JP5233459B2 - Power reception control device, power reception device, and electronic device - Google Patents

Description

  The present invention relates to a power reception control device, a power reception device, an electronic device, and the like.

  In recent years, contactless power transmission that uses electromagnetic induction and enables power transmission even without a contact of a metal part has been in the spotlight. As an application example of this non-contact power transmission, charging of a mobile phone or a household device (for example, a handset of a phone) has been proposed.

A non-contact power transmission device using a primary coil and a secondary coil is described in Patent Document 1, for example.
JP 2006-60909 A

  In recent years, secondary batteries such as lithium ion batteries and lithium polymer batteries have been widely used as batteries for portable terminals such as portable telephones and notebook personal computers. These secondary batteries such as lithium ion batteries and lithium polymer batteries have the advantage that the energy density is extremely higher than other batteries, but on the other hand, it is necessary to perform strict charge control in consideration of deterioration and safety. Yes, high-accuracy charge management technology is required.

  Therefore, it can be said that it is preferable to use a charging circuit using a regulator (for example, a series regulator) capable of performing highly accurate output control in order to charge the secondary battery.

  Also, considering the convenience of the user of the mobile terminal, the charging time of the secondary battery is better, but the charging efficiency of the secondary battery when using non-contact power transmission is a normal charger (AC adapter). The charging efficiency tends to be lower than the charging efficiency of the charger using the battery. Therefore, when charging a portable terminal using contactless power transmission, it is important to reduce power loss during charging as much as possible.

  According to the study of the inventor of the present invention, when it is necessary to flow a large amount of charging current, for example, when a rechargeable secondary battery is charged, there is a power loss (power loss) in the regulator described above. It has become clear that this may hinder the shortening of the charging time. In consideration of the safety of the mobile terminal, it is desirable to suppress the heat generation of the regulator during charging to a minimum.

  Therefore, the inventor of the present invention bypasses the regulator when the amount of power supplied to the secondary battery is insufficient (for example, when the voltage at the output node of the regulator drops below a given threshold voltage). A technique for reducing loss and heat generation in the regulator by forming a path and supplying necessary current to a load (secondary battery, etc.) to be fed via this bypass path was studied.

  As a result of the examination, the bypass path is turned on after the bypass path is turned off (for example, immediately after), or the bypass path is turned off after the bypass path is turned on (for example, immediately after). It has been found that an oscillating operation (which may be repeated in some cases) may occur.

  The cause of the oscillation is, for example, that the secondary coil employed in the power receiving module passes more current beyond the standard range, or the on-resistance of the regulator and the switch circuit that constitutes the bypass path The difference from the on-resistance is greater than the designed value.

  For example, when the bypass path switches from an on state (a state in which a large current flows) to an off state (a state in which current and voltage are controlled by the regulator), the current flowing through the regulator and the on resistance of the regulator Due to the voltage drop caused by, the voltage at the output node of the regulator drops instantaneously. If the degree of the decrease is larger than the hysteresis width of the hysteresis characteristic given to the bypass control circuit, the bypass path is turned on again, and an oscillation state occurs.

  When designing a power receiving module (including a secondary coil and a power receiving device), a hysteresis characteristic is added to the bypass control circuit, for example, a malfunction that switches on / off of the bypass due to fine noise. Is prevented from occurring. However, a secondary coil, a regulator (for example, a series regulator such as an LDO), and a switch circuit (for example, a power switching transistor) for forming a bypass path are external components. As a general rule, it is left to the judgment of the manufacturer that manufactures the power receiving module to determine what characteristics are used.

  Therefore, depending on the characteristics of the external parts employed, an unexpected and instantaneous large voltage change may occur in the rectified voltage when the bypass is turned on / off.

  An IC manufacturer that supplies a power reception control device (power reception control IC: including a bypass control circuit that performs bypass control) is strongly required to ensure the reliability of the power receiving module. In order to increase the reliability of the power receiving module, the oscillation state is reliably prevented even when an unexpected large instantaneous voltage change occurs in the rectified voltage of the power receiving device when switching the bypass on / off. This is very important. Such matters have been clarified by studies by the inventors of the present invention.

  The present invention has been made based on such consideration. According to some aspects of the present invention, for example, power loss and heat generation in the power receiving device can be reduced by regulator bypass technology, while switching the bypass on / off to the rectified voltage of the power receiving device. Even when an unexpected large instantaneous voltage change occurs, oscillation can be reliably prevented and the reliability of the power receiving apparatus can be improved.

  (1) In one aspect of the power reception control device of the present invention, the primary coil and the secondary coil are electromagnetically coupled to transmit power from the power transmission device to the power reception device including the rectifier circuit and the regulator, A power receiving control device provided in the power receiving device in a non-contact power transmission system for supplying the power to a load to be fed from a voltage output node of the device, the power receiving side control circuit controlling the operation of the power receiving device The power receiving side control circuit includes a bypass control unit that controls whether or not to turn on a switch circuit provided between an input node and an output node of the regulator, and the bypass control unit includes: A voltage detection circuit for detecting a voltage level of at least one of the input node and the output node of the regulator, and a detection signal output from the voltage detection circuit; Accordingly, a bypass control signal output circuit that outputs a bypass control signal that controls whether the switch circuit is turned on or off, and the switch circuit is turned on after the switch circuit is turned off. Or an oscillation prevention circuit for preventing an oscillation state in which the switch circuit is turned off after the switch circuit is turned on, and the oscillation state or the oscillation is generated by the oscillation prevention circuit. When a state that can cause a state is detected, the bypass control signal output circuit turns off the switch circuit.

  In this aspect, the power reception side control circuit of the power reception control device has a bypass control unit, and the bypass control unit may be generated when the bypass is turned on / off (that is, the switch circuit is turned on / off). An oscillation prevention circuit is provided for preventing the possibility of oscillation. In the oscillation prevention circuit, for example, the switch circuit is turned on after the switch circuit is turned off (immediately after), or the switch circuit is turned off after the switch circuit is turned on (immediately after). An oscillation state or a state that can cause an oscillation state is detected.

  The voltage detection circuit monitors the rectified voltage (the voltage at the input node of the regulator, the voltage at the output node, or both voltages) of the power receiving device.

  In principle, the bypass control signal output circuit controls ON / OFF of the switch circuit (that is, ON / OFF of the bypass) based on the detection signal of the voltage detection circuit. However, when an oscillation state or a state that can cause an oscillation state is detected by the oscillation prevention circuit, the bypass control signal from the bypass control signal output circuit is fixed to an inactive level, for example, and the switch circuit is turned off. To do.

  Therefore, according to the present aspect, power loss and heat generation in the power receiving device can be reduced by the bypass technology of the regulator, and on the other hand, the rectified voltage of the power receiving device can be reduced to an unexpected moment by switching the bypass on / off. Even when a large voltage change occurs, the oscillation state can be reliably prevented. Thus, the reliability of the power receiving device can be increased.

  (2) In another aspect of the power reception control device of the present invention, the voltage detection circuit includes a hysteresis comparator that outputs the detection signal, and the voltage level of the detection signal output from the hysteresis comparator is the regulator. When the voltage level of at least one of the input node and the output node is lower than the first threshold voltage, the first threshold is reached, and the second threshold is higher than the first threshold voltage. When the value voltage is exceeded, the second level is reached.

  The bypass control circuit has a hysteresis comparator having hysteresis characteristics. That is, when the rectified voltage drops to the first threshold level, the switch circuit (that is, bypass) is turned on, and then when the rectified voltage rises to the second threshold level, the switch circuit (that is, bypass) is turned on. Turn off. As a result, for example, a malfunction that switches on / off of the bypass due to fine noise does not occur.

  Here, for example, when the first threshold voltage is further reduced and the hysteresis width is expanded, the possibility of an oscillation state occurring when the bypass is switched on / off is reduced. However, the degree of voltage fluctuation of the rectified voltage that occurs when the bypass is turned on / off varies depending on the characteristics of external components (for example, constants that determine input / output characteristics). If the hysteresis width for bypass control is set too wide, the bypass is difficult to turn on even when the amount of power supplied to the load to be supplied is reduced. In addition, it becomes difficult to turn on the bypass, and in this case, the period during which the control of the power supply voltage by the regulator does not work is lengthened. As a result, the withstand voltage margin of the power receiving device is reduced. In this case, the original purpose of achieving high efficiency and ensuring safe operation cannot be achieved.

  Therefore, the hysteresis width of the hysteresis comparator is set within a range where the above-mentioned original purpose can be achieved, and oscillations that may occur when the bypass is turned on / off should be separately dealt with by an oscillation prevention circuit. It is a thing.

  (3) In another aspect of the power reception control device of the present invention, the bypass control signal output circuit is configured such that the number of times the switch circuit is turned on by the oscillation prevention circuit is a given permission number m (m is 1 or more). (M + 1) times, the switch circuit is prohibited from being turned on.

  In this mode, by setting a limit on the number of times that the bypass (switch circuit) can be turned on (bypass on frequency), oscillation caused by switching on / off of the bypass (switch circuit) is surely prevented. To do. During the period of supplying power to the same load, it is considered that there are not many situations where the bypass is turned on to compensate for the shortage of power supply.

  Therefore, the number of times that the bypass (switch circuit) is allowed to be in the ON state (bypass-on permitted number) is set to m times. If the value of m is set to an appropriate value, oscillation can be reliably prevented without preventing the bypass (switch circuit) from being turned on in order to compensate for the shortage of power supply. That is, since the (m + 1) -th bypass (switch circuit) is turned on, oscillation is reliably prevented.

  (4) In another aspect of the power reception control device of the present invention, the given permission count m is set to “1”.

  During the power supply period to the same load, it is considered that there are not so many situations where the bypass is turned on to compensate for the shortage of power supply. Basically, it is considered that it is often sufficient to turn on the bypass only once during the period of supplying power to the same load. For example, when charging a secondary battery, the bypass is often turned on in the initial stage of charging because of the need to supply a large amount of current to the depleted secondary battery. After that, when the secondary battery is charged to some extent, the rectified voltage of the power receiving device gradually increases, the bypass where the rectified voltage exceeds a given level is released, the rectified voltage of the power receiving device stabilizes, and eventually It is a general charging operation that the secondary battery is fully charged. Even when power is supplied to a load other than the secondary battery, it is considered that there are many cases in which the bypass only needs to be turned on once during the power supply to the same load.

  Therefore, in this aspect, during the power supply period to the same target load, the bypass is turned on only once. Accordingly, when the bypass is turned on to compensate for the shortage of the power supply capability of the power receiving device, the second bypass on (that is, the second switch circuit is turned on) is prohibited.

  For example, when the bypass is turned on to compensate for the shortage of power supply capability of the power receiving device (first turn on), and then the oscillation prevention circuit detects that the bypass is switched from the on state to the off state. The second bypass is prohibited from being turned on. In this case, the “state in which the first bypass on-state is completed” is the “state in which oscillation can occur”. In other words, when it is detected by the oscillation prevention circuit that the oscillation can be generated, the second bypass ON is prohibited, thereby causing the oscillation caused by switching the bypass on / off. The condition is reliably prevented before it happens.

  (5) In another aspect of the power reception control device of the present invention, when the bypass control signal output circuit detects the oscillation state or a state that can cause the oscillation state by the oscillation prevention circuit, The switch-on is prohibited for a given time, and after the given time has elapsed, the switch circuit is no longer turned on.

  During the power supply period for the same power supply target load, the number of times the bypass is turned on is considered to be about 1 time. However, for some reason, the state where the power supply capacity is insufficient is twice or three times. May occur. In such a case, it is preferable to turn on the bypass so that a sufficient current can be supplied to the load. On the other hand, the large fluctuation of the instantaneous rectified voltage caused by the on / off of the bypass does not continue for a long time, and generally converges after a certain period of time.

  Therefore, in this aspect, for example, the bypass control signal is prohibited from becoming an active level within a given time (for example, about 10 seconds), and thereby, the bypass (switch circuit) is prohibited from being turned on within this period. Is done. When the given time elapses, the prohibition of turning on the bypass (switch circuit) is canceled. Since the bypass is prohibited from being turned on for a given time from the bypass on / off switching timing, oscillation caused by the bypass on / off is reliably prevented. In addition, during a power supply period for the same power supply target load, when a state in which the power supply capability is insufficient occurs a plurality of times, the shortage of power supply can be compensated by turning on the bypass each time.

  (6) In another aspect of the power reception control device of the present invention, when the bypass control signal output circuit detects a change from the first on state to the off state of the switch circuit by the oscillation prevention circuit, The switch circuit is inhibited from being turned on for a given time, and after the given time has elapsed, the switch circuit is turned off.

  In this mode, the oscillation prevention circuit detects that the bypass is turned on to compensate for the lack of power supply capability of the power receiving device (first turn on), and that the bypass is then switched from the on state to the off state. Then, the second bypass is prohibited from being turned on for a given period (for example, a period of about 10 seconds) from that timing. In this case, the “state in which the first bypass on-state is completed” is the “state in which oscillation can occur”. In other words, when it is detected by the oscillation prevention circuit that the oscillation can be generated, the second bypass (switch circuit) is prohibited from being turned on for a given time. An oscillation state caused by switching off is surely prevented.

  (7) In another aspect of the power reception control device of the present invention, the bypass control signal output circuit changes the bypass path from the first on state to the off state and further to the on state by the oscillation prevention circuit. When this is detected, the switch circuit is turned off for a given time, and after the given time has elapsed, the switch circuit is turned off.

  In this aspect, the bypass is turned on to compensate for the shortage of the power supply capability of the power receiving device (first turn-on), then the bypass is switched from the on state to the off state, and then the bypass is performed (for example, immediately after). When the oscillation prevention circuit detects that is turned on again (on for the second time), the bypass is turned off, and for a given period (for example, a period of about 10 seconds) from that timing, On (third bypass on) is prohibited.

  In this case, the bypass changes from the on-state to the off-state, and immediately after that changes to the on-state again, an oscillation state is generated only once. However, the bypass is not repeatedly turned on thereafter. Therefore, it is possible to reliably prevent the oscillation state caused by the on / off switching of the bypass from being continued. In this aspect, since an actual oscillation state is detected, there is an advantage that the oscillation prevention function does not operate by mistake.

  (8) In another aspect of the power reception control device of the present invention, the voltage detection circuit includes a hysteresis comparator that outputs the detection signal, and the oscillation state or the oscillation state can be generated by the oscillation prevention circuit. Before a state is detected, the level of the output signal of the hysteresis comparator is the first level when the voltage level of at least one of the input node and the output node of the regulator falls below a first threshold voltage. A level that exceeds the second threshold voltage, which is higher than the first threshold voltage, becomes the second level, and the oscillation state or the oscillation state can be generated by the oscillation prevention circuit Is detected, the hysteresis characteristic of the hysteresis comparator is changed, whereby the hysteresis is The level of the output signal of the cis-comparator is lower than a third threshold voltage at which the voltage level of at least one of the input node and the output node of the regulator is lower than the first threshold voltage. And the first level, and the third threshold voltage is a voltage that does not drop in the oscillation state, and is lower when the amount of power supplied to the load to be fed is insufficient. Set to a certain voltage.

  In this aspect, when an oscillation state or a state that can cause an oscillation state is detected by the oscillation prevention circuit, the hysteresis width of the hysteresis comparator used for bypass control is expanded to prevent oscillation.

  As described above, bypass ON / OFF switching control is executed using the hysteresis width of the hysteresis comparator. That is, the bypass is turned on when the rectified voltage falls to the first threshold level, and then the bypass is turned off when the rectified voltage rises to the second threshold level. In this aspect, when the oscillation prevention circuit detects an oscillation state or a state that can cause an oscillation state, the threshold voltage for turning on the bypass is a voltage lower than the first threshold voltage. The third threshold voltage is changed. As a result, even if an oscillation state occurs, it becomes difficult for the rectified voltage (at least one of the voltage at the input node and the voltage at the output node of the regulator) to fall below the third threshold voltage, thereby preventing oscillation. Alternatively, it is possible to prevent the oscillation from continuing.

  The third threshold voltage is preferably set to a voltage that does not fall below in the oscillation state and that may fall below when the amount of power supplied to the load to be fed is insufficient. That is, if the hysteresis width for bypass control is too wide, the bypass is difficult to turn on even when the amount of power supplied to the load to be fed is reduced, and the bypass is not easily released. The level of the third threshold voltage is preferably set to an appropriate level that can prevent oscillation and respond to a request for bypass-on due to a shortage of power supply.

  (9) In another aspect of the power reception control device of the present invention, when the oscillation prevention circuit detects a change from the first on state to the off state of the switch circuit, the hysteresis characteristic of the hysteresis comparator is changed. As a result, the level of the output signal of the hysteresis comparator becomes the first level when the voltage level of at least one of the input node and the output node of the regulator falls below the third threshold voltage.

  When the bypass is turned on to compensate for the lack of power supply capability of the power receiving apparatus (first turn on), and then the oscillation prevention circuit detects that the bypass is switched from the on state to the off state, The threshold value for turning on is changed from the first threshold voltage to the third threshold voltage.

  In this case, the “state in which the first bypass on-state is completed” is the “state in which oscillation can occur”. That is, when the oscillation preventing circuit detects that the oscillation can be generated, the hysteresis width is expanded. Therefore, an oscillation state caused by switching on / off of the bypass is prevented in advance.

  (10) In another aspect of the power reception control device of the present invention, when it is detected by the oscillation prevention circuit that the switch circuit is changed from an initial on state to an off state and further changed to an on state, When the hysteresis characteristic of the hysteresis comparator is changed, the level of the output signal of the hysteresis comparator is changed when the voltage level of at least one of the input node and the output node of the regulator is lower than the third threshold voltage. This is the first level.

  In this aspect, the bypass is turned on to compensate for the shortage of the power supply capability of the power receiving device (first turn-on), then the bypass is switched from the on state to the off state, and immediately after that, the bypass is turned on again. When the oscillation prevention circuit detects that (second turn-on) has occurred, the threshold value for turning on the bypass is changed from the first threshold voltage to the third threshold voltage. The hysteresis width is expanded. Therefore, an oscillation state caused by switching on / off of the bypass is prevented. In this aspect, since the fact that the oscillation state has actually occurred is detected, there is an advantage that the oscillation prevention function (function for expanding the hysteresis width) does not operate by mistake.

  (11) In another aspect of the power reception control device of the present invention, the state in which the hysteresis characteristic of the hysteresis comparator is changed continues for a given time from the timing of the change, and when the time has elapsed, the hysteresis comparator The hysteresis characteristic returns to the state before the change of the hysteresis characteristic.

  In this aspect, the change of the hysteresis width of the hysteresis comparator is continued for a given time (for example, about 10 seconds), and the hysteresis characteristic of the hysteresis comparator returns to the state before the change after the time has elapsed.

  Oscillation is prevented by increasing the hysteresis width within a given period from the on / off switching timing of the bypass. On the other hand, after the lapse of a given period, the hysteresis width is restored to the original state so that the situation in which the bypass is difficult to turn on is eliminated, and when the power supply capacity to the load is insufficient, the bypass can be turned on quickly. To.

  (12) One aspect of the power receiving device of the present invention includes the rectifier circuit, and includes a power receiving unit that converts an induced voltage of the secondary coil into a DC voltage, the regulator, and an input terminal and an output terminal of the regulator. And a power feeding control unit that controls power feeding to the load to be fed.

  According to this aspect, there is provided a highly reliable non-contact power transmission system having excellent characteristics of small size, low loss, and low heat generation and capable of reliably preventing an oscillation state in which bypass is repeatedly turned on and off. A power receiving apparatus is realized.

  (13) In another aspect of the power receiving device of the present invention, the regulator and the switch circuit are external components.

  The degree of voltage fluctuation of the rectified voltage that occurs when the bypass is turned on / off varies depending on the characteristics of external components (for example, constants that determine input / output characteristics). When the present invention is not used, external parts that can be employed may be limited from the viewpoint of preventing oscillation. According to the present invention, oscillation is reliably prevented. Therefore, a user who uses the power receiving module can freely select a secondary coil or a regulator as an external component, a power switching transistor for forming a bypass path, or the like.

  (14) One embodiment of the electronic device of the present invention includes the above power receiving device and a load to be supplied with power supplied by the power receiving device.

  The present invention can be applied to various electronic devices (for example, wristwatches, cordless telephones, shavers, electric toothbrushes, wrist computers, handy terminals, portable information terminals, electric bicycles, etc.). Examples of particularly suitable electronic devices include mobile terminals (including mobile phone terminals, PDA terminals, portable personal computer terminals) and watches (watches). Since the power receiving device of the present invention is simple in configuration and small in size, it can be mounted on a portable terminal or the like and has low loss. For example, the charging time of a secondary battery in an electronic device can be shortened. In addition, since the heat generation is reduced, the reliability of the electronic device from the viewpoint of safety is also improved. In addition, since an oscillation state in which the bypass is repeatedly turned on / off is reliably prevented, stable power supply to the power supply target load is realized. Therefore, the reliability of the electronic device is further improved.

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
The present embodiment described below does not unduly limit the contents of the present invention described in the claims, and all the configurations described in the present embodiment are indispensable as means for solving the present invention. Not necessarily.

(First embodiment)
Hereinafter, the non-contact power transmission system will be described.

(Configuration of electronic equipment)
FIG. 1A to FIG. 1C are diagrams illustrating a configuration of an example of a contactless power system. FIG. 1A shows an example of an electronic device to which the contactless power transmission method of this embodiment is applied. A charger 500 (cradle) which is one of electronic devices has a power transmission device 10. A mobile phone 510 that is one of the electronic devices includes a power receiving device 40. The mobile phone 510 includes a display unit 512 such as an LCD, an operation unit 514 including buttons and the like, a microphone 516 (sound input unit), a speaker 518 (sound output unit), and an antenna 520.

  Electric power is supplied to the charger 500 via the AC adapter 502, and this electric power is transmitted from the power transmitting device 10 to the power receiving device 40 by contactless power transmission. Thereby, the battery of the mobile phone 510 can be charged or the device in the mobile phone 510 can be operated.

  The electronic device to which this embodiment is applied is not limited to the mobile phone 510. For example, the present invention can be applied to various electronic devices such as wristwatches, cordless telephones, shavers, electric toothbrushes, wrist computers, handy terminals, portable information terminals, electric bicycles, and IC cards.

  As schematically shown in FIG. 1B, power transmission from the power transmission device 10 to the power reception device 40 is performed on the primary coil L1 (power transmission coil) provided on the power transmission device 10 side and on the power reception device 40 side. This is realized by electromagnetically coupling the secondary coil L2 (power receiving coil) formed to form a power transmission transformer. Thereby, non-contact power transmission becomes possible.

  In FIG. 1B, the primary coil L1 and the secondary coil L2 are, for example, air-core planar coils formed by winding a coil wire spirally on a plane. However, the coil of the present embodiment is not limited to this, and any shape, structure, or the like may be used as long as the primary coil L1 and the secondary coil L2 can be electromagnetically coupled to transmit power.

  For example, in FIG. 1C, the primary coil L1 is formed by winding a coil wire around the X-axis around the magnetic core in a spiral shape. The same applies to the secondary coil L2 provided in the mobile phone 510. The present embodiment can also be applied to a coil as shown in FIG. In the case of FIG. 1 (C), as the primary coil L1 and the secondary coil L2, in addition to the coil wound around the X axis, a coil wound around the Y axis may be combined. .

  Further, the electronic device to which the present embodiment is applied is not limited to the mobile phone 510. For example, the present invention can be applied to various electronic devices such as wristwatches, cordless telephones, shavers, electric toothbrushes, wrist computers, handy terminals, portable information terminals, and electric bicycles.

  Examples of particularly suitable electronic devices include mobile terminals (including mobile phone terminals, PDA terminals, portable personal computer terminals) and watches (watches). Since the power receiving device of the present invention is simple in configuration and small in size, it can be mounted on a portable terminal or the like and has low loss. For example, the charging time of a secondary battery in an electronic device can be shortened. In addition, since the heat generation is reduced, the reliability of the electronic device from the viewpoint of safety is also improved.

  In particular, mobile terminals (including mobile phone terminals, PDA terminals, and portable personal computer terminals) have a large amount of charging current at high loads, and the problem of heat generation is likely to become obvious. A watch (watch) is a device that is required to be downsized and have low power consumption, and low loss during battery charging is important. Therefore, these devices can be said to be devices that can fully utilize the low loss and low heat generation characteristics of the present invention.

(Specific examples of the configuration of the power transmitting device and the power receiving device)
FIG. 2 is a circuit diagram illustrating an example of a specific configuration of each unit in a contactless power transmission system including a power transmission device and a power reception device.

  The power transmission device 10 includes a power transmission control device 20, a power transmission unit 12, a waveform monitor circuit 14, and a display unit 16. The power transmission control device 20 includes a power transmission side control circuit 22, an oscillation circuit 24, a driver control circuit 26, and a waveform detection circuit 28.

  In addition, the power receiving device 40 includes a power receiving unit 42, a load modulation unit 46, a power supply control unit 48, and a power reception control device 50. Further, the load to be fed in the non-contact power transmission system is a secondary battery (for example, a lithium ion battery) 94. Charging of the secondary battery 94 is managed by a charging device (charger) 90. This will be specifically described below.

  The electronic device on the power transmission side such as the charger 500 includes at least the power transmission device 10 shown in FIG. In addition, the electronic device on the power receiving side such as the mobile phone 510 includes at least the power receiving device 40, the charging device 90, and the load 94 to be supplied with power.

  2, the primary coil L1 and the secondary coil L2 are electromagnetically coupled to transmit power from the power transmitting device 10 to the power receiving device 40, and power is supplied from the voltage output terminal TA1 of the power receiving device 40. A non-contact power transmission (non-contact power transmission) system for supplying power to the target load 94 is realized.

  The power transmission device 10 (power transmission module, primary module) can include a primary coil L1, a power transmission unit 12, a waveform monitor circuit 14, a display unit 16, and a power transmission control device 20. The power transmission device 10 and the power transmission control device 20 are not limited to the configuration in FIG. 2, and some of the components (for example, the display unit and the waveform monitor circuit) are omitted, other components are added, and the connection is made. Various modifications such as changing the relationship are possible.

  The power transmission unit 12 generates an AC voltage having a predetermined frequency during power transmission, and generates an AC voltage having a different frequency according to data during data transfer, and supplies the AC voltage to the primary coil L1. The power transmission unit 12 forms a resonance circuit together with the first power transmission driver that drives one end of the primary coil L1, the second power transmission driver that drives the other end of the primary coil L1, and the primary coil L1. One capacitor can be included. Each of the first and second power transmission drivers included in the power transmission unit 12 is, for example, an inverter circuit (or buffer circuit) configured by a power MOS transistor, and is controlled by the driver control circuit 26 of the power transmission control device 20. The

  The primary coil L1 (power transmission side coil) is electromagnetically coupled to the secondary coil L2 (power reception side coil) to form a power transmission transformer. For example, when electric power transmission is required, as shown in FIG. 1, the mobile phone 510 is placed on the charger 500 so that the magnetic flux of the primary coil L1 passes through the secondary coil L2. On the other hand, when power transmission is unnecessary, the charger 500 and the mobile phone 510 are physically separated so that the magnetic flux of the primary coil L1 does not pass through the secondary coil L2.

  For example, planar coils can be used as the primary coil L1 and the secondary coil L2. The waveform monitor circuit 14 is a circuit that detects an induced voltage of the primary coil L1, and is, for example, between resistors RA1 and RA2 or a connection node NA3 between RA1 and RA2 and GND (low-potential side power supply in a broad sense). It includes a provided diode DA1. Specifically, a signal PHIN obtained by dividing the induced voltage of the primary coil by the resistors RA1 and RA2 is input to the waveform detection circuit 28 of the power transmission control device 20.

  The display unit 16 displays various states of the contactless power transmission system (during power transmission, ID authentication, etc.) using colors, images, and the like. For example, an LED (light emitting diode) or LCD (liquid crystal display device). And so on.

  The power transmission control device 20 is a device that performs various controls of the power transmission device 10, and can be realized by an integrated circuit device (IC) or the like. The power transmission control device 20 includes a power transmission side control circuit 22, an oscillation circuit 24, a driver control circuit 26, and a waveform detection circuit 28.

  The power transmission side control circuit 22 controls the power transmission device 10 and the power transmission control device 20, and can be realized by, for example, a gate array or a microcomputer.

  Specifically, the power transmission side control circuit 22 performs various sequence controls and determination processes necessary for power transmission, load detection, frequency modulation, foreign object detection, and attachment / detachment detection. For example, when the operation switch is turned on, the power transmission side control circuit 22 starts temporary power transmission for position detection and ID authentication for the power receiving device 40.

  The oscillation circuit 24 is composed of, for example, a crystal oscillation circuit, and generates a primary side clock (drive clock DRCK). The driver control circuit 26 generates a control signal having a desired frequency based on the clock generated by the oscillation circuit 24, the frequency setting signal from the control circuit 22, and the like, and outputs the control signal to a power transmission driver (not shown) of the power transmission unit 12. Then, the operation of the power transmission driver is controlled.

  The waveform detection circuit 28 monitors the waveform of the signal PHIN corresponding to the induced voltage at one end of the primary coil L1, and performs load detection, foreign object detection, and the like. For example, when the load modulation unit 46 of the power receiving device 40 performs load modulation for transmitting data to the power transmission device 10, the signal waveform of the induced voltage of the primary coil L1 changes correspondingly.

  For example, when the load modulation unit 46 of the power receiving device 40 decreases the load to transmit data “0”, the amplitude (peak voltage) of the signal waveform decreases, and the load increases to transmit the data “1”. As a result, the amplitude of the signal waveform increases. Therefore, the waveform detection circuit 28 performs peak hold processing of the signal waveform of the induced voltage and determines whether or not the peak voltage exceeds the threshold voltage, whereby the data from the power receiving device 40 is “0”. Whether it is “1” or not. Note that the method of waveform detection is not limited to the above-described method. For example, whether the load on the power receiving side has increased or decreased can be determined using physical quantities other than the peak voltage (phase difference between current and voltage, pulse width of a pulse generated based on a voltage waveform, etc.). Good.

  The power reception device 40 (power reception module, secondary module) can include a secondary coil L2, a power reception unit 42, a load modulation unit 46, a power supply control unit 48, and a power reception control device 50. The power reception device 40 and the power reception control device 50 are not limited to the configuration shown in FIG. 2, and various modifications such as omitting some of the components, adding other components, and changing the connection relationship. Implementation is possible.

  The power receiving unit 42 converts the AC induced voltage of the secondary coil L2 into a DC voltage. This conversion is performed by a rectifier circuit 43 included in the power receiving unit 42. The rectifier circuit 43 includes diodes DB1 to DB4. The diode DB1 is provided between the node NB1 at one end of the secondary coil L2 and the generation node NB3 of the DC voltage VDC, and DB2 is provided between the node NB3 and the node NB2 at the other end of the secondary coil L2. , DB3 is provided between the node NB2 and the VSS node NB4, and DB4 is provided between the nodes NB4 and NB1.

  The resistors RB1 and RB2 of the power receiving unit 42 are provided between the nodes NB1 and NB4. A signal CCMPI obtained by dividing the voltage between the nodes NB1 and NB4 by the resistors RB1 and RB2 is input to the frequency detection circuit 60 of the power reception control device 50.

  The capacitor CB1 and the resistors RB4 and RB5 of the power receiving unit 42 are provided between the node NB3 of the DC voltage VDC and the node NB4 of VSS. A divided voltage VD4 obtained by dividing the voltage between the nodes NB3 and NB4 by the resistors RB4 and RB5 is input to the power receiving side control circuit 52 and the position detection circuit 56 via the signal line LP2. As for the position detection circuit 56, the divided voltage VD4 serves as a signal input (ADIN) for position detection.

  The load modulation unit 46 performs load modulation processing. Specifically, when transmitting desired data from the power receiving device 40 to the power transmitting device 10, the load at the load modulation unit 46 (secondary side) is variably changed according to the transmission data, and the primary coil L1 The signal waveform of the induced voltage is changed. For this purpose, the load modulation unit 46 includes a resistor RB3 and a transistor TB3 (N-type CMOS transistor) provided in series between the nodes NB3 and NB4.

  This transistor TB3 is ON / OFF controlled by a control signal P3Q given from the power reception side control circuit 52 of the power reception control device 50 via the signal line LP3. In the authentication stage before the actual power transmission is started, the load modulation transistor TB3 is turned on / off to perform load modulation, and a signal is transmitted to the power transmission apparatus.

  For example, when the secondary side is made to have a low load (high impedance) in order to transmit data “0”, the drive signal P3Q of the load modulation transistor TB3 becomes L level and the load modulation transistor TB3 is turned off. As a result, the load of the load modulator 46 becomes almost infinite (no load). On the other hand, when the secondary side is set to a high load (impedance is small) to transmit data “1”, the drive signal P3Q of the load modulation transistor TB3 becomes H level and the load modulation transistor TB3 is turned on. . As a result, the load of the load modulation unit 46 becomes the resistance RB3 (high load).

  The power feeding control unit 48 controls power feeding to the load 94 to be fed. The regulator (LDO) 49 adjusts the voltage level of the DC voltage VDC obtained by the conversion in the rectifier circuit 43, and generates a power supply voltage VD5 (for example, 5V). VD 5 is a voltage at the output terminal of the regulator (LDO) 49. The power reception control device 50 operates with the power supply voltage VD5.

  Further, a switch circuit composed of a PMOS transistor (M1) is provided between the input terminal and the output terminal of the regulator (LDO) 49. By turning on the PMOS transistor (M1) as the switch circuit, a path bypassing the regulator (LDO) 49 is formed. For example, at the time of high load (for example, in the initial stage of charging of a rechargeable secondary battery, it is necessary to constantly flow a substantially constant large current, and such time corresponds to the time of high load) Since the power loss increases and the heat generation increases due to the equivalent impedance of the regulator 49 itself, the regulator is bypassed and current is supplied to the load via the bypass path.

  In order to control the on / off of the PMOS transistor M1 as a bypass forming switch, a bypass control NMOS transistor M2 and a pull-up resistor R8 are provided.

  When the high-level bypass control signal VPBP is supplied from the power receiving side control circuit 52 to the gate of the NMOS transistor M2 via the signal line LP4, the NMOS transistor M2 is turned on. Then, the gate of the PMOS transistor M1 becomes a low level, and the PMOS transistor M1 is turned on to form a path that bypasses the regulator (LDO) 49. On the other hand, when the NMOS transistor M2 is in an off state, the gate of the PMOS transistor M1 is maintained at a high level via the pull-up resistor R8, so that the PMOS transistor M1 is turned off and no bypass path is formed.

  ON / OFF of the bypass path (that is, ON / OFF of the NMOS transistor M2) is controlled by a power reception side control circuit 52 included in the power reception control device 50. The configuration and operation of the power receiving side control circuit 52 related to the on / off of the bypass will be described later.

  The transistor TB2 (P-type CMOS transistor) is provided between the generation node NB5 (output node of the regulator 49) of the power supply voltage VD5 and the transistor TB1 (node NB6), and the power reception side control circuit of the power reception control device 50. Controlled by a signal P1Q from 52. Specifically, the transistor TB2 is turned on when the ID authentication is completed (established) and normal power transmission is performed.

  A pull-up resistor RU2 is provided between the power supply voltage generation node NB5 and the node NB8 of the gate of the transistor TB2.

  The power reception control device 50 is a device that performs various controls of the power reception device 40 and can be realized by an integrated circuit device (IC) or the like. The power reception control device 50 can be operated by a power supply voltage VD5 generated from the induced voltage of the secondary coil L2. The power reception control device 50 can include a power reception side control circuit 52, a position detection circuit 56, an oscillation circuit 58, a frequency detection circuit 60, and a full charge detection circuit 62.

  The power receiving side control circuit 52 controls the power receiving device 40 and the power receiving control device 50, and can be realized by, for example, a gate array or a microcomputer. The power receiving side control circuit 52 operates using the constant voltage (VD5) at the output node of the series regulator (LDO) 49 as a power source. This power supply voltage (VD5) is given to the power receiving side control circuit 52 via the power supply line LP1.

  Specifically, the power receiving side control circuit 52 includes ID authentication, position detection, frequency detection, full charge detection, load modulation for communication for authentication, and load for communication to enable foreign object insertion detection. Various sequence control and determination processing necessary for modulation and the like are performed.

  The power reception control circuit 52 also has a power supply control signal output terminal for outputting a power supply control signal (ICUTX) for temporarily stopping power supply to the load 94 to be supplied during normal power transmission. TS1 is provided. The power supply control signal (ICUTX) is at an active level during a period in which load modulation is performed (that is, a period in which the load modulation transistor TB3 is turned on / off). The power supply control signal (ICUTX) is given to the charging device 90. That is, the power supply control signal (ICUTX) passes through the power supply control signal output terminal TS1, the terminal TA3 provided in the power receiving device (power receiving module) 40, and the terminal TA7 provided in the charging device 90, It is supplied to the charging device 90.

  The charging device 90 is provided with a power supply control transistor (PMOS transistor) M3. In the normal state, the gate of the power supply control transistor (PMOS transistor) M3 is grounded by the pull-down resistor R16. Therefore, the power supply control transistor (PMOS transistor) M3 is in the on state. Therefore, in a normal state, a current is supplied to the secondary battery (power supply target load) 94 via the power supply control transistor (PMOS transistor) M3.

  When the power supply control signal (ICUTX) output from the power supply control signal output terminal TS1 of the power receiving side control circuit 52 becomes active level (H level), the charging device 90 includes a power supply control transistor (PMOS transistor) M3. The gate becomes high level, and the power supply control transistor (PMOS transistor) M3 is turned off. As a result, power supply to the secondary battery (load) 94 is temporarily stopped. When the power supply control signal (ICUTX) becomes an inactive level (L level), the power supply control transistor (PMOS transistor) M3 returns to the on state.

  Further, the position detection circuit 56 monitors the waveform of the signal ADIN corresponding to the waveform of the induced voltage of the secondary coil L2, and determines whether the positional relationship between the primary coil L1 and the secondary coil L2 is appropriate. Specifically, the signal ADIN is converted into a binary value by a comparator, and it is determined whether or not the positional relationship is appropriate.

  The oscillation circuit 58 is constituted by a CR oscillation circuit, for example, and generates a secondary clock. The frequency detection circuit 60 detects the frequency (f1, f2) of the signal CCMPI and determines whether the transmission data from the power transmission device 10 is “1” or “0”.

  A signal LEDR output from the charging control device 92 included in the charging device 90 is input to the full charge detection circuit 62 (charge detection circuit) via the terminal TA4 and the terminal TS2. The charge control device 92 monitors the state of charge of the secondary battery 94 that is a load to be fed, and a predetermined condition (for example, the voltage is 4.2 V and the current is below a predetermined value continues for a predetermined time). Whether or not the secondary battery 94 is fully charged is detected depending on whether or not the above condition is satisfied. When full charge is detected, charge control device 92 changes signal LEDR from the H level to the L level. As a result, the light emitting diode (LED) used for displaying the charge state is forward-biased and lit. Further, the full charge detection circuit 62 can know that the secondary battery 94 has been fully charged based on the change in the voltage level of the signal LEDR.

  In addition, the charging device 90 includes a power supply control transistor (PMOS transistor) M3, a charging control device 92 that performs charging control of a secondary battery (battery) 94 that is a power supply target load, a charging control transistor M5, a current And a detection resistor R15. For example, the charge control device 92 detects the potential at both ends of the current detection resistor R15, and executes negative feedback control based on the detection result, for example, so that the charge current is constant (or the charge voltage is constant). As such, the ON state of the charge control transistor M5 is controlled. Moreover, the charge control apparatus 92 can detect a full charge state based on the lighting state of the light-emitting device (LED). The charge control device 92 (charge control IC) can be realized by an integrated circuit device or the like.

  In addition, the power receiving apparatus 40 has four terminals (TA1 to TB1). The charging device (charger) 90 has five terminals (TA5 to TA9). The power reception control device 50 has two terminals (ICUTX signal output terminal TS1, LEDR signal input terminal TS2). The load to be fed is not limited to the secondary battery. For example, when a predetermined circuit operates, the circuit may become a load.

  (Description of communication method)

  3A and 3B are diagrams for explaining a communication method between the power transmission device and the power reception device. FIG. 3A illustrates a communication method (frequency modulation) when a signal is transmitted from the power transmission device to the power reception device, and FIG. 3B illustrates a communication method (frequency modulation) when the signal is transmitted from the power reception device to the power transmission device. Load modulation).

  As illustrated in FIG. 3A, the power transmission device can transmit “1” and “0” to the power receiving device by switching the transmission frequency between f1 and f2 by frequency modulation.

  Further, as illustrated in FIG. 3B, the power receiving device can transmit “0” and “1” to the power transmitting device by modulating the load of the power receiving device. That is, when the load modulation transistor TB3 provided in the load modulation unit 46 is turned on / off, the coil end voltage of the primary coil L1 changes as shown in FIG. 3B, for example. Therefore, the power transmission side control circuit 22 compares the voltage at the coil end (node NA2) of the primary coil L1 with the threshold voltage, for example, so that the load modulation signal is “0” or “1”. It can be detected.

(Configuration example for preventing oscillation due to bypass ON / OFF switching)
FIG. 4 is a diagram illustrating an example of a configuration for preventing oscillation due to bypass on / off switching.

  The power reception control device 50 includes a power reception side control circuit 52, and the power reception side control circuit 52 includes a bypass control unit 105. The bypass control unit 105 outputs a bypass control signal VPBP for controlling on / off of the bypass control switch (switch circuit) SW10 based on the voltage detection circuit 106 and the detection signal SCMP output from the voltage detection circuit 106. A control signal output circuit 109 and an oscillation prevention circuit 111 are included.

  The voltage detection circuit 106 detects the voltage level of the rectified voltage in the power receiving device 40. That is, the voltage detection circuit 106 can detect at least one of the voltage Vin at the input node of the regulator (LDO) 49 and the voltage VD5 at the output node. If the voltage Vin at the input node fluctuates, the voltage VD5 at the output node also fluctuates. Therefore, basically, the voltage detection circuit 106 only has to detect either the voltage Vin or the voltage VD5. Both of the voltage VD5 can also be detected.

  However, since the output node of the regulator (LDO) 49 is closer to the load (secondary battery 94) to be fed, monitoring the output node voltage VD5 can more accurately detect the voltage level of the feeding voltage. . Therefore, if one of the voltage Vin and the voltage VD5 is detected, it is preferable to detect the voltage level of the voltage VD5 at the output node. In the following description, it is assumed that the voltage detection circuit 106 detects the voltage VD5 at the output node of the regulator (LDO) 49.

  The voltage detection circuit 106 includes, for example, a hysteresis comparator, and the voltage level of the detection signal SCMP output from the hysteresis comparator is such that the voltage level of the voltage VD5 of the output node of the regulator (LDO) 49 is the first threshold voltage. (For example, H: active level) when lower than (for example, 4.9 V), a second threshold voltage (for example, 5.2 V) that is higher than the first threshold voltage is set. When it exceeds, it becomes the second level (for example, L: inactive level).

  The bypass control signal output circuit 109 sets the bypass control signal VPBP to an active level (for example, H) during a period in which the detection signal SCMP output from the voltage detection circuit 106 is at an active level. As a result, the switch circuit (switch circuit for forming a bypass path) SW10 is turned on to form a bypass path (hereinafter sometimes simply referred to as a bypass), and current is supplied to the load 94 to be fed via the bypass. Supplied. Therefore, the shortage of the power supply amount is solved, and power loss and heat generation in the regulator (LDO) 49 do not occur. The switch circuit SW10 can be configured by a PMOS transistor M1 and an NMOS transistor M2, for example, as shown in FIG.

  The bypass control signal output circuit 109 sets the bypass control signal VPBP to an inactive level (eg, L) when the detection signal SCMP output from the voltage detection circuit 106 becomes an inactive level (eg, L). As a result, the bypass control switch SW10 is turned off and the bypass is turned off.

  By using the hysteresis comparator for the on / off control of the bypass, for example, a malfunction that switches the on / off of the bypass due to fine noise does not occur.

  The oscillation prevention circuit 111 is provided in order to prevent an oscillation state that may occur with the on / off switching of the bypass. Here, the oscillation is, for example, after the bypass is turned off (specifically immediately after), or after the bypass is turned on (specifically immediately after). The operation in which the bypass is turned off or the operation is repeated.

  As described above, the bypass control signal output circuit 109 controls on / off of the bypass based on the detection signal SCMP of the voltage detection circuit 106 in principle. However, when the oscillation prevention circuit 111 detects an “oscillation state” or “a state that can cause an oscillation state”, the bypass positive control signal output circuit 109 fixes the level of the bypass control signal VPBP to an inactive level. Thus, the switch circuit SW10 is turned off. That is, the bypass control signal output circuit 109 prohibits the bypass from being turned on when an oscillation state or a state that can cause an oscillation state is detected. Here, the “state in which the oscillation state can be generated” is, for example, when the on-state bypass is shifted to the off-state. That is, immediately after that, when the bypass is turned on again, the oscillation state is entered. In other words, when the bypass in the on state shifts to the off state, it can be considered that there is a possibility that oscillation occurs immediately after that. In this way, “a state where a possibility of occurrence of oscillation” is “a state where an oscillation state can be generated”.

  Therefore, according to the circuit configuration of FIG. 4, the power loss and heat generation in the power receiving device 40 can be reduced by the bypass technology of the regulator (LDO) 49, while the bypass of the power receiving device can be reduced by switching the bypass on / off. Even when an unexpected large instantaneous voltage change occurs in the rectified voltage, the oscillation state can be reliably prevented. Thus, the reliability of the power receiving device can be increased.

  FIG. 5 is a diagram for explaining an example of bypass on / off control. As shown in FIG. 5, the voltage VD5 at the output node of the regulator (LDO) 49 falls below the first threshold voltage (4.9 V) at time t1, and this state continues until time t4. Therefore, the period T100 from time t1 to time t4 is the bypass on period. At time t4, the voltage VD5 exceeds the second threshold voltage (5.2V), so the bypass is turned off. Period T99 and period T101 are bypass-off periods.

(Description of oscillation state)
FIG. 6 is a diagram for explaining an oscillation state caused by the on / off of the bypass. In FIG. 6, after the time t4, the bypass is repeatedly turned on / off, and an oscillation state is generated.

  As described above, the secondary coil, the regulator (for example, a series regulator such as LDO), the switch circuit (for example, the power switching transistor) for forming the bypass path, and the like are external parts and adopted. Depending on the characteristics of the external parts, unexpected large instantaneous voltage changes may occur in the rectified voltage when the bypass is turned on / off.

  For example, when the bypass is switched from an on state (a state in which a large current flows) to an off state (a state in which current and voltage are controlled by the regulator 49), the current flowing through the regulator 49 and the regulator on Due to the voltage drop caused by the resistance, the voltage VD5 at the output node of the regulator 49 is instantaneously reduced. When the degree of the reduction is larger than the hysteresis width for bypass control (difference voltage between 5.2 V and 4.9 V in FIG. 5), the bypass is turned on again and an oscillation state occurs.

  Here, for example, when the second threshold voltage (4.9 V) is further lowered and the hysteresis width is expanded, the possibility of an oscillation state occurring when switching the bypass on / off is reduced. . However, the degree of voltage fluctuation of the rectified voltage (voltage VD5) generated when the bypass is switched on / off varies depending on the characteristics of external components (for example, constants that determine input / output characteristics). If the hysteresis width for bypass control is set too wide, the bypass is difficult to turn on even if the amount of power supplied to the load 94 to be supplied decreases. In addition, it becomes difficult to turn on the bypass, and in this case, the period during which the control of the power supply voltage by the regulator (LDO) 49 does not work is lengthened. As a result, the withstand voltage margin of the power receiving device is reduced. In this case, the original purpose of achieving high efficiency and ensuring safe operation cannot be achieved.

  Therefore, in this embodiment, the hysteresis width for the on / off control of the bypass (that is, the hysteresis width of the hysteresis comparator) is set to a range in which the above-mentioned original purpose can be achieved, and when the bypass is turned on / off. Oscillation that may occur in the case is taken by providing an oscillation prevention circuit 111 separately.

(Description of specific oscillation countermeasures)
As measures for preventing oscillation, there are a method of limiting the number of times the bypass is turned on, a method of setting a bypass-prohibited section, and a method of expanding the hysteresis width. Hereinafter, it demonstrates in order.

(1) Method of limiting the number of bypass ONs FIG. 7 is a diagram for explaining an example of oscillation countermeasures (limitation of the number of bypass ONs). For example, when the oscillation prevention circuit 111 detects that the bypass control signal output circuit 109 has reached a given permitted number m (m is an integer equal to or greater than 1), (m + 1) ) The bypass is turned on (that is, the switch circuit is turned on). In other words, by setting a limit on the number of times the bypass can be turned on (bypass on number), it is possible to reliably prevent oscillation caused by switching on / off of the bypass.

  In FIG. 7, a period from time t1 to time t4 (period T100) is a first output period of the bypass control signal VPBP (that is, a first period in which VPBP is in an active level). Bypass is released at time t4.

  Here, when the bypass ON permission count m = 1, the second and subsequent bypass ONs are prohibited. That is, at time t5, the voltage VD5 falls below the first threshold value 4.9V, but the bypass is not turned on because the bypass control signal VPBP does not become the active level. Therefore, oscillation is prevented in advance.

  Here, consider the case of m = 1. Basically, it is considered that it is often sufficient to turn on the bypass only once during the period of supplying power to the same load. For example, when charging a secondary battery, the bypass is often turned on in the initial stage of charging because of the need to supply a large amount of current to the depleted secondary battery. After that, when the secondary battery is charged to some extent, the rectified voltage of the power receiving device gradually increases, the bypass where the rectified voltage exceeds a given level is released, the rectified voltage of the power receiving device stabilizes, and eventually It is a general charging operation that the secondary battery is fully charged. Even when power is supplied to a load other than the secondary battery, it is considered that there are many cases in which the bypass only needs to be turned on once during the power supply to the same load.

  In this case, it is effective to set m = 1. In other words, the bypass is turned on (the switch circuit SW10 is turned on) only once during the power supply period to the same target load. Therefore, when the bypass is turned on to compensate for the shortage of the power supply capability of the power receiving device, the second bypass on is prohibited.

  In FIG. 7, the bypass is turned on to compensate for the shortage of power supply capability of the power receiving device 40 (first on: time t <b> 1), and then the bypass is switched from the on state to the off state (time t <b> 4). As described above, the state in which the first bypass on-state is completed (the state at time t4) is the “state in which oscillation can occur”. In other words, when the oscillation prevention circuit 111 detects that the oscillation can be generated, the second bypass on at time t5 is prohibited, thereby causing the bypass on / off switching. The oscillation state that occurs is surely prevented beforehand.

  Further, when m = 2 is set, the bypass is turned on twice and the third bypass is prohibited during power feeding to the same target load. In FIG. 7, the bypass is instantaneously turned on at time t5 (second turn-on), but the third turn-on at time t7 is reliably prevented.

  By setting the value of the number of times that the bypass is allowed to be turned on (number of times the bypass is allowed) m to an appropriate value, oscillation can be ensured without preventing the bypass from being turned on to compensate for insufficient power supply. Can be prevented. That is, since the (m + 1) th bypass is prohibited from being turned on, oscillation is reliably prevented.

(2) Method of Setting Bypass Prohibited Section FIG. 8 is a diagram for explaining another example of oscillation countermeasures (method of setting a bypass prohibited section). As shown in FIG. 8, when the oscillation prevention circuit 111 detects an oscillation state or a state that can cause an oscillation state, the level of the bypass control signal VPBP is set to an inactive level for a given time (for example, 10 seconds). During this period, the switch circuit SW10 is inhibited from being turned on. Then, after the given time has elapsed, the prohibition of turning on of the switch circuit SW10 is released.

  For example, when the oscillation prevention circuit 111 detects that the bypass has changed from the on state to the off state (time t4 in FIG. 8), the bypass prohibition section T200 for 10 seconds is changed from the timing ((time t4)). Can be provided.

  The state in which the first bypass on state is completed (the state at time t4) is a state in which oscillation can occur. That is, when the oscillation prevention circuit 111 detects that the oscillation can be generated, turning on the bypass is prohibited for a given time. As a result, an oscillation state caused by switching on / off of the bypass is surely prevented.

  When the bypass is changed from the on state to the off state (time t4) and immediately after that, the oscillation prevention circuit 111 detects that the bypass is turned on again (time t5 in FIG. 8), the timing ((time t5 For example, in this example, the bypass is turned on (time t1) to compensate for the shortage of the power supply capability of the power receiving apparatus, and then the bypass is turned on. When the oscillation prevention circuit detects immediately after that that the bypass is turned on again (time t5), the bypass is turned off and from that timing (time t5). During a given period (for example, a period of about 10 seconds), the next bypass is prohibited from being turned on (the third bypass is turned on).

  In this case, the bypass changes from the on-state to the off-state, and immediately after that changes to the on-state again, an oscillation state is generated only once. However, the bypass is not repeatedly turned on thereafter. Therefore, it is possible to reliably prevent the oscillation state caused by the on / off switching of the bypass from being continued. In the case of this example, since the fact that an oscillation state has actually occurred is detected, there is an advantage that the oscillation prevention function does not operate by mistake.

  During the power supply period for the same power supply target load, the number of times the bypass is turned on is considered to be about 1 time. However, for some reason, the state where the power supply capacity is insufficient is twice or three times. May occur. In such a case, it is preferable to turn on the bypass so that a sufficient current can be supplied to the load. On the other hand, the large fluctuation of the instantaneous rectified voltage caused by the on / off of the bypass does not continue for a long time, and generally converges after a certain period of time.

  Therefore, in this embodiment, turning on of the bypass (switch circuit) due to the bypass control signal VPBP becoming active level is prohibited within a given time (for example, about 10 seconds), and when the time elapses, the bypass control is performed. Release the signal output prohibition. The period in which the bypass is prohibited is set to be sufficiently longer than the time during which a large fluctuation of the instantaneous rectified voltage caused by the on / off of the bypass continues.

  In this embodiment, since the bypass (switch circuit) is prohibited from being turned on within a given time from the bypass on / off switching timing, oscillation caused by the bypass on / off is reliably prevented. . Further, in this embodiment, since the number of times the bypass is turned on is not limited, when the power supply capability is insufficient several times during the power supply period for the same power supply target load 94, the bypass is performed each time. It can be turned on to compensate for the shortage of power supply.

(3) Method for Enlarging the Hysteresis Width FIG. 9 is a diagram for explaining still another example (method for enlarging the hysteresis width) of countermeasures against oscillation.

  In this embodiment, when the oscillation prevention circuit 111 detects an oscillation state or a state that can cause an oscillation state, the hysteresis width of the hysteresis comparator used for bypass control is expanded to prevent oscillation.

  As described above, bypass ON / OFF switching control is executed using the hysteresis width of the hysteresis comparator. That is, the bypass is turned on when the rectified voltage falls to the first threshold level, and then the bypass is turned off when the rectified voltage rises to the second threshold level. In this embodiment, when the oscillation prevention circuit 111 detects an oscillation state or a state that can cause an oscillation state, the threshold voltage for turning on the bypass is the first threshold voltage (for example, 4. 9V) is changed to a third threshold voltage (for example, 4.75 V), which is a lower voltage.

  As a result, even if an oscillation state occurs, it becomes difficult for the rectified voltage (voltage VD5) to fall below the third threshold voltage, and oscillation can be prevented or continuation of oscillation can be prevented. .

  The third threshold voltage is preferably set to a voltage that does not fall below in the oscillation state and that may fall below when the amount of power supplied to the load to be fed is insufficient. That is, if the hysteresis width for bypass control is too wide, the bypass is difficult to turn on even when the amount of power supplied to the load to be fed is reduced, and the bypass is not easily released. The level of the third threshold voltage is preferably set to a level that can prevent oscillation and respond to a request for bypass-on due to insufficient power supply.

  As shown in FIG. 9, when the time t4 is set as the timing for changing the hysteresis width (example (1) and example (3)), and when the time t5 is set as the timing for changing the hysteresis width (example ( 2) and Example (4)).

  Here, time t4 is a timing at which the oscillation preventing circuit 111 detects a state where oscillation can occur as described above. Time t <b> 5 is timing when the oscillation state is detected by the oscillation prevention circuit 111.

  Further, as shown in examples (3) and (4) in FIG. 9, the changed hysteresis width can be returned to the original hysteresis width after a given time has elapsed.

  In the case of Example 1 in FIG. 9, when it is detected that the oscillation can be generated (time t4), the threshold voltage for turning on the bypass is changed from the first threshold voltage to the third threshold voltage. As a result, the hysteresis width is expanded from the first hysteresis width HY1 to the second hysteresis width HY2. Therefore, an oscillation state caused by switching on / off of the bypass is prevented in advance.

  In the case of Example 2 in FIG. 9, when the oscillation prevention circuit 111 detects that oscillation has occurred (time t5), the threshold voltage for turning on the bypass is changed from the first threshold voltage. By changing to the third threshold voltage, the hysteresis width is expanded from the first hysteresis width HY1 to the second hysteresis width HY2. Accordingly, it is possible to prevent an oscillation state caused by switching on / off of the bypass. In this example (2), since an actual oscillation state is detected, there is an advantage that the oscillation prevention function (function to increase the hysteresis width) does not operate by mistake.

  In the example (3) and the example (4) in FIG. 9, the change of the hysteresis width of the hysteresis comparator is continued for a given time (for example, about 10 seconds). Sex returns to the state before the change.

  That is, the oscillation is prevented by widening the hysteresis width within a given period from the on / off switching timing of the bypass. On the other hand, after the lapse of a given period, the hysteresis width is restored to the original state so that the situation in which the bypass is difficult to turn on is eliminated, and when the power supply capacity to the load is insufficient, the bypass can be turned on quickly. To.

  In the example (3) of FIG. 9, in the period T250 from time t4 to time t10, the hysteresis width is expanded to the second hysteresis width HY2, and in the period after the time t10 (period T260), the original hysteresis width (ie, Return to the first hysteresis width HY1).

  In the example (4) of FIG. 9, in the period T270 from time t5 to time t11, the hysteresis width is expanded to the second hysteresis width HY2, and in the period after the time t11 (period T280), the original hysteresis width (ie, Return to the first hysteresis width HY1).

(Example of specific circuit configuration of bypass control unit having oscillation prevention circuit)
FIG. 10 is a diagram illustrating an example of a specific circuit configuration of a bypass control unit having an oscillation prevention circuit.

  The power reception side control circuit 52 included in the power reception control device 50 includes a bypass control unit 105.

  Further, the power supply control unit 48 of the power receiving apparatus is provided with a bypass control switch A and a control circuit B for the bypass control switch. The bypass control switch A is configured by a PMOS transistor M1. Further, the control circuit B of the bypass control switch includes an NMOS transistor M2 and a pull-up resistor R8. The bypass control switch A and the control circuit B of the bypass control switch constitute a switch circuit SW10 for turning on / off the bypass (however, the configuration is not limited to this).

  The bypass control unit 105 performs bypass control based on a voltage detection circuit 106 that detects the voltage level of the voltage VD5 at the output terminal of the regulator (LDO) 49, and a detection signal (comparator output) SCMP output from the voltage detection circuit 106. And a logic circuit 107 that switches a voltage level of the signal VPBP.

  The logic circuit 107 includes a bypass control signal output circuit 109, an oscillation prevention circuit 111, and a hysteresis control circuit 113.

  The voltage detection circuit 106 is configured by, for example, a hysteresis comparator. The voltage detection circuit 106 in FIG. 10 includes a comparator 108, voltage dividing resistors R50 to R53, and transistors MA and MB for switching threshold values. The voltage at the common connection point X1 of the voltage dividing resistor R50 and the voltage dividing resistor R51 is supplied to the inverting terminal of the comparator 108, and the reference voltage Vref (for example, 1.3 V) is supplied to the non-inverting terminal.

  The resistance value of the voltage dividing resistor R52 is set larger than the resistance value of the voltage dividing resistor R53. Accordingly, the amount of bias current I1 that flows when the transistor MA is turned on is smaller than the amount of bias current I2 that flows when the transistor MB is turned on.

  In a state where the bypass is off, the transistor MA is turned on and the transistor MB is turned off under the control of the hysteresis control circuit 113. Therefore, the bias current I1 flows through the voltage dividing resistors R50, R51 and R52. At this time, the voltage at the inverting terminal of the comparator 108 (the potential at the node X1) is larger than the reference voltage Vref, and the output of the comparator 108 is at the L level.

  Further, as described above, since the resistance value of the resistor R52 is larger than the resistance value of the resistor 53, the current amount of the bias current I1 is small. Therefore, the voltage drop generated by the voltage dividing resistor R50 is small. Therefore, unless the voltage VD5 at the output terminal of the regulator 49 becomes sufficiently small, the voltage level (potential of the node X1) supplied to the inverting terminal of the comparator 108 is the reference voltage Vref (for example, 1.. Not less than 3V).

  Next, when the voltage VD5 falls below the first threshold value (4.9 V), the voltage at the inverting terminal of the comparator 108 (the potential at the node X1) falls below the reference voltage Vref, and the output of the comparator 108 (SCMP). ) Changes from L level (inactive level) to H level (active level). Then, the hysteresis control circuit 113 turns off the transistor MA and turns on the transistor MB.

  Since the resistance value of the resistor R53 is smaller than the resistance value of the resistor R52, the current amount of the bias current I2 is larger than the current amount of the bypass current I1. Therefore, the voltage drop at the resistor R50 increases. Therefore, unless the voltage level of the voltage VD5 is sufficiently high, the voltage at the inverting terminal of the comparator 108 (the potential at the node X1) does not exceed the reference voltage Vref. That is, after the bypass is turned on, the voltage level of the output (SCMP) of the comparator 108 changes from the H level to the L level when the voltage VD5 exceeds the second threshold voltage (5.2V). . In this manner, bypass on / off control using hysteresis is executed.

  On the other hand, as described above, the bypass control signal output circuit 109 outputs the bypass control signal VPBP (that is, the bypass control signal VPBP is output during the period when the voltage level of the output (SCMP) of the comparator 108 is the active level (H)). Active level (H).

  Further, the oscillation prevention circuit 111 monitors the voltage of the output (SCMP) of the comparator 108, and detects that the oscillation state is entered or that the oscillation state can occur.

(Example of configuration of oscillation prevention circuit)
FIG. 11 is a diagram illustrating an example of the configuration of the oscillation prevention circuit. According to the circuit configuration of FIG. 11, the measures described with reference to FIGS. 7 and 8 (measures for limiting the number of times the bypass is turned on and measures for providing a bypass-on prohibited section) can be executed.

  The oscillation prevention circuit 111 in FIG. 11 includes a level determination circuit 201, a counter 203, and a reset circuit 205.

  When the bypass ON frequency limit is executed, the permitted number m is set in the counter 203. When the count value of the counter 203 is less than the permitted number m, the control signal QX output from the counter 203 is at an active level. When the control signal QX is at the active level, the bypass control signal output circuit 109 switches the level of the bypass control signal VPBP based on the output of the comparator 108 (detection signal of the voltage detection circuit 106) SCMP, and bypasses (switches Circuit) can be controlled.

  The level determination circuit 201 detects a change from the inactive level (L) to the active level (H) of the output of the comparator 108 (detection signal of the voltage detection circuit 106) SCMP. The counter 203 is incremented for each detection, and when the count value matches m, the control signal QX output from the counter 203 changes to an inactive level. Accordingly, the bypass control signal output circuit 109 thereafter fixes the level of the bypass control signal VPBP to the inactive level regardless of the output of the comparator 108 (detection signal of the voltage detection circuit 106) SCMP, and bypasses ( Switch circuit) is prohibited.

  Moreover, when setting a bypass prohibition area, the following operation | movement is performed, for example. That is, the control signal QX becomes an inactive level at the timing when the count value of the counter 203 coincides with m. The reset circuit 205 uses the timer 121 to measure that a predetermined time has elapsed from the timing, and resets the counter 203 at the timing. As a result, the control signal QX changes to the active level, and thereafter, the bypass can be turned on.

(Another example of a specific circuit configuration of a bypass control unit having an oscillation prevention circuit)
FIG. 12 is a diagram illustrating another example of a specific circuit configuration of the bypass control unit having the oscillation prevention circuit. According to the bypass control unit of FIG. 12, the countermeasure described with reference to FIG. 9 (the countermeasure for changing the hysteresis width) can be executed.

  In the voltage detection circuit 106 shown in FIG. 12, a transistor MC and a voltage dividing resistor R54 are added. The resistance value of the voltage dividing resistor R54 is larger than the resistance value of the voltage dividing resistor R52. Therefore, when the current amounts of the bias currents I1, I2, and I3 are compared, I3 <I1 <I2.

  Since the amount of the bias current I3 is small, the voltage drop generated by the voltage dividing resistor R50 is small. Therefore, as long as the voltage VD5 at the output terminal of the regulator 49 does not further decrease (that is, does not fall below the third threshold voltage of 4.75 V), the voltage level (node) supplied to the inverting terminal of the comparator 108 X1 potential) does not fall below a reference voltage Vref (eg, 1.3 V) supplied to the non-inverting terminal. Therefore, when the bypass is turned off, the transistor MA is turned off and the transistor MC is turned on, so that the voltage level of the threshold used for the bypass on determination can be lowered from 4.9 V to 4.75 V, for example. it can. That is, the hysteresis width can be expanded.

(Other examples of oscillation prevention circuit configuration)
FIG. 13 is a diagram illustrating another example of the configuration of the oscillation prevention circuit (a configuration corresponding to the circuit configuration of FIG. 12). The circuit configuration of the oscillation prevention circuit 111 shown in FIG. 13 is almost the same as the circuit configuration shown in FIG. However, in the oscillation prevention circuit 111 in FIG. 13, the control signal QY output from the counter 203 is supplied to the hysteresis control circuit 113.

  In the oscillation prevention circuit 111 of FIG. 13, for example, the control signal QY becomes inactive level at the timing when the count value of the counter 203 coincides with m. At that timing, the hysteresis control circuit 113 turns off the transistor MA and turns on the transistor MC. As a result, the voltage level of the threshold used for determining whether the bypass is on can be reduced from 4.9 V to 4.75 V, for example, and the hysteresis width is expanded.

  Further, when the expanded hysteresis width is returned to the original hysteresis width after the predetermined time has elapsed, the following control is executed. That is, the reset circuit 205 uses the timer 121 to measure that a predetermined time has elapsed from the timing, and resets the counter 203 at the timing. As a result, the control signal QX changes to the active level. At this timing, the hysteresis control circuit 113 turns off the transistor MC and turns on the transistor MA. As a result, the hysteresis width returns to the original hysteresis width.

  As described above, according to some aspects of the present invention, power loss and heat generation in a power receiving device can be reduced by, for example, regulator bypass technology, while power is received by switching on / off of the bypass. Even when an unexpected large instantaneous voltage change occurs in the rectified voltage of the device, the oscillation state can be reliably prevented, and the reliability of the power receiving device can be improved.

  Therefore, it has excellent characteristics such as small size, low loss, and low heat generation, and does not generate oscillation caused by switching on / off of the bypass, and has high reliability, and a power receiving device and power receiving device for a contactless power transmission system. A control device is realized.

  According to this aspect, there is provided a highly reliable non-contact power transmission system having excellent characteristics of small size, low loss, and low heat generation and capable of reliably preventing an oscillation state in which bypass is repeatedly turned on and off. A power receiving apparatus is realized.

  In addition, since the degree of voltage fluctuation of the rectified voltage that occurs when switching the bypass on / off varies depending on the characteristics of external components (for example, constants that determine input / output characteristics, etc.), the present invention is not used. From the viewpoint of preventing oscillation, external parts that can be employed may be limited. According to the present invention, oscillation is reliably prevented. Therefore, a user who uses the power receiving module can freely select a secondary coil or a regulator as an external component, a power switching transistor for forming a bypass path, or the like.

  In addition, since the power receiving device of the present invention has a simple configuration and is small, it can be mounted on a portable terminal or the like and has low loss. For example, the charging time of a secondary battery in an electronic device can be shortened. In addition, since the heat generation is reduced, the reliability from the viewpoint of safety of the electronic device is also improved. In addition, since an oscillation state in which the bypass is repeatedly turned on / off is reliably prevented, stable power supply to the power supply target load is realized. Therefore, the reliability of the electronic device is further improved.

  The present invention can be applied to various electronic devices (for example, wristwatches, cordless telephones, shavers, electric toothbrushes, wrist computers, handy terminals, portable information terminals, electric bicycles, etc.). Examples of particularly suitable electronic devices include mobile terminals (including mobile phone terminals, PDA terminals, portable personal computer terminals) and watches (watches). Since the power receiving device of the present invention is simple in configuration and small in size, it can be mounted on a portable terminal or the like and has low loss. For example, the charging time of a secondary battery in an electronic device can be shortened. In addition, since the heat generation is reduced, the reliability of the electronic device from the viewpoint of safety is also improved. Further, since oscillation due to switching of bypass on / off does not occur, stable power supply to the load is always realized. Therefore, the reliability of the electronic device is further improved.

  Although the present embodiment has been described in detail as described above, it will be easily understood by those skilled in the art that many modifications can be made without departing from the novel matters and effects of the present invention. Accordingly, all such modifications are intended to be included in the scope of the present invention.

  For example, when the switch circuit is turned on and the regulator is bypassed, the operation of the regulator itself is also stopped, thereby further suppressing unnecessary power consumption and heat generation and minimizing the loss of received power. it can. When all the components of the regulator are deactivated, the power consumption and heat generation in the regulator can be made zero. In addition, even when only a part of the components is set in a non-operating state, the power consumption and heat generation of the regulator can be reduced. Therefore, according to this aspect, in the power receiving device using contactless power transmission, it is possible to effectively improve the power supply capability to the load while minimizing the loss of the received power, and to solve the problem of heat generation in the regulator. To do.

  In addition, for example, in the specification or the drawings, at least once, terms (AC adapter, GND, mobile phone terminal, etc.) described together with different terms having a broader meaning or the same meaning (external power supply device, low-potential side power supply, electronic device, etc.) Charger, etc.) may be replaced by the different terms anywhere in the specification or drawings. All combinations of the present embodiment and the modified examples are also included in the scope of the present invention. Further, the configuration and operation of the power reception control device and other control circuits, the power transmission method when AC adapter connection is detected, and the like are not limited to those described in the present embodiment, and various modifications can be made.

  The optimum configuration of the switch circuit for bypassing the regulator (LDO) and the configuration of the bypass controller for turning on / off the regulator (LDO) can be selected as appropriate. For example, a highly functional circuit including a plurality of semiconductor elements can be used. Further, it is possible to use such that the temperature around the regulator is detected, and when the temperature becomes high, the bypass path is turned on to actively reduce the heat generation of the regulator.

  The present invention can effectively reduce, for example, power loss and heat generation in a power receiving device (device that receives power supply) using contactless power transmission technology with a simple configuration, and can turn on a bypass. Thus, it is possible to reliably prevent oscillation caused by off / off. Therefore, for example, a power reception control device (power reception control LSI), a power reception device (power reception module), and an electronic device (portable) using non-contact power transmission Terminal).

1A to 1C are diagrams illustrating an example of a configuration of a contactless power system. The circuit diagram which shows an example of the concrete structure of each part in the non-contact electric power transmission system containing a power transmission apparatus and a power receiving apparatus 3A and 3B are diagrams for explaining a communication method between a power transmission device and a power reception device. The figure which shows an example of the structure for preventing the oscillation resulting from ON / OFF switching of a bypass The figure for demonstrating the control example of ON / OFF of a bypass The figure for demonstrating the oscillation state resulting from on / off of a bypass Diagram for explaining an example of oscillation countermeasures (limit on number of bypasses) Diagram for explaining another example of oscillation countermeasures (method of setting a bypass bypass prohibited section) Diagram for explaining another example of oscillation countermeasures (method of expanding hysteresis width) The figure which shows an example of the concrete circuit structure of the bypass control part which has an oscillation prevention circuit The figure which shows an example of a structure of an oscillation prevention circuit The figure which shows the other example of the concrete circuit structure of the bypass control part which has an oscillation prevention circuit The figure which shows the other example (structure corresponding to the circuit structure of FIG. 12) of a structure of an oscillation prevention circuit.

Explanation of symbols

L1 primary coil, L2 secondary coil, 10 power transmission device, 12 power transmission unit,
14 waveform monitor circuit, 16 display unit, 20 power transmission control device, 22 power transmission side control circuit,
24 oscillation circuit, 26 driver control circuit, 28 waveform detection circuit, 40 power receiving device,
42 power receiving unit, 43 rectifier circuit, 46 load modulation unit, 48 power feeding control unit,
49 Regulator (LDO), 50 Power reception control device, 52 Power reception side control circuit,
56 position detection circuit, 58 oscillation circuit, 60 frequency detection circuit, 62 full charge detection circuit,
72 voltage detection circuit, 90 charging device (charger),
92 Charging control device (charging control IC), 94 Power supply load (secondary battery, battery),
103 load modulation unit, 105 bypass control unit, 107 logic circuit,
106 Voltage detection circuit (hysteresis comparator),
109 bypass control signal output circuit, 111 oscillation prevention circuit,
113 hysteresis control circuit, 121 timer,
SW10 switch circuit,
A bypass control switch, B bypass control switch control circuit,
M1 PMOS transistor as a bypass control switch,
NMOS transistor as a control circuit of the M2 bypass control switch,
VPBP bypass control signal, QX oscillation prevention control signal

Claims (14)

The primary coil and the secondary coil are electromagnetically coupled to transmit power from the power transmission device to the power reception device including the rectifier circuit and the regulator, and the voltage output node of the power reception device to the load to be fed In a contactless power transmission system for supplying power, a power reception control device provided in the power reception device,
A power receiving side control circuit for controlling the operation of the power receiving device;
The power receiving side control circuit has a bypass control unit that controls whether or not to turn on a switch circuit provided between an input node and an output node of the regulator,
The bypass control unit
A voltage detection circuit for detecting a voltage level of at least one of the input node and the output node of the regulator;
A bypass control signal output circuit that outputs a bypass control signal that controls whether the switch circuit is turned on or off based on a detection signal output from the voltage detection circuit;
An oscillation prevention circuit for preventing an oscillation state in which the switch circuit is turned on after the switch circuit is turned off, or the switch circuit is turned off after the switch circuit is turned on; Have
When the oscillation prevention circuit detects the oscillation state or a state that can cause the oscillation state, the bypass control signal output circuit turns off the switch circuit.
A power reception control device characterized by that. The power reception control device according to claim 1,
The voltage detection circuit has a hysteresis comparator that outputs the detection signal;
The voltage level of the detection signal output from the hysteresis comparator becomes a first level when the voltage level of at least one of the input node and the output node of the regulator falls below a first threshold voltage, A power reception control device characterized in that a second level is reached when a second threshold voltage that is higher than the first threshold voltage is exceeded. The power reception control device according to claim 1 or 2,
When the bypass control signal output circuit detects that the number of times the switch circuit is turned on reaches a given permitted number m (m is an integer of 1 or more) by the oscillation prevention circuit, (m + 1) ) A power reception control device for prohibiting turning on of the switch circuit for the second time. The power reception control device according to claim 3,
The power reception control device, wherein the given permission count m is set to "1". The power reception control device according to claim 1 or 2,
The bypass control signal output circuit prohibits the switch circuit from being turned on for a given time when the oscillation prevention circuit detects the oscillation state or a state that can cause the oscillation state. After the elapse of time, the power reception control device releases the prohibition of turning on of the switch circuit. The power reception control device according to claim 5,
The bypass control signal output circuit prohibits the switch circuit from being turned on for a given time when the oscillation prevention circuit detects a change from the first on state to the off state of the bypass path. A power reception control device that cancels the prohibition of turning on of the switch circuit after a lapse of a given time. The power reception control device according to claim 5,
The bypass control signal output circuit is configured to turn on the switch circuit when the oscillation prevention circuit detects that the bypass path has changed from an initial on state to an off state and further to an on state. The power reception control apparatus is characterized in that the switch circuit is prohibited only for a predetermined period of time, and the prohibition of turning on the switch circuit is canceled after the lapse of the given time. The power reception control device according to claim 1 or 2,
The voltage detection circuit has a hysteresis comparator that outputs the detection signal;
Before the oscillation prevention circuit detects the oscillation state or a state that can cause the oscillation state, the level of the output signal of the hysteresis comparator is at least one of the input node and the output node of the regulator. When the voltage level falls below the first threshold voltage, it becomes the first level, and when the voltage level exceeds the second threshold voltage, which is higher than the first threshold voltage, the second level,
When the oscillation prevention circuit detects the oscillation state or a state that can cause the oscillation state, the hysteresis characteristic of the hysteresis comparator is changed, whereby the level of the output signal of the hysteresis comparator is changed to that of the regulator. When the voltage level of at least one of the input node and the output node falls below a third threshold voltage, which is a voltage lower than the first threshold voltage, the first level is reached.
The third threshold voltage is set to a voltage that does not fall below in the oscillation state and that may fall below when the amount of power supplied to the load to be fed is insufficient. A power reception control device characterized by that. The power reception control device according to claim 8, wherein
When the oscillation prevention circuit detects a change from the first on state to the off state of the switch circuit, the hysteresis characteristic of the hysteresis comparator is changed, whereby the level of the output signal of the hysteresis comparator is The power reception control device according to claim 1, wherein when the voltage level of at least one of the input node and the output node of the regulator falls below the third threshold voltage, the power reception control device becomes the first level. The power reception control device according to claim 8, wherein
When it is detected by the oscillation prevention circuit that the switch circuit is changed from the first on state to the off state, and further changed to the on state, the hysteresis characteristic of the hysteresis comparator is changed, whereby the hysteresis comparator is changed. The power reception control device is characterized in that the level of the output signal of the regulator becomes the first level when the voltage level of at least one of the input node and the output node of the regulator falls below the third threshold voltage. . The power reception control device according to claim 9 or 10, wherein
The state where the hysteresis characteristic of the hysteresis comparator is changed continues for a given time from the timing of the change, and when the time elapses, the hysteresis characteristic of the hysteresis comparator returns to the state before the change of the hysteresis characteristic. A power reception control device characterized by that. The power reception control device according to any one of claims 1 to 11,
A power receiving unit that includes the rectifier circuit and converts the induced voltage of the secondary coil into a DC voltage;
A power supply control unit that controls power supply to the load to be supplied, including the regulator and the switch circuit provided between an input terminal and an output terminal of the regulator;
A power receiving device comprising: The power receiving device according to claim 12,
The power receiving device, wherein the regulator and the switch circuit are external components. A power receiving device according to claim 12 or claim 13,
An electronic device comprising: a power supply target load to which electric power is supplied by the power receiving device.

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