JP2773223B2 - Electronic equipment and backup voltage monitoring method - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device with a battery backup that supplies power to an electronic device that needs a temporary power backup at the time of a power failure, and an electronic device.

[Prior Art] A conventional power supply device with a battery backup has no means for informing the load of an electronic device or the like of the output voltage state when backing up the electronic device with a built-in battery when the input voltage is cut off. It was only passively supplied with power from a power supply device with a battery backup and could not have a method of recognizing the state after the input voltage was cut off.

[Problems to be Solved by the Invention] However, the power supply device with a battery backup as described above has the following two problems during the backup by the battery.

(1) After the input voltage of the power supply device with the battery backup is cut off, it is difficult to determine the timing at which the electronic device performs a power-off process such as a backup of its own data or a process such as a battery over-discharge prevention.

(2) The operation of the electronic device becomes unstable due to a decrease in the output voltage of the battery.

The present invention makes it possible for a power supply device with a battery backup to notify an electronic device of the state of an output voltage during backup by a battery, and for the electronic device to execute an appropriate process after an input voltage cutoff using the same. Things.

An object of the present invention is to prevent malfunction of an electronic device and prevent overdischarge of a battery.

[Means for Solving the Problems] An electronic device of the present invention includes: a backup battery; a first voltage monitoring circuit that monitors whether a charged voltage value of the backup battery is a value at which the electronic device can be continuously operated; A second voltage monitoring circuit that monitors whether a charging voltage value of the backup battery is operable for a predetermined time up to an operation lower limit value of the electronic device, and wherein the first voltage monitoring circuit comprises: Display means for detecting a charge voltage value of the backup battery after detecting the value capable of continuous operation, and displaying a power-off warning to a user if the charge voltage value is equal to or more than the value operable for the predetermined time; Is provided.

In addition, the backup voltage monitoring method for an electronic device according to the present invention includes an output voltage monitoring circuit that monitors a charging voltage of a backup battery by using a plurality of voltage values. The second value is an operable value, and the second value is a backup voltage monitoring method of the electronic device, the electronic device being a value operable for a predetermined time until the operation lower limit value, wherein the backup battery starts discharging, After the charge voltage value of the battery has reached the first value, the charge voltage value of the backup battery is detected, and if the charge voltage value is equal to or greater than the second value, a warning of power-off is displayed to the user. It is characterized by doing.

Further, the output voltage monitoring circuit monitors an operation lower limit of the electronic device, which is a third value, and performs the highest priority interrupt to the electronic device when the charging voltage value is the third salt. Features.

Embodiment FIG. 1 is a schematic diagram of a power supply device showing an embodiment of the present invention. 1 is a DC power supply for converting an AC input voltage to a DC output voltage. 2 is a power backup battery. 3, 4, 5
Are three output voltage monitoring circuits each including a reference voltage source, a voltage comparator, and an output terminal for notifying the load of the result of the voltage comparison.
This part can be replaced by an A / D converter. Reference numeral 6 denotes a main switch for turning on / off the power supply with battery backup.

Vout is the voltage between A and C and is the output voltage to the load.
VB is the voltage between A and B and is the output voltage of the backup battery.

V1 is the voltage between A and D and is the output voltage of the reference voltage source. S1 is a signal for notifying the load of the result of the output voltage monitoring circuit 3.

V2 is the voltage between A and E and is the output voltage of the reference voltage source. S2 is a signal for notifying the load of the result of the output voltage monitoring circuit 4.

V3 is the voltage between A and F, which is the output voltage of the reference voltage source. S3 is a signal for notifying the load of the result of the output voltage monitoring circuit 5. The mutual relationship between V1, V2, and V3 will be described later with reference to FIGS.

FIG. 2 is a schematic diagram of an example of an electronic device serving as a load of the power supply device with a battery backup shown in FIG. C, A, S3, S2, S1 in FIG. 1 are C, A,
Connected to S3, S2, S1.

7 is a switch circuit composed of one thyristor and three resistors, 8 is a switch circuit composed of two transistors and three resistors, 9 is a microprocessor (CPU), 10 is a CRT, 11 is a keyboard, 12 is a main memory, and 13 Is CMOSSRAM for data backup, 14 is the battery for CMOSRAM backup, 15 is an auxiliary storage device, and 16 is an interface between 9 and various input / output devices.

17 is an interrupt controller. Reference numeral 18 denotes a three-state buffer that receives the signal of S2. G is the voltage output for 9 to 18, H is the control signal for 7 output from 16,
Normally, it is at the LOW level. Re is the ground output for 9 to 18. S1 and S3 are connected to CPU 9 through interrupt controller 17.
, And their priorities are S3> S1. S2 is connected to the data bus 9 through the free state buffer 18, and the microprocessor can read the state of S2.

3 and 4 show output voltage characteristics of Vout when the power supply device of FIG. 1 is connected to the electronic device of FIG.

FIG. 3 shows output voltage characteristics when the battery is sufficiently charged. FIG. 4 shows output voltage characteristics when the battery is not sufficiently charged.

 t0 is the time when the AC input voltage is cut off.

t1 is the time when Vout = V1. S1 changes from H to L,
An interrupt (hereinafter, referred to as an S1 interrupt) occurs at No. 9.

 t2 is the time when Vout = V2. S2 changes from H to L.

t3 is the time when Vout = V3. S3 changes from H to L,
An interrupt (hereinafter, referred to as an S3 interrupt) occurs at No. 9.

V4 is the voltage of Vout after dt from t1. dt is set to 1 second.

V1>V2> V3 is set, and V3 is a potential having a margin slightly below the lower limit of the voltage at which the electronic device of FIG. 2 normally operates.

If the battery is fully charged as shown in FIG.
The potential is determined so that t2 to t3 can be secured in at least 5 minutes, and V1 is a limit voltage at which the electronic device can continue normal operation if Vout> V1.

Vout is the output voltage from DC power supply 1 from 0 to t0,
After t0, it is the output voltage VB from the battery 2.

FIG. 5 shows that when the electronic device shown in FIG. 2 is backed up by the battery 2, S1 changes from HIGH (hereinafter, H) to LOW (hereinafter, S1).
Interrupts that transition to L), S1 interrupts, and S3 from H to L
9 is a flowchart of an operation performed by an interrupt and a S3 interrupt.

The operation of the circuits shown in FIGS. 1 and 2 will be described with reference to FIG. C, A, S1, S2, S3 in FIG. 1 and C in FIG.
A, S1, S2, and S3 are connected respectively. Switch 6
When turned on, the AC input voltage is supplied to the DC power supply unit 1.
The DC power supply unit outputs a DC voltage (Vout) to the electronic device. At this time, the battery 2 is charged. S1, S2, S3
Becomes H and is output.

When Vout is input to the electronic device, the switch 8 is turned on, power is supplied from the CPU 9 to the three-state buffer 18, and the electronic device starts operating. At this time, the output of H keeps the L level, the thyristor 7 remains off, and the switch circuit 7 remains off.

In this state, if the AC input voltage is cut off due to a power failure, the battery 2 will be
Is supplied. Even if VBH temporarily drops due to a short-term instantaneous power failure, if VB> V1, the electronic device operates normally with S1 = S2 = S3 = H.

If the interruption time is prolonged, VB decreases. Vout at the same time
Also decrease. When Vout = V1, 9 recognizes the transition of S1 from H to L by the S1 interrupt. At this time, 9 checks the status of S2, and if S2 = L, moves to the processing (the latter operation) in FIG.

If S2 = H, after waiting dt (1 second), S2 is checked again. At this time, if S2 = L, the process proceeds to (5-3). If S2 = H, the step 9 judges that the battery capacity is sufficient and performs the processing of (5-2).

State the reason for checking S2 twice. In the case of FIG.
After the S1 interrupt, check Vout once to confirm that Vout> V2, and when checking again at the time (t1 + dt), Vo
Since ut (= V4)> V2, the normal operation of the electronic device is guaranteed for at least 5 minutes from t2 to t3.
The normal operation of the electronic device is also guaranteed for at least 5 minutes from (t1 + dt) to t3.

However, after the S1 interrupt as in the case of FIG.
Is checked once to confirm that Vout> V2, and when it is checked again at the time of (t1 + dt), since Vout (= V4) <V2, the normal operation of the electronic device for at least 5 minutes is not guaranteed. The time of 5 minutes is the minimum time required for the processing of (5-2). Therefore, since the slope of the discharge voltage with respect to the time axis differs depending on the state of charge of the battery VB, two checks are performed to reliably perform the process of (5-2).

In the process (5-2), the electronic device informs the user that the power supply has been interrupted, immediately terminates the application program currently in progress, and backs up necessary data to the auxiliary storage device 15. Warning. When the electronic device confirms that the user has received the warning and completes the process, the electronic device proceeds to the process of (5-3).

In (5-3), the electronic device performs processing for power-off. For example, the control information of the current electronic device is saved in 14 battery-backed CMOS RAMs. This control information is minimum necessary information when the electronic device is restarted. Then, the output of the switch is changed from L to H, the thyristor is triggered, and the switch circuit 7 is turned on. As a result, the switch circuit 8 is turned off, and power is not supplied to 9 to 18. In this state, since the current flows only through 7, the electronic device has reduced the load on the battery by itself and has reduced the discharge current of the battery.

After the occurrence of the S1 interrupt, during the above operation, the S3 interrupt is the highest priority interrupt and is always accepted (5-3).
Is performed.

[Effects of the Invention] As described above, according to the present invention, after the first voltage monitoring circuit detects a value that allows continuous operation, the charging voltage value of the backup battery is detected, and the charging voltage value is set to a predetermined value. A display means for displaying a power-off warning to the user if the value is equal to or greater than the time operable value is provided, so that the state of charge of the backup battery can be detected and the user can save data when the battery is sufficiently charged. It can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment according to the present invention. FIG. 2 is a schematic diagram of an electronic device serving as a load of the power supply device with a battery backup shown in FIG. FIG. 3 is a diagram showing output voltage characteristics of Vout when the circuits of FIGS. 1 and 2 operate. FIG. 4 is a diagram showing output voltage characteristics of Vout when the circuits of FIGS. 1 and 2 operate. FIG. 5 is a flowchart when the electronic device of FIG. 2 is backed up by the battery 2. 1: DC power supply unit 2: Backup battery 3: Reference voltage source, voltage comparator, and output voltage monitoring circuit consisting of an output that informs the load of the result of voltage comparison to the load 4: Reference voltage source, voltage comparator, and the result of voltage comparison Output voltage monitoring circuit consisting of an output notifying the load 5: Output voltage monitoring circuit consisting of a reference voltage source, voltage comparator and an output notifying the result of the voltage comparison to the load 6: Main switch of the power supply 7: One thyristor and three resistors 8: Switch circuit consisting of two transistors and three resistors 9: Microprocessor (CPU) 10: CRT 11: Keyboard 12: Main memory 13: CMOSRAM for data backup 14: Battery for CMOSRAM backup 15: Auxiliary storage Interface between device 16: 9 and various input / output devices 17: Interrupt controller 18: Three-state buffer receiving S2 signal

Claims (3)

(57) [Claims] A backup battery; a first voltage monitoring circuit that monitors whether a charge voltage value of the backup battery is a value at which the electronic device can be continuously operated; A second voltage monitoring circuit that monitors whether the value is operable for a predetermined time up to an operation lower limit value. An electronic apparatus comprising: a first voltage monitoring circuit that detects the value that allows continuous operation; An electronic apparatus, comprising: a display unit that detects a charging voltage value of the backup battery and displays a power-off warning to a user if the charging voltage value is equal to or greater than a value operable for the predetermined time. 2. An output voltage monitoring circuit for monitoring a charging voltage of a backup battery based on a plurality of voltage values, wherein the plurality of voltage values are such that a first value is a value at which the electronic device can be continuously operated, and a second value is a second value. Is a value of the backup voltage of the electronic device, wherein the backup battery starts discharging, and the charge voltage value of the backup battery is the first value. After detecting the value of the backup battery, a charge voltage value of the backup battery is detected, and if the charge voltage value is equal to or more than the second value, a warning of power-off is displayed to a user. Backup voltage monitoring method. 3. The output voltage monitoring circuit monitors an operation lower limit of the electronic device, which is a third value, and when the charging voltage value is the third value, issues a highest priority interrupt to the electronic device. 3. The method of monitoring a backup voltage of an electronic device according to claim 2, wherein the method is performed.