JPH06342326A - Power unit - Google Patents

Abstract

PURPOSE:To supply a backup voltage by a subordinate battery in resume mode and memory backup mode and to eliminate the need for an auxiliary battery exclusively for backing up a memory as to the power unit of a device equipped with the subordinate battery which substitutes for a main battery. CONSTITUTION:The power unit is equipped with a main control means 5 which controls the operation of the power unit, the subordinate battery 3 which supplies the electric power to a main circuit 6 and a backed-up circuit 9 in the resume mode and supplies the electric power to the backed-up circuit 9 in the memory backup mode, and a voltage converting means 8 which inputs the voltage of an overdischarge preventing means 7 for the subordiante battery 3 and the subordinate battery 3 converts it into the operating voltage of the backed-up circuit 9; and the voltage is supplied by the subordinate battery 3 in the resume mode and backup mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is provided with a sub-battery for supplying power instead of a main battery so that data of a computer circuit is not lost in a resume mode. The present invention relates to a power supply device that supplies power by a sub-battery even in a memory backup mode in which a power supply voltage is supplied only to a data holding circuit (hereinafter referred to as a backup target circuit).

[0002]

2. Description of the Related Art A conventional portable computer such as a portable personal computer has an AC for supplying power from a commercial AC power source.
Main battery to be used in place of the adapter or AC adapter, a sub-battery that supplies a power supply voltage to each part of the circuit in the resume mode in which the data of the computer circuit is retained when the main battery is replaced or the power switch is off, and further resume To prevent the clock from stopping operating after switching from the mode, CMOS RAM
In order to prevent the stored contents of the memory from being lost, four types of power supply units of a vanadium lithium battery that supplies power to the backed up circuit in the memory backup mode in which voltage is supplied only to the backed up circuit are required.

FIG. 9 shows the configuration of a conventional power supply device. In the figure, 101 is an AC adapter for converting a commercial AC power supply into a DC power supply (9V, 6V, etc.).

102 is a main battery (9V, 6V
Etc.) and is a secondary battery used as a DC power source instead of the AC adapter 101. Reference numeral 103 denotes a sub-battery which supplies a voltage to a main circuit (internal circuit of a computer such as a system logic circuit) and a circuit to be backed up when the main battery 102 is removed for replacement or in a resume mode of power off. is there.

Reference numeral 104 denotes a vanadium lithium battery, which is a clock and CMO in the memory backup mode.
It backs up SRAM and the like. Reference numeral 106 denotes a main circuit, which is a computer circuit such as a system logic circuit.

Reference numeral 109 is a circuit to be backed up, which is a circuit such as a clock or a CMOS RAM. A DD converter 121 converts the voltage of the AC adapter 101, the main battery 102, and the sub-battery 103 into the operating voltage (3V, 5V, etc.) of the main circuit 106.

Reference numerals 130, 131 and 132 denote diodes which prevent current from flowing backward between the AC adapter 101, the main battery 102 and the sub battery 103, respectively.

133 and 134 are high withstand voltage ports,
It is a high breakdown voltage port for supplying a control signal of the microcomputer 123 to the semiconductor switch 134. High voltage port is H
It outputs L at the input and becomes Hi-Z (high impedance) at the L input.

Reference numeral 135 denotes a semiconductor switch (1) for turning on and off the voltage supply from the main battery 102 to the D-D converter 121, and for the P channel M.
It is an OS semiconductor switch.

Reference numeral 136 denotes a semiconductor switch (2) for turning on / off the voltage supply from the sub-battery 103 to the D / D converter 121, which is a P channel MO.
S semiconductor switch.

A charging circuit 137 is a charging circuit for the vanadium lithium battery. Reference numeral 140 denotes a diode, which prevents current from flowing backward from the vanadium lithium battery 104 to the main circuit 106 side.

Reference numeral 141 denotes a diode, which prevents a current from flowing backward from the DD converter 121 to the vanadium lithium battery 104. In the configuration shown in the figure, when the AC adapter 101 is used, the semiconductor switch (1) 135 is controlled by the microcomputer 123.
The semiconductor switch (2) 136 is turned off, and the D-D converter 121 outputs the output of the AC adapter 101 to the main circuit 106.
Is converted into the operating voltage of and is supplied to the main circuit 106 and the backup target circuit 109. At the same time, the charging circuit 137 charges the vanadium lithium battery 104.

When using the main battery 102,
Semiconductor switch (1) 135
Is turned on and the semiconductor switch (2) 136 is turned off, the output of the main battery 102 is input to the D-D converter 121, converted in voltage and applied to the main circuit 106 and the circuit to be backed up 109.

In the resume mode, the microcomputer 1
23, the semiconductor switch (1) 135 is turned off, the semiconductor switch (2) 136 is turned on, the voltage of the sub-battery 103 is input to the D-D converter 121, and the voltage is converted to the main circuit 106 and the circuit to be backed up. 109 is applied.

When the resume mode is switched to the memory backup mode, the vanadium lithium battery 104 supplies a voltage to the circuit to be backed up 109 to maintain the clock operation, hold the CMOS RAM memory, and the like.

[0016]

The power supply of the conventional portable computer has two sub batteries 103 and a vanadium lithium battery 104 as auxiliary batteries.

Therefore, the conventional power supply device has a large battery mounting area and a high cost. Further, if the vanadium lithium battery 104 is not provided, the backed-up circuit 109 will not operate and the stored contents will be lost.

An object of the present invention is to construct a highly reliable power supply device with a small number of batteries.

[0019]

The present invention monitors the voltage of a sub-battery to prevent over-discharge of the sub-battery, and supplies the voltage to the circuit to be backed up by the sub-battery even in the memory backup mode. This makes it possible to back up without using a Banadium Lithium battery.

FIG. 1 shows the basic configuration of the present invention. In the figure, reference numeral 1 is an AC adapter for supplying power from a commercial AC power supply.

Reference numeral 2 is a main battery. A sub-battery 3 is a small capacity nickel cadmium battery or the like, and is used in the resume mode.

Reference numeral 4 denotes a voltage converting means (1), such as a D-D converter, which converts the voltage of the AC adapter 1, the main battery 2, and the sub battery 3 into the operating voltage of the main circuit 6 and the circuit 9 to be backed up. To do.

Reference numeral 5 denotes a main control means, such as a microcomputer, which controls the power supply device. A main circuit 6 is an internal circuit of the computer such as a system logic circuit.

Reference numeral 7 is an over-discharge preventing means, which monitors the voltage of the sub-battery 3 and prevents the sub-battery 3 from being over-discharged. Reference numeral 8 denotes a voltage conversion means (2) for inputting the voltage of the sub-battery 3 and converting the voltage when the sub-battery 3 supplies a voltage to the circuit to be backed up in the memory backup mode. Voltage conversion means
(2) 8 is composed of, for example, a three-terminal regulator or the like.

Reference numeral 9 is a circuit to be backed up, which is a clock,
It is a CMOS RAM or the like. Reference numeral 10 is a switching means for switching the connection between the AC adapter 1, the main battery 2, the sub-battery 3 and the voltage converting means (1) 4.

[0026]

The operation of the configuration shown in the figure will be described. When the AC adapter 1 is used as a power source, the main control means 5 controls the switching means 10 to convert the AC adapter 1 into a voltage conversion means.
(1) Make sure that voltage is input to 4. Voltage conversion means
(1) 4 converts the voltage of the AC adapter 1 into the operating voltage of the main circuit 6 and the backed up circuit 9 and supplies it to the main circuit 6 and the backed up circuit 9.

When the main battery 2 is used, the main control means 5 controls the switching means 10 so that the voltage is input from the main battery 2 to the voltage conversion means (1) 4. The voltage converting means (1) 4 converts the voltage of the main battery 2 into the operating voltage of the main circuit 6 and the backup target circuit 9 and supplies it to the main circuit 6 and the backup target circuit 9.
In the sub-battery resume mode, the main control means 5 controls the switching means 10 so that the voltage is input from the sub-battery 3 to the voltage conversion means (1) 4. Then, the voltage converting means (1) 4 converts the voltage of the sub-battery 3 into the operating voltage of the main circuit 6 and the backed up circuit 9 and supplies it to the main circuit 6 and the backed up circuit 9 in the resumed state.

At this time, the over-discharge prevention means 7 starts to operate. Then, the voltage of the sub-battery 3 is monitored. Then, when overdischarge is detected, an overdischarge control notification is sent to the main control means 5. Upon receiving the notification, the main control unit controls the switching unit 10 to forcibly stop the voltage supply from the sub battery.

When a predetermined time elapses from the sub-battery resume mode, the memory backup mode is entered. In the memory and clock backup mode, the main control means 5 controls the switching means 10 to disconnect the AC adapter 1, the main battery 2, the sub-battery 3 and the voltage conversion means (1) 4.

Then, the over-discharge prevention means 7 monitors the voltage of the sub-battery, and if the voltage is equal to or higher than the discharge end voltage, the voltage of the sub-battery is supplied to the voltage conversion means (2) 8 and the voltage conversion means (2) 8 Converts the voltage into the operating voltage of the backed up circuit 9. The backed up circuit 9 is a voltage conversion means (2)
Input the voltage converted in 8 to maintain the clock operation, CM
The stored contents such as OSRAM are maintained.

When the over-discharge preventing means 7 detects that the voltage of the sub-battery 3 is lower than the discharge end voltage, the voltage supply to the voltage converting means (2) 8 is cut off and the over-discharge of the sub-battery 3 is prevented.

Further, the AC adapter 1, the main battery 2
When the use of is restored, the main control means 5 resumes operation. Then, the operation of the main circuit 6 and the backed up circuit 9 is started. It also charges the sub-battery 3 (a charging circuit is not shown).

[0033]

Embodiment FIG. 2 shows an embodiment (1) of the present invention. In the figure, 1 is an AC adapter.

Reference numeral 2 is a main battery. 3 is a sub battery. Reference numeral 6 is a main circuit (a system logic circuit or the like).

Reference numeral 9 is a circuit to be backed up (clock, CMOS
RAM, etc.). 20 is a D-D converter,
The voltage supplied from the AC adapter 1, the main battery 2, and the sub-battery 3 is converted into the operating voltage (3V, 5V, etc.) of the main circuit 6 and the backup target circuit 9.

Reference numeral 21 is a semiconductor switch (1) for turning on and off the voltage supplied from the main battery 2 to the D-D converter 20, and is a P-channel MOS.
It is composed of a semiconductor device.

Reference numeral 22 is a semiconductor switch (2) for turning on and off the voltage supplied from the sub-battery 3 to the D-D converter 20, and is composed of a P-channel MOS semiconductor device. is there.

23 is a microcomputer (main control means),
It controls the power supply device. Reference numeral 24 is an overdischarge prevention circuit, which is a circuit for preventing overdischarge of the sub-battery.

Reference numeral 25 denotes a three-terminal regulator for converting the voltage of the sub-battery 3 into the operating voltage of the backed-up circuit 9 in the sub-battery mode.

Reference numerals 30, 31, 32 are backflow preventing diodes. Reference numerals 39 and 40 denote backflow prevention diodes. Reference numeral 34 is a resistor, and 35 is a diode, which supplies the voltage from the AC adapter 1 and the main battery 2 to the sub-battery 3 via the resistor 34 and the diode 35 to trickle charge.

Reference numerals 36 and 37 are high withstand voltage ports, and control signals of the microcomputer 23 are sent to the semiconductor switch (1) 2 respectively.
1, applied to the semiconductor switch (2) 22. Three
Reference numeral 8 is a logic gate which gives logic for controlling the semiconductor switch (2) 22. The high voltage port outputs L at H input and becomes Hi-Z (high impedance) at L input. In Hi-Z, the output side is pulled up to H.

The operation of FIG. 2 will be described later. FIG. 3 shows an embodiment of the overdischarge prevention circuit 24 of the present invention. In the figure, reference numeral 24 is an overdischarge prevention circuit.

Reference numeral 25 is a three-terminal regulator. Reference numeral 50 is a semiconductor switch, which is composed of a P-channel MOSFET.

Reference numeral 50 'is an OR circuit. Reference numerals 51 and 52 are diodes of the OR circuit 50 '. Reference numeral 53 is a high withstand voltage open drain (high withstand voltage port), which is an OR circuit 50 '.
To invert the output of.

Reference numeral 54 is a voltage detecting element for detecting the output voltage of the sub-battery 3 (FIG. 2). Figure 2,
The operation of the circuit of FIG. 3 will be described.

During normal operation, the operating voltage of the main circuit 6 and the backed up circuit 9 is supplied from the DD converter 20 using the main battery 2 as a power source. The microcomputer 23 operates by the power supply thereof, and turns on the high withstand voltage port 36 of the semiconductor switch (1) 21 to form a self-holding circuit.

In the sub-battery resume mode,
The microcomputer 23 outputs "L" from the control port 1, the control signal thereof is inverted at the high breakdown voltage port 36, and the semiconductor switch (1) 21 is turned off. Further, the control signal of “H” is output from the control port 2. The control signal is input to the high withstand voltage port 36 via the logic gate 38 and is inverted to "L" to turn on the semiconductor switch (2) 22.

At this time, "H" is output from the control port 3.
The control signal of is output. The control signal is input to the diode 51 of the overdischarge prevention circuit 24, inverted by the high breakdown voltage open drain 53, and the semiconductor switch 50 is turned on. Then, the voltage detection element 54 of the overdischarge prevention circuit 24 monitors the voltage of the sub-battery 3 by the output of the semiconductor switch 50. If the voltage is equal to or higher than the discharge end voltage, the voltage detection element 54 outputs the control signal 1 of "H". The control signal 1 is input to the high breakdown voltage port 37 via the logic gate 38 and is inverted there to become “L” to keep the semiconductor switch (2) 22 turned on. When the voltage of the sub-battery 3 becomes equal to or lower than the discharge end voltage, the voltage detection element 54 outputs the control signal 1 of "L". The control signal 1 is input to the high breakdown voltage port 37 via the logic gate 38 and is inverted there to become "H" to turn off the semiconductor switch (2) 22.
Further, the control signal 1 is input to the high breakdown voltage open drain 53 via the diode 52, the signal is inverted and becomes “H”, and the semiconductor switch 50 is turned off to shift to the overdischarge prevention mode. In this way, the sub battery 3
To prevent over discharge.

The microcomputer 23 monitors the time and stops the resume state after a predetermined time has elapsed.
This time is determined by the capacity of the sub-battery 3, the current consumption during resume, the clock, the backup current consumption of the CMOS RAM, and the like.

When the resume is completed and the memory backup mode is entered, the microcomputer 23 outputs "L" from the control port 2.
Is output and the semiconductor switch (2) 22 is turned off. “H” is output from the control port 3. As a result, the over-discharge prevention circuit 24 turns on the semiconductor switch 50 when the voltage of the sub-battery 3 is equal to or higher than the discharge end voltage as in the resume mode, and the three-terminal regulator 25 converts the voltage of the sub-battery 3. It is applied to the circuit 9 to be backed up. When the output of the sub-battery 3 becomes equal to or lower than the discharge end voltage, the voltage detection element 54 outputs L and is input to the high withstand voltage port 53 via the diode 52. The signal thereof is inverted to turn off the semiconductor switch 50, and the sub-battery is turned off. 3 over-discharge is prevented.

At this time, since the power is off, it is necessary to prevent the main circuit 6 from being supplied with voltage. The diode 39 prevents the voltage from the three-terminal regulator 25 from flowing to the main circuit 6.

Further, in the present invention, since the microcomputer 23 does not monitor the voltage of the sub-battery, the resume state by the sub-battery 3 is tried to be continued even when the sub-battery is in the discharged state. At this time, there is a possibility that the microcomputer 23 will run out of control due to the sudden decrease in the voltage of the sub-battery. In order to prevent this, in the present invention, the control signal (over-discharge state notification signal) from the sub-battery over-discharge prevention circuit 24 is input to the high breakdown voltage port 37 via the logic gate 38, and inverted to "H". The control signal is applied to the gate of the semiconductor switch 2 (22),
Turn off 2).

When returning, power is supplied from the AC adapter 1. When the microcomputer 23 starts operating, the control port 3 is set to "H" and the semiconductor switch 50 is turned off. When the microcomputer 23 starts to operate, the signal of the control port 3 is set to "H" and is input to the high voltage port 53 to keep the semiconductor switch 50 off.

Using the AC adapter 1 or the main battery 2 as a supply source, trickle charge is performed on the sub-battery 3 through the current limiting resistor 34 and the backflow prevention diode 35 so that the sub-battery 3 is always above the discharge end voltage. To be When the output of the sub-battery 3 is equal to or higher than the reference voltage, the voltage detection element 54 outputs “H”, and the self-holding circuit that turns on the semiconductor switch 50 is activated, the microcomputer 23 of the control port 3 operates. The signal is "L".

With the above structure, it is possible to perform the backup, which was conventionally performed on the circuit to be backed up (clock, CMOS RAM, etc.) by the sub-battery and the vanadium lithium battery, only by the sub-battery.

FIG. 4 shows an embodiment (2) of the present invention. The figure is
By using a microcomputer having an A / D conversion function, the voltage of the sub-battery 3 is supplied to the microcomputer 23, and the microcomputer 23 monitors the voltage of the sub-battery 3 to perform over-discharge prevention control of the sub-battery 3. It was done.

In the figure, the same numbers as in FIG. 2 indicate the same components. 39 'is the three-terminal regulator 25 to the main circuit 6
This is a backflow prevention diode that prevents current from flowing into the diode.

Reference numeral 61 is a semiconductor switch (3) for turning on and off the voltage supplied from the sub-battery 3 to the three-terminal regulator 25. Reference numeral 63 is a voltage monitoring means included in the microcomputer 23, which monitors the voltage of the sub-battery 3.

The operation of the configuration shown in the figure will be described later. FIG. 5 shows a configuration example of the voltage monitoring means. In the figure, 23 is a microcomputer.

Reference numeral 61 'is an A / D port for inputting the voltage of the sub-battery 3. 62 'is the control port 3.

Reference numeral 63 is a voltage monitoring means. 64 is A / D
The conversion unit converts an analog voltage value input to the A / D port 61 'into a digital voltage value.

Reference numeral 65 is a reference value holding unit for holding a reference value corresponding to the discharge end voltage. Reference numeral 66 is a comparison unit for comparing the analog voltage value obtained by A / D conversion with the reference value of the reference value holding unit 65.

The operation of the embodiment (2) of the present invention will be described with reference to FIGS. In the resume mode by the sub battery (3), the semiconductor switch 1 (21) is turned off by the control signal of the control port 1. The semiconductor switch 2 (22) is turned on by the signal from the control port 2. As a result, the power supply voltage is supplied from the sub-battery 3 to the D-D converter 20 to the main circuit 6 and the backup target circuit 9.

During this time, the voltage monitoring means 63 monitors the over-discharge of the sub battery 3. The voltage monitoring means 63 is
The voltage of the sub-battery 3 input from the A / D port 61 ′ is converted into a digital value in the A / D converter 64. The voltage is applied to the reference value holding unit 65 in the comparison unit 66.
Is compared with the reference value set in advance. And
If the voltage of the sub-battery 3 is equal to or higher than the discharge end voltage (reference value), the comparison unit 66 outputs a control signal of "H", and if equal to or lower than the discharge end voltage (reference value), the comparison unit 66 outputs "L". Output a control signal.

As a result, if the voltage of the sub-battery 3 is equal to or higher than the discharge end voltage, the output of the control port 2 becomes "H", the semiconductor switch 2 (22) continues to be turned on, and the voltage of the sub-battery 3 becomes D-. It is input to the D converter 20, converted in voltage, and applied to the main circuit 6 and the circuit to be backed up 9. When the output of the sub-battery 3 is equal to or lower than the discharge end voltage, the output of the control port 2 becomes "L", the semiconductor switch 2 (22) is turned off, and the over-discharge of the sub-battery 3 is prevented.

During this time, the microcomputer 23 monitors the time in the resume mode, and shifts to the memory backup mode after a certain period of time. The control signals of the control port 1 and the control port 2 of the microcomputer 23 become "L", respectively, and the semiconductor switch 1 (21) and the semiconductor switch 2 (22) are turned off.

The voltage monitoring means 63 monitors the over-discharge of the sub battery 3. Similar to the case of the resume mode, the voltage of the sub-battery 3 input from the A / D port 61 'is converted into a digital value in the A / D conversion unit 64. The voltage is compared with a reference value preset in the reference value holding unit 65 in the comparison unit 66. If the voltage of the sub-battery 3 is equal to or higher than the discharge end voltage (reference value), the comparison unit 66 outputs a control signal of "H", and if it is equal to or lower than the discharge end voltage (reference value), the comparison unit 66 outputs "L". "
The control signal of is output.

As a result, if the voltage of the sub-battery 3 is equal to or higher than the discharge end voltage value, the control signal of "H" output from the control port 3 is converted to "L" by the high withstand voltage port 62, and the semiconductor switch 3 When (61) is turned on, the three-terminal regulator 25 converts the voltage of the sub-battery 3 into a voltage and supplies it to the circuit to be backed up 9. In addition, the sub battery 3
If the voltage is less than or equal to the discharge end voltage value, the “L” control signal output from the control port 3 is converted to “H” at the high withstand voltage port 62, the semiconductor switch 3 (61) is turned off, and the sub battery 3 over-discharge is prevented.

The backflow prevention diode 39 'prevents the output voltage of the three-terminal regulator 25 from being input to the main circuit 6 by the microcomputer 23 in the overdischarge prevention mode of the sub-battery 3.

AC adapter 1 or main battery 2
When using as a supply source, the sub battery 3 is trickle charged through the current limiting resistor 34 and the diode 35. And AC adapter 1
If the power cannot be supplied while the main battery 2 is being used, the microcomputer 23 shifts to the low voltage mode and is operable even if the voltage of the sub battery 3 is low. And
As described above, the voltage input from the A / D port is measured, and when the remaining voltage cannot maintain the resume state, the output of the control port 2 is set to "L" and the semiconductor switch 2 (22) is turned off. Stop the resume state and shift to the memory backup mode. Further, if the memory backup mode cannot be maintained, the output of the control port 3 is set to "L" and the semiconductor switch 3 (6
1) is turned off, the voltage supply to the three-terminal regulator 25 is stopped, and the over-discharge of the sub battery is prevented.

In FIG. 6, the overdischarge prevention circuit 24, the high breakdown voltage port 36, and the high breakdown voltage port 37 of FIG. 2 are CMOS ICs. In the figure, the numbers common to those in FIG. 2 indicate the common parts.

In the figure, 70 is an integrated IC, which includes an overdischarge prevention circuit 24, a high withstand voltage port 36, and a high withstand voltage port 3.
7 is configured as an IC such as CMOS.

Reference numeral 71 is a serial I / F. In the configuration shown, the integrated IC 70 and the microcomputer 23 are connected by a serial interface (serial I / F).

When the sub-battery over-discharge prevention mode is entered, the voltage supply from the integrated IC 70 to the microcomputer 23 is stopped, and only the three-terminal regulator 25 with extremely low power consumption and the quiescent current of the integrated IC are left.
Over discharge is prevented.

The three-terminal regulator 25 is also integrated IC
It can also be integrated into 70. FIG. 7 shows an embodiment of the present invention.
The operation flow of (1) and (3) is shown below. (a) is a flow in the regu-game mode by the sub battery.

The S1 sub-battery enters the resume state. The S2 microcomputer monitors the time after the resume state. When the maintenance time of the S3 resume state has elapsed, the output of the high withstand voltage port 37 is set to L.

S4 The semiconductor switch 2 is turned off (the microcomputer stops its operation). S5 Sub battery backup mode is set. S6 The voltage is monitored by the overcurrent protection circuit.

S7: It is determined whether or not the battery is over-discharged. If it is not in the over-discharged state, the process returns to S6 and the voltage monitoring is continued. If the over-discharge state is reached, the process proceeds to S8. S8 Further, the voltage supply to the circuit to be backed up is stopped (STBVCC2 supply stop).

(B) shows a flow for preventing runaway of the microcomputer in the sub battery mode. The resume mode by the S1 sub battery is set.

The S2 over-discharge prevention circuit monitors the voltage of the sub-battery. S3: Determine whether it is in the overdischarge state. S if not over-discharged
Return to 2 and monitor the voltage of the sub-battery. If the over-discharge state is reached, the process proceeds to S4.

S4 Since it is in the over-discharged state, the semiconductor switch 50 is turned off. Further, the voltage supply to the circuit to be backed up is stopped (STBVCC2 supply stop). Figure 8
Shows an operation flow of the embodiment (2) of the present invention.

The resumed state by the S1 sub-battery is set. The S2 microcomputer monitors the time after the resume state. When the maintenance time of the S3 resume state has elapsed, the output of the high withstand voltage port 37 is set to L.

S4 The semiconductor switch 3 is turned off. The S5 sub-battery backup mode is set (the microcomputer operates at a low speed). S6 The microcomputer 23 monitors the voltage of the sub battery input from the A / D port.

S7: It is determined whether the battery is over-discharged. If it is not in the over-discharged state, the process returns to S6 and the voltage monitoring is continued. If the over-discharge state is reached, the process proceeds to S8. S8 Further, the voltage supply to the circuit to be backed up is stopped (STBVCC2 supply stop).

[0085]

According to the present invention, only the sub-battery that backs up the circuit in the resume mode is used, and the clock and the CMOSR in the resume stop mode (power-off state) are used.
Backup of AM etc. becomes possible.

Therefore, according to the present invention, the number of batteries used can be reduced without losing the reliability of the power supply device, and the area occupied by the batteries can be reduced. Further, it is possible to prevent malfunction due to defective batteries and reduce the cost of the power supply device.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of the present invention.

FIG. 2 is a diagram showing an embodiment (1) of the present invention.

FIG. 3 is a diagram showing an embodiment of an overdischarge prevention circuit of an embodiment (1) of the present invention.

FIG. 4 is a diagram showing an embodiment (2) of the present invention.

FIG. 5 is a diagram showing a configuration example of a voltage monitoring means of an embodiment (2).

FIG. 6 is a diagram showing an embodiment (3) of the present invention.

FIG. 7 is a diagram showing an operation flow of embodiments (1) and (3) of the present invention.

FIG. 8 is a diagram showing an operation flow of the embodiment (2) of the present invention.

FIG. 9 is a diagram showing a conventional power supply device.

[Explanation of symbols]

 1: AC adapter 2: Main battery 3: Sub battery 4: Voltage conversion means (1) 5: Main control means 6: Main circuit 7: Over-discharge prevention means 8: Voltage conversion means (2) 9: Backup target circuit

Claims (5)

[Claims] 1. A main circuit (6) which is supplied with power in a resume mode, and a circuit to be backed up (9) which is supplied with power in a resume mode and a memory backup mode in which only the memory or the like is backed up from the resume mode. ), The main control means (5) for controlling the operation of the power supply and the main circuit (6) and the circuit to be backed up (9) in the resume mode are supplied with the memory backup mode. The sub-battery (3) that supplies power to the back-up circuit (9), the over-discharge prevention means (7) of the sub-battery (3), and the voltage of the sub-battery (3) are input to the back-up circuit.
It is equipped with voltage conversion means (8) for converting to the operating voltage of (9) to prevent over-discharge of the sub-battery (3) in resume mode or backup mode, and also in the memory backup mode, the sub-battery protects the circuit to be backed up. A power supply device characterized by supplying a backup voltage. 2. The main control means (5) according to claim 1, wherein the main control means (5) includes an over-discharge detection means for the sub-battery and operates with low power consumption even in a memory backup mode. A voltage conversion means for inputting the analog voltage value of the above and converting it into a digital value, a means for holding a reference voltage that serves as a reference for the over-discharge voltage of the sub-battery, and a comparison section for comparing the digital voltage value and the reference voltage value of the sub-battery. A power supply device equipped with the sub battery (3) to prevent over discharge. 3. The power supply device according to claim 1, wherein the voltage conversion means (8) for converting the voltage of the sub-battery in the memory backup mode is a three-terminal regulator. 4. The over-discharge prevention means (7) according to claim 1.
Or, a power supply device characterized by integrating the over-discharge prevention means (7) and the voltage conversion means (8) into an integrated circuit. 5. The power source according to claim 1, further comprising means for forcibly shifting to the over-discharge prevention mode when the voltage of the sub-battery becomes equal to or lower than the over-discharge prevention voltage in the sub-battery resume mode. apparatus.