Load switching system with miswiring detection and protection

Abstract

The invention relates to a load switching system with miswiring detection and protection. A load switch system and method of manufacture may include configuring a power switch to complete or interrupt a power circuit; the comparator is coupled with the low current comparator and is used for comparing the current with a low current threshold value and outputting a first current threshold value signal; coupling a filter to the low current comparator, the filter outputting the first current threshold signal after a predefined length of time; coupling a high current comparator to the current sensor, the high current comparator comparing the current to a high current threshold and outputting a second current threshold signal; and coupling a control logic to the low current comparator and to the high current comparator, the control logic opens the power switch and interrupts the power circuit based on the second current threshold signal output by the high current comparator or the first current threshold signal output by the filter.

Description

Technical Field

[0001] The present disclosure relates to industrial load switches, and more particularly to detection and protection against miswiring in high-side and low-side load switches. Background Art

[0002] Load switches are used in industrial settings to control the supply of power to a load. Load switches can be transistor-based, but any type of switch including discrete relays can also be employed. Furthermore, load switches can be of two types including high-side and low-side. Low-side load switches operate by completing or interrupting a ground connection in a power circuit between a power source and a load, while high-side load switches operate by completing or interrupting a supply connection in a power circuit between a power source and a load.

[0003] Load switches are capable of driving multiple loads at high currents and relatively high data rates in the hundreds of kilohertz range, where the loads are turned on and off quickly. The loads can be any type of load, but are typically factory hardware and tools, including actuators, motors, drives, integrated circuit boards, etc.

[0004] One problem that occurs with load switches is miswiring between the load switch and one of the many loads due to human error. Miswiring can occur during installation, maintenance, and upgrade procedures.

[0005] Miswiring can result in extended downtime, increased troubleshooting and repair costs, and can even result in damage or complete destruction of the load, the load switch, and the power supply used to power the load. To avoid damage caused by miswiring, previous developments implemented a current limiting trigger that would deactivate the switch within the load switch.

[0006] While these previous developments solved one problem, they also introduced other problems, including false triggering of the current limit trigger. False triggering can result when long connecting wires are used between the load switch and the load, which can allow large AC currents or ringing to be superimposed on the DC current supplied to the load.

[0007] If large enough, the AC current may appear to the current limit trigger as a miswiring and the current limit trigger will respond by closing the switches within the load switch for all loads connected to it and simultaneously opening the external reverse protection switch to ground or supply voltage. This can occur even if the load is properly connected to the load switch and can cause intermittent malfunction of the load.

[0008] In some cases, the load switch will perform multiple auto-retries, attempting to re-power the load after a time delay.During this auto-retry period, the load switch is closed and in a blind state.

[0009] Under these conditions, the load may fail to operate, and some power loads may lose power during operation, requiring a full or even manual reset, resulting in unacceptable tool downtime or unacceptable troubleshooting and repair costs. As a result, previous developments would intermittently and severely fail during normal operation due to false detections, and therefore lose functionality when implemented with long wires and capacitive loads common in industrial applications.

[0010] Solutions have long been sought, but prior developments have not taught or suggested any complete solutions, and solutions to these problems have long eluded those skilled in the art. Thus, there remains a great need for apparatus and methods that can provide reliable miswiring detection and protection for load switches in industrial environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] A load switch system is illustrated in the accompanying drawings, which are intended to be illustrative and not limiting, wherein like reference numerals are intended to refer to like components, and wherein:

[0012] Figure 1 is a block diagram of a load switch system in a low-side switch embodiment.

[0013] Figure 2 yes Figure 1 Block diagram of a load switch system under weak current miswiring.

[0014] Figure 3 yes Figure 1 Block diagram of a load switch system under high current miswiring.

[0015] Figure 4 Is a small LC Figure 1 Timing diagram of the load switch system.

[0016] Figure 5 It has a large LC Figure 1 Timing diagram of the load switch system.

[0017] Figure 6 It has an N-type low-side switch Figure 1 Schematic diagram of the switch module.

[0018] Figure 7 It has a universal switch Figure 1 Schematic diagram of the switch module.

[0019] Figure 8 is a block diagram of a load switch system in a high-side switch embodiment.

[0020] Fig. 9 It has an N-type high-side switch Figure 8Schematic diagram of the switch module.

[0021] Fig.10 It has a P-type high-side switch Figure 8 Schematic diagram of the switch module.

[0022] Fig.11 is a block diagram of a method of manufacturing a load switch system. DETAILED DESCRIPTION

[0023] In the following description, reference is made to the accompanying drawings which form a part hereof, and in which are shown by way of illustration embodiments in which the load switch system may be practiced. It should be understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the load switch system.

[0024] When features, aspects, or embodiments of a load switch system are described in terms of steps of a process, operation, control flow, or flowchart, it should be understood that the steps may be combined, performed in a different order, deleted, or include additional steps without departing from the load switch system as described herein.

[0025] The load switch system is described in sufficient detail to enable a person skilled in the art to make and use the load switch system, and numerous specific details are provided to give a thorough understanding of the load switch system; however, it will be apparent that the load switch system may be practiced without these specific details.

[0026] In order to avoid obscuring the load switch system, some well-known system configurations and descriptions are not disclosed in detail. Likewise, the drawings showing embodiments of the system are semi-schematic and not drawn to scale, and in particular, some dimensions are for clarity of presentation and are greatly exaggerated in the drawings. As used herein, the term "couple" as in "coupled" or "coupling" is defined as a direct or indirect physical connection between coupled elements.

[0027] Reference now Figure 1 , which shows a block diagram of a load switch system 100 in a low-side switch embodiment. The load switch system 100 may include a switch module 102, which includes at least one power switch, as described below with respect to Figure 6 and Figure 7 As shown and described.

[0028] The switch module 102 may be coupled to a plurality of loads 104 via connection lines 106. More specifically, the switch module 102 is shown to have a first output terminal 108 coupled to a first load 110, a second output terminal 112 coupled to a second load 114, and an nth output terminal 116 coupled to an nth load 118.

[0029] In an industrial environment, the connection line 106 may be very long, including lengths measured in kilometers. The switch module 102 may complete or interrupt a power circuit 120 between a power source 122 and one or more loads 104 .

[0030] The power source 122 may include a positive power source terminal 124 and a negative power source terminal 126. The power source circuit 120 may be composed of one of the loads 104 coupled to the positive power source terminal 124 and the negative power source terminal 126 via the connection line 106.

[0031] The load switch system 100 in the low-side switch embodiment selectively connects the negative power supply terminal 126 to the load 104 through the power switch in the switch module 102, while the load 104 is directly connected to the positive power supply terminal 124. The power circuit 120 can be completed individually for each of the loads 104, allowing current to flow through the load, thereby powering the load.

[0032] When interrupted by one of the power switches within switch module 102, current flow within power circuit 120 is shut off by removing the connection to ground and shutting off power to load 104. Switch module 102 may include switch module ground terminal 128, which is connected to negative power terminal 126 in normal operation.

[0033] The switch module 102 may optionally have a switch module positive terminal 130 coupled to the power source positive terminal 124 to provide power to the switch module 102. The switch module positive terminal 130 is depicted with a dashed line to indicate that the positive power connection 130 between the switch module 102 and the power source 122 is optional. When used, the positive power connection 130 can provide operating power to the switch module 102.

[0034] In the case or design where there is no connection between the switch module positive terminal 130 and the power supply positive terminal 124, the switch module 102 can be coupled to an auxiliary power supply 132, which can be located on the backplane. When the auxiliary power supply 132 is used, the auxiliary power supply 132 can provide power to the switch module 102 and provide power to activate the power switch within the switch module 102.

[0035] The auxiliary power supply 132 may provide both an auxiliary power positive terminal 134 and an auxiliary power negative terminal 136 to the switch module 102. The auxiliary power supply 132 may be electrically isolated from the power supply 122 or not.

[0036] Reference now Figure 2 , which shows Figure 11 is a block diagram of a load switch system 100 in a weak current miswiring condition. In this exemplary miswiring configuration, the switch module 102 is shown as having an nth output terminal 116 coupled to a negative power supply terminal 126 via one of the connection lines 106 .

[0037] In addition, the switch module ground terminal 128 is connected to the nth load 118 through another connection line 106. This miswiring configuration will cause the nth load 118 to be continuously turned on.

[0038] The current through the power circuit 120 will be the voltage of the power source 122 divided by the resistance of the nth load 118. This is considered a weak current because the load 104 can be designed to handle this current for a short time before being damaged by the current.

[0039] Reference now Figure 3 , which shows Figure 1 1. Block diagram of a load switch system 100 under high current miswiring. In this exemplary miswiring configuration, the switch module 102 is shown without the optional switch module positive terminal 130 coupled to the power supply positive terminal 124, but rather utilizing an auxiliary power supply 132 for powering within the switch module 102.

[0040] In addition, the switch module 102 is shown having an nth output 116 coupled to a negative power supply terminal 126 via one of the connection lines 106, and the nth load 118 remains open and not connected to the switch module 102. The positive power supply terminal 124 is shown connected to a switch module ground terminal 128 via another of the connection lines 106.

[0041] This miswiring configuration will send a high current from the power supply 122 through the auxiliary power supply negative terminal 136 which is limited only by the current capability of the power supply 122. This high current can damage the auxiliary power supply 132 and components within the switch module 102.

[0042] That is, a high current miswiring may be as high as 10 amps or 20 amps. This requires a very short microsecond detection time to turn off all power switches in the switch module 102.

[0043] Reference now Figure 4 , which shows a small LC Figure 1 The timing diagram of the load switch system 100 is measured in square seconds. The "L" component of the LC property may be due to Figure 1 The “C” component of the LC properties may be due to the long connecting line 106. Figure 4 caused by the capacitance of the remote load 104.

[0044] The load switch system 100 can be configured by Figure 1One of the power switches in the switch module 102 starts the DC voltage 402 through one of the loads to complete Figure 1 1. The DC voltage 402 is represented in the top timing diagram, where the voltage measured in volts is indicated along the vertical axis and the time measured in microseconds is indicated along the horizontal axis.

[0045] The DC voltage 402 may initiate a current 404 through the power circuit 120. The current 404 is represented in the bottom timing diagram, where current (I) in amperes is indicated along the vertical axis and time measured in microseconds is indicated along the horizontal axis, and where the horizontal axis represents zero amperes.

[0046] As can be seen, the current 404 may be a forward current (I) above the horizontal axis and a reverse current (ITH) below the horizontal axis. IDC represents the DC current that the load 104 is designed to receive when the power circuit 120 is completed.

[0047] ITH_low represents a low reverse current detection threshold of a low-side switch or a high-side switch. The low reverse current detection threshold ITH_low may be exceeded when the current 404 is a larger reverse current than indicated by the low reverse current detection threshold.

[0048] ITH_high represents a high reverse current detection threshold for a low-side switch or a high-side switch. The high reverse current detection threshold ITH_high may be exceeded when the current 404 is a larger reverse current than indicated by the high reverse current detection threshold.

[0049] I_LIM represents the current limit level of the switch in case of permanent high current condition. IPK represents the peak current due to small LC ringing. IPK is not controlled by the load switch system 100 and is not a parameter set by the switch module 102.

[0050] Current 404 is shown to oscillate between forward current and reverse current, which is called ringing. The ringing can come from the inductance of the connecting wire 106, which can be thousands of meters long, and the capacitance can come from the load 104, which can have a large capacitance of millifarads. This ringing can produce a reverse current detection event 406.

[0051] If a reverse current detection event 406 occurs, the switch module 102 will shut down all power switches within the switch module 102. In some cases, this switch shutdown event may last for several seconds, and some switch modules 102 will initiate a reset sequence, which may sometimes repeat over multiple cycles and take the switch module 102 offline for even longer periods of time.

[0052] When a reverse current detection event 406 occurs due to ringing, the switch module 102 should not handle the reverse current detection event 406 in this manner because it interferes with the normal operation of the system. Instead, the connection line 106 and the load 104 should be given a settling time for the ringing current to stabilize or "settling" to the desired IDC current.

[0053] For example, the settling time may be the average time that the current takes to oscillate between I_PK and ITH_low. It is also contemplated that the settling time may be the maximum time that the current takes to oscillate within a predetermined percentage of IDC. However, it is further contemplated that the settling time may be the maximum time that the current takes to oscillate above ITH_low.

[0054] An immediate interruption of the power circuit 120 should not be initiated because the load 104 is designed to handle the current involved in the ringing. The high reverse current detection threshold (ITH_high) should be greater than the peak current induced by the ringing.

[0055] Reference now Figure 5 , which shows a large LC Figure 1 The “L” component of the large LC property may be due to Figure 1 The “C” component of the large LC property may be caused by the long connecting line 106 , while the remote load 104 may be caused.

[0056] The load switch system 100 can be configured by Figure 1 The DC voltage 502 is started by one of the power switches in the switch module 102 through one of the loads 104 to complete Figure 1 1. The DC voltage 502 is represented in the top timing diagram, where the voltage measured in volts is indicated along the vertical axis and the time measured in microseconds is indicated along the horizontal axis.

[0057] The DC voltage 502 may initiate a current 504 through the power circuit 120. The current 504 is represented in the bottom timing diagram, where current in amperes is indicated along the vertical axis and time measured in microseconds is indicated along the horizontal axis, and where the horizontal axis represents zero amperes.

[0058] Current 504 is depicted as forward current (I) above the horizontal axis and reverse current (ITH) below the horizontal axis. IDC represents the DC current that load 104 is designed to receive when power circuit 120 is complete. Current 504 is shown as oscillating around IDC, with current 404 slowly rising to exceed I_LIM and cause a current limit event 506.

[0059] Reference now Figure 6 , which shows an N-type low-side switch Figure 1 Schematic diagram of the switch module 102. The switch can be any type of switch, including field effect transistors, bipolar transistors, or relays. N-type low-side switches are depicted as power switch 602 and protection switch 604.

[0060] The power switches 602 are shown as a first power switch 606 and an nth power switch 608. The first power switch 606 may provide the first output terminal 108 of the switch module 102.

[0061] When activated, the first power switch 606 can connect the first output terminal 108 to the internal ground 610. The internal ground 610 is internal to the switch module 102 and can be Figure 1 Auxiliary power supply 132 or Figure 1 The power supply 122 is provided.

[0062] Similarly, the nth power switch 608 can provide the nth output terminal 116 and can connect the nth output terminal 116 to the internal ground 610 when activated. For clarity of description, other output terminals (such as Figure 1 The power switch 602 of the second output terminal 112) is not shown, but has the same structure and operation as that depicted.

[0063] The power switches 602 are individually configured to complete the connection between the power source 122 and one of the loads 104 when activated. Figure 1 The power circuit 120 of the embodiment of the present invention is configured to interrupt the power circuit 120 when deactivated. The power switch 602 can be activated and deactivated by a switch driver 612, which can provide a drive signal for activating and deactivating the power switch 602.

[0064] The switch driver 612 can provide a low activation voltage (such as Figure 5 A DC voltage of 502 or Figure 4 The DC voltage 402 is used to activate the power switch 602. The switch driver 612 and the power switch 602 can be powered by the auxiliary power supply 132.

[0065] Between the internal ground 610 and the power switch 602, a current can be detected. This current can be Figure 5 The current 504 or Figure 4 The current 404 is the current within the power circuit 120. The current from each of the power switches 602 can be detected by a separate current sensor 614.

[0066] A separate current sensor 614 is located between each of the power switches 602 and the protection switch 604. The output of the current sensor 614 may be input into a current-to-voltage converter 616. The current-to-voltage converter 616 may be an operational amplifier based component that may output a voltage that is linearly related to the input current.

[0067] The output of the current-to-voltage converter 616 may be input to a low current comparator 618. The low current comparator 618 compares the current to a low current threshold 620 (such as Figure 4 The low reverse current detection threshold ITH_low) is compared, and a first current threshold signal is output based on the current exceeding the low current threshold 620.

[0068] The output of the low current comparator 618 indicates a first current threshold signal or a non-first current threshold signal. The non-first current threshold signal is a signal based on the current not exceeding the low current threshold 620. The output of the low current comparator 618 is input into an internal de-jitter filter 622.

[0069] If the current exceeds the low current threshold 620 for a predefined length of time, the internal de-jitter filter 622 may output a state change from a non-first current threshold signal to a first current threshold signal. The predefined length of time may be the duration of a current settling time of a ringing current through the power supply circuit 120. Illustratively, for example, it has been found that using the current settling time of the ringing current as the predefined length of time for the internal de-jitter filter 622 provides an unexpected solution for the ringing current through the power supply circuit 120 because when there is a weak miswiring (such as Figure 2 ), the current ringing is allowed to continue for a sufficient length of time to self-correct without causing the power circuit 120 to remain activated.

[0070] Thus, such implementation of the internal jitter removal filter 622 may prevent the power supply circuit 120 from being interrupted during normal operation.The predefined time length of the internal jitter removal filter 622 may vary based on the frequency of the ringing.

[0071] The output of the current-to-voltage converter 616 may also and additionally be input to a high current comparator 624. The high current comparator 624 compares the current to a high current threshold 626 (such as Figure 4 The high reverse current detection threshold ITH_high) is compared, and a second current threshold signal is output based on the current exceeding the high current threshold 626.

[0072] The output of the high current comparator 624 indicates either a second current threshold signal or a non-second current threshold signal. The non-second current threshold signal is a signal based on the current not exceeding the high current threshold 626. The high current comparator 624 is not shown coupled to the internal debouncing filter because the second current threshold signal output of the high current comparator 624 can be a signal of a high current miswiring (such as Figure 3 An indication of a high current miswiring as depicted in FIG.

[0073] Since the second current threshold signal can indicate a high current miswiring, it should be processed quickly, which makes the internal de-jitter filter an impractical solution in most cases. The outputs of the high current comparator 624 and the internal de-jitter filter 622 can be input into an OR logic gate 628, which can output a digital signal indicating that the second current threshold signal from the high current comparator 622 is present, the first current threshold signal from the internal de-jitter filter 624 is present, or both signals are present.

[0074] If the second current threshold signal is not present, and the first current threshold signal is not present, then OR logic gate 628 will indicate that the current has neither exceeded the low current threshold 620 nor the high current threshold 626 .

[0075] Although the low current comparator 618 and the high current comparator 624 are depicted as being based on operational amplifiers, any circuit that provides a comparison function is contemplated. The low current comparator 618 and the high current comparator 624 may be coupled to the control logic 630. The control logic 630 may be coupled to the high current comparator 624 via an OR logic gate 628, while the control logic 630 may be coupled to the low current comparator 618 via an OR logic gate 628 and an internal de-jitter filter 622.

[0076] Based on the second current threshold signal output by the high current comparator 624 or the first current threshold signal output by the internal de-jitter filter 622, the control logic 630 turns on each of the power switches 602 and interrupts the power circuit 120. More specifically, the control logic 630 can provide a signal to the switch driver 612, which will turn on the power switch 602.

[0077] Control logic 630 may also provide a signal to protection switch 604 to connect internal ground 610 and power switch 602 to external ground 632 , which may be a true earth ground. Protection switch 604 may be coupled to power switch 602 and to control logic 630 .

[0078] Protection switch 604 exposes power circuit 120 to an external connection based on the second current threshold signal output by high current comparator 624 or the first current threshold signal output by internal debouncing filter 622. The external connection may be an external ground for a low-side switch and an external voltage for a high-side switch.

[0079] Reference now Figure 7 , which shows a general switch Figure 1 Schematic diagram of the switch module 102. The common switches may be relays and are depicted as a power switch 702 and a protection switch 704.

[0080] The power switches 702 are shown as a first power switch 706 and an nth power switch 708. The first power switch 706 may provide the first output terminal 108 of the switch module 102.

[0081] When activated, the first power switch 706 can connect the first output terminal 108 to the internal ground 710. The internal ground 710 is internal to the switch module 102 and can be Figure 1 Auxiliary power supply 132 or Figure 1 The power supply 122 is provided.

[0082] Similarly, the nth power switch 708 can provide the nth output terminal 116 and can connect the nth output terminal 116 to the internal ground 710 when activated. For clarity of description, other output terminals (such as Figure 1 The power switch 702 of the second output terminal 112) is not shown, but has the same structure and operation as that depicted.

[0083] The power switches 702 are individually configured to complete the connection between the power source 122 and one of the loads 104 when activated. Figure 1 The power circuit 120 of the embodiment of the present invention is configured to interrupt the power circuit 120 when deactivated. The power switch 702 can be activated and deactivated by a switch driver 712, which can provide a drive signal for activating and deactivating the power switch 702.

[0084] The switch driver 712 can provide a low activation voltage (such as Figure 5 A DC voltage of 502 or Figure 4 The DC voltage 402 is used to activate the power switch 702. The switch driver 712 and the power switch 702 can be powered by the auxiliary power supply 132.

[0085] Between the internal ground 710 and the power switch 702, a current can be detected. This current can be Figure 5 The current 504 or Figure 4The current 404 is the current within the power circuit 120. The current from each of the power switches 702 can be detected by a separate current sensor 714.

[0086] A separate current sensor 714 may be located between each of the power switches 702 and the protection switch 704. The output of the current sensor 714 may be input into a current-to-voltage converter 716. The current-to-voltage converter 716 may be an operational amplifier based component that may output a voltage that is linearly related to the input current.

[0087] The output of the current-to-voltage converter 716 may be input to a low current comparator 718. The low current comparator 718 compares the current to a low current threshold 720 (such as Figure 4 The low reverse current detection threshold ITH_low) is compared, and a first current threshold signal is output based on the current exceeding the low current threshold 720.

[0088] The output of the low current comparator 718 indicates a first current threshold signal or a non-first current threshold signal. The non-first current threshold signal is a signal based on the current not exceeding the low current threshold 720. The output of the low current comparator 718 is input into an internal jitter elimination filter 722.

[0089] If the current exceeds the low current threshold 720 for a predefined length of time, the internal de-jitter filter 722 may output a state change from a non-first current threshold signal to a first current threshold signal. Illustratively, for example, it has been found that using the current settling time of the ringing current as the predefined length of time for the internal de-jitter filter 722 provides an unexpected solution to the ringing current through the power supply circuit 120 because when there is a weak miswiring (such as Figure 2 ), the current ringing is allowed to continue for a sufficient length of time to self-correct without causing the power circuit 120 to remain activated.

[0090] Thus, such implementation of the internal jitter removal filter 722 may prevent the power supply circuit 120 from being interrupted during normal operation.The predefined time length of the internal jitter removal filter 722 may vary based on the frequency of the ringing.

[0091] The output of the current-to-voltage converter 716 may also and additionally be input to a high current comparator 724. The high current comparator 724 compares the current to a high current threshold 726 (such as Figure 4 The high reverse current detection threshold ITH_high) is compared, and a second current threshold signal is output based on the current exceeding the high current threshold 726.

[0092] The output of the high current comparator 724 indicates a second current threshold signal or a non-second current threshold signal. The non-second current threshold signal is a signal based on the current not exceeding the high current threshold 726. The high current comparator 724 is not shown coupled to the internal debouncing filter because the second current threshold signal output from the high current comparator 724 can be a high current miswiring (such as Figure 3 An indication of a high current miswiring as depicted in FIG.

[0093] Since the second current threshold signal may indicate a high current miswiring, it should be processed quickly, which makes the internal de-bouncing filter an impractical solution in most cases. The outputs of the high current comparator 724 and the internal de-bouncing filter 722 may be input into an OR logic gate 728, which may output a digital signal indicating the presence of the second current threshold signal from the high current comparator 724, the presence of the first current threshold signal from the internal de-bouncing filter 722, or the presence of both signals.

[0094] If the second current threshold signal is not present, and the first current threshold signal is not present, then OR logic gate 728 will indicate that the current has neither exceeded the low current threshold 720 nor the high current threshold 726 .

[0095] Low current comparator 718 and high current comparator 724 may be coupled to control logic 730. Control logic 730 may be coupled to high current comparator 724 through OR logic gate 728, while control logic 730 may be coupled to low current comparator 718 through OR logic gate 728 and internal de-jitter filter 722.

[0096] Based on the second current threshold signal output by the high current comparator 724 or the first current threshold signal output by the internal de-jitter filter 722, the control logic 730 turns on each of the power switches 702 and interrupts the power circuit 120. More specifically, the control logic 730 can provide a signal to the switch driver 712, which will turn on the power switch 702.

[0097] Control logic 730 may also provide a signal to protection switch 704 to connect internal ground 710 and power switch 702 to external ground 732 , which may be a true earth ground. Protection switch 704 may be coupled to power switch 702 and to control logic 730 .

[0098] Protection switch 704 exposes power circuit 120 to an external connection based on the second current threshold signal output by high current comparator 724 or the first current threshold signal output by internal debouncing filter 722. The external connection may be an external ground for a low-side switch or an external voltage for a high-side switch.

[0099] Reference now Figure 8 , which shows a block diagram of a load switch system 800 in a high-side switch embodiment. The load switch system 800 may include a switch module 802, which includes at least one power switch, as described below with respect to Fig. 9 and Fig.10 As shown and described.

[0100] The switch module 802 may be coupled to a plurality of loads 804 via connection lines 806. More specifically, the switch module 802 is shown to have a first output terminal 808 coupled to a first load 810, a second output terminal 812 coupled to a second load 814, and an nth output terminal 816 coupled to an nth load 818.

[0101] In an industrial environment, the connection line 806 may be very long, including lengths measured in kilometers. The switch module 802 may complete or interrupt a power circuit 820 between a power source 822 and one or more loads 804 .

[0102] The power source 822 may include a positive power source terminal 824 and a negative power source terminal 826. The power source circuit 820 may be composed of one of the loads 804, which is coupled to the positive power source terminal 824 and the negative power source terminal 826 via the connection line 806.

[0103] The load switch system 800 in the high-side switch embodiment selectively connects the load 804 to the positive power terminal 824 through the power switch in the switch module 802, while the load 804 can be directly connected to the negative terminal 826. The power circuit 820 can be completed individually for each of the loads 804, allowing current to flow through the load, thereby powering the load.

[0104] When interrupted by one of the power switches within the switch module 802, current flow within the power circuit 820 is cut off by removing the connection to the power positive terminal 824 and disconnecting power to the load 804. The switch module 802 may include a switch module ground terminal 828, which in normal operation is connected to the power negative terminal 826. The switch module 802 is also shown as having a switch module positive terminal 830 coupled to the power positive terminal 824, thereby providing power to the switch module 802.

[0105] Reference now Fig. 9 , which shows an N-type high-side switch Figure 8 Schematic diagram of a switch module 802. N-type high-side switches are depicted as power switch 902 and protection switch 904.

[0106] The power switches 902 are shown as a first power switch 906 and an nth power switch 908. The first power switch 906 may provide a first output terminal 808 of the switch module 802.

[0107] When activated, the first power switch 906 can connect the first output terminal 808 to the internal voltage 910. The internal voltage 910 is internal to the switch module 802 and can be connected to the internal voltage 910. Figure 8 The positive power terminal 824 is provided.

[0108] Similarly, the nth power switch 908 can provide an nth output terminal 816 and can connect the nth output terminal 816 to the internal voltage 910 when activated. For clarity of description, other output terminals (such as Figure 8 The power switch 902 of the second output terminal 812) is not shown, but has the same structure and operation as that depicted.

[0109] The power switches 902 are individually configured to complete Figure 8 Power supply 822 and Figure 8 One of the loads 804 is between Figure 8 The power circuit 820 of the embodiment of the present invention is connected to the power circuit 820 of the embodiment of the present invention, and is configured to interrupt the power circuit 820 when deactivated. The power switch 902 can be activated and deactivated by a switch driver 912, which can provide a drive signal for activating and deactivating the power switch 902. The switch driver 912 can provide a high activation voltage (such as a high DC voltage) for activating the power switch 902.

[0110] Between the internal voltage 910 and the power switch 902 , a current can be detected. The current through the high-side switch will be the forward current in the power circuit 820 .

[0111] The current from each of the power switches 902 may be detected by an individual current sensor 914. The individual current sensor 914 is located between each of the power switches 902 and the protection switch 904.

[0112] The output of the current sensor 914 may be input into a current-to-voltage converter 916. The current-to-voltage converter 916 may be an operational amplifier based component that may output a voltage that is linearly related to the input current.

[0113] The output of the current-to-voltage converter 916 may be input to a low current comparator 918. The low current comparator 918 compares the current to a low current threshold 920 (such as Figure 4 The low reverse current detection threshold ITH_low) is compared, and a first current threshold signal is output based on the current exceeding the low current threshold 920.

[0114] The output of the low current comparator 918 indicates a first current threshold signal or a non-first current threshold signal. The non-first current threshold signal is a signal based on the current not exceeding the low current threshold 920. The output of the low current comparator 918 is input into an internal jitter elimination filter 922.

[0115] If the current exceeds the low current threshold 920 for a predefined length of time, the internal de-jitter filter 922 may output a state change from a non-first current threshold signal to a first current threshold signal. Illustratively, for example, it has been found that using the current settling time of the ringing current as the predefined length of time for the internal de-jitter filter 922 provides an unexpected solution to the ringing current through the power circuit 820 because when there is a weak miswiring, the current ringing is allowed to continue for a sufficient length of time to self-correct without causing the power circuit 820 to remain activated, similar to Figure 2 as depicted, except that load 804 would be miswired to connect to Figure 8 The power supply positive terminal 824 or the switch module positive terminal 830 instead of the load output terminal of the switch module 802.

[0116] Thus, this implementation of the internal jitter removal filter 922 prevents the power supply circuit 820 from being interrupted during normal operation.The predefined time length of the internal jitter removal filter 922 may vary based on the frequency of the ringing.

[0117] The output of the current-to-voltage converter 916 may also and additionally be input to a high current comparator 924. The high current comparator 924 compares the current to a high current threshold 926 (such as Figure 4 The high reverse current detection threshold ITH_high) is compared, and a second current threshold signal is output based on the current exceeding the high current threshold 926.

[0118] The output of the high current comparator 924 indicates a second current threshold signal or a non-second current threshold signal. The non-second current threshold signal is a signal based on the current not exceeding the high current threshold 926. The high current comparator 924 is not shown coupled to the internal de-jitter filter because the second current threshold signal output from the high current comparator 924 can be Figure 3 Similar instructions for high current miswiring as depicted in the high current miswiring diagram, but Figure 8 The negative power supply terminal 826 is connected to the switch module positive terminal 830 , and the positive power supply terminal 824 is coupled to the output end of the switch module 802 .

[0119] Since the second current threshold signal may indicate a high current miswiring, it should be processed quickly, which makes the internal de-bouncing filter an impractical solution in most cases. The outputs of the high current comparator 924 and the internal de-bouncing filter 922 may be input into an OR logic gate 928, which may output a digital signal indicating the presence of the second current threshold signal from the high current comparator 924, the presence of the first current threshold signal from the internal de-bouncing filter 922, or the presence of both signals.

[0120] If the second current threshold signal is not present, and the first current threshold signal is not present, then OR logic gate 928 will indicate that the current has neither exceeded the low current threshold 920 nor the high current threshold 926 .

[0121] Low current comparator 918 and high current comparator 924 may be coupled to control logic 930. Control logic 930 may be coupled to high current comparator 924 through OR logic gate 928, while control logic 930 may be coupled to low current comparator 918 through OR logic gate 928 and internal de-jitter filter 922.

[0122] Based on the second current threshold signal output by the high current comparator 924 or the first current threshold signal output by the internal de-jitter filter 922, the control logic 930 turns on each of the power switches 902 and interrupts the power circuit 820. More specifically, the control logic 930 can provide a signal to the switch driver 912, which will turn on the power switch 902.

[0123] The control logic 930 may also provide a signal to the protection switch 904 to connect the internal voltage 910 and the power switch 902 to the external voltage 932. The protection switch 904 may be coupled to the power switch 902 and to the control logic 930.

[0124] The protection switch 904 exposes the power circuit 820 to an external connection based on the second current threshold signal output by the high current comparator 924 or the first current threshold signal output by the internal debouncing filter 922. The external connection can be an external ground for the low-side switch and an external voltage for the high-side switch, such as Figure 8 The switch module ground terminal 828 for the power supply 822.

[0125] Reference now Fig.10 , which shows a P-type high-side switch Figure 8 Schematic diagram of the switch module 802. P-type high-side switches are depicted as power switch 1002 and protection switch 1004.

[0126] The power switches 1002 are shown as a first power switch 1006 and an nth power switch 1008. The first power switch 1006 may provide a first output terminal 808 of the switch module 802.

[0127] When activated, the first power switch 1006 can connect the first output terminal 808 to the internal voltage 1010. The internal voltage 1010 is internal to the switch module 802 and can be connected to the internal voltage 1010. Figure 8 The positive power terminal 824 is provided.

[0128] Similarly, the nth power switch 1008 can provide an nth output terminal 816 and can connect the nth output terminal 816 to the internal voltage 1010 when activated. For clarity of description, other output terminals (such as Figure 8 The power switch 1002 of the second output terminal 812) is not shown, but has the same structure and operation as that depicted.

[0129] The power switches 1002 are individually configured to complete the switching between the power source 822 and one of the loads 804 when activated. Figure 8 The power circuit 820 of the embodiment of the present invention is connected to the power circuit 820 of the embodiment of the present invention, and is configured to interrupt the power circuit 820 when deactivated. The power switch 1002 can be activated and deactivated by a switch driver 1012, which can provide a drive signal for activating and deactivating the power switch 1002. The switch driver 1012 can provide a high activation voltage (such as a high DC voltage) for activating the power switch 1002.

[0130] Between the internal voltage 1010 and the power switch 1002 , a current can be detected. The current through the high-side switch will be the forward current in the power circuit 820 .

[0131] The current from each of the power switches 1002 may be detected by an individual current sensor 1014. The individual current sensor 1014 is located between each of the power switches 1002 and the protection switch 1004.

[0132] The output of the current sensor 1014 may be input into a current-to-voltage converter 1016. The current-to-voltage converter 1016 may be an operational amplifier based component that may output a voltage that is linearly related to the input current.

[0133] The output of the current-to-voltage converter 1016 may be input to a low current comparator 1018. The low current comparator 1018 compares the current to a low current threshold 1020 (such as Figure 4 The low reverse current detection threshold ITH_low) is compared, and a first current threshold signal is output based on the current exceeding the low current threshold 1020.

[0134] The output of the low current comparator 1018 indicates a first current threshold signal or a non-first current threshold signal. The non-first current threshold signal is a signal based on the current not exceeding the low current threshold 1020. The output of the low current comparator 1018 is input into an internal de-jitter filter 1022.

[0135] If the current exceeds the low current threshold 1020 for a predefined length of time, the internal de-jitter filter 1022 may output a state change from a non-first current threshold signal to a first current threshold signal. Illustratively, for example, it has been found that using the current settling time of the ringing current as the predefined length of time for the internal de-jitter filter 1022 provides an unexpected solution to the ringing current through the power circuit 820 because when there is a weak miswiring, the current ringing is allowed to continue for a sufficient length of time to self-correct without causing the power circuit 820 to remain activated, similar to Figure 2 as depicted, except that load 804 would be miswired to connect to Figure 8 The power supply positive terminal 824 or the switch module positive terminal 830 instead of the load output terminal of the switch module 802.

[0136] Thus, this implementation of the internal jitter removal filter 1022 prevents the power supply circuit 820 from being interrupted during normal operation. The predefined time length of the internal jitter removal filter 1022 may vary based on the frequency of the ringing.

[0137] The output of the current-to-voltage converter 1016 may also and additionally be input to a high current comparator 1024. The high current comparator 1024 compares the current to a high current threshold 1026 (such as Figure 4 The high reverse current detection threshold ITH_high) is compared, and a second current threshold signal is output based on the current exceeding the high current threshold 1026.

[0138] The output of the high current comparator 1024 indicates a second current threshold signal or a non-second current threshold signal. The non-second current threshold signal is a signal based on the current not exceeding the high current threshold 1026. The high current comparator 1024 is not shown coupled to the internal de-jitter filter because the second current threshold signal output from the high current comparator 1024 can be Figure 3 Similar instructions for high current miswiring as depicted in the high current miswiring diagram, but Figure 8 The negative power supply terminal 826 is connected to the switch module positive terminal 830 , and the positive power supply terminal 824 is coupled to the output of the switch module 802 .

[0139] Since the second current threshold signal may indicate a high current miswiring, it should be processed quickly, which makes the internal de-jitter filter an impractical solution in most cases. The outputs of the high current comparator 1024 and the internal de-jitter filter 1022 may be input into an OR logic gate 1028, which may output a digital signal indicating the presence of the second current threshold signal from the high current comparator 1024, the presence of the first current threshold signal from the internal de-jitter filter 1022, or the presence of both signals.

[0140] If the second current threshold signal is not present, and the first current threshold signal is not present, then OR logic gate 1028 will indicate that the current has neither exceeded the low current threshold 1020 nor the high current threshold 1026 .

[0141] The low current comparator 1018 and the high current comparator 1024 may be coupled to the control logic 1030. The control logic 1030 may be coupled to the high current comparator 1024 through the OR logic gate 1028, while the control logic 1030 may be coupled to the low current comparator 1018 through the OR logic gate 1028 and the internal de-jitter filter 1022.

[0142] Based on the second current threshold signal output by the high current comparator 1024 or the first current threshold signal output by the internal de-jitter filter 1022, the control logic 1030 turns on each of the power switches 1002 and interrupts the power circuit 820. More specifically, the control logic 1030 can provide a signal to the switch driver 1012, which will turn on the power switch 1002.

[0143] The control logic 1030 may also provide a signal to the protection switch 1004 to connect the internal voltage 1010 and the power switch 1002 to the external voltage 1032. The protection switch 1004 may be coupled to the power switch 1002 and to the control logic 1030.

[0144] Protection switch 1004 exposes power circuit 820 to external connections based on the second current threshold signal output by high current comparator 1024 or the first current threshold signal output by internal debouncing filter 1022. The external connections may be external ground for the low side switch and external voltage for the high side switch.

[0145] Reference now Fig.11, which shows a block diagram of a method for manufacturing a load switch system. The manufacturing method may include, in block 1102, configuring a power switch to complete or interrupt a power circuit between a power source and a load; in block 1104, configuring a current sensor to detect a current in the power circuit; in block 1106, coupling a low current comparator to the current sensor, the low current comparator comparing the current with a low current threshold and outputting a first current threshold signal based on the current exceeding the low current threshold; in block 1108, coupling an internal jitter elimination filter to the low current comparator, the internal jitter elimination filter outputting a first current threshold signal based on the first current threshold signal remaining activated for a predefined length of time; in block 1110, coupling a high current comparator to the current sensor; A sensor, a high current comparator compares the current with a high current threshold and outputs a second current threshold signal based on the current exceeding the high current threshold; in box 1112, a control logic is coupled to the low current comparator and to the high current comparator, the control logic opens the power switch and interrupts the power circuit based on the second current threshold signal output by the high current comparator or the first current threshold signal output by the internal jitter elimination filter; and in box 1114, a protection switch is coupled to the power switch and to the control logic, the protection switch exposes the power circuit to an external connection based on the second current threshold signal output by the high current comparator or the first current threshold signal output by the internal jitter elimination filter.

[0146] Thus, it has been discovered that a load switch system provides important and heretofore unknown and unavailable solutions, capabilities and functional aspects. The resulting configuration is straightforward, cost-effective, uncomplicated, highly versatile, precise, sensitive and efficient, and can be implemented by modifying known components to facilitate rapid, effective and economical manufacture, application and utilization.

[0147] The load switch system prevents intermittent false detection and loss of functionality when using long wires and capacitive loads common in industrial applications. The load switch system thus provides reliable miswiring detection and protection for load switches in industrial environments.

[0148] Although the load switch system has been described in conjunction with a specific best mode, it should be understood that many alternatives, modifications and variations will be apparent to those skilled in the art based on the foregoing description. Therefore, it is intended to cover all such alternatives, modifications and variations that fall within the scope of the included claims. All matters set forth herein or shown in the accompanying drawings should be interpreted in an illustrative and non-restrictive sense.

Claims

1. A load switch system, comprising: a power switch configured to complete or interrupt a power circuit between a power source and a load; a current sensor configured to detect a current in the power circuit; a low current comparator coupled to the current sensor, the low current comparator comparing the current to a low current threshold and outputting a first current threshold signal based on the current exceeding the low current threshold; a filter coupled to the low current comparator, the filter outputting the first current threshold signal based on the first current threshold signal remaining active for a predefined length of time; a high current comparator coupled to the current sensor, the high current comparator comparing the current to a high current threshold and outputting a second current threshold signal based on the current exceeding the high current threshold; as well as A control logic is coupled to the low current comparator and to the high current comparator, and the control logic opens the power switch and interrupts the power circuit based on the second current threshold signal output by the high current comparator or the first current threshold signal output by the filter.

2. The system according to claim 1, further comprising: A current-to-voltage converter is coupled to the current sensor, the current-to-voltage converter converting the current from the current sensor into a voltage for comparison by the high current comparator and the low current comparator.

3. The system of claim 1, further comprising: An OR logic gate is coupled to a filter output of the filter and to a comparator output of the high current comparator.

4. The system of claim 1, further comprising: An auxiliary power source is coupled to the power switch, the auxiliary power source providing power to activate the power switch.

5. The system of claim 1, further comprising: A switch driver is coupled to the power switch, the switch driver providing a drive signal to the power switch.

6. A load switch system, comprising: a power switch configured to complete or interrupt a power circuit between a power source and a load; a current sensor configured to detect a current in the power circuit; a low current comparator coupled to the current sensor, the low current comparator comparing the current to a low current threshold and outputting a first current threshold signal based on the current exceeding the low current threshold; a filter coupled to the low current comparator, the filter outputting the first current threshold signal based on the first current threshold signal remaining active for a predefined length of time; a high current comparator coupled to the current sensor, the high current comparator comparing the current to a high current threshold and outputting a second current threshold signal based on the current exceeding the high current threshold; a control logic coupled to the low current comparator and to the high current comparator, the control logic turning on the power switch and interrupting the power circuit based on the second current threshold signal output by the high current comparator or the first current threshold signal output by the filter; as well as A protection switch is coupled to the power switch and the control logic, the protection switch exposing the power circuit to an external connection based on the second current threshold signal output by the high current comparator or the first current threshold signal output by the filter.

7. The system of claim 6, wherein: The load switch system is a low-side load switch system; The power switch is coupled to an internal ground; and The protection switch exposes the power supply circuit to an external ground based on the second current threshold signal output by the high current comparator or the first current threshold signal output by the filter.

8. The system of claim 6, wherein: The load switch system is a high-side load switch system; The power switch is coupled to an internal voltage; and The protection switch exposes the power supply circuit to an external voltage based on the second current threshold signal output by the high current comparator or the first current threshold signal output by the filter.

9. The system of claim 6, wherein: The filter outputs the first current threshold signal based on the first current threshold signal remaining activated during a settling time of the current.

10. The system of claim 6, wherein: The power switch is a field effect transistor, a bipolar transistor or a relay.

11. A method of manufacturing a load switch system, comprising: Configuring a power switch to complete or interrupt a power circuit between a power source and a load; configuring a current sensor to detect current in the power circuit; coupling a low current comparator to the current sensor, the low current comparator comparing the current to a low current threshold and outputting a first current threshold signal based on the current exceeding the low current threshold; coupling a filter to the low current comparator, the filter outputting the first current threshold signal based on the first current threshold signal remaining active for a predefined length of time; coupling a high current comparator to the current sensor, the high current comparator comparing the current to a high current threshold and outputting a second current threshold signal based on the current exceeding the high current threshold; as well as Control logic is coupled to the low current comparator and to the high current comparator, and the control logic opens the power switch and interrupts the power circuit based on the second current threshold signal output by the high current comparator or the first current threshold signal output by the filter.

12. The method according to claim 11, further comprising: A current-to-voltage converter is coupled to the current sensor, the current-to-voltage converter converting current from the current sensor into a voltage for comparison by the high current comparator and the low current comparator.

13. The method according to claim 11, further comprising: An OR logic gate is coupled to a filter output of the filter and to a comparator output of the high current comparator.

14. The method according to claim 11, further comprising: An auxiliary power source is connected to the power switch, the auxiliary power source providing power to activate the power switch.

15. The method according to claim 11, further comprising: A switch driver is coupled to the power switch, the switch driver providing a drive signal to the power switch.

16. The method according to claim 11, further comprising: A protection switch is coupled to the power switch and the control logic, the protection switch exposing the power circuit to an external connection based on the second current threshold signal output by the high current comparator or the first current threshold signal output by the filter.

17. The method of claim 16, wherein: Manufacturing the load switch system includes manufacturing a low-side load switch system; Configuring the power switch includes coupling the power switch to an internal ground; and Coupling the protection switch includes coupling the protection switch to an external ground, and the protection switch exposes the power circuit to the external ground based on the second current threshold signal output by the high current comparator or the first current threshold signal output by the filter.

18. The method of claim 16, wherein: Manufacturing the load switch system includes manufacturing a high-side load switch system; Configuring the power switch includes coupling the power switch to an internal voltage; and Coupling the protection switch includes coupling the protection switch to an external voltage, and the protection switch exposes the power circuit to the external voltage based on the second current threshold signal output by the high current comparator or the first current threshold signal output by the filter.

19. The method of claim 16, wherein: Coupling the filter includes configuring the filter to output the first current threshold signal based on the first current threshold remaining active for a settling time of the current.

20. The method of claim 16, wherein: Configuring the power switch includes configuring a field effect transistor, a bipolar transistor, or a relay.

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