Voltage detection device and method for preventing system failure

Abstract

A voltage detection device and a method for preventing system failure are disclosed. The voltage detection device includes a reference voltage latch circuit, first and second voltage detectors, and a digital circuit. The reference voltage latch circuit outputs one of first and second sets of reference voltages as a third set of reference voltages according to a selection signal, and selectively resets or continuously outputs the one of the first and second sets of reference voltages as the third set of reference voltages according to a first detection signal. The first set of reference voltages is lower than the second set of reference voltages. The first voltage detector generates the first detection signal according to a fourth set of reference voltages and an input voltage, wherein the fourth set of reference voltages is lower than or the same as the first set of reference voltages. The second voltage detector generates a second detection signal according to the third set of reference voltages and the input voltage. The digital circuit generates the selection signal according to the second detection signal. The accuracy of voltage detection can be improved.

Description

Technical Field

[0001] This application relates to the field of voltage detection device technology, and in particular to a voltage detection device that can prevent electronic circuits from malfunctioning due to sudden power-on / off switching, and a method for preventing system malfunctions thereon. Background Technology

[0002] In existing electronic devices, if the power supply voltage or its internal voltage experiences a momentary voltage drop due to sudden power-on or power-off events, the electronic circuits or circuit system within the device may malfunction or malfunction. Current technology uses a single set of reference voltages to detect whether a voltage drop has occurred in the power supply voltage or its internal voltage. However, if the voltage drop is not large enough, the aforementioned voltage detection mechanism cannot accurately determine that a voltage anomaly has occurred, allowing the electronic circuits and / or circuit system to still malfunction. Summary of the Invention

[0003] In some embodiments, one of the objectives of this invention is to provide a voltage detection device and a method for preventing system failures, which can improve the accuracy of voltage detection and overcome the shortcomings of prior art.

[0004] In some embodiments, the voltage detection device includes a reference voltage latching circuit, a first voltage detector, a second voltage detector, and digital circuitry. The reference voltage latching circuit outputs one of a first set of reference voltages and a second set of reference voltages as a third set of reference voltages based on a selection signal, and selectively resets or continuously outputs the third set of reference voltages based on a first detection signal, wherein the first set of reference voltages is lower than the second set of reference voltages. The first voltage detector generates the first detection signal based on a fourth set of reference voltages and an input voltage, wherein the fourth set of reference voltages is lower than or equal to the first set of reference voltages. The second voltage detector generates a second detection signal based on the third set of reference voltages and the input voltage. The digital circuitry generates the selection signal based on the second detection signal.

[0005] In some embodiments, the method for preventing system failure includes the following operations: outputting one of a first set of reference voltages and a second set of reference voltages as a third set of reference voltages according to a selection signal, wherein the first set of reference voltages is lower than the second set of reference voltages; selectively resetting or continuously outputting one of the first set of reference voltages and the second set of reference voltages as the third set of reference voltages according to a first detection signal; comparing a fourth set of reference voltages with an input voltage to generate the first detection signal, wherein the input voltage is used to drive the circuit system, and the fourth set of reference voltages is lower than or the same as the first set of reference voltages; comparing the third set of reference voltages with the input voltage to generate a second detection signal; and generating the selection signal according to the second detection signal.

[0006] The technical solution provided in this application improves the accuracy of voltage drop detection by utilizing multiple sets of reference voltages and uses circuits such as latches to store the currently used reference voltage. This ensures that the circuit system correctly resets due to sudden voltage drops, thereby preventing malfunctions in the circuit system's operation. Attached Figure Description

[0007] Figure 1 This is a schematic diagram of a voltage detection device drawn according to some embodiments of this case;

[0008] Figure 2 Drawing based on some embodiments of this case Figure 1 A waveform diagram of multiple signals in the diagram;

[0009] Figure 3 Drawing based on some embodiments of this case Figure 1 A schematic diagram of the reference voltage latching circuit in the diagram;

[0010] Figure 4 Drawing based on some embodiments of this case Figure 1 A schematic diagram of the voltage detector in the diagram;

[0011] Figure 5 Drawing based on some embodiments of this case Figure 1 A schematic diagram of the voltage detector in the diagram; and

[0012] Figure 6 This is a flowchart illustrating a method for preventing system failures based on some embodiments of this case. Detailed Implementation

[0013] All terms used herein have their common meanings. The definitions of the terms used in commonly used dictionaries, and any examples of the use of any term discussed herein, are merely illustrative and should not be construed as limiting the scope or meaning of this document. Similarly, this document is not limited to the various embodiments shown in this specification.

[0014] As used herein, "coupling" or "connection" can refer to two or more components making direct physical or electrical contact with each other, or indirectly making direct physical or electrical contact with each other, or to two or more components operating or moving together. As used herein, the term "circuit" can refer to a device in which at least one transistor and / or at least one active or passive component are connected in a certain manner to process signals.

[0015] Figure 1This is a schematic diagram of a voltage detection device 100 according to some embodiments of the present invention. In some embodiments, the voltage detection device 100 can detect an input voltage VIN to prevent circuit system malfunctions under conditions such as sudden power-on or power-off. In some embodiments, the input voltage VIN can be used to drive a circuit system; for example, the input voltage VIN can be, but is not limited to, the supply voltage of a digital circuit system, the drive voltage used by an input / output interface circuit system, etc.

[0016] The voltage detection device 100 includes a reference voltage latch circuit 110, a voltage detector 120, a voltage detector 130, and digital circuitry 140. The reference voltage latch circuit 110 can output one of a first set of reference voltages VREF1 and a second set of reference voltages VREF2 as a third set of reference voltages VREF3 according to a selection signal SEL, wherein the first set of reference voltages VREF1 is lower than the second set of reference voltages VREF2. For example, the first set of reference voltages VREF1 includes voltages VH1 and VL1, and the second set of reference voltages VREF2 includes voltages VH2 and VL2. Voltage VH1 is higher than voltage VL1 and lower than voltage VH2, and voltage VL2 is lower than voltage VH2 and higher than voltage VL1. For example, voltage VH2 can be set to approximately 1.58 volts, voltage VL2 can be set to approximately 1.44 volts, voltage VH1 can be set to approximately 1.34 volts, and voltage VL1 can be set to approximately 1.3 volts. The voltage values ​​described above are for illustrative purposes only and are not intended to limit this application. The reference voltage latch circuit 110 may output voltages VH1 and VL1 as voltages VH3 and VL3 in the third set of reference voltages VREF3, respectively, according to the selection signal SEL, or output voltages VH2 and VL2 as voltages VH3 and VL3, respectively.

[0017] The reference voltage latch circuit 110 can store (or latch) the selection signal SEL as a switching signal (e.g., based on the default value P1 corresponding to the frequency signal CLK and the input voltage VIN). Figure 3The reference voltage latch circuit 110 can also selectively reset based on the detection signal SD1, or continuously output the third reference voltage VREF3 based on the first reference voltage VREF1 and the second reference voltage VREF2. For example, if the detection signal SD1 indicates that the input voltage VIN is not lower than the fourth voltage VREF4 (for example, if the fourth voltage VREF4 is the same as the first reference voltage VREF1, where the condition here refers to the input voltage VIN not being lower than the lower limit of the first reference voltage VREF1, i.e., voltage VL1), the reference voltage latch circuit 110 can continuously output the previously selected reference voltage (for example, the second reference voltage VREF2) as the third reference voltage VREF3. Alternatively, if the detection signal SD1 indicates that the input voltage VIN is lower than the fourth set of voltages VREF4 (described later) (for example, if the fourth set of voltages VREF4 is the same as the first set of reference voltages VREF1, where the condition here refers to the input voltage VIN being lower than voltage VL1), the reference voltage latch circuit 110 can be reset to clear the internal circuit settings and reselect a set of reference voltages. Detailed operation of the reference voltage latch circuit 110 will be described later. Figure 2 With / or Figure 3 illustrate.

[0018] Voltage detector 120 compares the input voltage VIN with a fourth voltage group VREF4 to generate a detection signal SD1. In some embodiments, if a portion of the circuitry in the system is configured to operate at a lower voltage, the fourth voltage group VREF4 may be set lower than the first reference voltage group VREF1. For example, the upper limit of the fourth voltage group VREF4 may be lower than voltage VH1, and the lower limit of the fourth voltage group VREF4 may be lower than voltage VL1. In some embodiments, the upper limit of the fourth voltage group VREF4 may be set to 0.6 to 0.9 times (e.g., approximately 0.75) of voltage VH1, and the lower limit of the fourth voltage group VREF4 may be set to 0.6 to 0.9 times (e.g., approximately 0.75) of voltage VL1. In some embodiments, the fourth voltage group VREF4 may be set to be the same as the first reference voltage group VREF1. For ease of understanding, the embodiments described below will be illustrated with the fourth voltage group VREF4 being the same as the first reference voltage group VREF1 as an example, but this is not a limitation of the present invention. When the fourth set of voltages VREF4 is the same as the first set of reference voltages VREF1, voltage detector 120 can compare the input voltage VIN with the first set of reference voltages VREF1 (in other embodiments, this can be replaced by another set of voltages lower than the first set of reference voltages VREF1) to generate a detection signal SD1. Detection signal SD1 indicates whether the input voltage VIN is higher than voltage VH1 or lower than VL1. Similarly, voltage detector 130 can generate a detection signal SD2 based on the third set of reference voltages VREF3 and the input voltage VIN. For example, voltage detector 130 can compare the input voltage VIN with the third set of reference voltages VREF3 to generate detection signal SD2. Detection signal SD2 indicates whether the input voltage VIN is higher than voltage VH2 or lower than VL2. If the input voltage VIN is higher than voltage VH2, it means that the input voltage VIN has risen to a target level and is stabilizing.

[0019] Digital circuit 140 generates a selection signal SEL based on the detection signal SD2. In some embodiments, digital circuit 140 is further controlled by software (or firmware) in the system to switch the selection signal SEL under default conditions. In some embodiments, digital circuit 140 is disposed in an electronic device including voltage detection device 100, such as control circuitry, central processing unit, etc. In some embodiments, digital circuit 140 may include a buffer storing control values ​​or parameters to control the operation of voltage detection device 100. The default conditions for switching the selection signal SEL will be referred to later. Figure 2 illustrate.

[0020] Figure 2 Drawing based on some embodiments of this case Figure 1The diagram illustrates the waveforms of multiple signals. During the initial period (e.g., when the system is first started), digital circuit 140 outputs a switching signal SEL (not shown) with a first value (e.g., logic 0), causing reference voltage latch circuit 110 to output the first set of reference voltages VREF1 as the third set of reference voltages VREF3. Under this condition, the level of voltage VH3 is the same as that of voltage VH1, and the level of voltage VL3 is the same as that of voltage VL1. At time t1, the input voltage VIN begins to be higher than voltage VH3, causing detection signals SD1 and SD2 to switch from a low level (corresponding to logic 0) to a high level (corresponding to logic 1). At time t2, controlled by the system's software or firmware, digital circuit 140 outputs a switching signal SEL with a second value (e.g., logic 1), causing reference voltage latch circuit 110 to switch according to this selection signal SEL to output the second set of reference voltages VREF2 as the third set of reference voltages VREF3. Under these conditions, the level of voltage VH3 will be raised to the level of voltage VH2, and the level of voltage VL3 will be raised to the level of voltage VL2. In other words, if the detection signal SD2 meets a default condition (e.g., the detection signal SD2 has a preset level (e.g., a high level) during a predetermined period (e.g., between time t1 and time t2) after the reference voltage latch circuit 110 outputs the first set of reference voltages VREF1 as the third set of reference voltages VREF3), the software or firmware in the system will control the digital circuit 140 to adjust the switching signal SEL so that the reference voltage latch circuit 110 switches to output the second set of reference voltages VREF2 as the third set of reference voltages VREF3.

[0021] Next, at time t3, due to factors such as a sudden power-on / off, the input voltage VIN falls below voltage VL3 (for example, below voltage VL2 but not below voltage VL1). Under this condition, the detection signal SD2 switches to a low level to notify the circuit system to reset and prevent circuit system failure. Simultaneously, since the input voltage VIN is not lower than voltage VL1, the detection signal SD1 remains at a high level. Under this condition, the reference voltage latch circuit 110 can continuously output the second set of reference voltages VREF2 as the third set of reference voltages VREF3. This ensures that the circuit system will not malfunction or fail due to this voltage drop. At time t4, the input voltage VIN again rises above voltage VH3, causing the detection signal SD2 to switch to a high level. Thus, the circuit system can continue its original operation. On the other hand, if the input voltage VIN falls below both voltage VL3 and voltage VL1 at time t3, both detection signals SD1 and SD2 will switch to a low level. Under these conditions, the level of the input voltage VIN is too low. The reference voltage latch circuit 110 can be reset according to the detection signal SD1 (e.g., to clear the internal circuit settings) so that a new set of reference voltages can be selected in the next operation and the third set of reference voltages VREF3 can be output accordingly.

[0022] In some related technologies, voltage detection mechanisms in electronic devices use only one set of reference voltages (e.g., a second set of reference voltages VREF2) to determine whether the input voltage has suddenly dropped. However, if the voltage drop of the input voltage is not significant (e.g., the input voltage VIN is lower than voltage VH2 but higher than voltage VL2), the voltage detection mechanism may still misjudge that the input voltage is still at a normal level and not perform any other operations. However, the actual circuit system may malfunction or generate erroneous signals due to this voltage drop. Compared to the above-mentioned technologies, in some embodiments of this invention, the voltage detection device 100 uses two sets of reference voltages and switches to use the reference voltage with the higher level for a period of time after power-on to determine whether the input voltage VIN has experienced the aforementioned voltage drop. In this way, it is possible to more accurately determine whether the input voltage VIN has experienced a voltage drop, thereby avoiding system malfunctions.

[0023] Figure 3 Drawing based on some embodiments of this case Figure 1A schematic diagram of the reference voltage latch-up circuit 110 is shown. The reference voltage latch-up circuit 110 includes a flip-flop 310, a flip-flop 320, and a multiplexer 330. The flip-flop 310 generates a trigger signal ST based on a frequency signal CLK and a default value P1. In some embodiments, the default value P1 may be a target level of the input voltage VIN. For example, if the input voltage VIN has a default value of 1.8 volts in steady state, the default value P1 may be a voltage of 1.8 volts. The flip-flop 310 includes a NAND gate 311 and an inverter 312. The NAND gate 311 generates a signal S1 based on the frequency signal CLK and the default value P1. The inverter 312 generates the trigger signal ST based on the signal S1.

[0024] The flip-flop 320 outputs the selection signal SEL as a switching signal SW based on the trigger signal ST, and selectively continues to output the selection signal SEL as the switching signal SW or resets the switching signal SW based on the detection signal SD1. For example, the flip-flop 320 can be a D-type flip-flop with a reset terminal (denoted as R), where the reset terminal receives the detection signal SD1. When the detection signal SD1 has a high level, the flip-flop 320 can sequentially output the selection signal SEL as the switching signal SW according to the trigger signal ST. When the detection signal SD1 has a low level, the flip-flop 320 can reset the switching signal SW (e.g., clear the signal value of the switching signal SW to a logic value of 0). On the other hand, as... Figure 2 As shown, when the input voltage VIN is lower than voltage VL2 but not lower than voltage VL1, the detection signal SD1 remains at a high level. Thus, the flip-flop 320 can continuously output the selection signal SEL as the switching signal SW based on the trigger signal ST. In other words, when the input voltage VIN is not too low (i.e., not lower than voltage VL1), the flip-flop 320 can continuously latch the selection signal SEL as the switching signal SW. Only when the input voltage VIN becomes too low (i.e., lower than voltage VL1) will the detection signal SD1 have a low level, causing the flip-flop 320 to reset the signal value of the switching signal SEL.

[0025] The multiplexer 330 can output either the first set of reference voltages VREF1 or the second set of reference voltages VREF2 as the third set of reference voltages VREF3 based on the switching signal SW. For example, the multiplexer circuit 330 includes multiple switches. Some of these switches are turned on when the switching signal SW has a logic value of 0 to output voltage VH1 as voltage VH3 and voltage VL1 as voltage VL3. Other switches are turned on when the switching signal SW has a logic value of 1 to output voltage VH2 as voltage VH3 and voltage VL2 as voltage VL3.

[0026] Figure 4 Drawing based on some embodiments of this case Figure 1A schematic diagram of a voltage detector 130 is shown. In this example, the voltage detector 130 includes a comparator 410, a comparator 420, and a latch 430. Comparator 410 compares the input voltage VIN with voltage VH3 to generate a setting signal SS. Comparator 420 compares the input voltage VIN with voltage VL3 to generate a reset signal SR. Latch 430 generates a detection signal SD2 based on the setting signal SS and the reset signal SR. For example, latch 430 can be an SR latch, with its setting input (labeled S) receiving the setting signal SS and its reset input (labeled R) receiving the reset signal SR. Thus, when the input voltage VIN is higher than voltage VH3, latch 430 can output a high-level detection signal SD2. Alternatively, when the input voltage VIN is lower than voltage VL3, latch 430 can output a low-level detection signal SD2.

[0027] Figure 5 Drawing based on some embodiments of this case Figure 1 A schematic diagram of a voltage detector 130 is shown. In this example, the voltage detector 130 includes a multiplexer 510 and a comparator 520. The multiplexer 510 selectively outputs either voltage VH3 or voltage VL3 as voltage V3 based on the detection signal SD2. For example, the multiplexer 510 includes a first switch and a second switch. When the detection signal SD1 has a low level (e.g., a logic value of 0), the first switch is turned on to output voltage VH3 as voltage V3. Alternatively, when the detection signal SD1 has a high level (e.g., a logic value of 1), the second switch is turned on to output voltage VL3 as voltage V3. The comparator 520 compares the input voltage VIN with the voltage V3 to generate the detection signal SD2. Thus, when the input voltage VIN is higher than the voltage VH3, the detection signal SD2 can have a high level. Alternatively, when the input voltage VIN is lower than the voltage VL3, the detection signal SD2 can have a low level.

[0028] In some embodiments, the voltage detector 120 may be implemented with reference to Figure 4 and Figure 5 Voltage detector 130 in the middle. For example, to implement voltage detector 120, one can... Figure 4 and Figure 5 Replace voltage VH3 with voltage VH1, and replace voltage VL3 with voltage VL1 (or replace it with another voltage set lower than the first set of reference voltages VREF1). Other operations and settings are the same as before. Figure 4 and Figure 5 Examples of this will not be repeated here.

[0029] Figure 6This is a flowchart illustrating a method 600 for preventing system failure according to some embodiments of this invention. In operation S610, one of a first set of reference voltages and a second set of reference voltages is output as a third set of reference voltages based on a selection signal, wherein the first set of reference voltages is lower than the second set of reference voltages. In operation S620, a reset is selectively performed or the output of one of the first set of reference voltages and the second set of reference voltages as the third set of reference voltages is continuously performed based on a first detection signal. In operation S630, a fourth set of reference voltages is compared with an input voltage to generate a first detection signal, wherein the input voltage is used to drive the circuit system, and the fourth set of reference voltages is lower than or equal to the first set of reference voltages. In operation S640, the third set of reference voltages is compared with the input voltage to generate a second detection signal. In operation S650, a selection signal is generated based on the second detection signal.

[0030] The descriptions of the above-mentioned operations can be found in the foregoing embodiments, and therefore will not be repeated. The operations of the above-described method 600 for preventing system failures are merely examples and are not limited to being performed in the order shown in this example. Without departing from the operation mode and scope of the embodiments of this invention, the various operations in the method 600 for preventing system failures may be appropriately added, replaced, omitted, or performed in a different order (for example, they may be performed simultaneously or partially simultaneously).

[0031] In summary, the voltage detection device and the method for preventing system failure in some embodiments of this case can utilize multiple sets of reference voltages to improve the accuracy of detecting voltage drop and use circuit concepts such as latches to latch the currently used reference voltage. This ensures that the circuit system can be correctly reset due to sudden voltage drops, thereby ensuring that the operation of the circuit system will not malfunction.

[0032] Although the embodiments of this case are described above, these embodiments are not intended to limit this case. Those skilled in the art can make changes to the technical features of this case based on the express or implied content of this case. All such changes may fall within the scope of patent protection sought in this case. In other words, the scope of patent protection in this case shall be determined by the scope of the patent application in this specification.

[0033] [Symbol Explanation]

[0034] 100: Voltage detection device;

[0035] 110: Reference voltage latch-up circuit;

[0036] 120, 130: Voltage detector;

[0037] 140: Digital circuits;

[0038] 310: Trigger;

[0039] 311: NAND gate;

[0040] 312: Inverter;

[0041] 320: Flip-Flipper;

[0042] 330, 510: Multitasking;

[0043] 410, 420, 520: Comparators;

[0044] 430: Latch;

[0045] 600: Methods to prevent system failure;

[0046] CLK: Frequency signal;

[0047] P1: Default value;

[0048] S610, S620, S630, S640, S650: Operation;

[0049] SD1, SD2: Detection signals;

[0050] SEL: Selection signal;

[0051] SR: Reset signal;

[0052] SS: Set signal;

[0053] ST: Trigger signal;

[0054] SW: Switching signal;

[0055] V3, VH1~VH3, VL1~VL3: Voltage;

[0056] VIN: Input voltage;

[0057] VREF1: First set of reference voltages;

[0058] VREF2: Second set of reference voltages;

[0059] VREF3: Third set of reference voltages;

[0060] t1~t4: Time.

Claims

1. A voltage detection device, characterized in that, include: A reference voltage latching circuit outputs one of a first set of reference voltages and a second set of reference voltages as a third set of reference voltages according to a selection signal, and selectively resets or continuously outputs one of the first set of reference voltages and the second set of reference voltages as the third set of reference voltages according to a first detection signal, wherein the first set of reference voltages is lower than the second set of reference voltages; A first voltage detector generates the first detection signal based on a fourth set of reference voltages and an input voltage, wherein the fourth set of reference voltages is lower than or the same as the first set of reference voltages. The second voltage detector generates a second detection signal based on the third set of reference voltages and the input voltage; as well as A digital circuit generates the selection signal based on the second detection signal.

2. The voltage detection device according to claim 1, characterized in that, If the first detection signal indicates that the input voltage is not lower than the fourth set of reference voltages, the reference voltage latching circuit continuously outputs one of the first set of reference voltages and the second set of reference voltages as the third set of reference voltages.

3. The voltage detection device according to claim 1, characterized in that, If the first detection signal indicates that the input voltage is lower than the fourth set of reference voltages, then the reference voltage latch circuit is reset.

4. The voltage detection device according to claim 1, characterized in that, If the second detection signal has a preset level during a predetermined period after the reference voltage latching circuit outputs the first set of reference voltages as the third set of reference voltages, then the reference voltage latching circuit switches to output the second set of reference voltages as the third set of reference voltages according to the selection signal.

5. The voltage detection device according to claim 1, characterized in that, The reference voltage latch circuit also stores the selection signal as a switching signal according to the default value corresponding to the frequency signal and the input voltage, and outputs the third set of reference voltages according to the switching signal.

6. The voltage detection device according to claim 1, characterized in that, The reference voltage latch circuit includes: The trigger generates a trigger signal based on the frequency signal and the default value corresponding to the input voltage. A flip-flop that outputs the selection signal as a switching signal based on the trigger signal, and resets the switching signal based on the first detection signal; and The multiplexer outputs one of the first set of reference voltages and the second set of reference voltages as the third set of reference voltages according to the switching signal.

7. The voltage detection device according to claim 6, characterized in that, The trigger includes: A NAND gate generates a first signal based on the frequency signal and the default value; and An inverter generates the trigger signal based on the first signal.

8. The voltage detection device according to claim 1, characterized in that, The second voltage detector includes: The first comparator compares the input voltage with a first voltage in the third set of reference voltages to generate a setting signal; A second comparator compares the input voltage with a second voltage from the third set of reference voltages to generate a reset signal, wherein the first voltage is higher than the second voltage; and The latch generates the second detection signal based on the setting signal and the reset signal.

9. The voltage detection device according to claim 1, characterized in that, The second voltage detector includes: A multiplexer selectively outputs either a first voltage or a second voltage from the third set of reference voltages as a third voltage based on the second detection signal, wherein the first voltage is higher than the second voltage; and A comparator compares the input voltage with the third voltage to generate the second detection signal.

10. A method for preventing system failures, characterized in that, include: Based on the selection signal, one of the first group of reference voltages and the second group of reference voltages is output as the third group of reference voltages, wherein the first group of reference voltages is lower than the second group of reference voltages; The first detection signal is used to selectively reset or continuously output one of the first set of reference voltages and the second set of reference voltages as the third set of reference voltages; The first detection signal is generated by comparing a fourth set of reference voltages with an input voltage, wherein the input voltage is used to drive the circuit system, and wherein the fourth set of reference voltages is lower than or the same as the first set of reference voltages. The third set of reference voltages is compared with the input voltage to generate a second detection signal; and The selection signal is generated based on the second detection signal.

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