiconductor device by a transient pulse or overvoltage condition can be predicted using the Wunsch-Bell electrical overstress model.According to the model, along with the peak voltage and current in a device, the pulse duration of an overvoltage condition is important in determining the amount of power necessary to cause a bipolar junction failure. Further details of the Wunsch-Bell module 50 are described below with reference to FIG. Fig. 5 discussed.

[0046] The protection logic 32C may include the comparator 54, which may be configured to output a signal indicating which input is greater. In the example of Fig. 4C, comparator 54 may output a signal indicating whether or not the power dissipated by switch 10 is greater than a power threshold (P_Thres). For example, comparator 54 may output a logic high signal to OR gate 56 when the amount of power dissipated by switch 10 is greater than the power threshold, or output a logic low signal to OR gate 56 when the amount of power dissipated by switch 10 is less than the power threshold.

[0047] The protection logic 32C may include the OR gate 56, which may be configured to activate the switch 10 in response to either a signal from the protection logic 32 or from the switch controller 15. For example, the OR gate 36 may still activate the switch in response to a signal from the protection logic 32 even if the switch controller 15 does not output a signal requesting activation of the switch 10.

[0048] Fig. Figure 5 is a graph illustrating an exemplary Wunsch-Bell characteristic of a switch according to one or more techniques of this description. As in Fig. 5, the graph 500 includes a horizontal axis representing time on a logarithmic scale, a vertical axis representing power on a logarithmic axis, a plot 502 representing a destruction threshold of a switch at a particular temperature, and a plot 508 representing an amount of power dissipated by the switch. For example, the plot 502 may represent a destruction threshold of the switch 10 at 25 degrees Celsius. The region 504 of the graph 500 represents a safe operating area (SOA) in which the switch can dissipate power indefinitely without suffering damage. The region 506 of the graph 500—the area above the plot 502—represents an area in which the switch suffers damage.For example, a transient that causes 0.1 watts of power dissipation in the switch for 10 seconds falls into region 504 and will not damage the switch. Similarly, a transient that causes 1 watt of power dissipation in the switch for 10 seconds falls into region 506 and will damage the switch.

[0049] Referring to Fig. 3, Fig. 4B and Fig. 5, during operation, a transient may occur on the supply line while the switch 10 is off (deactivated). Normally, while the switch 10 is off, the current measured by the current sensor 14 should be zero and the supply line voltage should be less than a voltage threshold. However, the transient may cause the supply line current level to rise above zero and / or the supply line voltage to rise above the threshold. In response to a supply line voltage (V) being greater than the voltage threshold or the supply line current level being greater than the current threshold, or both, the standby module 52 may bring the protection logic 32C out of a standby mode. For example, the standby module 52 may output a signal to the Wunsch-Bell module 50 indicating that a transient has been detected.

[0050] In response to receiving a signal indicating the detection of the transient, the Wunsch-Bell module 50 may monitor the amount of power dissipated by the switch 10 (represented by plot 508 versus time). Time zero ("Out of Standby") corresponds in Fig. 5 with the time at which the transient is detected by the protection logic 32C. The Wunsch-Bell module 50 can determine whether the switch 10 has suffered or will suffer damage based on the Wunsch-Bell characteristic of the switch 10. For example, the Wunsch-Bell module 50 can determine a power-time threshold for the switch 10 based on a temperature of the switch 10 and one or more Wunsch-Bell characteristics of the switch 10. In the example from Fig. 5, the desired Bell module 50 can determine the power-time threshold 510, which is also referred to as the turn-on threshold 510.

[0051] The wish-bell module 50 may determine that the switch 10 will suffer damage based on the amount of time for which the switch 10 has dissipated power that reaches the power-time threshold 510. As in Fig. 5, the Wunsch-Bell module may determine that the switch 10 will sustain damage at time 512. In response to determining that the switch 10 will sustain damage, the Wunsch-Bell module 50 may output a signal, such as a logic high signal, to the OR gate 56 or the set terminal (S) of the flip-flop 44.

[0052] In response to receiving a signal indicating that switch 10 will suffer damage, flip-flop 44 may output a logic high signal to OR gate 36 at output Q, which may activate switch 10. Activation of switch 10 may allow the transient to flow through switch 10 without causing damage.

[0053] As a result of the activation of switch 10, the voltage level of the supply line may drop. At time 514, the voltage level of the supply line may have reached a second voltage threshold (V_Thres2) (i.e., fallen below the second voltage threshold). In response to determining that the voltage level of the supply line has reached the second threshold, comparator 42 may output a logic high signal to flip-flop 44. The second voltage threshold may be set to a lower value than the first voltage threshold used by standby module 52.In response to receiving the signal indicating that the voltage level of the supply line has reached the second threshold, the flip-flop 44 may output a logic low signal at output Q to the OR getter 36, which may deactivate the switch 10 (unless the switch controller 15 outputs a signal to activate the switch 10).

[0054] In addition, the activation of switch 10 can cause the amount of power dissipated by switch 10 to decrease. In the example from Fig. 5, the power dissipated by switch 10 decreases by a factor of 10. As in Fig. 5, this reduction in power dissipation increases the robustness of the switch 10 because the transient duration before damage is caused (i.e., before the power dissipated by the switch 10 enters the region 506) is increased.

[0055] Fig. Figure 6 is a graph illustrating an exemplary Wunsch-Bell characteristic of a switch according to one or more techniques of this description. As in Fig. 6, graph 600 includes a horizontal axis representing time on a logarithmic scale, a vertical axis representing power on a logarithmic axis, and plots 602A-602C representing destruction limits of a switch at various temperatures. For example, plot 602A may represent a destruction limit of switch 10 at 40 degrees Celsius, plot 602B may represent a destruction limit of switch 10 at 60 degrees Celsius, and plot 602C may represent a destruction limit of switch 10 at 80 degrees Celsius.

[0056] As discussed above, the desired Bell module 50 can be Fig. 4C determine whether switch 10 has suffered or will suffer damage. As in Fig. As illustrated in Figure 6, the Wunsch-Bell characteristics and damage thresholds of a switch may change based on temperature. Thus, according to one or more of the techniques described herein, the Wunsch-Bell module 50 may determine whether the switch 10 has sustained or will sustain damage based on the temperature of the switch 10.

[0057] Fig. Figure 7 is a graph illustrating, by way of example, the effects of stress on a device according to one or more techniques of the present description. As in Fig. 7, graph 700 includes a horizontal axis representing the stress level, a vertical axis representing the failure rate, and a plot 702 representing the relationship between the stress level to which a component was subjected and the failure rate of the component.

[0058] As shown in Plot 702, the failure rate of the device does not increase unless the device is subjected to stress levels outside the device's safe operating area (SOA). Furthermore, the failure rate of the device does not increase unless the device is subjected to stress levels above a maximum limit (absolute maximum rating, AMR) of the device, although correct operation is not guaranteed.

[0059] Stress levels above the AMR but less than the low-limit robustness put the device into the electrical overstress (EOS) zone, where the device should not fail, but survival is not assured, and the device typically wears out as a result of the stress levels. Repeated exposure to stress levels above the AMR will therefore lead to degradation and eventual damage to the device.

[0060] Once the component is subjected to stress levels greater than its low-limit robustness, there is a known probability of failure. Furthermore, if the component is subjected to stress levels greater than its high-limit robustness, the probability of failure is 100%.

[0061] In the event of an AMR being exceeded, it may be desirable to minimize the amount of energy dissipated in a device to maximize the robustness of the device. As discussed above, and in accordance with one or more of the techniques described herein, protection logic may activate a device in response to the detection of a transient on a supply line to the device. For example, the protection logic 32 may be comprised of Fig. 3 activate the switch 10 in response to the detection of the transient 26. In this way, the techniques described here can reduce the amount of energy dissipated by the devices, which can increase the robustness of the devices.

[0062] Fig. Figure 8 is a flowchart illustrating an exemplary technique for protecting a switch from damage in accordance with one or more of the techniques described herein. For purposes of illustration only, the exemplary operations below are described in the context of the Fig. 3, although components other than the switch driver 6C also use the techniques of Fig. 8 can be carried out.

[0063] The switch driver 6C may selectively activate the switch 10 based on a control signal (802). According to one example, the switch controller 15 may output a logic high signal to the OR gate 36 to activate the switch 10 in response to receiving a control signal over the communication channels 20 requesting activation of the switch 10. According to another example, the switch controller 15 may output a logic low signal to the OR gate 36 to deactivate the switch 10 in response to receiving a control signal over the communication channels 20 requesting deactivation of the switch 10.

[0064] According to one or more of the techniques described herein, the switch driver 6C may determine whether an electrical characteristic of a signal supplied to the switch 10 has reached a threshold (804). According to one example, the protection logic 32 of the switch driver 6C may determine that the electrical characteristic of the signal supplied to the switch 10 has reached the threshold responsive to determining that the potential (V) of the signal has reached a threshold potential (e.g., V_Thres1 from Fig. 4A). According to another example, the protection logic 32 may determine that the electrical characteristic of the signal supplied to the switch 10 has reached the threshold value responsive to determining that a current level (I) of the signal exceeds a current threshold value (e.g., I_Thres1 from Fig. 4B). According to another example, the protection logic 32 may determine that the electrical characteristic of the signal supplied to the switch 10 has reached the threshold responsive to determining that the amount of power dissipated in the switch 10 is close to causing damage to the switch 10 (i.e., is greater than a power dissipation threshold).

[0065] If the electrical characteristic of the signal does not reach the threshold (“No” branch of 804), the switch driver 6C may continue to selectively activate the switch 10 based on the control signal (802). However, if the electrical characteristic of the signal has reached the threshold (“Yes” branch of 804), the switch driver 6C may activate the switch 10 (806). For example, in response to determining that the electrical characteristic of the signal has reached the threshold, the protection logic 32 may output a logic high signal to the OR gate 36, causing the activation of the switch 10 regardless of whether the switch controller 15 requests activation of the switch 10.

[0066] In some examples, the switch driver 6C may store and / or output a value indicating that a transient event has occurred. According to one example, the memory 34 of the switch driver 6C may store a value indicating that the switch was activated due to the occurrence of an electrical transient event. According to another example, the switch controller 15 may output a value indicating that the switch was activated due to the occurrence of an electrical transient event to an external device via the communication channels 20.

[0067] The switch driver 6C can determine whether a potential of the signal has reached a threshold potential (808). For example, the comparator 42 of the protection logic 32 can determine whether the potential of the signal is smaller than a threshold potential (e.g., V_Thres2 from Fig. 4A-4C).

[0068] If the signal potential does not reach the threshold potential (“No” branch of 804), the switch driver 6C may continue to monitor the signal to determine whether the signal potential has reached a threshold potential (808). If the signal potential has reached the threshold potential (“Yes” branch of 808), the switch driver 6C may continue to selectively activate the switch 10 based on the control signal (802). For example, the switch driver 6C may deactivate the switch 10 if the signal potential has reached the threshold potential and the control signal does not request activation of the switch 10.

[0069] In this way, the techniques described here can reduce the amount of power dissipated by transients in a switch. By reducing the amount of power dissipated by transients in a switch, the techniques described here can improve the robustness and longevity of the switch.

[0070] The following numbered examples may illustrate one or more aspects of the description: Example 1. A method comprising: selectively activating a switch by means of control logic and based on a control signal; activating the switch by means of the control logic and regardless of the control signal in response to determining that an electrical characteristic of a signal supplied to the switch has reached a threshold value, while the switch is deactivated until determining that a potential of the signal supplied to the switch has reached a threshold potential; and deactivating the switch in response to determining that the potential of the signal supplied to the switch has reached the threshold potential. Example 2. The method of Example 1, wherein the threshold potential is a second threshold potential, and wherein determining that the electrical characteristic of the signal supplied to the switch has reached the threshold comprises: determining that the electrical characteristic of the signal supplied to the switch has reached the threshold in response to determining that the potential of the signal has reached a first threshold potential that is greater than the second threshold potential. Example 3. The method of example 2, wherein the first threshold potential is less than or equal to a breakdown voltage of the switch. Example 4. The method of any combination of Examples 1-3, wherein determining that the electrical characteristic of the signal supplied to the switch has reached the threshold comprises: determining that the electrical characteristic of the signal supplied to the switch has reached the threshold in response to determining that a current level of the signal has reached a current level. Example 5. The method according to any combination of Examples 1-4, wherein the threshold potential is less than or equal to a breakdown voltage of the switch. Example 6. The method of any combination of Examples 1-5, further comprising: determining an amount of power dissipated by the switch based on a current level of the signal; determining a power-time threshold for the switch based on a temperature of the switch and one or more Wunsch-Bell characteristics of the switch; determining that the electrical characteristic of the signal supplied to the switch has reached a threshold in response to determining that a period of time for which the switch has dissipated the amount of power has reached the power-time threshold for the switch. Example 7. The method of any combination of examples 1-6, further comprising: determining the power-time threshold for the switch based on one or more Wunsch-Bell characteristics of the switch. Example 8. The method of any combination of Examples 1-7, wherein the control logic is included in a switch driver, and the method further comprises, in response to determining that the electrical characteristic of the signal supplied to the switch has reached the threshold while the switch is deactivated: storing a value indicating that an electrical transient event has occurred in a memory device included in the switch driver; and / or outputting, by the control logic, a value indicating that an electrical transient event has occurred to a device external to the switch driver. Example 9. The method of any combination of Examples 1-8, wherein the signal is supplied to a plurality of switches, and wherein activating the switch in response to determining that the electrical characteristic of the signal supplied to the switch has reached the threshold value until determining that the potential of the signal supplied to the switch has reached the threshold potential, comprises: activating the plurality of switches in response to determining that the electrical characteristic of the signal supplied to the plurality of switches has reached the threshold value until determining that the potential of the signal supplied to the plurality of switches has reached the threshold potential. Example 10. The method of any combination of Examples 1-9, further comprising: activating the switch in response to a drain-to-gate or collector-to-base voltage of the switch exceeding a voltage threshold of one or more diodes, by the one or more diodes electrically disposed between the drain and gate or the collector and base of the switch, respectively. Example 11. A system comprising: a switch configured to receive a signal; and control logic configured to: selectively activate the switch based on a control signal; activate the switch regardless of the control signal in response to determining that an electrical characteristic of a signal applied to the switch reaches a threshold while the switch is deactivated until determining that a potential of the signal applied to the switch reaches a threshold potential; and deactivate the switch in response to determining that a potential of the signal applied to the switch reaches the threshold potential. Example 12. The system of Example 11, wherein the threshold potential is a second threshold potential, and wherein, to determine that the electrical characteristic of the signal supplied to the switch has reached the threshold, the control logic is configured to determine that the electrical characteristic of the signal supplied to the switch has reached the threshold in response to determining that the potential of the signal has reached a first threshold potential that is greater than the second threshold potential. Example 13. The system of any combination of Examples 11-12, wherein the first threshold potential is less than or equal to a breakdown voltage of the switch. Example 14. The system of any combination of examples 11-13, wherein, to determine that the electrical characteristic of the signal supplied to the switch has reached the threshold, the control logic is further configured to determine that the electrical characteristic of the signal supplied to the switch has reached the threshold in response to determining that a current level of the signal has reached a current level. Example 15. The system of any combination of Examples 11-15, wherein the control logic is further configured to determine an amount of power dissipated by the switch based on a current level of the signal; determine a power-time threshold for the switch based on a temperature of the switch; and determine that the electrical characteristic of the signal supplied to the switch has reached a threshold in response to determining that an amount of time for which the switch has dissipated the amount of power has reached the power-time threshold for the switch. Example 16. The system of any combination of examples 11-15, wherein the control logic is further configured to determine the power-time threshold for the switch based on one or more desired Bell characteristics of the switch. Example 17. The system of any combination of Examples 11-16, wherein the control logic is included in a switch driver, and wherein the control logic is further configured to, in response to determining that the electrical characteristic of the signal supplied to the switch has reached the threshold while the switch is deactivated: cause a memory device included in the switch driver to store a value indicating that an electrical transient event has occurred; and / or output a value to a device external to the switch driver indicating that an electrical transient event has occurred. Example 18. The system of any combination of Examples 11-17, wherein the signal is supplied to a plurality of switches, and wherein, to activate the switch in response to determining that the electrical characteristic of the signal supplied to the switch has reached the threshold value until determining that the potential of the signal supplied to the switch has reached the threshold potential, the control logic is configured to activate the plurality of switches in response to determining that the electrical characteristic of the signal supplied to the plurality of switches has reached the threshold value until determining that the potential of the signal supplied to the plurality of switches has reached the threshold potential. Example 19. The system of any combination of Examples 11-18, further comprising: one or more diodes electrically disposed between the drain and gate or the collector and base of the switch, wherein the one or more diodes are configured to activate the switch in response to a drain-to-gate or collector-to-base voltage of the switch exceeding a voltage threshold of one or more diodes. Example 20. A system or device comprising means for performing the method according to any combination of Examples 1-10.

[0071] The techniques discussed in this specification may be implemented, at least in part, in hardware, software, firmware, or a combination thereof. For example, various aspects of the described techniques may be implemented within one or more processors, including one or more microprocessors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other equivalent integrated or discrete logic circuitry, as well as a combination of these components. The term "processor" or "processing circuitry" may generally refer to any of the foregoing logic circuitry alone or in combination with other logic circuitry or other equivalent circuitry. A hardware-comprising controller may also perform one or more of the techniques of this disclosure.

[0072] This hardware, software, and firmware may be implemented within the same device or within separate devices to support the various operations and functions described in this disclosure. In addition, any of the described units, modules, or components may be implemented together or separately as discrete but interoperable logic devices. The representation of various features as modules or units is intended to highlight different functional aspects and does not necessarily imply that these modules or units must be implemented by separate hardware or software components. Rather, functionality associated with one or more modules or units may be implemented by separate hardware or software components, or integrated within common or separate hardware or software components.

[0073] Various examples have been described. These and other examples are within the scope of the following claims.

Claims

[1] A method comprising: selectively activating a switch (10) by means of control logic (12, 13) and based on a control signal; Activating the switch (10) by means of the control logic (12, 13) and regardless of the control signal in response to the determination that an electrical characteristic of a signal supplied to the switch (10) has reached a threshold value, while the switch (10) is deactivated until it is determined that a potential of the signal supplied to the switch (10) has reached a threshold potential; and Deactivating the switch (10) in response to determining that the potential of the signal supplied to the switch (10) has reached the threshold potential; wherein the determination that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold value comprises: Determining that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold in response to determining that a current level of the signal (I) has reached a current threshold. [2] A method comprising: selectively activating a switch (10) by means of control logic (12, 13) and based on a control signal; Activating the switch (10) by means of the control logic (12, 13) and regardless of the control signal in response to the determination that an electrical characteristic of a signal supplied to the switch (10) has reached a threshold value, while the switch (10) is deactivated until it is determined that a potential of the signal supplied to the switch (10) has reached a threshold potential; and Deactivating the switch (10) in response to determining that the potential of the signal supplied to the switch (10) has reached the threshold potential; wherein the determination that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold value comprises: Determining an amount of power dissipated by the switch (10) based on a current level of the signal (I); Determining a power-time threshold for the switch (10) based on a temperature (T) of the switch (10) and one or more desired Bell characteristics of the switch (10); and Determining that the electrical characteristic of the signal supplied to the switch (10) has reached a threshold in response to determining that a period of time for which the switch (10) has dissipated the amount of power has reached the power-time threshold for the switch (10). [3] The method according to claim 2, further comprising: Determining the power-time threshold for the switch (10) based on one or more desired Bell characteristics of the switch (10). [4] The method according to any one of claims 1 to 3, wherein the threshold potential is less than or equal to a breakdown voltage of the switch (10). [5] The method according to any one of claims 1 to 4, wherein the threshold potential is a second threshold potential, and wherein determining that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold comprises: Determining that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold in response to determining that the potential of the signal has reached a first threshold potential which is greater than the second threshold potential. [6] The method according to claim 5, wherein the first threshold potential is less than or equal to a breakdown voltage of the switch (10). [7] The method according to any one of claims 1 to 6, wherein the control logic (12, 13) is included in a switch driver (6A, 6B, 6C) and the method further comprises, in response to determining that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold value while the switch (10) is deactivated: storing a value indicating that an electrical transient event has occurred in a memory device contained in the switch driver (6A, 6B, 6C); and / or outputting a value indicating that an electrical transient event has occurred through the control logic (12, 13) and to a component external to the switch driver (6A, 6B, 6C). [8] The method according to any one of claims 1 to 7, wherein the signal is supplied to a plurality of switches (10), and wherein activating the switch (10) upon determining that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold value until determining that the potential of the signal supplied to the switch (10) has reached the threshold potential comprises: activating the plurality of switches (10) in response to determining that the electrical characteristic of the signal supplied to the plurality of switches (10) has reached the threshold value until determining that the potential of the signal supplied to the plurality of switches (10) has reached the threshold potential. [9] The method according to any one of claims 1 to 8, further comprising: activating the switch (10) in response to a drain-gate or collector-base voltage of the switch (10) exceeding a voltage threshold of one or more diodes (24, 30) by the one or more diodes (24, 30) electrically arranged between the drain and gate or the collector and base of the switch (10). [10] A system that has: a switch (10) configured to receive a signal; and Control logic (12, 13) designed to: selectively activate the switch (10) based on a control signal; to activate the switch (10) regardless of the control signal in response to the detection that an electrical characteristic of a signal supplied to the switch (10) reaches a threshold value, while the switch (10) is deactivated until it is detected that a potential of the signal supplied to the switch (10) reaches a threshold potential; and deactivating the switch (10) in response to determining that a potential of the signal supplied to the switch (10) reaches the threshold potential; wherein in order to determine that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold value, the control logic (12, 13) is further designed to to determine that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold value in response to determining that a current level of the signal (I) has reached a current threshold value. [11] A system that has: a switch (10) configured to receive a signal; and Control logic (12, 13) designed to: selectively activate the switch (10) based on a control signal; to activate the switch (10) regardless of the control signal in response to the detection that an electrical characteristic of a signal supplied to the switch (10) reaches a threshold value, while the switch (10) is deactivated until it is detected that a potential of the signal supplied to the switch (10) reaches a threshold potential; and deactivating the switch (10) in response to determining that a potential of the signal supplied to the switch (10) reaches the threshold potential; wherein, in order to determine that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold value, the control logic (12, 13) is further configured to: to determine an amount of power dissipated by the switch (10) based on a current level of the signal (I); to determine a power-time threshold for the switch (10) based on a temperature (T) of the switch (10); to determine that the electrical characteristic of the signal supplied to the switch (10) has reached a threshold in response to determining that a period of time for which the switch (10) has dissipated the amount of power has reached the power-time threshold for the switch (10). [12] The system of claim 11, wherein the control logic (12, 13) is further configured to determine the power-time threshold for the switch (10) based on one or more desired Bell characteristics of the switch (10). [13] The system according to any one of claims 10 to 12, wherein the threshold potential is a second threshold potential, and wherein, in order to determine that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold, the control logic (12, 13) is adapted to: determine that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold value in response to determining that the potential of the signal has reached a first threshold potential which is greater than the second threshold potential. [14] The system of claim 13, wherein the first threshold potential is less than or equal to a breakdown voltage of the switch (10). [15] The system according to any one of claims 10 to 14, wherein the control logic (12, 13) is included in a switch driver (6A, 6B, 6C), and wherein the control logic (12, 13) is further configured, in response to determining that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold value while the switch (10) is deactivated: to cause a memory device contained in the switch driver (6A, 6B, 6C) to store a value indicating that an electrical transient event has occurred; and / or output a value to a component external to the switch driver (6A, 6B, 6C) indicating that an electrical transient event has occurred. [16] The system according to any one of claims 10 to 15, wherein the signal is supplied to a plurality of switches (10), and wherein, in order to activate the switch (10) in response to the determination that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold value until it is determined that the potential of the signal supplied to the switch has reached the threshold potential, the control logic (12, 13) is arranged to: to activate the plurality of switches (10) in response to the determination that the electrical characteristic of the signal supplied to the plurality of switches (10) has reached the threshold value, until it is determined that the potential of the signal supplied to the plurality of switches (10) has reached the threshold potential. [17] The system according to any one of claims 10 to 16, further comprising: one or more diodes (24, 30) electrically arranged between the drain and the gate or the collector and the base of the switch (10), wherein the one or more diodes (24, 30) are configured to activate the switch (10) in response to a drain-gate or collector-base voltage of the switch (10) exceeding a voltage threshold of one or more diodes (24, 30). [18] A component that has: Means for selectively activating a switch (10) based on a control signal; Means for activating the switch (10) regardless of the control signal in response to determining that an electrical characteristic of a signal supplied to the switch (10) reaches a threshold value, while the switch (10) is deactivated until it is determined that a potential of the signal supplied to the switch (10) reaches a threshold potential; and means for determining that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold in response to determining that a current level of the signal (I) has reached a current threshold; Means for deactivating the switch (10) in response to detecting that the potential of the signal applied to the switch (10) reaches the threshold potential. [19] A component that has: Means for selectively activating a switch (10) based on a control signal; Means for activating the switch (10) regardless of the control signal in response to determining that an electrical characteristic of a signal supplied to the switch (10) reaches a threshold value, while the switch (10) is deactivated until it is determined that a potential of the signal supplied to the switch (10) reaches a threshold potential; Means for deactivating the switch (10) in response to determining that the potential of the signal applied to the switch (10) reaches the threshold potential; and means for determining that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold value, wherein the determination that the electrical characteristic of the signal supplied to the switch (10) has reached the threshold value comprises: Determining an amount of power dissipated by the switch (10) based on a current level of the signal (I); Determining a power-time threshold for the switch (10) based on a temperature (T) of the switch (10) and one or more desired Bell characteristics of the switch (10); and Determining that the electrical characteristic of the signal supplied to the switch (10) has reached a threshold in response to determining that a period of time for which the switch (10) has dissipated the amount of power has reached the power-time threshold for the switch (10).

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