JP2011234112A - Radio apparatus and overheat prevention method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio apparatus which is comprised of small-sized inexpensive components, and is capable of taking measures to cope with overcurrent/overheat for a transmission power amplifier having higher safety.SOLUTION: Based on temperature and a current value of a transmission power amplifier 2 for transmitting information as a radio signal, a current supplied from a battery 1 of a power source to the transmission power amplifier 2 is turned on/off by a switch section 11. A control section 11 operated by low-voltage power from a power supply section 15 different from the battery 1 of the power source is disposed in the vicinity of the transmission power amplifier 2 and when the temperature of the transmission power amplifier 2 detected by a temperature sensor 12b in the control section 12 exceeds a temperature threshold arbitrarily set beforehand or when the current value of the transmission power amplifier 2 detected by a current detector 12a in the control section 12 exceeds a current threshold arbitrarily set beforehand, the control section 12 controls the switch section 11 to switch off, through an FET 13, a current monitor section 14 and a control terminal 16, thereby stopping supplying the current to the transmission power amplifier 2.

Description

  The present invention relates to a wireless device and a method for preventing overheating of the wireless device, and more particularly, wireless such as a mobile phone, a PHS (Personal Handyphone System) terminal, a PDA (Personal Data Assistance, Personal Digital Assistants). The present invention relates to a protection mechanism against overcurrent / overheating of a transmission power amplifier that can be suitably applied to an apparatus.

  In various wireless devices including portable terminals such as recent cellular phones, PHS (Personal Handyphone System) terminals, PDAs (Personal Data Assistance, Personal Digital Assistants), CDMA (Code Division Multiple access), etc., a method of constantly transmitting information, and TDMA (Time Division Multiple Access), etc., are intermittent as information transmission operations, but consume a large current and generate a large transmission output. Necessary methods are becoming mainstream.

  For this reason, as shown in FIG. 2, in order to transmit information as a high-power radio signal, a transmission power amplifier capable of outputting a high transmission power is mounted on a radio apparatus. FIG. 2 is a circuit diagram showing a circuit configuration for supplying transmission power of a conventional wireless device, in which power is directly supplied from a battery 1 serving as a power source to a transmission power amplifier 2 capable of outputting high transmission power. It is configured.

  In the circuit configuration of high transmission power as shown in FIG. 2, the battery 1 and the transmission power amplifier 2 are directly connected, and no measures are taken for overheating protection of the wireless device for the person who operates the wireless device. Absent. However, if the wireless device is used in such a situation, the power consumption of the transmission power amplifier 2 is large, so that a burn (burn) due to abnormal heat generation due to a short circuit of the transmission power amplifier 2 or the like, and a steady state of the transmission power amplifier 2 Such as low-temperature burns (low-temperature burns) due to normal heat generation may cause damage to the human body of the person operating the wireless device. Therefore, high safety has been demanded against overcurrent and overheating of such wireless devices.

  As an example, wireless devices adopting the following circuit configuration have also appeared. FIG. 3 is a circuit diagram showing a circuit configuration for transmission power supply in which a countermeasure against overcurrent is taken in a conventional wireless device, and Japanese Patent Application Laid-Open No. 2005-341408 of Patent Document 1 is provided in order to prevent a heat generation accident to a human body. As described in the publication “Mobile Phone and Control Method Therefor”, power is supplied to the transmission power amplifier 2 capable of outputting high transmission power from the battery 1 through the fuse 3 for preventing overcurrent. It is configured as follows. FIG. 4 is a circuit diagram showing another circuit configuration for transmission power supply in which a countermeasure against overcurrent is taken in a conventional radio apparatus. The human body is configured so that the transmission power amplifier 2 operates at an appropriate voltage. In order to prevent a heat generation accident, a transmission power amplifier 2 capable of outputting high transmission power from the battery 1 as described in Japanese Patent Application Laid-Open No. 2002-076951 “Transmitter Power Circuit” On the other hand, power is supplied through a regulator 4 for voltage control.

Japanese Patent Laying-Open No. 2005-341408 (page 4-6) JP 2002-076951 (page 4-5)

  However, in the circuit configuration in which the fuse 3 is interposed as shown in FIG. 3, it is possible to protect against a steady overcurrent, but provide sufficient protection against an instantaneous overcurrent. I can't. Further, after the fuse 3 is disconnected, the communication function of the wireless device cannot be automatically restored, which is insufficient as a countermeasure for protecting the function of the wireless device.

  Further, in the circuit configuration using the protection function by the regulator 4 as shown in FIG. 4, since it is impossible to protect the abnormality of the regulator 4 itself, the protection function against overcurrent and overheat is insufficient. Even in the low voltage operation, it is difficult to reduce the power consumption due to the power loss of the regulator 4 that always operates.

  The present invention has been made in view of such circumstances, and is composed of small and inexpensive parts by adopting a combination of a switch unit and a control unit instead of the protection circuit as shown in FIGS. An object of the present invention is to provide a wireless device and a method for preventing overheating of the wireless device that can take safer overcurrent / overheat protection measures.

  In order to solve the above-described problems, the wireless device and the overheating prevention method of the wireless device according to the present invention mainly adopt the following characteristic configuration.

  (1) A radio apparatus according to the present invention is a radio apparatus including at least a transmission power amplifier for transmitting information as a radio signal, and a current supplied from the temperature and power source of the transmission power amplifier to the transmission power amplifier. A switch unit is provided for turning on / off the current supplied from the power source to the transmission power amplifier based on the value.

  (2) A method for preventing overheating of a wireless device according to the present invention is a method for preventing overheating of a wireless device including at least a transmission power amplifier for transmitting information as a wireless signal, wherein the method is based on the temperature and power of the transmission power amplifier. Based on a current value supplied to the transmission power amplifier, the current supplied from the power source to the transmission power amplifier is turned on / off.

  According to the wireless device and the overheating prevention method of the wireless device of the present invention, the following effects can be obtained.

  First, a switch unit is interposed between the power source and the transmission power amplifier, and the temperature / current detection function of the transmission power amplifier and arbitrarily set temperature threshold / current threshold are provided in the vicinity of the transmission power amplifier. By providing a control unit that has a comparison function that determines whether or not an abnormal condition (overheating / overcurrent condition) has occurred, when the transmission power amplifier overheats / overcurrent occurs, Current supply can be stopped, and abnormal overheating of the transmission power amplifier can be reliably prevented.

  Second, since the current supply to the transmission power amplifier is turned ON / OFF by connecting a switch unit having a low ON resistance between the transmission power amplifier and the battery, It is possible to reliably prevent the deterioration of the transmission characteristics due to the voltage drop. In addition, it is possible to easily expect a decrease in battery voltage.

  Thirdly, since the control unit can operate at a low voltage, the circuit that controls the power supply to the transmission power amplifier can be used as it is, and the circuit with higher safety can be used without changing the conventional technology. The configuration can be realized, and simplification, miniaturization, and low cost are possible.

It is a circuit diagram which shows an example of the circuit structure for the transmission power supply which took the overcurrent prevention measure as a radio | wireless apparatus which concerns on this invention. It is a circuit diagram which shows the circuit structure for transmission power supply of the conventional radio | wireless apparatus. It is a circuit diagram which shows the circuit structure for the transmission power supply which applied the overcurrent prevention measure in the conventional radio | wireless apparatus. It is a circuit diagram which shows the other circuit structure for transmission power supply which applied the overcurrent prevention measure in the conventional radio | wireless apparatus.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a wireless device and a method for preventing overheating of a wireless device according to the present invention will be described with reference to the accompanying drawings. Note that the wireless device according to the present invention includes a mobile phone, a PHS (Personal Handyphone System) terminal, a PDA (Personal Data Assistance, Personal Digital Assistants), a portable notebook PC (Personal Computer), It may be a portable terminal device such as a portable music player, or a wireless telephone that outputs various types of transmission information as a high-power wireless signal, such as a fixed telephone set on a desktop, a desktop PC, an image processing device, and an information processing device. Any wireless device may be used as long as it has a communication function.

(Features of the present invention)
Prior to the description of the embodiments of the present invention, an outline of the features of the present invention will be described first. The present invention employs an overcurrent / overheat protection circuit consisting of a switch unit and a control unit to protect against heat generation due to overcurrent caused by short-circuiting of the transmission power amplifier or ESD (Electro-Static Discharge). Thus, the main feature is that a wireless device that can use small and inexpensive parts and has higher safety against heat generation accidents on the human body is realized.

  More specifically, the present invention is composed of the following techniques. In the conventional circuit configuration, protection measures are taken by interposing a fuse as shown in FIG. 3 or a regulator having a protection function as shown in FIG. 4 between the battery of the power source and the transmission power amplifier. However, although the function can be realized as a protection against a steady or temporary overcurrent, it is not sufficient as a heat generation protection function for a human body of a person who uses a wireless device. In addition, when the battery voltage as a power source has dropped, inserting a protective circuit with high power consumption, such as a regulator, between the battery and the transmission power amplifier will greatly reduce the voltage of the transmission power amplifier. As a result, the output characteristics of the transmission power amplifier may be deteriorated, and it is not preferable to insert a protection circuit between the battery and the transmission power amplifier. Yes.

  In the present invention, a low ON resistance having a current ON / OFF function that does not connect a GND (Ground) composed of, for example, a P-ch FET (Field Effect Transistor) between the power source battery and the transmission power amplifier. In the temperature sensor that operates by inserting power from a power supply unit that is different from the power supply (battery) that inserts the switch unit and supplies current to the transmission power amplifier, The switch unit is controlled through an N-ch FET of an open drain type (a type in which a drain is directly pulled out to an output terminal without being connected anywhere inside).

  In addition, as a current monitor unit, an open drain type N-ch FET is connected by connecting a P-ch FET having a current mirror function with the switch unit and a current measurement resistor in series. The power amplifier current can be monitored, and the current monitor unit detects an abnormal current (overcurrent) of the transmission power amplifier current, and controls the switch unit via an open drain type N-ch FET.

  Therefore, it is possible to prevent the output characteristics from being degraded due to the voltage drop of the transmission power amplifier, and to prevent overheating and overcurrent protection that can stop the power supply to the transmission power amplifier in the event of overheating and overcurrent. By configuring the circuit using inexpensive and small components, a wireless device capable of ensuring higher safety can be realized.

(Configuration example of embodiment)
Next, an example of the circuit configuration of the wireless device according to the present invention will be described with reference to FIG. FIG. 1 is a circuit diagram showing an example of a circuit configuration for transmission power supply in which overcurrent prevention measures are taken as a radio apparatus according to the present invention. As an example of a radio apparatus, a transmission power amplifier using a battery as a power source For example, the main part of the overcurrent / overheat protection circuit of the transmission power amplifier mounted on the portable terminal device is shown as an example.

  The wireless device shown in FIG. 1 includes at least a switch unit 11, a control unit 12, an FET 13, a current monitoring unit 14, and a power supply unit 15 for controlling power supply between the battery 1 and the transmission power amplifier 2. The control unit 12 is disposed at a position that is in thermal proximity to the transmission power amplifier 2 so that the amount of heat generated by the transmission power amplifier 2 can be detected.

  The switch unit 11 is inserted between the battery 1 and the transmission power amplifier 2, and switches the current path from the battery 1 to the transmission power amplifier 2 according to a control signal applied to the control terminal 16. have. The switch unit 11 includes, for example, a P-ch FET (Field Effect Transistor) as a switching element having a low ON resistance, and has a current ON / OFF function that does not connect to GND (Ground). The switch unit 11 may be a semiconductor element or a mechanical element as long as it is an element other than the P-ch FET and has a low ON resistance and performs a similar operation.

  The control terminal 16 is a terminal that controls the ON / OFF operation of the switch unit 11, and is connected to the gate terminal of the current mirror FET 14 a of the current monitor unit 14. The gate (G) -source (S) of the current mirror FET 14 a. The voltage is the same value as the inter-voltage Vgs.

  The current monitor unit 14 inserts a current mirror FET 14a, which is a P-ch FET having a current mirror function with the switch unit 11, and a current measurement resistor 14b in series with respect to the open drain type FET 13, The current value flowing through the transmission power amplifier 2 is monitored by measuring the voltage across the current measuring resistor 14b.

  Further, the FET 13 is composed of, for example, an open drain N-ch FET, and the gate (G) -source (S) voltage Vgs of the current mirror FET 14a of the current monitor unit 14 is controlled according to the control from the control unit 12. By controlling, it has a switching function for controlling the control terminal 16 to switch ON / OFF of the switch unit 11, and the drain (D) side of the open drain type is in the current monitor unit 14. The source (S) side is connected to GND (ground), and the gate (G) side is connected to the output terminal of the control unit 12 via the current measurement resistor 14b.

  Further, the control unit 12 monitors the voltage across the current measurement resistor 14b in the current monitor unit 14 to detect the current value flowing through the transmission power amplifier 2 and the temperature of the transmission power amplifier 2 is detected. The current value of the transmission power amplifier 2 detected by the temperature sensor 12b and the current detection unit 12a is compared with a current threshold value arbitrarily set in advance for overcurrent detection, and detected by the temperature sensor 12b. At least a comparator 12c that compares the temperature of the transmission power amplifier 2 with a temperature threshold arbitrarily set in advance for detecting overheating is provided.

  Here, each circuit unit of the current detection unit 12a, the temperature sensor 12b, and the comparator 12c configuring the control unit 12 is supplied with a voltage (a voltage different from that of the battery 1) supplied from the power supply unit 15 that operates with power from the battery 1. The control unit 12 is connected to the gate (G) of the FET 13 according to an arbitrary current value and an arbitrary temperature, which are parameters independent of each other, of the current detection unit 12a and the temperature sensor 12b. The control unit 12 has a function of setting the output terminal to the high level / low level.

  When the current value of the transmission power amplifier 2 detected by the current detection unit 12a is compared with a current threshold value arbitrarily set in advance in the comparator 12c, an abnormal current (overcurrent) exceeding the current threshold value is detected. The switch unit 11 having a current ON / OFF function not connected to GND (Ground) such as a P-ch FET (Field Effect Transistor) is controlled via the FET 13 of the N-ch FET.

  Similarly, when the temperature of the transmission power amplifier 2 detected by the temperature sensor 12b is compared with a temperature threshold value arbitrarily set in advance by the comparator 12c, an abnormal temperature (overheating) exceeding the temperature threshold value is detected. The switch unit 11 having a current ON / OFF function not connected to GND (Ground) such as a P-ch FET (Field Effect Transistor) is controlled via the FET 13 of the N-ch FET.

(Description of operation of embodiment)
Next, an example of the operation of the wireless device illustrated in FIG. 1 will be described. In the control unit 12 of the wireless device shown in FIG. 1, the temperature sensor 12b detects the temperature of the transmission power amplifier 2 disposed in the vicinity, and the current detection unit 12a has a current mirror function. The current value flowing through the transmission power amplifier 2 is detected by monitoring the voltage across the current measuring resistor 14b within the power supply 14.

  The detected temperature and current value of the transmission power amplifier 2 are connected to the gate (G) of the FET 13 by comparing the temperature threshold value and the current threshold value arbitrarily set in advance in the comparator 12c. The output terminal of the control unit 12 is set to High level / Low level.

  Here, since the control unit 12 can have a circuit configuration that can be operated at a low voltage as compared with the transmission power amplifier 2, the control unit 12 operates on the voltage from the battery 1 instead of the voltage on the battery 1 itself. Then, the power supply unit 15 that supplies low-voltage power is operated. In the control unit 12 that operates by being supplied with the low-voltage power output from the power supply unit 15, the conventional protection circuit / protection function can be employed as it is, so that higher safety can be ensured. In addition, when no information is transmitted, the operation of the control unit 12 can be stopped together with the operation of the power supply unit 15 by connecting the power supply unit 15 to the GND (ground), thereby reducing power consumption. It is possible to produce an additional effect that it becomes possible.

  When the comparator 12c detects an overheating in which the temperature of the transmission power amplifier 2 exceeds the temperature threshold, the output terminal of the control unit 12 connected to the gate (G) of the FET 13 is set to the low level, and the gate (G) of the FET 13 Is set to Low level. As a result, the gate (G) -source (S) of the FET 13 becomes high impedance, and the control terminal 16 of the current mirror FET 14a in the current monitor unit 14 connected to the FET 13 becomes high level. Due to the function, the switch unit 11 is turned off, the current supply from the battery 1 to the transmission power amplifier 2 is turned off, and the operation of the transmission power amplifier 2 is stopped. Thus, the overheat state exceeding the temperature threshold of the transmission power amplifier 2 can be eliminated.

  When the comparator 12c detects that the temperature of the transmission power amplifier 2 at the time of transmission is a normal temperature equal to or lower than the temperature threshold, the output terminal of the control unit 12 connected to the gate (G) of the FET 13 is set to the high level. The gate (G) of the FET 13 is set to the high level. As a result, the gate (G) -source (S) of the FET 13 has a low impedance, and the control terminal 16 of the current mirror FET 14a in the current monitor unit 14 connected to the FET 13 becomes the low level. Due to the function, the switch unit 11 is turned on, and the current supply from the battery 1 to the transmission power amplifier 2 is turned on.

  When the comparator 12c detects an overcurrent in which the value of the current flowing through the transmission power amplifier 2 exceeds the current threshold, the output terminal of the control unit 12 connected to the gate (G) of the FET 13 is set to the low level, and the FET 13 The gate (G) is set to the low level. As a result, the gate (G) -source (S) of the FET 13 becomes high impedance, and the control terminal 16 of the current mirror FET 14a in the current monitor unit 14 connected to the FET 13 becomes high level. Due to the function, the switch unit 11 is turned off, the current supply from the battery 1 to the transmission power amplifier 2 is turned off, and the operation of the transmission power amplifier 2 is stopped. Thus, an overcurrent state exceeding the current threshold of the transmission power amplifier 2 can be eliminated.

  When the comparator 12c detects that the current value flowing through the transmission power amplifier 2 at the time of transmission is a normal current value equal to or less than the current threshold, the output terminal of the control unit 12 connected to the gate (G) of the FET 13 is set to High. The gate (G) of the FET 13 is set to the high level. As a result, the gate (G) -source (S) of the FET 13 has a low impedance, and the control terminal 16 of the current mirror FET 14a in the current monitor unit 14 connected to the FET 13 becomes the low level. Due to the function, the switch unit 11 is turned on, and the current supply from the battery 1 to the transmission power amplifier 2 is turned on. Under such circumstances, the current detection unit 12a of the control unit 12 detects the value of the current flowing through the transmission power amplifier 2 via the current measurement resistor 14b by the current mirror function of the current mirror FET 14a in the current monitor unit 14. Continue operation.

  As described above, when no information is transmitted, as a result of the power supply unit 15 switching to the GND (ground) connection, the operation of the control unit 12 is also stopped and the control connected to the gate (G) of the FET 13 is performed. The output terminal of the unit 12 becomes low level, and the gate (G) of the FET 13 also becomes low level. As a result, the gate (G) -source (S) of the FET 13 becomes high impedance, and the control terminal 16 of the current mirror FET 14a in the current monitor unit 14 connected to the FET 13 becomes high level. Due to the function, the switch unit 11 is turned off, and the current supply from the battery 1 to the transmission power amplifier 2 is turned off, so that the overheating state exceeding the temperature threshold of the transmission power amplifier 2 or the overcurrent state exceeding the current threshold. As in the case, the operation of the transmission power amplifier 2 is stopped. Thus, the power consumption of the wireless device can be reduced by stopping the operation of the transmission power amplifier 2.

(Explanation of effect of embodiment)
As described in detail above, the following effects are obtained in the present embodiment.

  First, the switch unit 11 is interposed between the power source battery 1 and the transmission power amplifier 2, and the temperature / current detection function of the transmission power amplifier 2 is arbitrarily disposed in the vicinity of the transmission power amplifier 2. By providing the control unit 12 having a comparison function for determining whether or not an abnormal state (overheating / overcurrent state) exceeding the set temperature threshold / current threshold has occurred, the overheating / overcurrent of the transmission power amplifier 2 is provided. When this occurs, current supply to the transmission power amplifier 2 can be stopped, and abnormal overheating of the transmission power amplifier 2 can be reliably prevented.

  Secondly, between the transmission power amplifier 2 and the battery 1, the current supply to the transmission power amplifier 2 is turned ON / OFF by connecting a switch unit 11 having a low ON resistance value. It is possible to reliably prevent the transmission characteristics from being deteriorated due to the voltage drop of the transmission power amplifier 2. In addition, it is possible to easily expect a decrease in battery voltage.

  Thirdly, since the control unit 12 can operate at a low voltage, the conventional technology is used as it is as a circuit for controlling the power supply to the transmission power amplifier 2, so that the safety can be improved. A high circuit configuration can be realized, and simplification, miniaturization, and low cost are possible.

  The configuration of the preferred embodiment of the present invention has been described above. However, it should be noted that such examples are merely illustrative of the invention and do not limit the invention in any way. Those skilled in the art will readily understand that various modifications and changes can be made according to a specific application without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Battery 2 Transmission power amplifier 3 Fuse 4 Regulator 11 Switch part 12 Control part 12a Current detection part 12b Temperature sensor 12c Comparator 13 FET
14 Current monitor part 14a Current mirror FET
14b Low resistance 15 Power supply 16 Control terminal

Claims (10)

  A wireless device comprising at least a transmission power amplifier for transmitting information as a radio signal, wherein the transmission power amplifier transmits the transmission power based on a temperature of the transmission power amplifier and a current value supplied from the power supply to the transmission power amplifier. A radio apparatus comprising a switch unit for turning on / off a current supplied to a power amplifier.   In the vicinity of the transmission power amplifier, a temperature sensor for detecting the temperature of the transmission power amplifier, a current detection unit for detecting a current value flowing through the transmission power amplifier, and the temperature of the transmission power amplifier detected by the temperature sensor A control unit is provided that compares at least a temperature threshold value arbitrarily set and a comparator that compares a current value of the transmission power amplifier detected by the current detection unit and a current threshold value arbitrarily set. The wireless device according to claim 1.   As a comparison result of the comparator of the control unit, when the temperature of the transmission power amplifier is equal to or lower than the temperature threshold, the switch unit is turned on to supply current from the power source to the transmission power amplifier, 3. When detecting that the temperature of the transmission power amplifier exceeds the temperature threshold, the switch unit is turned off to cut off the current supplied from the power source to the transmission power amplifier. A wireless device according to 1.   As a comparison result of the comparator of the control unit, when a current value flowing through the transmission power amplifier is equal to or less than the current threshold, the switch unit is turned on to supply current from the power source to the transmission power amplifier. On the other hand, when it is detected that the value of the current flowing through the transmission power amplifier exceeds the current threshold, the switch unit is turned off to cut off the current supplied from the power source to the transmission power amplifier. The wireless device according to claim 2 or 3.   5. The radio according to claim 2, wherein when the operation of the control unit is stopped, the switch unit is turned off, and a current supplied from the power source to the transmission power amplifier is cut off. 6. apparatus.   6. The control unit according to claim 2, wherein the control unit operates with low-voltage power supplied from a power source unit different from the power source, and the power source unit operates with power from the power source. A wireless device according to 1.   The wireless device according to claim 6, wherein the operation of the control unit is stopped by stopping the operation of the power supply unit during a period when there is no information to be transmitted as a wireless signal.   The switch section is a switching element having a low ON resistance, and is composed of a switching element having a current ON / OFF function that is not connected to a GND (Ground) consisting of a P-ch FET (Field Effect Transistor). The wireless device according to claim 2, wherein:   The current detection unit of the control unit includes a current monitor unit in which a P-ch FET having a current mirror function and a current measurement resistor are connected in series with the switch unit, and a current value flowing through the transmission power amplifier. And the comparison result of the temperature of the transmission power amplifier in the comparator of the control unit with the temperature threshold, or the current of the current value flowing through the transmission power amplifier in the comparator of the control unit Based on the comparison result with the threshold value, the control unit has an N-ch FET of the open drain type and a current mirror function in the current monitor unit connected in series to the drain of the N-ch FET. The wireless device according to claim 8, wherein the wireless device is set to ON or OFF via the P-ch FET.   A method of preventing overheating of a wireless device including at least a transmission power amplifier for transmitting information as a wireless signal, based on a temperature of the transmission power amplifier and a current value supplied to the transmission power amplifier from a power source, A method for preventing overheating of a wireless device, comprising: turning on / off a current supplied from a power source to the transmission power amplifier.

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