JP2008005564A - Power supply control circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply control circuit which can supply a stabilized power supply voltage to the internal circuit even if a voltage of ground GND level is applied to a power supply terminal for contact communication when contact communication is stopped and noncontact communication is performed. <P>SOLUTION: Stabilized power is supplied to the internal circuit by detecting communication situation of contact communication/noncontact communication and power supply situation and disconnecting/connecting the power supply terminal for contact communication from/with the internal circuit. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power supply control circuit for supplying a stable power supply to an internal circuit having a plurality of power supplies.

  In a mobile phone or the like, the inserted memory card performs contact-type communication (hereinafter referred to as contact communication) in which the conductive metal terminals are in physical contact with an external host, and simultaneously uses an electromagnetic wave with another external host. In the case of realizing simultaneous communication using a plurality of interfaces for performing non-contact communication (hereinafter referred to as non-contact communication), there are a plurality of power supply systems to the memory card controller.

  FIG. 2 shows a power supply circuit configuration of a conventional memory card controller, which includes a contact terminal 11, an antenna 13, a rectifier circuit 14, and an internal circuit 19. The contact terminal 11 is a terminal to which a power supply voltage is applied during contact communication. The antenna 13 generates an induced electromotive force by an electromagnetic wave generated from a host that supports non-contact communication. The rectifier circuit 14 is a circuit that rectifies the induced electromotive force generated as described above. The internal circuit 19 is a memory arithmetic circuit that processes data as a memory card controller, and it is necessary to supply a stable power supply voltage to the internal circuit 19 regardless of the communication state.

  An outline of the operation of the power supply circuit configured as described above will be described. During contact communication, the voltage applied to the contact terminal 11 is supplied to the internal circuit 19 as the power supply voltage 21. At the time of non-contact communication, the induced electromotive force generated by the antenna 13 is rectified by the rectifier circuit 14. FIG. 3 shows a specific configuration example of the antenna 13 and the rectifier circuit 14. The induced electromotive force (alternating voltage) generated in the antenna 13 is converted into a positive component voltage by the diode 31 in FIG. 3 and is flattened by the smoothing capacitor 32. The flattened voltage is clamped to a constant voltage by the shunt regulator 33, output as the power supply voltage 21 in FIG. 1, and supplied to the internal circuit 19.

At this time, a communication situation is also assumed in which contactless communication is started in a state in which contact communication is being performed, and then contact communication is stopped in a state in which contactless communication is being performed. The power supply voltage supplied to the internal circuit in the communication state described above is supplied from both the contact terminal 11 and the rectifier circuit 14 simultaneously with the start of non-contact communication from the state supplied from the contact terminal 11. Furthermore, when the contact communication is stopped, the power supply voltage is supplied only from the rectifier circuit 14.
In the communication state in which the non-contact communication is being performed and the contact communication is stopped, the voltage applied to the contact terminal 11 is an arbitrary voltage. This is because, for example, when contact communication is performed with a mobile phone, it is assumed that contact communication is stopped due to battery exhaustion.
JP 2000-123140 A

  In the above conventional configuration, when contact communication is stopped during non-contact communication and a power supply voltage (for example, ground GND level) equal to or lower than a voltage required for the operation of the internal circuit 19 is applied to the contact terminal 11, the rectifier circuit 14. The power supply voltage supplied from the power supply and the power supply voltage of the contact terminal 11 collide with each other, and a stable power supply voltage cannot be supplied to the internal circuit 19.

  In order to solve the above-mentioned problem, the solution provided by the invention of claim 1 includes a contact terminal to which a voltage is applied from the outside, and a voltage detection circuit for detecting a first power supply voltage having the same potential as the contact terminal. Generated from an antenna that generates an induced electromotive force by electromagnetic waves, a rectifier circuit that rectifies the induced electromotive force, a rectification operation detection circuit that detects an operating state of the rectifier circuit, and the first power supply voltage and the rectifier circuit A power supply separation circuit that separates the second power supply voltage, and a state control circuit that controls the state of the power supply separation circuit from the output of the voltage detection circuit and the output of the rectification operation detection circuit. Power supply control circuit.

  According to a second aspect of the present invention, there is provided a solution means comprising a power supply control circuit according to the first aspect, further comprising a resistor for connecting the first power supply voltage and the ground GND level.

  According to a third aspect of the present invention, there is provided a solving means comprising: a contact terminal to which a voltage is applied from the outside; a voltage detection circuit for detecting a first power supply voltage having the same potential as the contact terminal; and the first power supply voltage. Power supply voltage adjustment circuit that changes the power supply voltage and outputs a third power supply voltage, an antenna that generates an induced electromotive force by electromagnetic waves, a rectifier circuit that rectifies the induced electromotive force, and a rectifying operation that detects the operating state of the rectifier circuit A detection circuit; a power supply separation circuit that separates the third power supply voltage and the second power supply voltage generated from the rectifier circuit; an output of the voltage detection circuit and an output of the rectification operation detection circuit; A power control circuit including a state control circuit for controlling the state.

  According to a fourth aspect of the present invention, there is provided a solution provided by a power supply control circuit according to the third aspect, further comprising a resistor for connecting the first power supply voltage and the ground GND level.

  According to a fifth aspect of the present invention, there is provided a solution provided by a power supply control circuit according to the third aspect, further comprising a resistor for connecting the third power supply voltage and the ground GND level.

The solution provided by the invention of claim 6 is a contact terminal to which a voltage is applied from the outside,
An antenna that generates an induced electromotive force by electromagnetic waves, a rectifier circuit that rectifies the induced electromotive force and outputs a fifth power supply voltage, and a fourth power supply voltage and a fifth power supply voltage that have the same potential as the contact terminal. The power supply control circuit includes a diode to be connected.

A solution provided by the invention of claim 7 is a contact terminal to which a voltage is applied from the outside,
A power supply voltage adjusting circuit that outputs a seventh power supply voltage by changing a sixth power supply voltage that has the same potential as the contact terminal, an antenna that generates an induced electromotive force by electromagnetic waves, rectifies the induced electromotive force, and And a rectifier circuit that outputs the power supply voltage 7.

  According to an eighth aspect of the present invention, there is provided a solution provided by a power supply control circuit according to the seventh aspect, further comprising a resistor for connecting the sixth power supply voltage and the ground GND level.

  According to the present invention, when the contact communication is stopped and the non-contact communication is performed, the present invention is stable with respect to the internal circuit even when a ground GND level voltage is applied to the contact communication power supply terminal. A power supply voltage can be supplied.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a configuration diagram of a power supply control circuit according to the first embodiment of the present invention. 1 indicates a terminal to which a voltage is applied from the outside, and the applied voltage supplies a power supply voltage to the power supply separation circuit 1A via the first power supply voltage 16. The voltage detection circuit 12 is a detection circuit that detects that the voltage of the first power supply voltage 16 has exceeded a certain level. On the other hand, the antenna 13 generates an induced electromotive force by an electromagnetic wave generated from a host corresponding to non-contact communication. The rectifier circuit 14 rectifies the generated induced electromotive force and supplies a power supply voltage to the internal circuit 19 via the second power supply voltage 17. The rectification operation detection circuit 15 is a circuit that detects that the rectification circuit 14 is performing the rectification operation. The state control circuit 18 is a circuit that controls the power supply separation circuit 1A using the voltage detection signal 1B generated from the voltage detection circuit 12 and the operation detection signal 1C generated from the rectification operation detection circuit 15. The power supply isolation circuit 1A is a circuit that receives the power supply isolation circuit control signal 1D from the state control circuit 18 and separates and conducts the first power supply voltage 16 and the second power supply voltage 17.

  The operation of the power supply control circuit having the above configuration will be described below. First, an operation will be described for a state in which contact communication to which a power supply voltage is applied from the contact terminal 11 is performed and non-contact communication is stopped.

  At the start of contact communication, a power supply voltage is applied to the contact terminal 11 from an external contact communication compatible host (not shown), and the power supply voltage is propagated to the first power supply voltage 16 via the contact terminal 11 to the power supply separation circuit 1A. Applied. On the other hand, since non-contact communication is not performed, no electromagnetic wave is generated with respect to the antenna 13, and no induced electromotive force is generated. As a result, the diode 31 shown in FIG. 3 stops the backflow to the antenna 13, and the output from the rectifier circuit 14 to the second power supply voltage 17 becomes floating. The operation of the power supply separation circuit 1A in such a state will be described. FIG. 5 shows the inside of the power supply separation circuit 1A. The PMOS transistor 51 having the first power supply voltage 16 and the second power supply voltage 17 as the source / drain and the substrate voltage as the second power supply voltage 17, and the first power supply voltage 16 and the power supply separation circuit control signal 1D are input. The output is constituted by a NAND 52 whose output is connected to the gate of the PMOS transistor 51 described above. When the first power supply voltage in FIG. 2 gradually increases and rises above the PN junction threshold between the source and the substrate of the PMOS transistor 51, the first power supply voltage 16 is the source and substrate of the PMOS transistor 51. And propagates to the second power supply voltage 17. Thereby, as the first power supply voltage 16 increases, the arithmetic element operating with the second power supply voltage 17 starts to operate normally.

  At this time, the voltage detection circuit 12 of FIG. 1 outputs “H” as the voltage detection signal 1B from the time when the first power supply voltage 16 becomes equal to or higher than a certain level. When the level is below a certain level, “L” is output. The aforementioned constant level is a power supply voltage level at which the internal circuit 19 can operate normally.

  On the other hand, since non-contact communication is not performed, no electromagnetic wave is generated with respect to the antenna 13, and no induced electromotive force is generated. As a result, the rectification operation detection circuit 15 outputs “L” as the rectification operation detection signal 1C and propagates it to the state control circuit 18 in response to the fact that the rectification circuit 14 is not operating.

  The state control circuit 18 receives the voltage detection signal 1B and the rectification operation detection signal 1C, performs calculation, and outputs a signal to the power supply separation circuit 1A as the power supply separation circuit control signal 1D. FIG. 4 shows a specific circuit example of the state control circuit 18. From the above situation, in FIG. 4, the rectification operation detection signal 1C is “L”, the voltage detection signal 1B is “H”, the first power supply voltage 16 is “H”, and the second power supply voltage 17 is calculated. Since the voltage at which the element operates is reached, the power supply separation circuit control signal 1D is fixed to “H”.

  In response to the power supply separation circuit control signal 1D, the gate control signal 52 in FIG. 5 becomes “H”, and the source / drain of the PMOS transistor 51 becomes conductive. As a result, the first power supply voltage 16 becomes completely conductive with the second power supply voltage 17, and the voltage applied to the contact terminal 11 in FIG. 1 can be stably supplied to the internal circuit 19. .

  Next, the operation of the power supply control circuit in a state where contactless communication is started while contact communication is continued will be described.

  An induced electromotive force is generated in the antenna 13 by an electromagnetic wave transmitted from a host corresponding to non-contact communication (not shown), and the voltage is supplied to the second power supply voltage 17 via the rectifier circuit 14. Since the operations of the antenna 13 and the rectifier circuit 14 are as described in the prior art, they are not described here. In response to the operation of the rectifier circuit 14, “H” is input from the rectifier operation detection circuit 15 to the state control circuit 18 as the rectifier operation detection signal 1 </ b> C. On the other hand, since the contact communication is continuously performed, there is no change in the voltage detection circuit 12, and the voltage detection signal 1B remains “H”. In the state control circuit 18 shown in FIG. 4, since the voltage detection signal 1B is “H”, the power supply separation circuit control signal 1D output to the power supply separation circuit 1A remains “H”. In 1A, the first power supply voltage 16 and the second power supply voltage 17 remain in the same state.

  Next, the operation of the power supply control circuit in a situation where the contact communication is stopped and only the non-contact communication is continued from the state where the contact communication and the non-contact communication are performed will be described.

  When the contact communication is stopped, the power supply from the external host corresponding to the contact communication (not shown) is stopped, and the power supply voltage applied to the contact terminal 11 in FIG. 1 becomes a floating or ground GND level.

  In the prior art, when the contact terminal 11 is applied to the ground GND level in FIG. 2, there is a collision between the power supply voltage 21 supplied from the antenna 13 and the rectifier circuit 14 and the ground GND level applied to the contact terminal 11. It becomes impossible to supply a stable power to the internal circuit 19.

  On the other hand, in the first embodiment, the above-described problems can be avoided by performing the following operations.

  As the power supply voltage applied to the contact terminal 11 decreases, the first power supply voltage 16 also decreases accordingly. The voltage detection circuit 12 detects this drop in the power supply voltage, and changes the voltage detection signal 1B to “L”. At this time, the voltage level detected by the voltage detection circuit 12 is set to a voltage level at which the internal circuit 19 can operate.

  On the other hand, since the non-contact communication is continued, the rectification operation detection signal 1C remains “H”. When the voltage detection signal 1B is “L” and the rectification operation detection signal 1C is “H”, the power supply separation circuit control signal 1D is changed to “L” in the state control circuit 18 shown in FIG. Since the power supply separation circuit control signal 1D changes to “L”, the gate control signal 53 in the power supply separation circuit 1A shown in FIG. 5 becomes “H”, and the PMOS transistor 51 causes the first power supply voltage 16 and the second power supply voltage 16 to be changed. The power supply voltage 17 is separated.

  As described above, when the first power supply voltage 16 and the second power supply voltage 17 are separated, even when the voltage applied to the contact terminal 11 becomes the ground GND level, the first power supply voltage 16 second Thus, a stable power supply voltage can be supplied to the internal circuit 19 from the rectifier circuit 14 without causing the power supply voltage 17 to collide.

  Next, the operation of the power supply control circuit in a state where the noncontact communication and the contact communication are stopped and the noncontact communication is started from the state where the power supply voltage is not supplied will be described.

  An induced electromotive force is generated in the antenna 13 by an electromagnetic wave transmitted from a host corresponding to non-contact communication (not shown), and the voltage is supplied to the second power supply voltage 17 via the rectifier circuit 14. Since the operations of the antenna 13 and the rectifier circuit 14 are as described in the prior art, they are not described here. At this time, the first power supply voltage 16 is in the floating state or the ground GND level because contact communication has not started. In this state, the second power supply voltage 17 rises. In the PMOS transistor 51 of FIG. 5, the source that is the first power supply voltage 16 is not connected to the base and the drain that are the second power supply voltage 17. Not conducting. As a result, the second power supply voltage 17 rises until the arithmetic circuit driven thereby operates normally. When the second power supply voltage 17 rises to a level at which the arithmetic circuit can operate normally, since the first power supply voltage 16 in FIG. 2 is near the ground GND level, the gate control signal 53 becomes the “H” level. In the PMOS transistor 51, the first power supply voltage 16 and the second power supply voltage 17 are separated.

  By the operation as described above, the second power supply voltage 17 can supply a stable power supply voltage to the internal circuit 19 without colliding with the first power supply voltage 16.

  Preferably, as shown in FIG. 6, a resistance connected to the ground GND level is applied to the first power supply voltage 16. This resistor is a resistor that allows a current to flow so that the internal circuit 19 operates normally. As a result, even when the contact communication is not performed and the contact terminal 11 is in the floating state, the first power supply voltage 16 can be reliably set to the ground GND level, and the power supply isolation circuit 1A malfunctions. Can be prevented.

  Preferably, a regulator 71 is inserted between the contact terminal 11 and the first power supply voltage 16 as shown in the power supply control circuit of FIG. Further, the voltage detected by the voltage detection circuit 12 is a third power supply voltage 72 in FIG. Further, the voltage applied to the contact terminal 11, that is, the third power supply voltage 72 is set higher than the voltage at which the internal circuit 19 operates normally, the regulator 71 reduces the third power supply voltage 72, and the second power supply voltage 16 is applied. In such a configuration, the voltage level detected by the voltage detection circuit 12 is set to be equal to or lower than the third power supply voltage 72 and equal to or higher than the second power supply voltage. For example, when the third power supply voltage 72 is 3.3V and the second power supply voltage 16 is 1.8V, the detection level of the voltage detection circuit 12 is set to 2V.

  In such a configuration, at the moment when the contact communication is stopped, the third power supply voltage 72 starts to decrease, but the second power supply voltage 16 that applies the voltage to the internal circuit 19 does not decrease yet. At this stage, the voltage detection circuit 12 detects that the contact communication is stopped, and the power supply separation circuit 1A separates the second power supply voltage 17 and the first power supply voltage, thereby reducing the voltage supplied to the internal circuit 19. Can be prevented.

  At this time, a resistor 81 connected to the ground GND level is applied to the first power supply voltage 16 as shown in the power supply control circuit of FIG. The resistor 81 is a resistor that flows a current that allows the internal circuit 19 to operate normally. As a result, even when the contact communication is not performed and the contact terminal 11 is in a floating state, the first power supply voltage 16 can be reliably set to the ground GND level, and malfunction of the regulator 71 can be prevented. be able to.

  Further, as shown in the power supply control circuit of FIG. 9, a resistor 91 is added to the third power supply voltage 72. The resistor 91 is a resistor that flows a current that allows the internal circuit 19 to operate normally. As a result, the third power supply voltage 72 can be reliably set to the ground GND level even when the regulator 71 is stopped in a state in which contact communication is not performed and the output becomes floating depending on the circuit configuration. It is possible to prevent malfunction of the power supply separation circuit 1A and the state control circuit 18.

(Embodiment 2)
FIG. 10 is a configuration diagram of a power supply control circuit according to the second embodiment of the present invention. A contact terminal 11 in FIG. 10 is a terminal to which a voltage is applied from the outside, and is connected to the diode 101 via the fourth power supply voltage 103. The output of the diode 101 is connected to the internal circuit 82 as the fifth power supply voltage 102. About the structure of the antenna 13 and the rectifier circuit 14, it is the same as that of a prior art example, The output is connected to the 5th power supply voltage 82. FIG.

  In such a configuration, the power control circuit operation in a situation where the conventional technology cannot supply a stable power supply voltage to the internal circuit 19 and contact communication is stopped and non-contact communication is continued will be described.

  Since the contact communication is stopped, the power supply voltage applied to the contact terminal 11 is at the ground GND level or in a floating state where it is not applied. As a result, the power supply voltage of the fourth power supply voltage 103 input to the diode 101 is at or near the ground GND level. On the other hand, since non-contact communication is performed, the power supply voltage that allows the internal circuit 19 to operate is supplied to the fifth power supply voltage 102 by the antenna 13 and the rectifier circuit 14.

  At this time, the power supply voltage applied to the fifth power supply voltage 102 by the diode 101 does not flow into the fourth power supply voltage 103. Thereby, a stable power supply voltage can be supplied to the internal circuit 19.

(Embodiment 3)
FIG. 11 is a configuration diagram of a power supply control circuit according to the third embodiment of the present invention. A clock input terminal 111 in FIG. 11 is an external host (not shown) or a terminal to which an internally generated clock waveform signal is input. The clock waveform signal input to the clock input terminal 111 is input to the charge pump 114 via the clock 112. The contact terminal 11 is a terminal to which a power supply voltage is applied from an external host (not shown) as in the conventional case, and propagates the power supply voltage applied to the sixth power supply voltage 113. The sixth power supply voltage 113 is input to the charge pump 114. The charge pump 114 to which the clock 112 and the sixth power supply voltage 113 are input connects the output to the internal circuit 19 as the seventh power supply voltage 115. About the structure of the antenna 13 and the rectifier circuit 14, it is the same as that of a prior art example, The output is connected to the 7th power supply voltage 115. FIG.

  The operation of the power supply control circuit having the above configuration will be described below. When the contact communication is started, a power supply voltage is applied from an external host (not shown) to the contact terminal 11 in FIG. The applied power supply voltage is applied to the charge pump 114 as the sixth power supply voltage 113. On the other hand, the clock waveform signal input from the clock input terminal 111 is input to the charge pump 114 as the clock 112.

  FIG. 12 shows a circuit example of the charge pump 114, and a voltage higher than the sixth power supply voltage 113 is applied to the seventh power supply voltage 115 by the clock waveform signal supplied from the clock 112. The applied seventh power supply voltage 115 supplies the power supply voltage to the internal circuit 19 of FIG.

  On the other hand, when non-contact communication is started, an induced electromotive force is generated in the antenna 13 in FIG. 11 due to an electromagnetic wave transmitted from a host corresponding to non-contact communication (not shown), A voltage is supplied to the seventh power supply voltage 115. Since the operations of the antenna 13 and the rectifier circuit 14 are as described in the prior art, they are not described here. The supplied seventh power supply voltage 115 supplies a power supply voltage to the internal circuit 19.

  When the contact communication is stopped when the non-contact communication is being performed, the contact terminal 11 is at the ground GND level or a potential close thereto, and in the related art, a sixth power source having the same potential as the contact terminal 11 is used. A voltage level collision occurred between the voltage 113 and the seventh power supply voltage 115, and a stable power supply voltage could not be supplied to the internal circuit 19.

  On the other hand, in the third embodiment, the charge pump 114 is inserted between the sixth power supply voltage 113 and the seventh power supply voltage 115, and the seventh power supply voltage in FIG. A voltage level collision can be avoided by the NMOS transistor, and a stable power supply voltage can be supplied to the internal circuit 19.

  Preferably, as shown in FIG. 13, a resistor 131 connected to the ground GND level is applied to the sixth power supply voltage 113. This resistor is a resistor that allows a current to flow so that the internal circuit 19 operates normally. Accordingly, even when the contact communication is not performed and the contact terminal 11 is in the floating state, the sixth power supply voltage 113 can be reliably set to the ground GND level, and the malfunction of the charge pump 114 can be prevented. Can be prevented.

  The power supply control circuit in the present invention is effective for an IC card having a plurality of communication interfaces.

The figure which shows the power supply control circuit showing Embodiment 1 of this invention Diagram showing a conventional power supply control circuit Internal circuit diagram of the rectifier circuit 14 in FIG. Internal circuit diagram of the state control circuit 18 in FIG. Internal circuit diagram of the power supply separation circuit 1A in FIG. The figure which shows the power supply control circuit showing Embodiment 1 of this invention The figure which shows the power supply control circuit showing another example of Embodiment 1 of this invention The figure which shows the power supply control circuit showing another example of Embodiment 1 of this invention The figure which shows the power supply control circuit showing another example of Embodiment 1 of this invention The figure which shows the power supply control circuit showing Embodiment 2 of this invention The figure which shows the power supply control circuit showing Embodiment 3 of this invention 11 is an internal circuit diagram of the charge pump 114 in FIG. The figure which shows the power supply control circuit showing another example of Embodiment 3 of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Contact terminal 12 Voltage detection circuit 13 Antenna 14 Rectification circuit 15 Rectification operation detection circuit 18 State control circuit 19 Internal circuit 20 Power supply separation circuit 61 Resistance 71 Regulator 81 Resistance 91 Resistance 101 Diode 114 Charge pump

Claims (8)

A contact terminal to which a voltage is applied from the outside;
A voltage detection circuit for detecting a first power supply voltage having the same potential as the contact terminal;
An antenna that generates an induced electromotive force by electromagnetic waves;
A rectifier circuit for rectifying the induced electromotive force;
A rectification operation detection circuit for detecting an operation state of the rectification circuit;
A power supply separation circuit that separates the first power supply voltage and the second power supply voltage generated from the rectifier circuit;
A state control circuit for controlling the state of the power supply separation circuit from the output of the voltage detection circuit and the output of the rectification operation detection circuit;
A power supply control circuit comprising: The power supply control circuit according to claim 1, further comprising a resistor that connects the first power supply voltage and a ground GND level. A contact terminal to which a voltage is applied from the outside;
A voltage detection circuit for detecting a first power supply voltage having the same potential as the contact terminal;
A power supply voltage adjusting circuit for changing the first power supply voltage and outputting a third power supply voltage;
An antenna that generates an induced electromotive force by electromagnetic waves;
A rectifier circuit for rectifying the induced electromotive force;
A rectification operation detection circuit for detecting an operation state of the rectification circuit;
A power supply separation circuit for separating the third power supply voltage and a second power supply voltage generated from the rectifier circuit;
A state control circuit for controlling the state of the power supply separation circuit from the output of the voltage detection circuit and the output of the rectification operation detection circuit;
A power supply control circuit comprising: 4. The power supply control circuit according to claim 3, further comprising a resistor that connects the first power supply voltage and a ground GND level. 4. The power supply control circuit according to claim 3, further comprising a resistor for connecting the third power supply voltage and a ground GND level. A contact terminal to which a voltage is applied from the outside;
An antenna that generates an induced electromotive force by electromagnetic waves;
A rectifier circuit that rectifies the induced electromotive force and outputs a fifth power supply voltage;
A diode connecting the fourth power supply voltage and the fifth power supply voltage, which have the same potential as the contact terminal;
A power supply control circuit comprising: A contact terminal to which a voltage is applied from the outside;
A power supply voltage adjusting circuit for changing a sixth power supply voltage having the same potential as the contact terminal and outputting a seventh power supply voltage;
An antenna that generates an induced electromotive force by electromagnetic waves;
A rectifier circuit that rectifies the induced electromotive force and outputs the seventh power supply voltage;
A power supply control circuit comprising: 8. The power supply control circuit according to claim 7, further comprising a resistor that connects the sixth power supply voltage and a ground GND level.

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