JP3457364B2 - Power supply with backup function - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for electronic equipment.
Especially when the battery is built into the device.
If normal external power supply stops,
Power failure, the built-in battery
By supplying power, processing can be continued
The present invention relates to a power supply device for electronic equipment. 2. Description of the Related Art Generally, an electronic device having a computer
Indicates that the power supplied from the outside falls below a certain limit.
Or if the supply is stopped,
Unable to obtain the power required for normal processing operation,
Error in calculation due to the suspension of
Alternatively, a problem such as abnormal data writing occurs. In order to avoid such a problem, a power supply
Uninterruptible power supply connected to computer equipment,
Emergency battery inside computer equipment
Power supply from the
Processing work can be continued, or
An interruption consisting of a series of processes such as interrupting and saving data
It is normal to supply power required for normal stop processing to each part.
Have been done. For example, a computer having a remote power control function
In the computer device, the standby processing, that is, the original processing work is performed.
Power control logic and system control
Some circuits, such as the logic section, are powered so that they are always active.
Is supplied. For this reason, standby also at the power supply unit
Power for the time and power supply during the original operation
As shown in FIG. 18 having two power supply paths for
It has become. [0005] As shown in FIG.
AC power supply is DC stable and DC stable during normal operation
It is applied to the power supply units 1A and 1F. DC stabilized power supply 1A
Output B of the DC / DC converter 1 through the diode 2
B, 1C and 1D. A battery is connected to the output B terminal.
A lead 4 is connected through the diode 3. Power supply 1F
Is output to the DC / DC converter 1E through the diode 5.
Supply. The output A terminal passes through the diode 6
The battery 7 is connected. These batteries 4 and 7
The charger 1G and the charger 1H are connected for charging.
Has been continued. The DC stabilized power supply units 1A, 1F and
Inputs of the electric appliances 1G and 1H are connected to the AC power supply 1.
Further, each of the DC / DC converters 1B, 1C, 1D, 1E
Are output 2, output 3, output 4, and output 1.
This is supplied to the logic unit 8 outside the device. Next, a time chart in this configuration
Is shown in FIG. At time t0, connected to AC power supply 1
Then, the stabilized DC power supply unit 1F starts operating, and the output A
When the voltage rises, the output 1 is output from the DC / DC converter 1E.
Supply. The two chargers 1G and 1H also operate,
The charging current starts to be supplied to the batteries 4 and 6, respectively. At time t1, the logic unit 8 starts the electronic device.
When an ON signal is sent out,
DC power supply 1A starts operating, and output voltage B rises.
And the DC / DC converters 1B, 1C and 1D operate and output
2, output 3 and output 4 rise. In this state, at time t2, the AC power supply
When the power drops (power failure), the output of the DC power supply 1A, 1F
The output B and output A voltages also decrease. At the same time, the battery
Current flows to each DC / DC converter from 4, 7
Therefore, each DC / DC converter 1B, 1C, 1D, 1E operates.
And output 1, output 2, output 3, and output 4 decrease.
Without having to provide a constant output to the logic
It will work. At time t3, the AC power supply is restored (recovery).
And output A and output B also draw the same waveforms
Stands up and outputs from batteries 4 and 7
Take over. FIG. 20 shows a stabilized DC power supply unit shown in FIG.
General DC stabilized power supply showing 1A and its surroundings in detail
3 is a circuit configuration of the unit. This circuit is generally a double switch
A conversion method called a switching power supply of the ti-forward system.
It is an expression. Referring to FIG. 1, a rectifier circuit 51 includes an AC power source 1.
Is filtered by the condenser 52, and includes a few volts of an AC component in a steady state.
And converts this voltage to a MOS-FET 5
3. Primary winding of high frequency transformer 55, MOS-FET5
4 is applied to a circuit connected in series. Each end of the primary winding of the high-frequency transformer 55
A diode is connected to each terminal of potential farther from the capacitor 52 than the capacitor.
57 and 56 are connected, and the high-frequency transformer 55
Secondary winding is diode 58, capacitor 61, reactor
Are connected in series. Then, the cathode side of the diode 59 is
An anode of diode 58 is connected to the cathode terminal of diode 58.
Terminal is the winding end terminal of the secondary winding of the high-frequency transformer 55
It is configured to connect to The comparison amplifier 69 and the reference
Voltage 70 and a voltage-pulse width conversion circuit 68.
The source control unit 5B is a single monolithic IC (for example, Fujitsu
Commercially available as “MB3759” manufactured by
You. A resistor 7 connected between terminals of the capacitor 61
The middle point between 4 and 75 is connected to the (+)
Connect resistors 72 and 73 between 0V and 70V output
This midpoint is connected to the (-) terminal of the comparison amplifier 69,
(−) Input terminal of the comparator 69 and the output of the comparator 69.
A resistor 71 is connected between the force terminals. Voltage-pulse width conversion
The output of the path 68 is connected to an NPN transistor 66 and a PNP transistor.
Connect the base and emitter of each of the
Connected to the base terminal of the pulse amplifier circuit. Emitter end
Is connected to the primary of the pulse transformer 62 through the capacitor 63.
Connect to the winding. And these power control units, pulse increase
The voltage required to operate the width circuit is set to the bias power supply.
It supplies to each circuit from 76. Two of the pulse transformers 62
The secondary winding is MOS-F through resistors 65 and 64, respectively.
It is connected to the gate terminals of ET53 and ET54. An AC / DC converter having such a circuit configuration
The switching unit 5A is used for backup when a power failure occurs.
Road block, that is, the voltage between the terminals of the capacitor 52 is
A power failure detection circuit 5C that detects an input signal from a and b,
The output signals c and d from the power failure detection circuit 5C determine
-It is connected to a switching circuit 5E that performs switching control. In the rise control circuit 5D, an ON signal
Is received, the control signal g is transmitted to the power control unit 5B.
The power supply is configured to start up. Then, on the output side of the AC / DC converter 5A
Is connected to the switching circuit 5E through the diode 77,
It is connected to the DC / DC converter 79. AC / D
The (+) terminal of the C conversion unit minimizes the voltage drop during switching.
There is a capacitor 78 for the purpose of reducing. The operation of such an AC / DC converter is a
Commentary books on switching power supplies For example, "Sui" by Akira Hasegawa
Switching regulator design know-how "
Omitted. FIG. 21 illustrates the power failure detection circuit 5C in detail.
It is clear. In the figure, resistors are provided at both ends of terminals a and b.
101 and 102 are connected in series, and a resistor 107 and a photo
Light emitting diode side 108 of coupler, constant voltage control element 1
09 are also connected in series. This constant voltage control element 10
The gate terminal 9 is a connection point between the resistors 101 and 102 described above.
Connect to In this circuit configuration, the input AC power supply is low.
When the power goes down (power failure), each part in the time chart shown in FIG.
Operate. When a power failure occurs at time t1, a
Voltage V1 is determined by the load current and the capacitance of the input section capacitor
Function is reduced. Similarly, the voltage is divided by the resistance
The voltage V2 also drops at the same rate. Voltage V2 is constant voltage system
It is the same as the gate terminal of the control element 109. For example, constant voltage
Well-known 3-terminal shunt from TI as a control element
If the regulator "TL431" is used, the gate voltage
Is about 2.5 V with the threshold voltage as the threshold voltage.
And a function of transition between conduction and cutoff between the gate and the cathode.
The voltage V1 drops to V1a (at this time, V2 is about 2.
5V) and a constant voltage control element by an AC component superimposed on V2.
109 repeats conduction / interruption for a short time. Next, when the input power is restored at time t2,
The pressures V1 and V2 increase. When the voltage V2 is about 2.
When the voltage approaches 5 V, the constant voltage control element 10
After 9 repeats conduction / interruption, it becomes conductive. As described above, the transistor side of the photocoupler
The output signal cd of the power failure detection circuit of FIG.
Is repeated in the same manner. this
The phenomenon is generally called chatter. With this chatter, conduction / interruption is performed in a short time.
Is repeated, switch the connection connected to the battery
Large current flows through the switch. This is the
-There is a risk of contact welding due to
For electronic contacts, damage due to excess rating of semiconductor device
In all cases, the reliability is greatly impaired.
Cause. FIG. 23 shows the battery of FIG.
It shows the configuration of the switching circuit 5E in detail. In the figure
At the P-channel MOS from the (+) pole of battery 4
-Connect to output through FET 121 and diode 124
are doing. The output from the AC / DC converter 5A is also
Similarly, the output is connected through a node 138. MOS-
A resistor 122 is connected between the source and the gate of the FET 121,
Resistance 123 transistor from the gate of MOS-FET 121
Connect the collector of the star 125 and the emitter is the battery
4 (-) terminal. At both ends of the control voltage V3,
Resistor 135, resistor 139, resistor 134 and photocoupler
The transistor sides 110 are connected in series. Further, each middle point is set to the comparison amplifier 133.
Of the resistor 134 to the (+) terminal,
5 side is connected to the (-) terminal. Output of comparison amplifier 133
The terminal is connected to the base of the transistor 125 through the resistor 127.
To the base terminal of the transistor 125.
The resistor 126 is also connected between the terminals. The operation of this circuit is as shown in FIG.
Then, as the input AC power decreases (power failure),
As mentioned, the transistor side 110 of the photocoupler
cd is cut off, and the (+) input of the comparison amplifier 133 is turned on.
The voltage at the input terminal is higher than that at the (-) terminal.
The output of the amplifier 133 changes from LOW to HIGH.
You. When the output becomes HIGH, the resistance 127 is passed.
Current flows through the base of the transistor 125,
When the transistor 125 is turned on, the gate of the MOS-FET is
The gate voltage is a voltage determined by the resistors 122 and 123.
You. This voltage, that is, the voltage across the resistor 122 is
If it is set to 10 V to 15 V, the MOS-FET 12
1 is in a conductive state, and a MOS-FET is
Power is supplied to the output through a diode 124
You. However, when a power failure occurs, AC / D
Power is not supplied from the C conversion unit 5A. When the AC input power is restored, a power failure detection signal
Is LOW, that is, the transistor side 110 of the photocoupler.
Since the collector potential (c) of the output of the comparator
The potential of the (+) input terminal is lower than the (-) potential.
Then, the output of the comparison amplifier 133 changes from HIGH to LOW.
Change. Thus, the output of the comparison amplifier 133, the resistance 1
27, the current flows to the base terminal of the transistor 125
Does not flow, the transistor 125 is cut off, and the MOS-
Since the gate-source voltage of the FET 121 becomes zero,
The MOS-FET 121 is shut off and the output of the battery 4 is
No power is supplied. At this time, the AC / DC converter 5A starts up.
Output voltage of this converter reaches the rated value.
The DC output drops temporarily, but this voltage drop (△
V) set the power failure detection voltage high to keep it low.
Alternatively, the rise time of the AC / DC converter is shortened.
However, none of these methods are practical,
Increase the capacity of the capacitor 78 connected between the
Has been dealt with. FIG. 25 shows the rise control circuit 5 shown in FIG.
3 shows a circuit configuration of D. A power switch for the purpose of pulse width modulation control
Control element 5B (for example, “MB37 manufactured by Fujitsu Limited”).
59 "), the VREF terminal of the control element 5B and the DT
A resistor 155 between the terminals and a resistor 1 between the DT terminal and the 0 V terminal
56 is connected. Also, a capacitor is provided at both ends of the resistor 155.
154 and the transistor 152 and the resistor 153 are connected in series.
Then, the middle point between the resistor 151 and the resistor 150 is set to the transistor 1
52 to the base terminal of the
The collector-emitter of the transistor side 159 is the transistor 1
52 Connected between base-emitter, light emission of photocoupler
The diode side 160 outputs an ON signal through the resistor 161.
It is configured to connect. The via of the control element 5B
Power supply 76 is connected. Next, the operation of the circuit shown in FIG.
This will be described with reference to FIG. When the power supply rises, the ON signal becomes HIGH.
When it changes to LOW, light emitting diode of photo coupler
The current flows to the side 160, and the transistor side of the photocoupler
159 is turned on, and the base of the transistor 152 is turned on.
-Since the emitter-to-emitter voltage is
The star 152 is turned off. Therefore, the voltage of the DT terminal of the control element 5B
Sets the voltage of VREF from VREF to the resistance 155 and the resistance 1
Resistance towards the final voltage determined by the division ratio of 56
155, 156, capacitor 154, time constant determined by low
Go down. The voltage of the DT terminal of the control element 5B drops
, The output pulse from the control element 5B gradually widens.
Go on. According to this output pulse, the AC / DC conversion unit switches.
The same applies to the current flowing through the switching element (MOS-FET).
Waveform. This causes the output voltage to rise slowly.
Go up. Next, when the AC input power is restored, a power failure is detected.
The signal changes from HIGH to LOW (time t6). One
That is, the transistor side 110 of the photocoupler shown in FIG.
Shifts from the cutoff state to the conduction state. However, since the ON signal remains LOW,
A resistor 161 is connected to the light emitting diode side 160 of the photocoupler.
The current continues to flow through. For this reason,
The transistor side 159 remains conductive, and the input power supply
The operation of this circuit does not change at all even during a power failure / recovery.
However, when the power is restored, the voltage V1 shown in FIG.
The output of the AC / DC converter 5A also starts rising.
However, when the power failure detection signal is HIGH,
AC / DC conversion because current is supplied from Terry
Although almost no current flows from section 5A, this signal
At time t6 when the signal changes to LOW
Stops, and the entire current is supplied from the AC / DC converter 5A.
Will be. However, at the time of this switching, the output voltage is still constant.
Since the rated value has not been reached, the output of the power control element 5B
The pulse has a maximum width. Thus, the switching element, here
Now, the drains of the MOS-FETs 53 and 54 shown in FIG.
The current waveform flowing in
This is for over ten cycles until the output voltage reaches the rated value.
continue. This is a great stress on semiconductor devices.
You. Also, if a fuse or other device connected to the input line
A similar surge current flows through the current protection element, and the fuse
Equipment such as erroneous fusing and deterioration of parts on the same line
Is a major factor in reducing the reliability of [0045] In the above prior art,
The problems are summarized as follows. (1) Battery during power failure due to power supply battery
When the backup target consists of multiple modules,
Insufficient consideration in terms of product, reliability, cost, etc. (2) In the event of a power failure / recovery,
Of the battery switching unit
Double the tress. To reduce this and improve reliability.
No consideration has been given to (3) Switching to backup circuit at power failure
When the backup circuit is disconnected after power is restored, the output voltage
Measures to deal with the problem of
There is a problem in terms of product and cost. (4) Disconnect backup circuit at power recovery
Flows into the switching element and input of the basic power supply
Insufficient consideration has been given to surge currents. (5) Battery for backup
If the sealed lead-acid battery used for
If this happens, stop the charging current and lower the battery voltage.
However, although the characteristics of the battery were fully considered,
And does not play a sufficient role as a protection circuit. As described above, the present invention solves the above problems.
Reduce the number of parts used to reduce volume, cost, and reliability
And the use rating of the parts used is reduced,
The purpose is to improve reliability. [0052] To achieve the above object,
In addition, the following measures were taken. (1) Power failure due to providing a difference in voltage value
At times, set the voltage side that does not perform backup high, and
They operate independently at all times.
Normal voltage is higher than low side due to connected diode
Side of the DC / DC converter connected thereto.
It has no effect on the output. In addition, a normal DC power supply
Connected to the current detection circuit, and this current value is
Make the current detection value smaller than the current detection value and
To reduce the output voltage of the power supply. (2) A step is provided for the voltage detection level.
Stabilization control element for the purpose of accurately
Using the comparator as a comparator, the width of hysteresis
Is composed of a constant voltage diode and a resistor.
A circuit with few keys. (3) Changeover switch to battery
No delay when switching signal generation circuit is on, and no delay when switching signal generation circuit is off
Is a so-called off-delay circuit that delays by a specified time.
It depends. Also, the off-delay time is set to the main AC / D
Less than the sum of the rise time and rise delay time of the C converter
By setting above, switching can be performed without any step. (4) Switch used for AC / DC converter
Reset signal of pulse width control circuit of switching power supply control element
Can be switched at power failure by using the power failure detection signal.
Reset the pulse without fail,
Suppresses inrush current. (5) A certain value of the terminal voltage of the battery
Above this, the charge rises suddenly. Also battery
When the voltage exceeds the specified value, hydrogen gas starts to be generated suddenly.
Confuse. To prevent this, compare the battery voltage for detection
Detect with an amplifier. When charging stops, the battery
Voltage suddenly drops to a certain value and slowly drops to that voltage
Go down. Almost when near the steady value of the battery
Does not drop. Utilizing this property, the comparison amplifier can be used for external fluctuation.
By applying proper positive feedback that is not affected,
While backing up the battery
Be able to supply power. The structure which achieves the above object has the following effects.
You. (1) Two types of modules having different voltage values
And use only two diodes to connect the output only on the high voltage side.
Hard-wire connection. It also integrates the battery charger.
Combine. (2) Voltage level at power failure detection and power at power recovery
Provide a voltage difference to the pressure level and select this appropriately. (3) Backup circuit immediately after power failure
, And when power is restored, the AC / DC power supply rises
Circuit structure that switches with a delay of more than time
Be successful. (4) Stop operation of AC / DC power supply at power failure
Stop, and when power is restored, start the output by the power failure signal
Configuration. (5) Voltage according to the discharge characteristics of the battery
In addition, the voltage at the time of overcharging, the maximum charging voltage required at the time of charging stop
In consideration of the charging circuit. Embodiments of the present invention will be described in detail with reference to the drawings.
You. In FIG. 1, reference numeral 1 denotes an AC power supply, 1A and 1F.
Is a DC stabilized power supply, 1B, 1C, 1D, and 1E are DC /
DC converters, 2, 3, 5, 9 are diodes, 4 is battery
Lee, 1G is a charger for charging the battery 4, and 8 is
Shows the logic circuit part that performs various information processing and control.
It is. Each of these sections is a DC stabilized power supply section 1A,
Output voltages of 1F are output B and output A, respectively.
And the output B of the power supply section 1A passes through the diode 2 to DC /
DC converters 1B, 1C, and 1D, and outputs B
The same terminal of the battery 4 through the diode 3
Connected. The output A of the power supply section 1F passes through the diode 5
To the DC / DC converter 1E. And its output A
From one terminal of the power supply unit 1A
Through the diode 2 and the diode 9
Has been continued. The input of the charger 1G is supplied from the power supply section 1F.
Supplied from the DC / DC converter 1B.
Power is output 2, output of 1C is output 3, output of 1D is output
The output of 4, 1E is a logic circuit as each voltage of output 1.
Supply to section 8. A time chart in this configuration is shown in FIG.
Shown in At time t0, when an AC power supply is connected,
The source section 1F starts operating, the output voltage A rises, and the
The C / DC converter 1E operates and the output 1 rises. this
Only the output system from the power supply unit 1F supplies and operates.
At the time of the so-called standby operation, the charger 1G also
It operates and supplies a charging current to the battery 4. At time t1, the power is turned on from the logic circuit unit 8.
When the instructing ON signal is issued, the power supply unit 1A operates.
When the voltage of the output B rises, the DC / DC converter 1
B, 1C, and 1D operate and output 2, output 3, and output 4
The pressure rises respectively. In this state, at time t2,
When the power supply is insufficient, a so-called blackout
Power supply to the DC power supplies 1A and 1F
Also, the output A and the output B decrease. However, at the same time when the power drops, the battery
4 indicates that the currents of the DC / DC converters 1B, 1C, 1D, 1
E, each DC / DC converter 1B, 1C,
1D and 1E continue to operate, and output 1, output 2, output 3,
The output 4 supplies power to the logic circuit 8 without lowering.
Keep feeding. At time t3, the supply from the AC power supply is normal.
When the state is restored (power recovery), the state at the power supply unit time t1
The operation state is the same as that of. As described above, the configuration shown in FIG.
With the conventional, each power supply unit has a battery and a charger
Can be reduced to what was needed one set at a time
As a result, the volume, cost, and
Can be good. FIG. 3 shows the power supply section 1A in FIG. 1 in more detail.
This will be described in detail. In the figure, a rectifier circuit 51
Is filtered by the condenser 52, and includes a few volts of an AC component in a steady state.
And converts this voltage to a MOS-FET 5
3. Primary winding of high frequency transformer 55, MOS-FET5
4 is applied to a circuit connected in series. Each end of the primary winding of the high-frequency transformer 55
A diode is connected to each terminal of potential farther from the capacitor 52 than the capacitor.
57 and 56 are connected, and the high-frequency transformer 55
Secondary winding is diode 58, capacitor 61, reactor
Are connected in series. Then, the cathode side of the diode 59 is
An anode of diode 58 is connected to the cathode terminal of diode 58.
Terminal is the winding end terminal of the secondary winding of the high-frequency transformer 55
It is configured to connect to The comparison amplifier 69, the reference voltage 70,
Power supply control unit 5 composed of voltage-pulse width conversion circuit 68
B. The resistor 7 connected between the terminals of the capacitor 61
The middle point between 4 and 75 is connected to the (+)
Connect resistors 72 and 73 between 0V and 70V output
This midpoint is connected to the (-) terminal of the comparison amplifier 69,
(−) Input terminal of the comparator 69 and the output of the comparator 69.
A resistor 71 is connected between the force terminals. Voltage-pulse width conversion
The output of the path 68 is connected to an NPN transistor 66 and a PNP transistor.
Connect the base and emitter of each of the
Connected to the base terminal of the pulse amplifier circuit. Emitter end
Is connected to the primary of the pulse transformer 62 through the capacitor 63.
Connect to the winding. And these power control units, pulse increase
The voltage required to operate the width circuit is set to the bias power supply.
It supplies to each circuit from 76. Two of the pulse transformers 62
The secondary winding is MOS-F through resistors 65 and 64, respectively.
It is connected to the gate terminals of ET53 and ET54. The AC / DC converter having such a circuit configuration
The switching unit 5A has a power supply
Circuit block, that is, between the terminals of the capacitor 52
Power failure detection circuit 5C for detecting voltages as input signals a and b
And the output signals c and d from the power failure detection circuit 5C,
Switching the output from the power supply to control battery switching
There are signals e and f from the circuit 5E and the power failure detection circuit 5C.
Or from the outside or from the logic circuit unit 8 in FIG.
The control signal g is transmitted to the power control unit 5B by the
And a rise control circuit 5D for instructing the section to rise.
Is connected. Then, on the output side of the AC / DC converter 5A
Is connected to the switching circuit 5E through the diode 77,
It is connected to the DC / DC converter 79. AC / D
The (+) terminal of the C conversion unit minimizes the voltage drop during switching.
A capacitor 78 for the purpose of reduction is connected. Next, the stop which is the most characteristic part of the present invention is described.
Details of the power detection circuit 5C and the battery switching circuit E
Will be described. FIG. 4 shows a circuit configuration of the power failure detection circuit 5C.
Things. The AC voltage 1 in FIG.
After rectification, the voltage after filtering by the filtering capacitor 52 is used.
Between terminals of input signal lines a and b connected to obtain pressure
And resistors 101 and 102 connected in series,
7 and 1 on the light emitting diode side of the two photocouplers.
08, 111 and the stabilization control element 109 are connected in series.
Connect to And the middle point between the resistors 101 and 102 and the stability
To the gate terminal of the activation control element 109, and the connection line
To the collector terminal of the transistor 104 via the resistor 103
Connect the child. The emitter terminal of the transistor 104
Connect to signal line b side. Source of resistor 107 and photo coupler
From the connection point on the photodiode side 108, a constant voltage diode
105 and the resistor 106 to the signal line b side. Ma
A transistor is connected to the anode side of the
The base terminal of the star 104 is connected. Also, signal lines a and b
The voltage between V1 and the voltage applied between both terminals of the resistor 102 is
V2. Next, the normal power supply from the AC power supply 1 and the power failure
Operation of each part with time according to the time chart of FIG.
explain. AC power supply is in a normal state where normal supply is performed
At time (t1 period), the voltage V2 is
The voltage is determined by the division ratio of 2. Temporarily
A 3-terminal type shunt is used for the stabilization control element 109 used in
"TL431" manufactured by TI was used for the regulator.
Then, the threshold of the gate voltage of the stabilization control element 109 is
The threshold voltage is about 2.5V. This threshold
If V2 is set higher than the threshold voltage,
The element 109 is in a conductive state and the constant voltage diode 105
Has a cathode side voltage of about 3.5V. From this voltage, the constant voltage diode 105
If the rated voltage is set high (5V or more),
No current flows to the base of the star 104, and eventually the transistor
104 is in a cutoff state. If the AC power supply 1 drops for some reason or
Stop (when power is turned off) (period t2)
And the voltage of the voltage V1 between the terminals a and b is the
According to the function determined by the capacitance of the capacitor 52 shown in FIG.
Going down. At this time, the midpoint voltage V of the resistors 101 and 102
2, the voltage V2 also decreases.
The threshold voltage of the control element 109 (about 2.5V) or less
Between the anode and cathode of the stabilization control element 109
Goes into a cutoff state. At this time, the light emitting die of the photocoupler
The collection of the transistor side 112 facing the
Light emission between the emitter and the other photocoupler
The transistor 110 side facing the diode 111
The state between the collector and the emitter is also cut off. Next, the AC input power supply is restored (period t3).
Then, the voltage V1 between a and b also starts increasing slowly. This
In this case, the stabilization control element 109 is in the cutoff state,
The voltage diode 105 becomes conductive and the transistor 1
An electric current flows into the base terminal 04. And the transi
The collector-emitter of the star 104 is conductive. As a result, the voltage V2 is changed to the resistances 101, 10
2, 103, which is smaller than the voltage in the initial state.
Is increased. Therefore, when the voltage V2 is 2.5V
At the voltage V1 which exceeds the voltage V1, the voltage V1b
It becomes higher than the voltage V1a by ΔV. This ΔV is 15
It is set to about V. V1 must be larger than V1b
If so, it will be in the initial state. Here, ΔV is set to about 15 V.
Indicates that there is a voltage
Is a value selected so as not to cause a problem. Also shown here
The voltage control element 109 and the constant voltage diode 105
The one with very small variation is used. By using this circuit as described above, a simple configuration
Thus, a power failure detection circuit with high detection accuracy can be created. Inspection
Output level difference (about 15V)
When the pressure drops, there is no chatter due to the ripple component.
Value. Next, the power failure switching circuit 5E shown in FIG.
Will be described in detail. FIG. 6 shows a circuit configuration of the power failure switching circuit 5E.
FIG. The (+) terminal of the battery 4 is connected to the relay K1.
Connected to one end of the contact side 120, the other end is a P-channel MOS-
Connect to the output through FET 121 and diode 124
ing. The output from the AC / DC converter 5A is also a diode
It is connected to the output through 138. P channel MOS
-A resistor 122 is connected between the source and the gate of the FET 121.
Continue to connect the resistor 123 transistor 125 from the gate terminal.
And the emitter is connected to the (-) terminal of the battery.
Connecting. The control voltage V3 is connected to both ends of the relay K1.
File side 136 is connected. Similarly, resistors 135 and 13
9. Resistor 134 and transistor side 110 of photocoupler
Are connected in series. Compare the middle points of each
Connected to the input terminal of the band width 133. Resistor 134 side
The resistor 135 side is connected to the (+) terminal and the (-) terminal.
A diode 131 and a resistor are connected to the output terminal of the comparison amplifier 133.
To the base terminal of the transistor 125 through the anti-127,
Also, through the diode 132 and the resistors 130 and 128
Connected to the base terminal of the transistor 125. Transi
A resistor 126 is connected between the base and the emitter of the
And the transistor is connected from the connection point of the resistors 128 and 130.
The capacitor 129 is connected between the emitter terminals of the star 125
I do. When the AC power supply 1 is supplied, the control voltage V
3 also starts rising, and this voltage is equal to the coil of relay K1.
Operating voltage on the side 136 (normally 75% or more of the rated voltage)
), The contact 120 of the relay K1 is closed. This state is a steady state when the power supply is turned on.
It is a state. With this configuration, the voltage V3 becomes
Before establishment, battery contacts will not be blocked
No discharge loop is formed. This is because during transportation or storage of the device,
Due to the leakage current of the semiconductor switch, etc.
It is effective in suppressing discharge. Further, the semiconductor switch may be damaged in the short-circuit mode,
In that case, the computer worked without permission.
Such an accident does not occur. The leakage current
Supply the battery with doubled charging current
Therefore, no problems occur with this configuration.
No. Next, the operation of this switching control circuit will be described with reference to FIG.
This will be described in detail with reference to FIG. When the input AC power is reduced (power failure),
As described in the power failure detection circuit 5C,
Of the transistor side 110 is turned off,
The voltage of the (+) input terminal of the comparison amplifier 133 is the (-) terminal
, The output of the comparison amplifier 133 becomes LO
It changes from W to HIGH. When HIGH, the diode 131 and the resistor
To the base terminal of transistor 125 through anti-127
The current flows. The resistance 13 is supplied through the diode 132.
The capacitor 129 is charged to a voltage determined by 0 and 128.
You. When the transistor 125 is turned on, the MOS-
The gate voltage of the FET is determined by the resistors 122 and 123.
Voltage. This voltage, that is, the voltage across the resistor 122 is set to 1
If it is set to 0V to 15V, the MOS-FET 121
Becomes conductive, and the relays 120, M
Output to the output through OS-FET 121 diode 124
Power is supplied. At this time, since there is a power outage,
No power is supplied from the / DC converter 5A. Next, the operation when the AC input power supply is restored will be described.
explain. When the AC input power returns, the power failure detection signal
It changes from HIGH to LOW. In other words, the photo coupler
Since the collector potential c of the transistor side 110 decreases,
The potential of the (+) input of the comparison amplifier 133 is compared with the (-) potential.
Lower. As a result, the output of the comparison amplifier 133 becomes HI
It changes from GH to LOW. Thereby, the comparison amplifier 13
3. Transistor via diode 131 and resistor 127
There is no path for current to flow into the base terminal of the star 125
However, the electric charge charged in the capacitor 129 is
Via anti-128 to the base terminal of transistor 125
Capacitor 129, resistor 12
8. Period t determined by each constant of transistor 125
4. The transistor 125 keeps on and keeps off.
You. When the transistor 125 is turned off, the MOS-FET
121 is also in the cutoff state, and the power supply from the battery 4 is
Stop. That is, at time t4 when the power failure detection signal changes.
After a while, the battery output is cut off. On the other hand, when the AC input power is restored,
As a result, the output of the AC / DC power supply 5A also starts rising.
However, in general, the rise delay time t5,
AC / DC power supply unit 5A after the sum of t6 (t5 + t6) seconds
An output voltage is established and supplies energy to the output. In other words, if the time relationship of t5 + t6> t4 is satisfied, the output instantaneously drops when the output is switched.
However, in the present invention, the above-described constants are determined so that t5 + t6 <t4.
Without connecting a large-capacity capacitor as shown in
Also, there should be no drop in the output voltage.
And not. Next, the rising control circuit 5D in FIG.
Will be described with reference to FIG. In the figure, 5B indicates pulse width modulation control.
This is the intended power switching control element.
As control elements used for such purposes, for example, Fujitsu
There is “MB3759” manufactured by the company.
Between the REF terminal and the DT terminal, a resistor 155 and the DT terminal
A resistor 156 is connected between the V terminals, and both ends of the resistor 155
The capacitor 154, the transistor 152 and the resistor 1
53 are connected in series, and the midpoint between the resistors 151 and 150 is
Connect to the base terminal of the transistor and
Transistor the collector-emitter of transistor side 112
It is connected between the base and the emitter of the star 152. A photocoupler is used for on / off control.
Are connected to the same terminal. Note that
Connect 76 as a bias power supply for the control element 5B.
Good. Next, the operation of this circuit is shown in FIG.
Therefore, it will be described. When the AC input power is restored, a power failure detection signal
Changes from HIGH to LOW. That is, as shown in FIG.
The transistor side 112 of the photocoupler is blocked from the conductive state.
When the state shifts to the cutoff state, the transistor 152 is also turned off.
Therefore, the voltage of the DT terminal of the control element 5B is higher than VREF.
The voltage of VREF is divided by resistors 155 and 156 by the voltage dividing ratio.
The resistors 155, 156,
It decreases with the time constant determined by the capacitor 154. Control element
As the voltage of the DT terminal of the element 5B falls, the control element 5
The output pulse from B gradually spreads. In accordance with this output pulse, the AC / DC converter
The current flowing through the switching element (MOS-FET) is the same.
Waveform. This allows the output voltage to rise slowly.
Rise up. As described above, the power failure detection signal is output to the pulse width control I
When used as a start signal for C, a sudden
Input current can be effectively prevented. A rising system having an inrush current prevention function
Control circuit and the above-mentioned power failure detection circuit and switching control circuit.
When used together, the power can be restored even more effectively.
Can be solved. This is the device
Is as important as power failure
You. Next, the operation of the stabilized DC power supply 1F in FIG.
The road configuration will be described in detail with reference to FIG. In the drawing, an AC voltage 1 is applied to this circuit.
Then, the rectifier circuit 201 and the capacitor 202
It is converted to a DC voltage in the high-voltage rectifying and filtering unit formed. This DC voltage rectifies a sine wave to form a capacitor.
Since the waveform is only filtered by the filter 202,
The voltage waveform contains a lot. In general, the AC power supply voltage is
Because there is a fluctuation of about ± 10%,
As for voltage fluctuations, the difference between the upper and lower
Is about 1 when the voltage doubler rectifier circuit is used for the rectifier circuit at 100V.
00V will also fluctuate. Rectifier double voltage rectifier
The use of the circuit is intended to share the input voltage of 200V.
Often used. This voltage is connected to a switch in the high-frequency converter.
Pulse at the switching elements 203 and 204 and the high-frequency transformer 205
It converts to voltage and is composed of diodes 209 and 210
In addition to the low voltage rectifier, after rectification, the capacitor 213 and the rear
AC component is reduced by the filter circuit composed of the vector 211.
DC voltage. Also, the DC voltage output terminal is 21
4, 215. Disturbance due to input power supply voltage fluctuation, load fluctuation, etc.
Usually, the operation of the switching element in the high-frequency converter
There is a method to control the output voltage by controlling the duty.
Used. In this case, when decreasing the output voltage
To reduce the operation duty and increase the output voltage
In such a case, the operation may be performed in a reverse manner. Output power
Two resistors 216 and 222 are connected in series at both ends of the pressure
Then, connect the middle point to the (-) input terminal of the error amplifier 224.
You. The (+) input terminal of the error amplifier 224
Constant voltage from control bias power supply 217 through resistor 218
Voltage diode 219 is connected,
The cathode terminal of the gate 219 is connected here. Constant voltage die
Error to equal the voltage determined by the
The difference amplifier 224 operates and outputs. This voltage output is converted to a voltage-pulse width conversion circuit.
227 plus the desired pulse width
Is a path composed of two transistors 228 and 229.
Amplify the power with a pulse amplifier circuit and use a pulse transformer 231 resistor.
233, 232, high-frequency converter switch
Elements 204 and 203 (usually MOS-FETs are used
Drive). The voltage value of the output voltage deviates from a predetermined value.
Occurs, the error amplifier 224 operates, and the pulse width
Control to keep the output voltage constant. If any fault occurs on the load side of this output
As the force current increases, the low-voltage rectifier circuit
Converts current to voltage by resistor 212 inserted in series
Applied to the (+) input terminal of the current error amplifier 226.
It is. The (−) input terminal of the current error amplifier 226 has
Resistor 220, 2 to ground from bias reference voltage
21 are connected in series and connected to the dividing point. The electric current generated at both ends of the current detecting resistor 212
Voltage is determined by the bias reference voltage and the resistance ratio.
If it exceeds, the output voltage of the current error amplifier drops
Since the input voltage of the voltage pulse width conversion circuit drops,
The current becomes a constant value without increasing from the current value. Here, the resistor 223 is connected to the error amplifier 224
The resistance 225 is the amplification factor of the error amplifier 226.
Are used to determine each. FIG. 11 shows the voltage-current characteristics of this circuit.
In FIG. 11, the section (a) is a constant voltage control area.
The section (b) is a constant current control area. I1 is
This is the value of the set current. The characteristic shown in FIG. 11 is the same as the inverse L characteristic.
It is commonly called. The first output, which is the terminal 21 shown in FIG.
4 and 215. This is input to the second output circuit.
Apply as force. The configuration of the second output circuit is shown in more detail in FIG.
Will be described. The second output circuit is for charging a sealed lead-acid battery.
Used as a power supply circuit. FIG. 14 shows the charging characteristics of the sealed lead storage battery.
You. How to charge a lead-acid battery used for backup purposes
In the fully charged state, the floating charging method,
A method of applying voltage to the leads is used. Therefore, backup
After charging the battery, first charge it with a constant current and charge the battery.
When the voltage reaches the rated value, the charging current drops sharply.
Make sure to use a power supply that has the characteristics of switching to constant voltage charging.
I have to. Therefore, the charging current is first detected in FIG.
The voltage between both ends of the output resistor 150 is connected to the resistors 159, 1
60 and the error amplifier 15 through the resistors 161 and 162.
7 is applied to the positive and negative input terminals. Error amplifier 157
The output terminal is connected to the signal line h of FIG.
are doing. This resistor 158 determines the value of the droop current.
It is anti. The resistance 156 determines the gain of the error amplifier.
The value of this resistor 156
If the gain is set to several dB by setting, the resistance 150
Error amplifier 157 as the voltage across
Output decreases and the pulse width conversion circuit in the DC power supply
Operates in the direction of lowering the input voltage of
Both the output voltage and the second output voltage will decrease.
You. Normally, in the circuit having this configuration, the voltage / current
The characteristic shows a characteristic called the square character characteristic.
The characteristic is that when discharging, charge with the maximum current allowed,
As the voltage increases, the current should be reduced. As described above, this characteristic is useful for charging a battery.
Is not suitable. Therefore, the control voltage 167 is connected to the resistor 165
And the constant voltage diode 166, and the constant voltage diode
Amplification through resistor 163 from voltage determined by load
A positive bias is applied to the (-) input terminal of the
As the load resistance decreases, the output current increases slightly
It has a characteristic (reverse f-shaped characteristic). FIG. 13 shows the characteristics (breakdown) when the resistor 163 is not provided.
The solid line shows the characteristics when the resistor 163 is added.
is there. This is a method of charging a sealed lead battery.
Is the most suitable. The battery voltage after discharge is
Determined by the state of discharge of the battery, usually lead
Terry's final discharge voltage should not drop below 40V.
It is protected by the system. As described above, in FIG.
A constant voltage diode 16 through a resistor 165 from a source 167
6 and connect the connection point to the (-) input of the comparison amplifier 164.
Connect to the power terminal. The voltage of the battery 155 is
3 and 154, and the divided voltage point is compared with that of the comparison amplifier 164.
Connect to the (+) input terminal. Output terminal of comparison amplifier 164
A resistor 169 and a diode 168 are connected to the (+) input terminal.
Are connected in series. Further, the resistance from the output terminal of the comparison amplifier 164 is
Connected to the base terminal of transistor 171 through 170
I do. The collector of this transistor is the winding of relay K1
188 is connected to a bias power supply 167.
You. A diode 18 is provided at both ends of the winding 188 of the relay.
9 is connected. Battery 155 voltage is normal
At this time, the voltage of the (−) input terminal of the comparison amplifier 164 is
Battery voltage and resistors 153 and 154, comparison amplifier 164
And the voltage determined by the resistor 169.
You. At this time, the (+) of the comparison amplifier 164 must be used.
The input terminal voltage is higher than the (-) input terminal voltage.
I have. Therefore, the voltage of the output terminal of the comparison amplifier 164 is H
The transistor 171 which is at the high level is turned on.
The winding 188 of the relay K1 is in the excited state and the relay k
1 is in the closed state, so that the battery 15
5, a charging current is flowing. In this state, the charging
Pressure increases, resulting in an increase in battery 155 voltage
Then, the voltage of the (−) input terminal of the comparison amplifier 164 becomes
(+) When the voltage of the input terminal is exceeded,
The output voltage changes from HIGH to LOW and the transistor
171 is cut off, and as a result, the winding 188 of the relay is unenergized.
It becomes magnetized and the contact k1151 of the relay is opened. as a result
Charging of the battery 155 is stopped. At this time, the maximum charging voltage of the battery is:
It is set to 57V. When this voltage is exceeded, the seal type
In a lead battery, hydrogen gas is emitted from the battery.
There is a problem that life becomes intense. Therefore, stability is required for this voltage setting.
Is done. FIG. 15 shows the variation of the battery voltage with time.
Is the maximum value represented by Va in the figure.
If the charging voltage is set to 57 V, the battery 155
The charging stops when the voltage of the battery reaches 57V. afterwards
The battery voltage drops sharply, but to about 54V
, The rate of decrease becomes very slow. Vb
, The voltage at the (−) input terminal of the comparison amplifier 164
Is equal to or less than the voltage of the (+) input terminal (the voltage at this time is 52 V
The transistor 171 is turned on.
State, the relay contact k151 closes and charging starts again.
You. At this time, the (−) input of the comparison amplifier 164
The terminal voltage is the battery voltage and the resistances 153 and 154.
Is determined only by Although set to 52V here,
If the voltage falls below the voltage of the
Come out. Therefore, this voltage greatly fluctuates at the time of setting.
Is not tolerated. As described above, the hysteresis of the set value before and after the detection is obtained.
The teresis is about 5V. By setting this value,
Even if a power failure occurs during non-charging due to relay contact release,
Battery is fully charged so backup time
The problem of shortening does not occur. The output signal from the output terminal of the comparison amplifier 164 is
Configure so that positive feedback is applied only when the force is HIGH
Voltage fluctuation of bias power supply 167, comparison amplification
Recharge because there is no voltage change due to drift etc. of the heater 164
The problem of not being done does not occur. When the present invention is used as described above,
Adjustment man-hour can be greatly reduced. In the case of the present invention,
Terry's voltage was 48V, but this was the other voltage.
The idea is the same. Next, a backup configuration at the time of a power failure will be described.
This will be described with reference to FIG. The output of AC / DC conversion section 1A is converted to DC / DC
Connect to the converter 79. The output of the DC / DC converter 79
Output 1 The output of DC stabilized power supply 1F is
The DC / DC converter 1E is connected to the DC / DC converter 1E via the card 5.
The output of the DC / DC converter 1E is referred to as output 2. Also die
Connect the cathode of diode 5 and diode 9
The anode side of the diode 9 is (+) of the output of the AC / DC converter.
To the side. In addition, the DC stabilized power supply unit 1 is used as a common line.
A (-) terminal and another DC stabilized power supply 1F
Connect the (-) side. Next, the operation of the circuit will be described with reference to FIG.
I will tell. In the present invention, when an AC power is applied, the output
1 is output and output 2 is output according to the power-on signal.
It is configured as follows. Output voltage of DC stabilized power supply section 1A in steady state
V6 and the output voltage V7 of the stabilized DC power supply 1F are
So that V7> V6
If the voltage value is set, the diode 9 will be reverse biased in the steady state.
It is in a state and a diode is supplied from the stabilized DC power supply unit 1A.
9, power is supplied to the DC / DC converter 1E.
Nothing. In this state, the output voltages V6, V7 and
The relationship between the output 1 and the output 1 is shown by a solid line in FIG. Next, when the input power supply voltage drops due to a power failure,
The output of DC stabilized power supply 1F is
Because there is no pump, it drops at the same time as the input power supply voltage drops. The stabilized DC power supply section 1A is connected to a battery.
Is configured to be backed up
Voltage (52V in use example) from battery voltage (use example)
In this case, the voltage drops to 48 V).
In the replacement part 1E or 79, fluctuations that can sufficiently follow
Width. As a result, when V6> V7, the diode
9 is conducted, and the diode 9
Output to supply power to DC / DC conversion unit 1E by path
1 is no exception. However, since V7> V6, input
When the power supply drops, the input voltage V5 of the DC / DC converter becomes
As shown by the dashed line in FIG. 17, the DC / D
It is within the input fluctuation range of the C conversion unit and the output 1 is not affected. In the present invention, V6 = 52V, V7 = 56V
Diode 1 even if each output voltage fluctuates due to disturbance.
64 is set to a voltage that does not conduct. Of course, D
Output voltage drops at output 1 of C / DC converter B1
I will not. According to the present invention, the following effects can be obtained.
You. (1) Battery while maintaining the same performance
The number of chargers and the number of chargers used to charge them
It can be manufactured inexpensively with a small
Maintainability can be improved by reducing the number.
You. (2) Generated when a power failure occurs and when power is restored
Because there is no chatter of power failure signal,
The connection reliability of the disconnect switch can be improved. (3) When the power is restored after a power failure, the output voltage
You can switch smoothly without pressing. (4) Switch used for power supply at power recovery
No inrush current to the switching element increases reliability
I can do things. (5) Voltage required for battery charging characteristics
/ Longer battery life due to current characteristics
You. The frequency of battery replacement can be reduced. (6) Overcharging due to overcharging of the battery
In the event of a condition, the charging is stopped promptly to ensure safety.
Without loss of performance even if a power outage occurs
Can be backed up, so trust as a system
The performance is improved. Also, since the deviation range of the detection level is narrow,
The setting time can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an apparatus configuration diagram of one embodiment of the present invention. FIG. 2 is a time chart of each section in FIG. 1 FIG. 3 is a switching type stabilized power supply circuit diagram of one embodiment of the present invention. 4 is a circuit diagram of a power failure detection circuit according to an embodiment of the present invention; FIG. 5 is an operation waveform of each unit in FIG. 4; FIG. 6 is a circuit diagram of a switching control circuit according to an embodiment of the present invention; FIG. 8 is an operation time chart of a switching power supply according to an embodiment of the present invention. FIG. 9 is an operation time chart of each part in FIG. 8. FIG. 10 is a diagram of a switching type stabilized power supply circuit according to an embodiment of the present invention. FIG. 11 is a waveform diagram showing the relationship between current and voltage. FIG. 12 is a battery charge / overcharge protection circuit according to one embodiment of the present invention. FIG. 13 is a voltage / current characteristic in FIG. Fig. 15 Overcharge protection characteristic in Fig. 12 Fig. 16 Circuit diagram of backup system in one embodiment of the present invention Fig. 17 Operation time chart in Fig. 16 Conventional technology FIG. 19 is a time chart of each part in FIG. 18 FIG. 20 is a switching-type stabilized power supply according to the prior art FIG. 21 is a power failure detection circuit according to the prior art FIG. 22 A time chart in FIG. Switching circuit at the time of power failure in the prior art [FIG. 24] Operation time chart of each unit in FIG. 23 [FIG. 25] Starting circuit of switching power supply in the prior art [FIG. 26] Operation time chart of each unit in FIG. AC power supply, 1A DC stabilized power supply, 1B-1E DC / DC converter, 1F DC stabilized power supply , 1G, 1H charger, 2, 3 diode, 4 battery, 5 diode, 5A AC / DC conversion unit, 5B power control unit, 5C power failure detection circuit, 5D rise control circuit, 5E battery switching circuit, 6 diode 7 battery 8 Logic circuit section 9 diode 51 rectifier diode, 52 capacitor, 53, 54 MOS-FET, 55 high frequency transformer, 56 to 59 diode, 60 reactor, 61 capacitor, 62 pulse transformer, 63 capacitor, 64, 65 resistor, 66, 67 transistor, 68 voltage pulse width conversion circuit, 69 comparison amplifier, 70 reference voltage, 71 to 75 resistance, 76 DC power supply, 77, 78 diode, 79 DC / DC conversion unit, 101 to 103 resistance, 104 transistor, 105 constant voltage Diode, 10 6, 107 resistance, 108 photocoupler (light emitting diode side), 109 constant voltage control element, 110 photocoupler (transistor side), 111 photocoupler (light emitting diode side), 112 photocoupler (transistor side), 120 relay ( 121 MOS-FET, 122, 123 resistor, 124 diode, 125 transistor, 126-128 resistor, 129 capacitor, 130 resistor, 131, 132 diode, 133 comparative amplifier, 134, 135 resistor, 136 relay (winding) , 138 diode, 150, 151 resistor, 152 transistor, 153 resistor, 154 capacitor, 155, 156 resistor, 159 photocoupler (transistor side), 160 photocoupler (light emitting diode side), 161 resistor, 01 rectifier diode, 202 capacitor, 203, 204 MOS-FET, 205 high frequency transformer, 206, 207, 209, 210 diode, 211 reactor, 212 resistor, 213 capacitor, 214, 215 output terminal, 216 resistor, 217 DC power supply, 218 resistance, 219 constant voltage diode, 220-223 resistance, 224 comparison amplifier, 225 resistance, 226 comparison amplifier, 227 voltage pulse width conversion circuit, 228, 229 transistor, 230 capacitor, 231 pulse transformer, 232, 233 resistance

Continued on the front page (72) Inventor Tsutomu Imai 810 Shimo-Imaizumi, Ebina-shi, Kanagawa Prefecture Inside the Office Systems Division, Hitachi, Ltd. (72) Inventor Masaji Miyauchi 810 Shimoimaizumi, Ebina-shi, Kanagawa Prefecture Hitachi Systems, Ltd.Office Systems Division (72) Inventor Jin Ushida 1-Horiyamashita, Hadano-shi, Kanagawa Prefecture Inside Hitachi Computer Electronics (56 ) References Hikaru Hei 2-14072 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02J 9/00-9/08

Claims (1)

(57) [Claim 1] AC / DC power supplied from outside
First and second resistance elements connected to an input signal line for conversion by a conversion unit and supplied to a logic circuit, and connected in series to the input signal line; and the first and second resistance elements A power failure detection circuit having a stabilization control element that is connected to the connection point of the first and second resistance elements and is in a cutoff state when the connection point voltage of the second resistance element is equal to or less than a specified value, and is in a conductive state at or above a specified value. The stabilization control circuit is connected to the power failure detection circuit, the logic circuit, and the battery, respectively, is turned on when the stabilization control element is turned off, and is switched to start supplying power from the battery to the logic circuit. A switching circuit having a switch that switches off when the element is turned on and the supply of power from the battery to the logic circuit is stopped. A switch having a collector connected to a gate terminal of the switch, an emitter connected to the battery, and a fourth resistor connected to a base terminal of the transistor. And a capacitor connected to the fourth resistance element and the battery. When the stabilization control element is turned off, a current flows to a base terminal of the transistor, so that the switch is turned on. When the supply of power from the battery to the logic circuit is started, the capacitor is charged, and when the stabilization control element is turned on, the charged capacitor is connected to the logic circuit via the fourth resistance element. The on state of the switch is continued due to the current flowing through the base terminal of the transistor. , The transistor, the fourth
A power supply circuit, wherein the switch is turned off after a lapse of time determined by the resistance element and the capacitor, and the supply of power from the battery to the logic circuit is stopped.