JP3742737B2 - Power supply device and control method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a power supply device that supplies stabilized power to a power supply target device such as a mobile phone.
[0002]
[Prior art]
Conventionally, a mobile phone or the like is configured to operate by power supply from a battery. In a power supply device that performs this type of power supply, a voltage regulator that stabilizes the output voltage of the battery, which is the power supply, and supplies power, and an output of the voltage regulator to prevent malfunction of a mobile phone or the like. The voltage is monitored, and when the output voltage of the voltage regulator falls below the first voltage, a low voltage detection signal is output, and the output voltage of the voltage regulator reaches a second voltage greater than the first voltage. A low voltage detection circuit is provided for releasing the low voltage detection signal when recovered.
[0003]
FIG. 3 is a circuit diagram showing a conventional power supply device.
[0004]
In FIG. 3, the power supply device 1 is not shown in its entirety, for example, is built in a mobile phone, and operates by power supply from the battery 10 serving as a power source and the battery 10, and controls the overall operation of the mobile phone. The CPU (central processing unit) 20 to be controlled, the output voltage of the voltage regulator 30 which stabilizes the output voltage of the battery 10 to be stabilized and supplied to the CPU 20, and the output voltage of the voltage regulator 30 are monitored. When the voltage drops below a voltage (hereinafter referred to as a detection voltage), a low voltage detection signal is output to the CPU 20, and when the output voltage of the voltage regulator 30 recovers to a predetermined voltage (hereinafter referred to as an open circuit voltage) greater than the detection voltage, the low voltage detection signal is output. Low voltage detection circuit 40 for opening the voltage detection signal, power switch 50, Composed comprises a support 60.
[0005]
Here, the voltage regulator 30 includes a reference power source 31 that generates a predetermined reference voltage, a FET (field effect transistor) 32 that controls the output voltage of the battery 10, feedback resistors 33a and 33b that feed back the output of the FET 32, and a reference power source 31. A differential amplifier 34 for inputting a reference voltage outputted from the feedback resistor 33 and a feedback voltage by the feedback resistors 33a and 33b and outputting a control signal to the gate of the FET 32, and a switch 35 which is turned on when the power switch 50 is turned on. Is done.
[0006]
The low voltage detection circuit 40 feeds back a reference power supply 41 that generates a predetermined reference voltage and the output of the FET 32, and at the same time, a hysteresis circuit 42 that switches the feedback voltage between a detection voltage and an open voltage, and a reference output from the reference power supply 41. A comparator 43 that compares the voltage with a detection voltage or an open-circuit voltage that is switched by the hysteresis circuit 42, a first inverter 44 that inputs an output of the comparator 43, a second inverter 45, and an output of the second inverter 45, It comprises FETs 46 and 47 that output a low voltage detection signal to the CPU 20.
[0007]
In the above configuration, the differential amplifier 34 of the voltage regulator 30 outputs a voltage that eliminates the difference voltage between the reference voltage output from the reference power supply 31 and the feedback voltage due to the feedback resistors 33a and 33b. A voltage which is applied to the gate of the FET 32 and thereby stabilized to a predetermined voltage is supplied to the CPU 20.
[0008]
In the low voltage detection circuit 40, in a normal state, the hysteresis circuit 42 is switched to select the detection voltage side as shown in FIG. 3, and in this state, the output voltage of the FET 32 is a predetermined value. If the detected voltage is equal to or higher than the detection voltage, a high level signal is output from the comparator 43, whereby the output of the second inverter 45 becomes high level, the FET 46 is turned on, the FET 47 is turned off, and the CPU 20 is turned high. A level open signal is applied.
[0009]
In this state, when the output voltage of the FET 32 falls below a predetermined detection voltage, the output of the comparator 44 becomes low level, whereby the output of the second inverter 45 becomes low level, the FET 46 is off, and the FET 47 is on. Thus, a low level low voltage detection signal is applied to the CPU 20.
[0010]
Thereby, the hysteresis circuit 42 is switched to select the open circuit voltage side.
In this state, when the output voltage of the FET 32 recovers to a predetermined open-circuit voltage, the output of the comparator 44 becomes low level, whereby the output of the second inverter 47 becomes high level, and the FET 46 is turned on. A high level open signal is applied to the CPU 20.
[0011]
By the way, in the power supply device 1 shown in FIG. 3, the output voltage of the voltage regulator 30 is the minimum necessary for the CPU 20 to operate normally in order to reduce the power consumption of a mobile phone or the like that is a power supply target device. The resistance values of the feedback resistors 33a and 33b are set such that
[0012]
However, here, if the voltage output from the voltage regulator 30 is set to be lower than the open voltage of the low voltage detection circuit 40, for example, when the power switch 50 is turned on, the low voltage detection circuit 40 once becomes the low voltage. If this is detected, there is a disadvantage that it cannot be canceled.
[0013]
Further, in order to solve this inconvenience, when the open voltage of the low voltage detection circuit 40 is lowered, the low voltage detection is canceled in a state where the voltage of the power supply 10 is not sufficiently recovered. Another disadvantage is that low voltage detection is performed again and this is repeated.
[Problems to be solved by the invention]
As described above, in the conventional power supply device, once the resistance values of the feedback resistors 33a and 33b are set so that the output voltage of the voltage regulator 30 becomes the minimum voltage necessary for the CPU 20 to operate normally, the low voltage is once set. After the detection circuit 40 detects the low voltage, it becomes impossible to cancel the low voltage, and in order to solve this problem, if the open voltage of the low voltage detection circuit 40 is lowered, the voltage of the power supply 10 is reduced. The low voltage detection is canceled in a state where the recovery is not sufficiently performed. In this case, there is a problem in that another disadvantage that low voltage detection is performed again and this is repeated.
SUMMARY OF THE INVENTION An object of the present invention is to provide a power supply device that enables low power consumption and realizes stable operation of a power supply target device.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 stabilizes a voltage supplied from a power source to a predetermined target voltage and supplies the voltage to a target device, monitors an output voltage of the voltage regulator, and outputs the voltage. When the output voltage of the regulator drops below the first voltage , a low voltage detection signal is output to the target device, and when the output voltage of the voltage regulator recovers to a second voltage higher than the first voltage In the power supply apparatus including the low voltage detection circuit that opens the low voltage detection signal output to the target device, the voltage regulator outputs the low voltage detection signal from the low voltage detection circuit. In the state, the target voltage is set to a voltage equal to or higher than the second voltage, and is output from the low voltage detection circuit. Wherein when the low-voltage detection signal has been opened, characterized by including a target voltage setting means for setting the target voltage to the second voltage or lower voltage.
[0015]
Further, the invention of claim 2, in the invention of claim 1, wherein the voltage regulator includes a reference power supply, and a feedback resistor for feeding back the output voltage, the feedback voltage across the feedback resistor and the output voltage of the reference power source and A differential amplifier that outputs a voltage that eliminates the difference voltage between the output and the output voltage control means that controls the output voltage based on the output of the differential amplifier, and the target voltage setting means switches the feedback resistor A switching circuit is provided.
[0016]
According to a third aspect of the present invention, a voltage regulator that stabilizes a voltage supplied from a power source to a predetermined target voltage and supplies the voltage to a target device, an output voltage of the voltage regulator is monitored, and the output voltage of the voltage regulator is When the voltage drops below the first voltage, a low voltage detection signal is output to the target device, and when the output voltage of the voltage regulator recovers to a second voltage higher than the first voltage, the low voltage detection signal is output to the target device. In the power supply apparatus including the low voltage detection circuit that releases the low voltage detection signal, the voltage regulator includes a reference power supply, a feedback resistor that feeds back an output voltage, an output voltage of the reference power supply, and the A differential amplifier that outputs a voltage that eliminates the difference voltage from the feedback voltage via the feedback resistor; and An output voltage control means for controlling the Hazuki output voltage, the feedback resistor; and a switching circuit for switching, said by switching the that by the switching circuit the feedback resistor, the said low-voltage detection signal from the low voltage detection circuit output When the target voltage is set to a voltage equal to or higher than the second voltage and the low voltage detection signal output from the low voltage detection circuit is released, the target voltage is set to the second voltage. The voltage is set to a voltage equal to or lower than 2 .
[0017]
According to a fourth aspect of the present invention, a voltage regulator that stabilizes a voltage supplied from a power source to a predetermined target voltage and supplies the voltage to a target device, an output voltage of the voltage regulator is monitored, and the output voltage of the voltage regulator is When the voltage drops below the first voltage, a low voltage detection signal is output to the target device, and when the output voltage of the voltage regulator recovers to a second voltage higher than the first voltage, the low voltage detection signal is output to the target device. And a low voltage detection circuit that releases the low voltage detection signal, the voltage supplied to the target device when the low voltage detection signal from the low voltage detection circuit is released. When the target voltage is controlled to be equal to or lower than the second voltage, and the low voltage detection signal is output from the low voltage detection circuit, Wherein the voltage supplied to the target device comprises a control means for controlling the target voltage so that the second voltage or higher.
According to a fifth aspect of the present invention, a voltage regulator that stabilizes a voltage supplied from a power source to a predetermined target voltage and supplies the voltage to a target device, an output voltage of the voltage regulator is monitored, and the output voltage of the voltage regulator is When the voltage drops below the first voltage, a low voltage detection signal is output to the target device, and when the output voltage of the voltage regulator recovers to an open voltage greater than the first voltage, the low voltage detection signal is output to the target device. In the control method of the power supply apparatus comprising the low voltage detection circuit for releasing the low voltage detection signal, the target of the voltage regulator is in a state where the low voltage detection signal is output from the low voltage detection circuit. The voltage is set to a voltage higher than the open circuit voltage, and the low voltage detection output from the low voltage detection circuit is performed. If the signal is opened, and sets the target voltage of the voltage regulator to the open-circuit voltage below the voltage.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a power supply apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.
[0019]
FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a power supply apparatus according to the present invention. In FIG. 1, parts having the same functions as those of the conventional apparatus shown in FIG. 3 are denoted by the same reference numerals as those used in FIG.
[0020]
In FIG. 1, the power supply device 100 is not shown in its entirety, as in the power supply device 1 shown in FIG. 3. For example, the power supply device 100 is built in a mobile phone. A CPU (central processing unit) 20 that operates by feeding and controls the overall operation of the mobile phone, a voltage regulator 110 that stabilizes the output voltage of the battery 10 to a predetermined voltage and supplies the voltage to the CPU 20, and an output voltage of the voltage regulator 110 When the output voltage of the voltage regulator 110 drops below a predetermined voltage (detection voltage), a low voltage detection signal is output to the CPU 20, and the output voltage of the voltage regulator 110 is higher than the detection voltage by a predetermined voltage (open circuit). The low voltage detection circuit 120 opens the low voltage detection signal when the voltage is recovered to the voltage). Power switch 50, and comprises a capacitor 60.
[0021]
Here, the voltage regulator 110 includes a reference voltage source 31 that generates a predetermined reference voltage, a FET (field effect transistor) 32 that controls the output voltage of the battery 10, a feedback resistor 361 that feeds back the output of the FET 32, and the feedback resistor 361. A differential circuit that inputs a reference voltage output from the reference voltage source 31 and a feedback voltage output from the switching circuit 36 and outputs a control signal to the gate of the FET 32. An amplifier 34 and a switch 35 that is turned on when the power switch 50 is turned on are provided.
[0022]
Further, the low voltage detection circuit 120 feeds back the output of the reference voltage source 41 that generates a predetermined reference voltage and the FET 32, and is output from the hysteresis circuit 42 that switches the feedback voltage between the detection voltage and the open voltage, and the reference voltage source 41. The comparator 43 for comparing the reference voltage to be detected and the detection voltage or the open circuit voltage switched by the hysteresis circuit 42, the first inverter 44 for inputting the output of the comparator 43, the second inverter 45, and the output of the second inverter 45 are inputted. And FETs 46 and 47 that output a low voltage detection signal to the CPU 20.
[0023]
In the above configuration, the differential amplifier 34 of the voltage regulator 110 outputs a voltage that eliminates the difference voltage between the reference voltage output from the reference voltage source 31 and the feedback voltage output from the switching circuit 36. Is added to the gate of FET 32.
[0024]
As a result, the output voltage of the battery 10 is stabilized at a predetermined voltage by the FET 32 and supplied to the CPU 20.
Here, since the switching circuit 36 is configured so that the feedback resistor 361 can be switched by the switching switch 362, the target output voltage of the voltage regulator 110 is varied by switching the feedback resistor 361 by the switching circuit 36. be able to.
[0025]
Here, if the switching of the feedback resistor 361 by the switching circuit 36 of the voltage regulator 110 is switched so that the output of the voltage regulator 110 is lower than the open voltage of the low voltage detection circuit 120, the low voltage detection circuit 40 has a low voltage. The detection signal cannot be released.
[0026]
Therefore, first, the feedback resistor 361 in the switching circuit 36 of the voltage regulator 110 is set so that the output of the voltage regulator 110 is sufficiently higher than the open voltage of the low voltage detection circuit 120.
[0027]
However, in this state, the output voltage of the voltage regulator 110 becomes high and power saving cannot be achieved. Therefore, when the low voltage detection signal from the low voltage detection circuit 120 is released, the CPU 20 causes the switching circuit 36 to set the output voltage of the voltage regulator 110 to the minimum voltage necessary for the CPU 20 to operate normally. The switching of the feedback resistor 361 is controlled.
[0028]
That is, in this embodiment, the CPU 20 controls the switching of the feedback resistor 361 by the switching circuit 36 of the voltage regulator 120, so that the voltage regulator is output in a state where the low voltage detection signal is output from the low voltage detection circuit 120. When the target reference voltage of 30 is set to a voltage equal to or higher than the open circuit voltage of the low voltage detection circuit 120 and the low voltage detection signal output from the low voltage detection circuit 120 is released, the target reference voltage of the voltage regulator 110 is set. The low voltage detection circuit 120 is configured to be set to a voltage lower than the open circuit voltage.
[0029]
In FIG. 1, the switching circuit 36 is composed of a feedback resistor 361 and a selector switch 362 for switching taps connected to four locations of the feedback resistor 361. However, these configurations are configured using semiconductor elements. May be.
[0030]
Similarly, the hysteresis circuit 42 of the low voltage detection circuit 120 can be similarly configured using a semiconductor element.
[0031]
The hysteresis circuit 42 of the low voltage detection circuit 120 is configured to be switched by the CPU 20, but may be configured to be switched based on the output of the first inverter 44, for example.
[0032]
FIG. 2 is a flowchart showing a control example of the voltage regulator 110 and the low voltage detection circuit 120 by the CPU 20 shown in FIG.
[0033]
In FIG. 2, when this process is started, first, the hysteresis circuit 42 of the low voltage detection circuit 120 is set to the open voltage side by switching the hysteresis circuit 42 of the low voltage detection circuit 120 to the open voltage side (step 201). ). Further, by controlling the switching of the feedback resistor 361 by the switching circuit 36 of the voltage regulator 110, the output voltage of the voltage regulator 110 is set to be sufficiently higher than the open voltage of the low voltage detection circuit 120 (step 202).
[0034]
Next, it is checked whether the detection output from the low voltage detection circuit 120 is lost, that is, whether the open signal is output from the low voltage detection circuit 120 (step 203 ). If it is determined that there is no detection output from the low voltage detection circuit 120 (YES in step 203), the process proceeds to step 204.
[0035]
In step 204, the switching of the feedback resistor 361 by the switching circuit 36 of the voltage regulator 110 is controlled to set the output voltage of the voltage regulator 110 to be equal to or lower than the open circuit voltage of the hysteresis circuit.
[0036]
Next, if there is no detection output from the low voltage detection circuit 120 (NO in step 205), the state of step 204 is maintained, and if it is determined that there is low voltage detection power (YES in step 205), the process returns to step 201. .
[0037]
As described above, in this embodiment, since the target output voltage of the voltage regulator 110 can be varied by switching the feedback resistor 361 by the switching circuit 36, the CPU 20 uses the output voltage of the voltage regulator 110. By controlling the voltage to the minimum necessary voltage to operate normally, it is possible to reduce the power consumption, and the low voltage detection signal from the low voltage detection circuit 120 can be reliably canceled, so that the power supply It is possible to realize stable operation of the supply target device.
[0038]
【The invention's effect】
As described above, according to the present invention, since the target reference voltage of the voltage regulator can be arbitrarily switched in accordance with the detection output of the low voltage detection circuit, it is possible to reduce power consumption. The stable operation of the power supply target device can be realized.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of an embodiment of a power supply apparatus according to the present invention.
FIG. 2 is a flowchart showing a control example of the low voltage detection circuit 120 by the CPU 20 shown in FIG. 1;
FIG. 3 is a circuit diagram showing a conventional power supply device.
[Explanation of symbols]
10 Battery 20 CPU (Central processing unit)
30 Voltage Regulator 31 Reference Voltage Source 32 FET (Field Effect Transistor)
33a, 33b Feedback resistor 34 Differential amplifier 35 Switch 36 Switching circuit 40 Low voltage detection circuit 41 Reference voltage source 42 Hysteresis circuit 43 Comparator 44 First inverter 45 Second inverter 46, 47 FET (field effect transistor)
50 power switch 60 capacitor 100 power supply device 110 voltage regulator 120 low voltage detection circuit 361 feedback resistor 362 selector switch

Claims (5)

A voltage regulator that stabilizes the voltage supplied from the power source to a predetermined target voltage and supplies the voltage to the target device, and the output voltage of the voltage regulator is monitored, and when the output voltage of the voltage regulator drops below the first voltage Outputs a low voltage detection signal to the target device and outputs the low voltage detection signal output to the target device when the output voltage of the voltage regulator recovers to a second voltage higher than the first voltage. In a power supply device comprising a low voltage detection circuit to be opened,
The voltage regulator is
In a state where the low voltage detection signal is output from the low voltage detection circuit, the target voltage is set to a voltage equal to or higher than the second voltage, and the low voltage detection signal output from the low voltage detection circuit A power supply apparatus comprising: target voltage setting means for setting the target voltage to a voltage equal to or lower than the second voltage when is opened. The voltage regulator is
A reference power supply,
A feedback resistor that feeds back the output voltage;
A differential amplifier that outputs a voltage that eliminates the difference voltage between the output voltage of the reference power supply and the feedback voltage via the feedback resistor;
Output voltage control means for controlling the output voltage based on the output of the differential amplifier,
The target voltage setting means includes
The power supply apparatus according to claim 1, further comprising a switching circuit that switches the feedback resistor. A voltage regulator that stabilizes the voltage supplied from the power source to a predetermined target voltage and supplies the voltage to the target device, and the output voltage of the voltage regulator is monitored, and when the output voltage of the voltage regulator drops below the first voltage Outputs a low voltage detection signal to the target device and outputs the low voltage detection signal output to the target device when the output voltage of the voltage regulator recovers to a second voltage higher than the first voltage. In a power supply device comprising a low voltage detection circuit to be opened,
The voltage regulator is
A reference power supply,
A feedback resistor that feeds back the output voltage;
A differential amplifier that outputs a voltage that eliminates the difference voltage between the output voltage of the reference power supply and the feedback voltage via the feedback resistor;
Output voltage control means for controlling the output voltage based on the output of the differential amplifier;
A switching circuit for switching the feedback resistor,
The switching of the that by the switching circuit the feedback resistor, wherein in a state where the low-voltage detection signal from the low voltage detection circuit is outputted to set the target voltage to the second voltage or higher, the low When the low voltage detection signal output from the voltage detection circuit is released, the target voltage is set to a voltage equal to or lower than the second voltage . A voltage regulator that stabilizes the voltage supplied from the power source to a predetermined target voltage and supplies the voltage to the target device, and the output voltage of the voltage regulator is monitored, and when the output voltage of the voltage regulator drops below the first voltage Outputs a low voltage detection signal to the target device and outputs the low voltage detection signal output to the target device when the output voltage of the voltage regulator recovers to a second voltage higher than the first voltage . In a power supply device comprising a low voltage detection circuit to be opened,
When the low voltage detection signal from the low voltage detection circuit is released, the target voltage is controlled so that the voltage supplied to the target device is equal to or lower than the second voltage, and the low voltage detection circuit Control means for controlling the target voltage so that the voltage supplied to the target device is equal to or higher than the second voltage when the low voltage detection signal is output from the power supply. apparatus. A voltage regulator that stabilizes the voltage supplied from the power source to a predetermined target voltage and supplies the voltage to the target device, and the output voltage of the voltage regulator is monitored, and when the output voltage of the voltage regulator drops below the first voltage Outputs a low voltage detection signal to the target device and releases the low voltage detection signal output to the target device when the output voltage of the voltage regulator recovers to an open voltage greater than the first voltage. In a control method of a power supply device comprising a low voltage detection circuit,
In the state where the low voltage detection signal is output from the low voltage detection circuit, the target voltage of the voltage regulator is set to a voltage equal to or higher than the open circuit voltage,
When the low voltage detection signal output from the low voltage detection circuit is released, the target voltage of the voltage regulator is set to a voltage equal to or lower than the open voltage. .

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