JP2016032196A - Temperature compensation oscillation circuit, real time clock device and electronic apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow for appropriate action, by allowing notification of the occurrence of a problem, e.g., lowering of power supply voltage, and the extent thereof.SOLUTION: A temperature compensation oscillation circuit 2 includes detection means 3-6 for detecting the number of times when the voltage of the temperature compensation oscillation circuit 2 is lower than a second threshold voltage, required for performing normal temperature compensation operation, and/or the period of low voltage, in a period where the power supply voltage supplied is higher than a first threshold voltage for stopping oscillation operation of the temperature compensation oscillation circuit 2, and a number of times of low voltage register 28, a low voltage period register 29 and an accumulated low voltage period register 30, as storage means for storing the number of times of low voltage detected and the period of low voltage.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a temperature compensated oscillation circuit, a real-time clock device, and an electronic device.

  The temperature-compensated oscillation circuit has a built-in temperature compensation circuit that compensates for the frequency temperature characteristic unique to the vibrator, and outputs a flat and stable frequency over a wide temperature range. This temperature-compensated oscillation circuit is used in, for example, a real-time clock device having a clock / calendar function (see, for example, Patent Document 1).

  This real-time clock device is mounted on an electronic device that requires time data, such as a mobile phone, a computer, a video recorder with an automatic recording function, a camera (photographing time recording function), and the like.

  The real-time clock device is driven by a backup power source such as a primary battery or a secondary battery so that the timekeeping operation can be continued even if the main power of the electronic device in which the real-time clock device is mounted is turned off. It is configured. When the main power supply of the electronic device is turned on and restarted, time data is provided to the electronic device from the real-time clock device.

JP 2007-67675 A

  In the real-time clock device as described above, if the power supply voltage drops during backup with a backup power source such as a battery and falls below the voltage necessary for normal temperature compensation operation, accurate time data is obtained. Since there is a possibility that it has not been obtained, when the main power supply of the electronic device is turned on, it is necessary to notify the electronic device that a problem has occurred in the timekeeping operation of the real-time clock device.

  If it is possible to recognize that a malfunction has occurred, the electronic device prompts the user to reset the correct time, or obtains time information from the GPS or radio clock if it can be obtained. Thus, the time can be reset in the real-time clock device.

  However, as described above, if it is not possible to notify only the degree of the malfunction by notifying only that the malfunction that the power supply voltage has decreased during the backup, it is not possible to take appropriate measures according to the degree of the malfunction. This is not possible, and it is necessary to reset the time assuming the worst case.

  However, some troubles due to a drop in power supply voltage may require resetting the time, and depending on the application or usage environment of the electronic device, it is not always necessary to reset the time. In some cases, such as a problem that may occur, for example, a decrease in power supply voltage may occur in a relatively short time without causing a temperature change.

  The present invention has been made in view of the above circumstances, and in the case where a problem such as a decrease in power supply voltage occurs, the degree of the problem can be grasped, and the degree of the problem can be determined. The purpose is to be able to take appropriate measures.

  In order to achieve the above object, the present invention is configured as follows.

(1) A temperature-compensated oscillation circuit of the present invention is a temperature-compensated oscillation circuit that operates with a supplied power supply voltage and adjusts the oscillation frequency of the oscillation circuit based on the temperature detected by the temperature sensor.
In the period when the power supply voltage is higher than the first threshold voltage at which the oscillation operation of the temperature compensated oscillation circuit stops, the number of times the power supply voltage becomes a low voltage lower than the second threshold voltage and / or the low voltage period Detecting means for detecting
Storage means for storing the number of times of the low voltage detected by the detection means and / or a period of the low voltage,
The second threshold voltage is a voltage necessary for the temperature compensated oscillation circuit to perform a normal temperature compensation operation.

  According to the temperature compensated oscillation circuit of the present invention, the second threshold value which is a voltage necessary for performing a normal temperature compensation operation in a period in which the supplied power supply voltage is higher than the first threshold voltage at which the oscillation operation stops. When the low voltage becomes lower than the voltage, the number of times of the low voltage and / or the period of the low voltage is stored. Therefore, based on the stored number of times of the low voltage and / or the period of the low voltage, It is possible to grasp the number of periods in which the temperature compensation operation is not normally performed and / or the period in which the temperature compensation operation is not normally performed, that is, the length of time.

  (2) In a preferred embodiment of the temperature-compensated oscillation circuit of the present invention, the detection means includes a cumulative low voltage period obtained by accumulating the low voltage period over a plurality of times and / or the plurality of low voltage periods. The latest low voltage period of the low voltage periods is detected, and the storage means detects the cumulative low voltage period detected by the detection means and / or the latest low voltage period as the low voltage period. Memorize the low voltage period.

  According to this embodiment, the supplied power supply voltage is lower than the second threshold voltage, which is a voltage necessary for performing normal temperature compensation operation, in a period higher than the first threshold voltage at which the oscillation operation stops. When a period occurs a plurality of times, the latest low voltage period is stored among the accumulated low voltage period obtained by accumulating a plurality of low voltage periods and / or the plurality of low voltage periods. Based on the period and / or the latest low voltage period, it is possible to grasp the cumulative period of the plurality of periods in which the temperature compensation operation has not been performed normally and / or the latest period in which the temperature compensation operation has not been performed normally. It becomes possible.

  (3) In a preferred embodiment of the temperature compensated oscillation circuit of the present invention, the power supply voltage is a power supply voltage supplied from an auxiliary power supply to the temperature compensated oscillation circuit.

  According to this embodiment, when the power supply voltage from the auxiliary power supply becomes a low voltage lower than the second threshold voltage in a period higher than the first threshold voltage, the number of times of the low voltage and / or the low voltage period is set. Since it can be grasped, it is possible to grasp the time of replacement of the batteries constituting the auxiliary power source.

  (4) In another embodiment of the temperature compensated oscillation circuit of the present invention, the temperature compensation operation is stopped during the low voltage period.

  According to this embodiment, in a low voltage period in which the supplied power supply voltage is lower than the voltage necessary for normal temperature compensation operation, the temperature compensation operation is stopped and the state before the power supply voltage is lowered is reduced. maintain.

  (5) In still another embodiment of the temperature compensated oscillation circuit of the present invention, the storage means is constituted by a register.

  According to this embodiment, by accessing the register, it is possible to grasp the number of periods in which the temperature compensation operation is not normally performed and / or the period in which the temperature compensation operation is not normally performed.

(6) The real-time clock device according to the present invention is a real-time clock device that operates according to a supplied power supply voltage.
A temperature compensated oscillation circuit that adjusts the oscillation frequency of the oscillation circuit based on the temperature detected by the temperature sensor; and
Based on a clock signal output from the temperature compensated oscillation circuit, a clock circuit that generates time data,
In the period when the power supply voltage is higher than the first threshold voltage at which the oscillation operation of the temperature compensated oscillation circuit stops, the number of times the power supply voltage becomes a low voltage lower than the second threshold voltage and / or the period of the low voltage. Detecting means for detecting
Storage means for storing the number of times of the low voltage detected by the detection means and / or a period of the low voltage,
The second threshold voltage is a voltage necessary for the temperature compensated oscillation circuit to perform a normal temperature compensation operation.

  According to the real-time clock device of the present invention, the temperature-compensated oscillation circuit performs a normal temperature compensation operation in a period in which the supplied power supply voltage is higher than the first threshold voltage at which the oscillation operation of the temperature-compensated oscillation circuit stops. When the voltage becomes lower than the second threshold voltage, which is a voltage required for the above, the number of times of low voltage and / or the period of low voltage is stored, so the number of times of low voltage stored and / or Or, based on the low voltage period, it is possible to know the number of periods when the temperature compensation operation is not performed normally and / or the period when the temperature compensation operation is not performed normally, that is, the length of time. It becomes.

  Thus, when the temperature compensation operation cannot be performed normally, the period during which the temperature compensation operation cannot be performed normally and / or the number of periods during which the temperature compensation operation cannot be performed normally can be grasped. Since it is possible to grasp the extent to which no temperature compensation operation could be performed, appropriate measures can be taken according to the extent. For example, when the period during which the temperature compensation operation cannot be normally performed is a relatively short time that does not cause a temperature change, the time data of the real-time clock device is continued as it is, assuming that the time data is highly reliable. It can be used to reduce the time and effort of resetting the time. On the other hand, if the time during which the temperature compensation operation cannot be performed normally is relatively long and the number of periods during which the temperature compensation operation cannot be performed normally is relatively large, the reliability of the time data is assumed to be low. Can be reset.

  (7) In a preferred embodiment of the real-time clock device according to the present invention, the detecting means includes a cumulative low voltage period obtained by accumulating a plurality of low voltage periods and / or the plurality of times as the low voltage period. The latest low voltage period in the low voltage period is detected, and the storage means detects the cumulative low voltage period detected by the detection means and / or the latest low voltage as the low voltage period. Remember the period.

  According to this embodiment, the supplied power supply voltage is lower than the second threshold voltage, which is a voltage necessary for performing normal temperature compensation operation, in a period higher than the first threshold voltage at which the oscillation operation stops. When a period occurs a plurality of times, the latest low voltage period is stored among the accumulated low voltage period obtained by accumulating a plurality of low voltage periods and / or the plurality of low voltage periods. Based on the period and / or the latest low voltage period, it is possible to grasp the cumulative period of the plurality of periods in which the temperature compensation operation has not been performed normally and / or the latest period in which the temperature compensation operation has not been performed normally. It becomes possible.

  (8) In a preferred embodiment of the real-time clock device of the present invention, the power supply voltage is a power supply voltage supplied from an auxiliary power supply to the real-time clock device.

  According to this embodiment, when the power supply voltage from the auxiliary power supply becomes a low voltage lower than the second threshold voltage in a period higher than the first threshold voltage, the number of times of the low voltage and / or the low voltage period is set. Since it can be grasped, it is possible to grasp the time of replacement of the batteries constituting the auxiliary power source.

  (9) In another embodiment of the real-time clock device of the present invention, the temperature compensation operation of the temperature compensated oscillation circuit is stopped during the low voltage period.

  According to this embodiment, in a low voltage period in which the supplied power supply voltage is lower than the voltage necessary for normal temperature compensation operation, the temperature compensation operation is stopped and the state before the power supply voltage is lowered is reduced. maintain.

  (10) In still another embodiment of the real-time clock device of the present invention, the storage means is constituted by a register.

  According to this embodiment, by accessing the register, it is possible to grasp the number of periods in which the temperature compensation operation is not normally performed and / or the period in which the temperature compensation operation is not normally performed.

(11) An electronic device of the present invention is an electronic device including the real-time clock device according to any one of (6) to (10) above,
And determining means for determining whether or not it is necessary to set a time for the real-time clock device based on the number of times of the low voltage stored in the storage means and / or the period of the low voltage.

  According to the electronic device of the present invention, the temperature compensated oscillation circuit performs a normal temperature compensation operation in a period in which the supplied power supply voltage is higher than the first threshold voltage at which the oscillation operation of the temperature compensated oscillation circuit stops. When the voltage becomes lower than the second threshold voltage, which is a voltage necessary for the above, the number of times of the low voltage and / or the period of the low voltage is stored, so that the determination means sets the stored low voltage. Based on the number of times and / or the low voltage period, it can be determined whether or not time setting is necessary.

  (12) In another embodiment of the real-time clock device of the present invention, when the determination unit determines that time setting is necessary, the real-time clock device includes a notification unit that notifies that fact.

  According to this embodiment, when it is determined by the determining means that the time setting is necessary, the notification means notifies the user and can prompt the user to set the time.

  According to the present invention, a low voltage lower than a second threshold voltage, which is a voltage necessary for performing a normal temperature compensation operation, in a period in which the power supply voltage is higher than the first threshold voltage at which the oscillation operation of the oscillation circuit stops. Since the number of times of low voltage and / or the period of low voltage is stored, the temperature compensation operation is normally performed based on the stored number of times of low voltage and / or period of low voltage. It is possible to grasp the number of periods that have not occurred and / or the period in which the temperature compensation operation has not been performed normally. As a result, appropriate measures can be taken depending on the degree to which the temperature compensation operation cannot be normally performed.

FIG. 1 is a block diagram of a real-time clock device according to an embodiment of the present invention. FIG. 2 is a time chart for explaining the operation of the real-time clock device of FIG. FIG. 3 is a block diagram of a main part of an electronic device that receives time data from the real-time clock device. FIG. 4 is a block diagram of a temperature compensated oscillation circuit according to an embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Embodiment 1]
FIG. 1 is a block diagram of a real-time clock device 1 according to an embodiment of the present invention. The real-time clock device 1 is mounted on an electronic device, and a time-counting circuit described later with respect to a microcomputer 35 of the electronic device. The time data is supplied from 8 through the interface circuit 9.

  The real-time clock device 1 of this embodiment includes a temperature-compensated oscillation circuit 2, first to third voltage detection circuits 3 to 5 that detect a decrease in power supply voltage supplied from the main power supply 22 or the auxiliary power supply 24, respectively. Time data is created based on a control circuit 6 for controlling each part, a register group 7 as storage means for holding each information to be described later in response to a decrease in power supply voltage, and a clock signal from the temperature compensated oscillation circuit 2 The timer circuit 8, the interface circuit 9, and the clock output control circuit 10 are provided.

  The temperature compensated oscillation circuit 2 includes an oscillation circuit 11 and a temperature compensation circuit 12. The oscillation circuit 11 includes a crystal resonator 13, a feedback resistor 14, an inverter 15, and a variable capacitance array 16. The oscillation frequency of the oscillation circuit 11 of this embodiment is 32.768 KHz, and includes a tuning fork type crystal resonator 13 that has good oscillation stability and can be miniaturized.

  The temperature compensation circuit 12 includes a temperature sensor 17 that detects the ambient temperature of the crystal resonator 13, an A / D conversion circuit 18 that converts an analog signal from the temperature sensor 17 into a digital signal, and correction data corresponding to the ambient temperature. A stored memory 19 and a capacity variable circuit 20 that varies the capacity of the variable capacity array 16 of the oscillation circuit 11 based on correction data read from the memory 19 in accordance with a digital signal from the A / D conversion circuit 18; And compensates for the effects of changes in ambient temperature.

  The time measuring circuit 8 includes a frequency dividing circuit 34 that divides the clock signal from the oscillation circuit 11, a time data generating circuit 32 that generates time data based on the divided clock, and a time that includes a register that holds the time data. And a data storage circuit 33. The clock circuit 8 divides and counts the 32.768 KHz clock signal from the oscillation circuit 11 to generate time data of year, month, day, hour, minute, and second.

  The real-time clock device 1 includes a first power supply terminal 23 connected to a main power supply 22 via a power switch 21 of an electronic device, and a second power supply terminal 25 connected to an auxiliary power supply 24 made of, for example, a secondary battery. I have.

  The real-time clock device 1 operates by supplying power from the main power supply 22 to each unit during normal operation when the power switch 21 is turned on, and from the auxiliary power supply 24 to each unit during backup operation when the power switch 21 is turned off. Operates with power supplied.

In this embodiment, a switching circuit 26 that is controlled to be switched by the control circuit 6 is provided. The switching circuit 26 includes a first individual contact 26 ₁ connected to the first power supply terminal 23, a second individual contact 26 ₂ connected to the second voltage detection circuit 4, and a charging circuit 27 including a resistor. It is connected to the second power supply terminal 25, first, a common contact 26 ₃ connected to the third voltage detecting circuit 3 and 5.

The switching circuit 26 is controlled to be switched by the control circuit 6 as described above, and in the normal operation when the power switch 21 is turned on, the common contact 26 ₃ is connected to the first individual contact 26 ₁ side and the main power supply 22 is connected. The auxiliary power supply 24 is charged via the charging circuit 27, while the main power supply 22 is connected to the first and third voltage detection circuits 3 and 5. The switching circuit 26 connects the common contact 26 ₃ to the second individual contact 26 ₂ side and connects the auxiliary power supply 24 to the second voltage detection circuit 4 during the backup operation when the power switch 21 is turned off. At this time, the auxiliary power supply 24 is also connected to the first and third voltage detection circuits 3 and 5.

  The first to third voltage detection circuits 3 to 5 detect a decrease in power supply voltage supplied from the main power supply 22 or the auxiliary power supply 24.

  The first voltage detection circuit 3 detects that the supplied power supply voltage is equal to or lower than the backup voltage VBAK that needs to be backed up by the auxiliary power supply 24, and provides a detection output to the control circuit 6. Based on the detection output of the first voltage detection circuit 3, the control circuit 6 supplies the voltage supplied to each part from the main power supply 21 when the power supply voltage becomes equal to or lower than the backup voltage VBAK that requires backup by the auxiliary power supply 24. Switch to power supply 24.

  In this embodiment, the auxiliary power supply 24 uses a secondary battery and does not always supply the necessary voltage. In secondary batteries, voltage drops can occur due to the number of charges and the amount of discharge, and in applications where high reliability is required, stopping temperature compensation due to voltage drop during backup affects the reliability of time data. give.

  The second voltage detection circuit 4 detects that the supplied power supply voltage is lower than the second threshold voltage VTL, which is the lowest voltage at which the temperature compensation circuit 12 can operate normally, and outputs the detection output to the control circuit 6. give. The second threshold voltage VTL is a voltage lower than the backup voltage VBAK.

  The third voltage detection circuit 5 detects that the supplied power supply voltage is equal to or lower than the first threshold voltage VOSC, which is a voltage that causes a complete malfunction due to the oscillation of the oscillation circuit 11 being stopped, and outputs a detection output. This is given to the control circuit 6. The first threshold voltage VOSC that falls into this malfunction is a voltage lower than the second threshold voltage VTL at which the temperature compensation circuit 12 can operate normally.

  In the normal operation in which the power switch 21 is turned on and power is supplied from the main power supply 22, the control circuit 6 determines that the power supply voltage is less than the backup voltage VBAK based on the detection output of the first voltage detection circuit 3. Assuming that the switch 21 is turned off, the switching circuit 26 is switched to switch from the main power supply 22 to the auxiliary power supply 24, and the operation proceeds to the backup operation.

  During this backup operation, when the second voltage detection circuit 4 detects that the power supply voltage is lower than the second threshold voltage VTL, which is the lowest voltage at which the temperature compensation circuit 12 can operate normally, the control circuit 6 In this case, the operation of the variable capacitance circuit 20 is stopped and the capacitance of the variable capacitance array 16 is not changed, but the capacitance is maintained as it is, and the temperature compensation operation is substantially stopped. When the power supply voltage becomes equal to or higher than the second threshold voltage VTL, which is the lowest voltage at which the temperature compensation circuit 12 can operate normally, the control circuit 6 restarts the temperature compensation operation by the temperature compensation circuit 12.

  The temperature compensation operation by the temperature compensation circuit 12 is stopped not only when the power supply voltage is lowered but also when the temperature detected by the temperature sensor 17 is outside the temperature compensation range.

  In the control circuit 6, during the backup operation, the third detection circuit 5 detects that the power supply voltage is higher than the first threshold voltage VOSC, which is a voltage that causes the oscillation of the oscillation circuit 11 to stop and causes complete malfunction. When the second voltage detection circuit 4 detects a low voltage state in which the power supply voltage is lower than the second threshold voltage VTL, which is the lowest voltage at which the temperature compensation circuit 12 can operate normally, during that period, the low voltage The number of occurrences and the low voltage period are measured and held in the corresponding register of the register group 7.

  That is, the register group 7 includes a low voltage count register 28 that holds the number of periods in which the low voltage has occurred when a low voltage period occurs, and the latest low voltage period register in which the low voltage period has occurred a plurality of times. A low voltage period register 29 for holding a voltage period, and a cumulative low voltage period register 30 for holding a cumulative low voltage period obtained by accumulating the plurality of low voltage periods are provided.

  The low voltage period is a period during which the power supply voltage is higher than the first threshold voltage VOSC, which is a voltage at which the oscillation of the oscillation circuit 11 stops and completely fails, and the temperature compensation circuit 12 can operate normally. This is a period in which the voltage is less than the second threshold voltage VTL, that is, a period in which temperature compensation is not normally performed.

  In the period when the temperature compensation is not normally performed, the oscillation circuit 11 continues the oscillation operation and the temperature compensation circuit 12 stops operating, but the time data is a real time clock having no temperature compensation function. It is as good as the accuracy of the device.

  The values in the registers 28 to 30 indicate the number of periods in which the temperature compensation is not normally performed and the time length of the period, and indicate how much the normal temperature compensation has not been performed. . Therefore, it is possible to take appropriate measures according to the extent to which normal temperature compensation has not been performed based on the values of these registers 28-30. For example, when the time during which normal temperature compensation has not been performed is relatively short and no temperature change has occurred, the reliability of time data is high, so without inadvertently stopping the temperature compensation operation, While the time measurement can be continued, if the time when normal temperature compensation has not been performed is relatively long and the number of times is high, the time data is not reliable, and the time is reset. Is possible.

The low voltage frequency register 28 is preferably a register of 4 bits or more. When the supplied power supply voltage becomes lower than the second threshold voltage VTL, the low voltage frequency register 28 stores the number of low voltage occurrences by adding 1 bit. . The number of times that data can be stored is 2 ⁴ = 16 times when the low voltage number register 28 is formed of a 4-bit register.

The low voltage period register 29 is preferably a register of 6 bits or more, and at the same time when the supplied power supply voltage becomes lower than the second threshold voltage VTL, it is reset and added 1 bit every second, and the supplied power supply is supplied. When the voltage returns to the second threshold voltage VTL or higher, the addition operation is stopped. Since the low voltage period register 29 starts counting after being reset to “0” before counting, it always stores the latest low voltage period. The time that can be stored is 2 ⁶ = 64 seconds when configured with 6 bits.

The cumulative low voltage period register 30 is preferably a register of 16 bits or more. At the same time when the supplied power supply voltage becomes less than the second threshold voltage VTL, 1 bit is added every second, and the supply voltage is When returning to the threshold voltage VTL or higher, the addition operation is stopped. The cumulative low voltage period that can be stored is 2 ¹⁶ = 65536 seconds (18.2 hours) when the cumulative low voltage period register 29 is composed of 16 bits.

  The control circuit 6 that constitutes the detection means together with each of the voltage detection circuits 3 to 5 has a low voltage state in which the supplied power supply voltage is lower than the second threshold voltage VTL during the period when the supplied power supply voltage exceeds the first threshold voltage VOSC. The number of occurrences is stored in the low voltage number register 28, and when a plurality of low voltage periods occur, the latest low voltage period is stored in the low voltage period register 29, and the plurality of low voltage periods are stored in the low voltage period register 29. When it occurs, the accumulated low voltage period obtained by accumulating the plurality of low voltage periods is stored in the accumulated low voltage period register 30.

  When the third voltage detection circuit 5 causes the power supply voltage to become lower than the voltage VOSC that causes the oscillation of the oscillation circuit 11 to stop and causes a complete malfunction, the control circuit 6 displays a power-on reset flag. 7 in the power-on reset register 31 of FIG.

  2 is a time chart for explaining the operation of the real-time clock device shown in FIG. 1. FIG. 2A shows a change in power supply voltage, FIG. 2B shows a power-on reset flag, and FIG. ) Shows the power-on reset signal, FIG. 6D shows the number of times of low voltage stored in the low voltage number register 28, and FIG. 5E shows the low voltage period stored in the low voltage period register 29. FIG. 5F shows the accumulated low voltage period stored in the accumulated low voltage period register 30. In FIG. 2A, ON1 to ON6 and OFF1 to OFF5 respectively indicate the time point when the power switch 21 is turned on (on) and the time point when the power switch 21 is turned off (off).

  First, at the first on time (ON1), which is the time when the power switch 21 is first turned on, the ground (which is lower than the first threshold voltage VOSC, which is a voltage at which the oscillation of the oscillation circuit 11 stops and completely malfunctions) ( Since the power supply voltage rises from GND), the power-on reset flag is reset as shown in FIG. 5B, and a power-on reset is applied as shown in FIG. As a result, as shown in FIGS. 5D to 5F, all the registers including the registers 29 to 31 are initialized and the time data is also initialized by the microcomputer 35 of the user or the electronic device. The time is set.

  When the electronic device that receives the time data from the real-time clock device 1 includes time information acquisition means 37 such as a GPS or a radio clock as shown in FIG. 3, the microcomputer 35 of the electronic device The standard time data is acquired by activating the GPS or the radio timepiece that constitutes the time information acquisition means 37, and the time data of the real-time clock device 1 is automatically set based on the acquired standard time data. If the time information acquisition means 37 is not provided, the user operates the input device 36 to set the time in accordance with a blinking lamp (not shown) or a message prompting the setting of the time displayed on the display device 38. I do.

  Referring to FIG. 2 again, when the power switch 21 is turned off, the power supply voltage decreases from the first OFF time point (OFF1), and when the backup voltage VBAK becomes lower than the backup voltage VBAK, the main power supply 22 supplies power to each part. The power supply 24 is switched to make a backup operation.

  After the first off time (OFF1), the power supply switch 21 is turned on without the power supply voltage from the auxiliary power supply 24 becoming lower than the second threshold voltage VTL that is the lowest voltage at which the temperature compensation circuit 12 can operate normally. Then, from the second on time (ON2), the power source is switched from the auxiliary power source 24 to the main power source 22 to shift to the normal operation.

  During the period from the first off time (OFF1) when the power switch 21 is turned off to the second on time (ON2) when the power switch 21 is turned on, the power supply voltage from the auxiliary power supply 24 becomes less than the second threshold voltage VTL. Therefore, the temperature compensation circuit 12 can continue normal temperature compensation operation.

  Further, after the second on time (ON2) when the power switch 21 is turned on, the microcomputer 35 of the electronic device refers to the number “0” of the low voltage stored in the low voltage number register 28. It can be recognized that there is no problem due to a decrease in power supply voltage.

  As described above, the usage period of the electronic device elapses. Next, when the power switch 21 is turned off, the power supply voltage decreases from the second off time (OFF2), and when the backup voltage VBAK or lower is reached, the main power supply 22 is switched to the auxiliary power supply 24 and a backup operation is performed.

  During this backup operation, when the power supply voltage from the auxiliary power supply 24 decreases and becomes a low voltage lower than the second threshold voltage VTL, which is the lowest voltage at which the temperature compensation circuit 12 can operate normally, the voltage becomes low at that time. The number of times “1” is counted and stored in the low voltage number register 28 as shown in FIG. 4D, and the low voltage period register 29 is stored in the low voltage period register 29 as shown in FIG. While resetting to “0” and starting the counting operation every second to measure the latest low voltage time, the cumulative low voltage period register 30 is reset to “0” as shown in FIG. Instead, the counting operation every second is started to measure the accumulated low voltage time.

  The low voltage period stored in the low voltage period register 29 is reset to “0” every time the low voltage is reached and is measured in units of 1 second. The low voltage period is measured and held. On the other hand, the accumulated low voltage period stored in the accumulated low voltage register 30 accumulates (accumulates) the previous low voltage period, and does not reset to “0” even when the voltage becomes low. Measure and accumulate low voltage periods in 1 second increments.

  When the power switch 21 is turned on, the power source is switched from the auxiliary power source 24 to the main power source 22 from the third ON time point (ON3) to shift to the normal operation, the power source voltage rises, and the second threshold voltage VTL or higher. At that time, the low voltage period register 29 and the cumulative low voltage register 30 stop the count operation and hold the measured low voltage period and cumulative low voltage period, that is, the low voltage period and cumulative low voltage period are Stored. Since this low voltage period is the first time, the low voltage period stored in the low voltage period register 29 and the cumulative low voltage period stored in the cumulative low voltage period register 30 are the same.

  After the third on time (ON3) when the power switch 21 is turned on, the microcomputer 35 of the electronic device refers to the power supply voltage by referring to the number of times “1” stored in the low voltage number register 28. It is possible to recognize that the temperature compensation operation has stopped once due to a decrease in the temperature. Therefore, the microcomputer can recognize the low voltage period, that is, the period during which the temperature compensation operation is stopped by referring to the values of the low voltage period register 29 and the cumulative low voltage period register 30.

  For the microcomputer 35 of the electronic device, the user operates the input device 36 in advance for setting values serving as a criterion for determining whether to prompt the user to reset the time or to use the time data of the real-time clock device 1. To set.

  That is, the period held in the low voltage period register 29 and the cumulative low voltage period register 30 is a period in which the temperature compensation operation is not normally performed and the actual temperature change is not followed. When the period is short and the temperature fluctuation is small, the user sets in advance a period in which the time difference can be assumed to be within the standard as a setting value serving as a reference for the determination.

  With this setting, the user can determine whether to reset the time or to continue using the time data of the real-time clock device 1 without resetting the time. .

  The microcomputer 35 of the electronic device makes a determination by comparing the values of the registers 28 to 30 with the set values set in advance by the user. In this example, at the third ON time point (ON3), the values of the registers 28 to 30 do not reach the set values, so that the operation of the real-time clock device 1 is continued without doing anything.

  Next, when the power switch 21 is turned off, the power supply voltage decreases from the third OFF time point (OFF3). When the power switch 21 becomes lower than the backup voltage VBAK, the power supply is switched from the main power supply 22 to the auxiliary power supply 24 to shift to the backup operation. .

  During this backup operation, when the power supply voltage from the auxiliary power supply 24 decreases and becomes a low voltage lower than the second threshold voltage VTL, which is the lowest voltage at which the temperature compensation circuit 12 can operate normally, the low voltage count register 28 “2”, which is the number of times that 1 is added and becomes a low voltage, is stored as shown in FIG. At the same time, as shown in FIG. 5E, the low voltage period register 29 resets to “0” and starts a count operation every second to measure the latest low voltage time, while the accumulated low voltage period As shown in FIG. 5F, the register 30 starts the count operation every second without resetting to “0” and measures the accumulated low voltage time.

  Next, when the power switch 21 is turned on, the power source is switched from the auxiliary power source 24 to the main power source 22 from the fourth ON point (ON4), and the power source voltage is increased, and the second threshold voltage is increased. When the voltage becomes VTL or higher, the low voltage period register 29 and the cumulative low voltage register 30 stop the count operation and hold the measured low voltage period and cumulative low voltage period.

  After the fourth on time (ON4) when the power switch 21 is turned on, the microcomputer 35 of the electronic device refers to the power supply voltage by referring to the number “2” of the low voltage stored in the low voltage number register 28. It can be recognized that the temperature compensation operation has stopped twice due to a decrease in the temperature. Further, the microcomputer 35 can recognize the period in which the temperature compensation operation is stopped by referring to the values of the low voltage period register 29 and the cumulative low voltage period register 30.

  In this example, since the values of the low voltage period register 29 and the accumulated low voltage period register 30 have not reached the set values at the fourth on time (ON4), the operation of the real time clock device 1 is performed without any particular action. Let it continue.

  Next, when the power switch 21 is turned off, the power supply voltage decreases from the fourth OFF time point (OFF4), and when the backup voltage VBAK or lower is reached, the power supply is switched from the main power supply 22 to the auxiliary power supply 24 to shift to the backup operation. To do.

  During this backup operation, when the power supply voltage from the auxiliary power supply 24 decreases and becomes a low voltage lower than the second threshold voltage VTL, which is the lowest voltage at which the temperature compensation circuit 12 can operate normally, the low voltage count register 28 “3”, which is the number of times 1 is added and the voltage becomes low, is stored as shown in FIG. At the same time, as shown in FIG. 5E, the low voltage period register 29 resets to “0” and starts a count operation every second to measure the latest low voltage time, while the accumulated low voltage period As shown in FIG. 5F, the register 30 starts the count operation every second without resetting to “0” and measures the accumulated low voltage time.

  Next, when the power switch 21 is turned on, the power source is switched from the auxiliary power source 24 to the main power source 22 from the fifth ON time point (ON5) to shift to the normal operation, the power source voltage rises, and the second threshold voltage When the voltage becomes VTL or higher, the low voltage period register 29 and the cumulative low voltage register 30 stop the count operation and hold the measured low voltage period and cumulative low voltage period.

  After the fifth on time (ON5) when the power switch 21 is turned on, the microcomputer 35 of the electronic device refers to the power supply voltage by referring to the number of times “3” stored in the low voltage number register 28. It can be recognized that the temperature compensation operation has been stopped three times. Further, the microcomputer 35 can recognize the period in which the temperature compensation operation is stopped by referring to the values of the low voltage period register 29 and the cumulative low voltage period register 30.

  At the fifth ON point (ON5) when the power switch 21 is turned on, the number of times of low voltage by the low voltage number register 28 is 3, and the auxiliary power source 24 tends to discharge in a short time. When the charging time from the ON point (ON4) to the fourth OFF point (OFF4) is examined, and the second threshold voltage VTL or lower occurs despite the sufficient charging time, the secondary of the auxiliary power source 4 For example, a message for prompting battery replacement is displayed on the display device 38 of the electronic device. Since this is the third time, a strong message such as replacement is immediately displayed on the display device 38.

  At this time, a lamp (not shown) may be blinked. In the case of an electronic device that is connected to the management center via a communication network, measures such as sending a notification for urging maintenance and inspection are taken.

  Further, at the fifth on time (ON5) when the power switch 21 is turned on, the values of the low voltage period register 29 and the cumulative low voltage period register 30 reach the respective set values. The acquisition unit 37 acquires the standard time and automatically resets the time.

  Next, when the power switch 21 is turned off, the power supply voltage decreases from the fifth OFF time point (OFF5), and when it becomes lower than the backup voltage VBAK, the power supply is switched from the main power supply 22 to the auxiliary power supply 24 to shift to the backup operation. To do.

  During this backup operation, when the power supply voltage from the auxiliary power supply 24 decreases and becomes a low voltage lower than the second threshold voltage VTL, which is the lowest voltage at which the temperature compensation circuit 12 can operate normally, the low voltage count register 28 “4”, which is the number of times when 1 is added and the voltage becomes low, is stored as shown in FIG. At the same time, as shown in FIG. 5E, the low voltage period register 29 resets to “0” and starts a count operation every second to measure the latest low voltage time, while the accumulated low voltage period As shown in FIG. 5F, the register 30 starts the count operation every second without resetting to “0” and measures the accumulated low voltage time.

  In this example, since the above-described battery replacement or the like has not been performed, the power supply voltage is further lowered, and the first threshold voltage VOSC, which is a voltage at which the oscillation of the oscillation circuit 11 stops and completely malfunctions, is reduced. The power-on flag is set as shown in FIG. This flag is composed of a non-volatile memory that does not disappear even if the power is cut off. Further, when the power supply voltage becomes equal to or lower than the first threshold voltage VOSC, which is a voltage that causes a complete malfunction due to the oscillation of the oscillation circuit 11 being stopped, the measurement of the low voltage period is stopped.

  Next, when the power switch 21 is turned on (ON6), the power supply voltage rises from the ground (GND) lower than the first threshold voltage VOSC, which is a voltage at which the oscillation of the oscillation circuit 11 stops and completely fails. As shown in FIG. 6B, a power-on reset flag is set, and a power-on reset is applied as shown in FIG. As a result, as shown in FIGS. 5D to 5F, all the registers 29 to 31 are initialized, the time data is also initialized, and the time is set.

  Since the power-on reset flag is set at the sixth on-point (ON6) when the power switch 21 is turned on, the electronic device microcomputer 35 has stopped operating the real-time clock device 1 during the power-off period. I understand. The real-time clock device 1 automatically performs a time resetting operation. Immediately, a power-on reset operation is performed to set all register values to “0” or an initial value, and then a time reset operation is performed. Thereafter, the electronic device enters a normal operation state.

  As described above, in the present embodiment, the state of low voltage generation at the end of backup when the power switch 21 is turned on based on the number of times of low voltage generated at the time of backup of the auxiliary power supply 24, the low voltage period, and the cumulative low voltage period. In other words, depending on the degree to which normal temperature compensation has not been performed, appropriate measures such as whether to continue the timekeeping operation, prompt battery replacement, or reset the time data are taken. be able to.

  Therefore, for example, when the time during which normal temperature compensation has not been performed is relatively short and no temperature change has occurred, the accuracy equivalent to that of a real-time clock device without a temperature compensation function is ensured. Since the reliability is high, the time measurement can be continued without inadvertently stopping the temperature compensation operation. As a result, the number and time of resetting the time can be reduced.

  Conversely, if the time when normal temperature compensation has not been performed is relatively long and the number of times is high, the timekeeping reliability is low, so reset the time or reset the time to the user. The electronic device can be operated in a normal state by resetting accurate time data.

(Other embodiments)
(1) Although the above embodiment has been described by applying to the real-time clock device 1, it can also be applied to a temperature compensated oscillation circuit as shown in FIG.

That is, FIG. 4 is a block diagram of a temperature-compensated oscillator circuit 2 ₁ according to an embodiment of the present invention, portions corresponding to FIG. 1, the same reference characters.

The temperature compensated oscillator circuit 2 ₁ is provided with a oscillator circuit 11 and the temperature compensation circuit 12, switching circuit 26, first to third voltage detection circuit 3-5, a control circuit 6 ₁ and the register group 7 Yes.

In the temperature compensated oscillator circuit 2 _1, as in the above embodiment, the number of low voltage, the period of low voltage, and, the duration of accumulation of low voltage, is stored in each register 28-30.

  (2) As an electronic device on which the real-time clock device of the present invention is mounted, for example, a mobile phone that operates by a timer such as an answering machine, a recording / playback device, and the like are suitable, and low power consumption is preferable. Desirably, the time error becomes an error in billing, so the electricity meter with communication function that is strictly managed, or the weather and ground data are automatically collected at regular time intervals in the mountainous area where people can not reach A device for transmitting data is suitable.

  (3) In the above embodiment, both the number of times of low voltage and the period of low voltage are detected and stored, but either one may be detected and stored. Further, although both the latest low voltage period and the accumulated low voltage period are detected and stored, either one may be detected and stored.

  (4) The number of detected low voltages and / or the low voltage period may be notified to the user by a notification means such as a display device.

1 Real-time clock device 2, 2 ₁ Temperature compensated oscillation circuit 3 First voltage detection circuit 4 Second voltage detection circuit 5 Third voltage detection circuit 6, 6 ₁ Fourth voltage detection circuit 7 Register group 8 Clock circuit 11 Oscillation circuit 12 Temperature compensation circuit 21 Power switch 22 Main power supply 24 Auxiliary power supply 28 Low voltage frequency register 29 Low voltage period register 30 Cumulative low voltage period register

Claims (12)

A temperature-compensated oscillation circuit that operates with a supplied power supply voltage and adjusts the oscillation frequency of the oscillation circuit based on the temperature detected by the temperature sensor,
In the period when the power supply voltage is higher than the first threshold voltage at which the oscillation operation of the temperature compensated oscillation circuit stops, the number of times the power supply voltage becomes a low voltage lower than the second threshold voltage and / or the low voltage period Detecting means for detecting
Storage means for storing the number of times of the low voltage detected by the detection means and / or a period of the low voltage,
The second threshold voltage is a voltage necessary for the temperature compensated oscillation circuit to perform a normal temperature compensation operation.
A temperature compensated oscillation circuit characterized by the above. The detection means may be a cumulative low voltage period obtained by accumulating a plurality of low voltage periods and / or a latest low voltage period among the plurality of low voltage periods as the low voltage period. Detect
The storage means stores the cumulative low voltage period detected by the detection means and / or the latest low voltage period as the low voltage period.
The temperature compensated oscillation circuit according to claim 1. The power supply voltage is a power supply voltage supplied from an auxiliary power supply to the temperature compensated oscillation circuit.
The temperature compensated oscillation circuit according to claim 1 or 2. During the low voltage period, the temperature compensation operation is stopped.
The temperature compensated oscillation circuit according to any one of claims 1 to 3. The storage means comprises a register;
The temperature compensated oscillation circuit according to any one of claims 1 to 4. A real-time clock device that operates according to a supplied power supply voltage,
A temperature compensated oscillation circuit that adjusts the oscillation frequency of the oscillation circuit based on the temperature detected by the temperature sensor; and
Based on a clock signal output from the temperature compensated oscillation circuit, a clock circuit that generates time data,
In the period when the power supply voltage is higher than the first threshold voltage at which the oscillation operation of the temperature compensated oscillation circuit stops, the number of times the power supply voltage becomes a low voltage lower than the second threshold voltage and / or the period of the low voltage. Detecting means for detecting
Storage means for storing the number of times of the low voltage detected by the detection means and / or a period of the low voltage,
The second threshold voltage is a voltage necessary for the temperature compensated oscillation circuit to perform a normal temperature compensation operation.
A real-time clock device. The detection means may be a cumulative low voltage period obtained by accumulating a plurality of low voltage periods and / or a latest low voltage period among the plurality of low voltage periods as the low voltage period. Detect
The storage means stores the cumulative low voltage period detected by the detection means and / or the latest low voltage period as the low voltage period.
The real-time clock device according to claim 6. The power supply voltage is a power supply voltage supplied from an auxiliary power supply to the real-time clock device.
The real-time clock device according to claim 6 or 7. In the period of the low voltage, the temperature compensation operation of the temperature compensated oscillation circuit is stopped.
The real-time clock device according to any one of claims 6 to 8. The storage means comprises a register;
The real-time clock device according to claim 6. An electronic device comprising the real-time clock device according to any one of claims 6 to 10,
A determination unit that determines whether or not it is necessary to set a time for the real-time clock device based on the number of times of the low voltage stored in the storage unit and / or the period of the low voltage.
An electronic device characterized by that. When it is determined by the determination means that time setting is necessary, a notification means for notifying that effect is provided.
The electronic device according to claim 11.

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