JP5636822B2 - Real-time clock module, electronic device and control method - Google Patents

Description

The present invention relates to a real-time clock module, an electronic device, and a control method for recording events.

Patent Document 1 discloses an electronic device having a real-time clock that is operated by a backup power source. This real-time clock has an oscillation circuit, an event detection circuit, and an event storage memory. This real-time clock can store events even when there is no voltage application from the main power supply due to voltage application from the backup power supply.

JP 2003-132470 A

In general, since an oscillation circuit consumes a relatively large amount of power, there is a limit to the time during which data stored in a memory can be maintained using only a backup power source even with the technique disclosed in Patent Document 1.
The present invention provides a technique for extending the time during which data stored in a memory can be maintained when a power supply voltage is lowered.

[Application Example 1] An oscillation circuit that generates a clock signal when a power supply voltage is applied, a timing circuit that outputs timing data based on the clock signal, an event detection circuit that detects an input of an event, the event, and the event A recording control circuit that records data associated with timing data in a memory based on a signal output from the event detection circuit, a first voltage detection circuit that monitors the power supply voltage, and a first control circuit that monitors the power supply voltage. A second voltage detection circuit, a first switch circuit for controlling the operation of the oscillation circuit to reduce power consumption of the oscillation circuit based on a signal output from the first voltage detection circuit, and the second voltage And a second switch circuit for controlling the operation of the event detection circuit based on a signal output from the detection circuit. Le.
Application Example 2 According to Application Example 1, in which the operation of the oscillation circuit is controlled to reduce the power consumption of the oscillation circuit, the stop of the oscillation circuit is controlled. Real-time clock module.
Application Example 3 The real-time clock module according to Application Example 1 or 2, wherein the first voltage detection circuit outputs a signal obtained by comparing a first threshold value and the power supply voltage.
Application Example 4 The first switch circuit controls the operation of the oscillation circuit based on a signal output from the first voltage detection circuit and a signal output from the event detection circuit. The real-time clock module according to any one of Application Examples 1 to 3.
Application Example 5 A delay circuit that outputs a signal to the first switch circuit based on a signal output from the first voltage detection circuit is provided, and the first switch circuit is output from the delay circuit. The real-time clock module according to any one of application examples 1 to 4, wherein the operation of the oscillation circuit is controlled so as to reduce power consumption of the oscillation circuit based on a signal.
Application Example 6 The recording control circuit outputs a signal to the first switch circuit based on the signal output from the first voltage detection circuit, and the first switch circuit outputs the signal from the recording control circuit. 6. The real-time clock module according to claim 1, wherein the operation of the oscillation circuit is controlled so as to reduce power consumption of the oscillation circuit based on the received signal.
Application Example 7 An electronic device having the real-time clock module according to any one of Application Examples 1 to 6.
Application Example 8 The step in which the oscillation circuit generates a clock signal when a power supply voltage is applied, the step in which the timing circuit outputs timing data based on the clock signal, and the first voltage detection circuit includes the power supply A step of outputting a signal detecting that the voltage has become equal to or lower than a first threshold to the first switch circuit; a step of causing the first switch circuit to stop the operation of the oscillation circuit; and an event detection circuit. Outputting a signal detecting the detected event to the storage control circuit, causing the storage control circuit to record data associating the event with the timing data, and a second voltage detection circuit including the power supply Outputting to the second switch circuit a signal detected that the voltage has become equal to or lower than a second threshold lower than the first threshold; and the second switch Road is, a control method and a step of stopping the operation of said event detection circuit.
The present invention relates to an oscillation circuit that generates a clock signal in response to application of a power supply voltage from the outside, a clock circuit that outputs clock data based on the clock signal, and the power supply voltage is equal to or lower than a first threshold value. A first voltage detection circuit for detecting, a recording control circuit for associating an input event with the time-measured data and recording the data in a memory for holding data based on the power supply voltage; and the power supply voltage is less than or equal to the first threshold value A real-time clock module is provided that includes a first switch circuit that stops the operation of the oscillation circuit when it is detected.
According to this real-time clock module, it is possible to extend the time during which the data stored in the memory can be maintained, as compared with the case where the operation of the oscillation circuit is not stopped when the power supply voltage falls below the first threshold value. it can.

In a preferred aspect, the real-time clock module includes a second voltage detection circuit that detects that the power supply voltage is equal to or lower than a second threshold value that is lower than the first threshold value, and an event that detects that the event is input. A detection circuit and a second switch circuit that stops the operation of the event detection circuit when it is detected that the power supply voltage is equal to or lower than the second threshold value may be included.
According to the real-time clock module, even when the power supply voltage becomes equal to or lower than the first threshold value, the event can be detected when the event occurs.

In another preferable aspect, after the first switch circuit stops the operation of the oscillation circuit, when the event is input when the power supply voltage is higher than the second threshold, the event is recorded. The operation of the oscillation circuit may be resumed for a period of time recorded in the memory by the control circuit.
According to the real-time clock module, even when the power supply voltage becomes equal to or lower than the first threshold value, the event can be recorded when the event occurs.

In still another preferred embodiment, the real-time clock module includes a delay circuit that instructs the first switch circuit after waiting for a predetermined time when it is detected that the power supply voltage is equal to or lower than the first threshold value. The first switch circuit may stop the operation of the oscillation circuit in response to an instruction from the delay circuit.
According to this real-time clock module, the data transfer time can be secured.

In still another preferred aspect, the recording control circuit sends a signal indicating whether or not a recording operation is being performed to the first switch circuit when it is detected that the power supply voltage is equal to or lower than the first threshold value. The first switch circuit may stop the operation of the oscillation circuit when the signal from the recording control circuit indicates that the recording operation is not being performed.
According to this real-time clock module, the data transfer time can be secured.

The present invention also provides an electronic device having any one of the above real-time clock modules.
According to this electronic apparatus, it is possible to extend the time during which the data stored in the memory can be maintained as compared with the case where the operation of the oscillation circuit is not stopped when the power supply voltage becomes equal to or lower than the first threshold value. .

Further, according to the present invention, an oscillation circuit receives a power supply voltage from the outside to generate a clock signal, a timekeeping circuit outputs timekeeping data based on the clock signal, and the power supply voltage A step in which the first voltage detection circuit detects that the threshold voltage is less than or equal to one threshold, and a recording control circuit associates the input event with the time measurement data and records the event in a memory holding data based on the power supply voltage And the power supply voltage is the first
And a step of causing the first switch circuit to stop the operation of the oscillation circuit when it is detected that the threshold value is below the threshold value.
According to this control method, compared with the case where the operation of the oscillation circuit is not stopped when the power supply voltage becomes equal to or lower than the first threshold value, the time during which the data stored in the memory can be maintained can be made longer. .

1 is a block diagram illustrating a configuration of an RTC module 10 according to a first embodiment. 4 is a flowchart showing an operation of the RTC module 10. It is a block diagram which shows the structure of the RTC module 20 which concerns on 2nd Embodiment. 3 is a flowchart showing the operation of the RTC module 20. It is a block diagram which shows the structure of the RTC module 30 which concerns on a modification. 3 is a flowchart showing the operation of the RTC module 30. 1 is a block diagram showing a configuration of an electronic device 100. FIG.

1. First Embodiment FIG. 1 is a block diagram showing a configuration of an RTC (Real Time Clock) module 10 according to a first embodiment. The RTC module 10 includes an oscillation circuit 11, a frequency dividing circuit 12, a recording control circuit 13, an event detection circuit 14, a delay circuit 15, a time measuring circuit 16,
A memory 17, a switch circuit 18, and a voltage monitoring circuit 19 are included. The RTC module 10 operates with a power supply voltage supplied from the main power supply Vmain. The operation of the RTC module 10 with the power supply voltage supplied from the main power supply Vmain is referred to as “normal operation”. When the application of the power supply voltage from the main power supply Vmain is stopped, the RTC module 10 operates with the power supply voltage supplied from the backup power supply Vbak. The backup power source Vbak is a battery, for example. The operation of the RTC module 10 by the power supply voltage supplied from the backup power supply Vbak is referred to as “backup operation”.

The oscillation circuit 11 is a circuit that generates a clock signal having a predetermined frequency in response to application of a power supply voltage, for example, a crystal oscillation circuit. The frequency dividing circuit 12 is a circuit that divides the frequency of the clock signal generated by the oscillation circuit 11 into 1 / n. The frequency dividing circuit 12 outputs the frequency-divided signal as an operation clock to the recording control circuit 13, the delay circuit 15, and the time measuring circuit 16. The clock circuit 16 measures time using the operation clock, and counts time data (for example, the last two digits of the year, month,
Data indicating the day, day of the week, hour, minute, and second). The event detection circuit 14 detects that an event (event signal notifying that an event has occurred) is input from the outside. In this example, when an event is input from the outside, the event detection circuit 14 outputs an event detection signal indicating that the event has been detected. In this example, the event detection signal is a pulse signal that is at a High (H) level for a predetermined number of clocks. The recording control circuit 13 writes data in the memory 17 when the event detection signal is input. The data written at this time includes, for example, flag data indicating that an event has been detected, and time measurement data indicating the time at which the event has been detected. The memory 17 is a volatile storage device such as R
While it is an AM (Random Access Memory) and the power supply voltage is applied, the recording control circuit 1
The data written by 3 is held.

The voltage monitoring circuit 19 (an example of a first voltage detection circuit) is a circuit that monitors a power supply voltage and includes a comparator. The voltage monitoring circuit 19 includes a power supply voltage and a predetermined reference voltage Vth1 (
An example of the first threshold value is input. The voltage monitoring circuit 19 includes a power supply voltage and a reference voltage Vth1
The voltage monitoring signal is output according to In this example, the voltage monitoring signal has a power supply voltage of the reference voltage Vt.
The signal is H level when it is lower than h1, and is Low (L) level when the power supply voltage is higher than the reference voltage Vth1. Here, the reference voltage Vth1 is stored in the memory 1
7 has a value higher than the lowest voltage capable of holding data.

The delay circuit 15 is a circuit for securing a data transfer time to the memory 17. An operation clock and a voltage monitoring signal are input to the delay circuit 15. The delay circuit 15 outputs a control signal that instructs the switch circuit 18 to turn on or off the power supply voltage in accordance with the operation clock and the voltage monitoring signal. In this example, the control signal is a normally H signal. When an H level voltage monitoring signal is input, that is, when a signal indicating that the power supply voltage is lower than the reference voltage Vth1 is input, a predetermined signal is input. After waiting for the count number, it becomes L level. The number of counts is a number corresponding to a time longer than the time required to write data related to one event in the memory 17. The delay circuit 15 has a counter. When an H level voltage monitoring signal is input, the delay circuit 15 initializes the counter and changes the value of the counter by one unit in synchronization with the operation clock. When the counter value reaches the threshold value, the control signal output from the delay circuit 15 becomes L level.

The switch circuit 18 (an example of a first switch circuit) is a circuit that starts or stops the application of the power supply voltage to the oscillation circuit 11, the frequency divider circuit 12, the recording control circuit 13, the event detection circuit 14, and the delay circuit 15. . A power supply voltage, a voltage monitoring signal, and a control signal are input to the switch circuit 18. The switch circuit 18 starts or stops (on or off) the application of the power supply voltage in accordance with the voltage monitoring signal and the control signal. In this example, when an H level voltage monitoring signal and an L level control signal are input to the switch circuit 18, the oscillation circuit 11 and the frequency dividing circuit 12.
The power supply voltage is not applied to the recording control circuit 13, the event detection circuit 14, and the delay circuit 15. When the voltage monitoring signal is at the L level or when the control signal is at the H level, the switch circuit 18 supplies the power supply voltage to the oscillation circuit 11, the frequency dividing circuit 12, the recording control circuit 13, the event detection circuit 14, and the delay circuit 15. Is applied. That is, the switch circuit 18 has a power supply voltage of Vt
When it is detected that the frequency is equal to or lower than h1, the operation of the oscillation circuit 11 is stopped.

FIG. 2 is a flowchart showing the operation of the RTC module 10. The flow of FIG.
It is started when the RTC module 10 shifts from the normal operation to the backup operation.

In step S100, the voltage monitoring circuit 19 monitors the power supply voltage. That is, the voltage monitoring circuit 19 determines whether the power supply voltage has fallen below the reference voltage Vth1. When the power supply voltage falls below the reference voltage Vth1 (S100: YES), the voltage monitoring signal output from the voltage monitoring circuit 19 becomes H level. The process proceeds to step S104. When the power supply voltage is not lower than the reference voltage Vth1 (S100: NO), the voltage monitoring signal output from the voltage monitoring circuit 19 becomes L level. The process proceeds to step S101.

The processing in steps S101 to S103 includes the event detection circuit 14 and the recording control circuit 13.
The processes of steps S100 and S104-S111 by the delay circuit 15, the switch circuit 18, and the voltage monitoring circuit 19 are performed in parallel. At this time, the event detection circuit 14 is waiting for an event input (step S101). That is,
The event detection circuit 14 determines whether an event is input (step S102). When no event is input (S102: NO), the event detection circuit 14 stands by in a state waiting for event input. When an event is input (S102: YES), the event detection circuit 14 outputs an event detection signal. When the event detection signal is input, the recording control circuit 13 writes data in the memory 17. That is, the recording control circuit 13 transfers data to the memory 17 (step S103).

The processing in steps S104 to S111 is processing when the power supply voltage is lower than the reference voltage Vth1. When the H level signal is input from the voltage monitoring circuit 19, the delay circuit 15 starts counting (step S104). Steps S101-S as already explained
Since the process 103 is performed in parallel with the processes in steps S104 to S111, when the delay circuit 15 is counting and the recording control circuit 13 is in the middle of data transfer (S105: YES), the recording is performed. The control circuit 13 performs data transfer during this time (step S1).
06). When the counter value reaches a predetermined threshold, the delay circuit 15 finishes counting (
Step S107). When the count ends, the control signal output from the delay circuit 15 is L
Become a level. When an H level voltage monitoring signal and an L level control signal are input, the switch circuit 18 includes an oscillation circuit 11, a frequency dividing circuit 12, a recording control circuit 13, an event detection circuit 14,
And the application of the power supply voltage to the delay circuit 15 is stopped. That is, the switch circuit 18 switches off these circuits (step S108).

According to the RTC module 10, when the power supply voltage falls below the reference voltage Vth1, the oscillation circuit 1
The operation of 1 is stopped. Compared with the case where the operation of the oscillation circuit 11 is not stopped, the power consumption of the RTC module 10 is reduced. That is, the time that the memory 17 can hold data becomes longer.

The processing of steps S109 to S111 is processing until the operation is started again after the operation of the oscillation circuit 11 is stopped. In step S109, the oscillation circuit 11 and the frequency divider 12
The recording control circuit 13 and the event detection circuit 14 are in a stopped state, that is, in a waiting state for return. During this time, the voltage monitoring circuit 19 monitors the power supply voltage. That is, the voltage monitoring circuit 19 determines whether the power supply voltage has exceeded the reference voltage Vth1 (step S
110). While the power supply voltage is lower than the reference voltage Vth1 (S110: NO), the return waiting state is maintained. For example, when the main power supply starts, the power supply voltage increases. When the power supply voltage exceeds the reference voltage Vth1 (S110: YES), the voltage monitoring signal output from the voltage monitoring circuit 19 becomes L level. When an L-level voltage monitoring signal is input, the oscillation circuit 11, the frequency dividing circuit 12, the recording control circuit 13, the event detection circuit 14, and the delay circuit 15 are input.
Start application of power supply voltage to. That is, the switch circuit 18 switches on these circuits (step S111). When the supply of main power is started, the RTC module 10 shifts to normal operation hereinafter.

2. Second Embodiment FIG. 3 is a block diagram showing a configuration of an RTC module 20 according to a second embodiment. In the following description, common reference numerals are used for elements common to the first embodiment. RT
The C module 20 includes a voltage monitoring circuit 21 and a switch circuit 22 in addition to the configuration of the RTC module 10.

The voltage monitoring circuit 21 (an example of a second voltage detection circuit) is a circuit that monitors a power supply voltage and includes a comparator. The voltage monitoring circuit 21 includes a power supply voltage and a predetermined reference voltage Vth2 (
An example of a second threshold value is input. The voltage monitoring circuit 21 has a power supply voltage and a reference voltage Vth2
The voltage monitoring signal is output according to In this example, the voltage monitoring signal has a power supply voltage of the reference voltage Vt.
This signal is H level when it is lower than h2, and L level when the power supply voltage is higher than the reference voltage Vth2. Here, the reference voltage Vth2 is lower than the reference voltage Vth1 and higher than the lowest voltage at which the data stored in the memory 17 can be maintained.

The switch circuit 22 (an example of a second switch circuit) is a circuit that starts or stops the application of the power supply voltage to the event detection circuit 14. The switch circuit 22 receives a power supply voltage and a voltage monitoring signal from the voltage monitoring circuit 21. The switch circuit 22 starts or stops application of the power supply voltage according to the voltage monitoring signal. In this example, the switch circuit 22 does not apply a power supply voltage to the event detection circuit 14 when an H level voltage monitoring signal is input. When an L level voltage monitoring signal is input, the switch circuit 22 applies a power supply voltage to the event detection circuit 14. That is, the switch circuit 22 stops the operation of the event detection circuit 14 when it is detected that the power supply voltage is equal to or lower than Vth2.

In the RTC module 20, an event detection signal is input to the switch circuit 18 in addition to the power supply voltage, the control signal, and the voltage monitoring signal from the voltage monitoring circuit 19. The switch circuit 18 starts or stops the application of the power supply voltage according to the voltage monitoring signal, the control signal, and the event detection signal. In this example, when an H level voltage monitoring signal and an L level control signal are input to the switch circuit 18, the oscillation circuit 11, the frequency dividing circuit 12, and the recording control circuit 13 are input.
, And no power supply voltage is applied to the delay circuit 15. When an event detection signal is input in this state, the switch circuit 18 applies a power supply voltage to the oscillation circuit 11, the frequency dividing circuit 12, the recording control circuit 13, and the delay circuit 15. That is, the switch circuit 18 resumes the operation of the oscillation circuit 11. Thus, in the RTC module 20, the oscillation circuit 11 and the event detection circuit 14 are controlled to be turned on and off by the different switch circuits.

In the RTC module 20, the event detection signal is input to the delay circuit 15 in addition to the operation clock and the voltage monitoring signal. Similar to the operation for the voltage monitoring signal, the delay circuit 15 outputs a control signal instructing the switch circuit 18 to turn on or off the power supply voltage in accordance with the operation clock and the event detection signal. When the event detection signal is input, the control signal becomes L level after waiting for a predetermined count number.

FIG. 4 is a flowchart showing the operation of the RTC module 20. The flow of FIG.
It is started when the RTC module 10 shifts from the normal operation to the backup operation.

In step S200, the voltage monitoring circuit 19 monitors the power supply voltage. That is, the voltage monitoring circuit 19 determines whether the power supply voltage has fallen below the reference voltage Vth1. When the power supply voltage falls below the reference voltage Vth1 (S200: YES), the voltage monitoring signal output from the voltage monitoring circuit 19 becomes H level. The process proceeds to step S204. When the power supply voltage is not lower than the reference voltage Vth1 (S200: NO), the voltage monitoring signal output from the voltage monitoring circuit 19 becomes L level. The process proceeds to step S201.

The processing in steps S201 to S203 includes the event detection circuit 14 and the recording control circuit 13.
The processes of steps S200 and S204 to S208 by the delay circuit 15, the switch circuit 18, and the voltage monitoring circuit 19 are performed in parallel. At this time, the event detection circuit 14 is waiting for an event input (step S201). That is,
The event detection circuit 14 determines whether an event has been input (step S202). When no event is input (S202: NO), the event detection circuit 14 stands by in a state waiting for event input. When an event is input (S202: YES), the event detection circuit 14 outputs an event detection signal. When the event detection signal is input, the recording control circuit 13 writes data in the memory 17. That is, the recording control circuit 13 transfers data to the memory 17 (step S203).

The processing in steps S204 to S208 is processing when the power supply voltage is lower than the reference voltage Vth1. When the H level signal is input from the voltage monitoring circuit 19, the delay circuit 15 starts counting (step S204). Step S201-S as already explained
Since the processing of 203 is performed in parallel with the processing of steps S204 to S208, when the delay control circuit 15 is counting and the recording control circuit 13 is in the middle of data transfer (S205: YES), recording is performed. The control circuit 13 performs data transfer during this time (step S2
06). When the counter value reaches a predetermined threshold, the delay circuit 15 finishes counting (
Step S207). When the count ends, the control signal output from the delay circuit 15 is L
Become a level. When the H level voltage monitoring signal and the L level control signal are input, the switch circuit 18 stops applying the power supply voltage to the oscillation circuit 11, the frequency dividing circuit 12, the recording control circuit 13, and the delay circuit 15. . That is, the switch circuit 18 switches off these circuits (step S208).

In step S209, the voltage monitoring circuit 21 monitors the power supply voltage. That is, the voltage monitoring circuit 21 determines whether the power supply voltage has fallen below the reference voltage Vth2. When the power supply voltage falls below the reference voltage Vth2 (S209: YES), the voltage monitoring signal output from the voltage monitoring circuit 21 becomes H level. The process proceeds to step S217. When the power supply voltage is not lower than the reference voltage Vth2 (S209: NO), the voltage monitoring signal output from the voltage monitoring circuit 21 becomes L level. The process proceeds to step S210.

The processing in steps S210 to S216 is processing when the power supply voltage is lower than Vth1 and higher than Vth2. At this time, the power supply voltage is not supplied to the oscillation circuit 11, the frequency dividing circuit 12, the recording control circuit 13, and the delay circuit 15, but the power supply voltage is supplied to the event detection circuit 14. At this time, the event detection circuit 14 is waiting for an event input (step S210). That is, the event detection circuit 14 determines whether an event is input (step S211). When no event is input (S211: NO),
The event detection circuit 14 waits in an event input waiting state. When an event is input (S211: YES), the event detection circuit 14 outputs an event detection signal.

At this time, the voltage monitoring signal from the voltage monitoring circuit 19 is at the H level, and the control signal is at the L level. When an event detection signal is input in this state, the switch circuit 18 applies a power supply voltage to the oscillation circuit 11, the frequency dividing circuit 12, and the recording control circuit 13. That is, the switch circuit 18 switches on these circuits (step S212). At this time, since the power supply voltage is applied to the delay circuit 15, the control signal becomes the H level. Since an event detection signal is input to the delay circuit 15 in this state, the delay circuit 15 starts counting (step S214). Further, since the event detection signal is also input to the recording control circuit 13, the recording control circuit 13 transfers the data to the memory 17 (step S214). When the counter value reaches a predetermined threshold value, the delay circuit 15 finishes counting (step S215).
. When the counting ends, the delay circuit 15 outputs an L level control signal. At this time,
Since the voltage monitoring signal remains at the H level, when the L level control signal is input, the switch circuit 18 causes the power supply voltage to the oscillation circuit 11, the frequency dividing circuit 12, the recording control circuit 13, and the delay circuit 15. The application of is stopped. That is, the switch circuit 18 switches off these circuits (step S216).

In the RTC module 20, the oscillation circuit 11 and the event detection circuit 14 are independently controlled for power. Therefore, the event detection circuit 14 may be operating although the oscillation circuit 11 is stopped. In such a case, when an event is detected, the oscillation circuit 1
1 and the recording control circuit 13 are applied with power supply voltage, and data relating to the event is
7 is written.

When an H level voltage monitoring signal is input from the voltage monitoring circuit 21, the switch circuit 22
Application of the power supply voltage to the event detection circuit 14 is stopped (step S217). Step S
The processing in 218-S220 is processing until the operation is started again after the operations of the oscillation circuit 11 and the event detection circuit 14 are stopped. In step S218, the oscillation circuit 11
The frequency divider circuit 12, the recording control circuit 13, the event detection circuit 14, and the delay circuit 15 are in a stopped state, that is, in a return waiting state. During this time, the voltage monitoring circuit 19 and the voltage monitoring circuit 21 monitor the power supply voltage. For example, when the main power supply starts,
The power supply voltage rises. First, the voltage monitoring circuit 21 determines whether the power supply voltage exceeds the reference voltage Vth2. When the power supply voltage exceeds the reference voltage Vth2, the voltage monitoring signal output from the voltage monitoring circuit 21 becomes L level. When the L-level voltage monitoring signal is input, the switch circuit 22 starts applying the power supply voltage to the event detection circuit 14. The voltage monitoring circuit 1
9 determines whether the power supply voltage exceeds the reference voltage Vth1 (step S219). While the power supply voltage is lower than the reference voltage Vth1 (S219: NO), the return waiting state is maintained. For example, when the main power supply starts, the power supply voltage increases. When the power supply voltage exceeds the reference voltage Vth1 (S219: YES), the voltage monitoring signal output from the voltage monitoring circuit 19 becomes L level. When an L level voltage monitoring signal is input from the voltage monitoring circuit 19, the switch circuit 18 includes the oscillation circuit 11, the frequency dividing circuit 12, the recording control circuit 13, and the delay circuit 1.
Application of the power supply voltage to 5 is started. That is, the switch circuit 18 switches on these circuits (step S220). When the main power supply is started, the RTC module 20 shifts to the normal operation.

3. Other Embodiments The present invention is not limited to the above-described embodiments, and various modifications can be made. Hereinafter, some modifications will be described. Two or more of the following modifications may be used in combination.

FIG. 5 is a block diagram showing a configuration of the RTC module 30 according to the modification. The configuration of the RTC module is not limited to that described with reference to FIGS. For example, the delay circuit 1
5 may be omitted. The RTC module 30 is different from the RTC module 10 in that the delay circuit 15 is not provided. In this case, a voltage monitoring signal is input to the recording control circuit 13. The recording control circuit 13 sends a control signal to the switch circuit 1 in accordance with the voltage monitoring signal.
8 is output. In this example, the recording control circuit 13 outputs a control signal corresponding to the voltage monitoring signal when an H level voltage monitoring signal is input, that is, when it is detected that the power supply voltage is equal to or lower than Vth1. . At this time, the control signal becomes H level when the recording control circuit 13 is transferring data to the memory 17 and is L when not transferring data.
Become a level. On the other hand, when an L level voltage monitoring signal is input and the power supply voltage exceeds Vth1, the recording control circuit 13 outputs an H level signal regardless of the data transfer state.

FIG. 6 is a flowchart showing the operation of the RTC module 30. Step S300
The voltage monitoring circuit 19 monitors the power supply voltage. The power supply voltage is the reference voltage Vth1
(S300: YES), the voltage monitoring signal output from the voltage monitoring circuit 19 becomes H level. The process proceeds to step S304. When the power supply voltage is not lower than the reference voltage Vth1 (S300: NO), the voltage monitoring signal output from the voltage monitoring circuit 19 becomes L level. The process proceeds to step S301.

The event detection circuit 14 is waiting for an event input (step S301). That is, the event detection circuit 14 determines whether an event has been input (step S302).
. When no event is input (S302: NO), the event detection circuit 14 stands by in a state waiting for event input. When an event is input (S302: YES), the event detection circuit 14 outputs an event detection signal. When an event detection signal is input,
The recording control circuit 13 writes data in the memory 17. That is, the recording control circuit 13 transfers data to the memory 17 (step S303).

The processes in steps S304 to S306 are processes when the power supply voltage is lower than the reference voltage Vth1. When an H level signal is input from the voltage monitoring circuit 19, the recording control circuit 1
3 determines whether data is being transferred (step S304). Whether or not data transfer is in progress is determined by, for example, the value of a flag recorded in a register provided in the recording control circuit 13. During the data transfer, the recording control circuit 13 outputs an H level control signal. During this time, the recording control circuit 13 transfers the data to the memory 17 (step S30).
5). When the data transfer is completed, the recording control circuit 13 outputs an L level control signal. When the voltage monitor signal at H level and the control signal at L level are input, the switch circuit 18
Application of the power supply voltage to the oscillation circuit 11, the frequency dividing circuit 12, the recording control circuit 13, and the event detection circuit 14 is stopped. That is, the switch circuit 18 switches off these circuits (step S306). Hereinafter, the processing in steps S307 to S309 is the same as that in steps S109 to S111 in FIG.

The same applies to the RTC module 20 in which the delay circuit 15 may be omitted. In another example, the RTC module 10 and the RTC module 20 may not have the memory 17. That is, the recording control circuit 13 may write data in an external memory. In yet another example, the oscillator of the oscillation circuit 11 is not limited to a crystal. A ceramic oscillator or a SAW (Surface Acoustic Wave) vibrator may be used. Further, signal levels and combinations used for operations are merely examples, and are not limited to those described in the embodiments.

The circuit that is the target of control of application of the power supply voltage by the switch circuit 18 is not limited to that described in the embodiment. For example, the switch circuit 18 may control the application of the power supply voltage only to the oscillation circuit 11.

FIG. 7 is a block diagram illustrating a configuration of the electronic device 100. The electronic device 100 includes an RTC module 10 and a processor 50. The processor 50 outputs an event to the RTC module 10. The electronic device 100 is, for example, a play equipment, a home appliance, a watch, or a car. In the case of an amusement machine such as a pachinko machine, for example, an event that a housing has been opened or a processor has been modified is used. In the case of home appliances, usage frequency, usage time, and the like may be recorded as events and used for quality checks during recycling. In the case of an automobile, the usage status of the engine, such as the travel distance or exceeding the limit value, may be used as an event.

DESCRIPTION OF SYMBOLS 10 ... RTC module, 11 ... Oscillator circuit, 12 ... Frequency divider circuit, 13 ... Recording control circuit, 14
... Event detection circuit, 15 ... delay circuit, 16 ... timer circuit, 17 ... memory, 18 ... switch circuit, 19 ... voltage monitoring circuit, 20 ... RTC module, 21 ... voltage monitoring circuit, 22 ... switch circuit, 30 ... RTC module 50 ... Processor 100 ... Electronic equipment

Claims (8)

An oscillation circuit that generates a clock signal when a power supply voltage is applied;
A timing circuit that outputs timing data based on the clock signal;
An event detection circuit for detecting an event input;
A recording control circuit for recording data in which the event and the time measurement data are associated with each other based on a signal output from the event detection circuit;
A first voltage detection circuit for monitoring the power supply voltage;
A second voltage detection circuit for monitoring the power supply voltage;
A first switch circuit for controlling an operation of the oscillation circuit so as to reduce power consumption of the oscillation circuit based on a signal output from the first voltage detection circuit;
A second switch circuit for controlling the operation of the event detection circuit based on a signal output from the second voltage detection circuit;
A real-time clock module.   The real-time clock module according to claim 1, wherein controlling the operation of the oscillation circuit so as to reduce power consumption of the oscillation circuit is controlling the stop of the oscillation circuit.   3. The real-time clock module according to claim 1, wherein the first voltage detection circuit outputs a signal obtained by comparing a first threshold value and the power supply voltage. 4. The first switch circuit controls the operation of the oscillation circuit based on a signal output from the first voltage detection circuit and a signal output from the event detection circuit.
The real-time clock module according to claim 1, wherein the real-time clock module is provided. A delay circuit that outputs a signal to the first switch circuit based on the signal output from the first voltage detection circuit;
The first switch circuit controls the operation of the oscillation circuit to reduce power consumption of the oscillation circuit based on a signal output from the delay circuit;
The real time clock module according to claim 1, wherein the real time clock module is provided. The recording control circuit outputs a signal to the first switch circuit based on the signal output from the first voltage detection circuit;
The first switch circuit controls the operation of the oscillation circuit based on a signal output from the recording control circuit so as to reduce power consumption of the oscillation circuit.
The real-time clock module according to claim 1, wherein the real-time clock module is provided.   An electronic apparatus comprising the real-time clock module according to claim 1. An oscillation circuit generating a clock signal by applying a power supply voltage;
A timing circuit outputting timing data based on the clock signal;
A first voltage detection circuit outputting to the first switch circuit a signal detected that the power supply voltage has become equal to or lower than a first threshold;
The first switch circuit stopping the operation of the oscillation circuit;
An event detection circuit that outputs a signal that detects the input event to the storage control circuit;
The storage control circuit recording data associating the event and the time data in a memory; and
A second voltage detection circuit that outputs to the second switch circuit a signal that detects that the power supply voltage has become equal to or lower than a second threshold that is lower than the first threshold;
The second switch circuit stopping the operation of the event detection circuit;
Control method.

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