JP2008045912A - Voltage detection circuit, and timepiece equipped with the voltage detection circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a voltage detection circuit of a microcomputer capable of newly allocating a selection voltage value, even after the manufacture of the microcomputer, having high versatility, and high flexibility for setting the selection voltage value the corresponds to the kind of a battery or a portable electronic device or the like. <P>SOLUTION: The microcomputer is equipped with a peripheral circuit control resister 51 and an SVD circuit 52. The peripheral circuit control resister 51 is equipped with SVDSX513, S15VXXX515, and S3VXXX516. The SVD circuit 52 is equipped with a voltage selection circuit 521, and a selected voltage allocation circuit 522. The voltage selection circuit 521 selects a voltage value from among the selected candidate voltage values allocated to the S15VXXX515 and S3VXXX516. The selected voltage allocation circuit 522 arranges each voltage value that is selected by the voltage selection circuit 521, in the ascending order, and allocates it to the SVDSX513 as the selected voltage value. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a voltage detection circuit and a timepiece including the voltage detection circuit.

2. Description of the Related Art Conventionally, a microcomputer mounted on a portable electronic device such as a watch has a built-in voltage detection circuit that compares a power supply voltage value with a predetermined voltage value (hereinafter referred to as a comparison voltage value), and changes in power supply voltage, etc. Are known, and control is performed according to the detection result.
Here, the microcomputer refers to an integrated circuit (IC) that includes a storage device, an input / output device, and a processing device.

A voltage detection circuit that can select a comparison voltage value from a predetermined number of voltage values (hereinafter referred to as a selection voltage value) is also used. For example, Patent Document 1 discloses a voltage detection circuit realized on an integrated circuit, and a comparison voltage value can be selected from eight selection voltage values.
Thus, for example, by detecting the power supply voltage value in the region between the selected voltage values by sequentially changing the comparison voltage value from the low voltage value to the high voltage value and comparing it with the power supply voltage value. Can do. Therefore, control according to the current power supply voltage value can be flexibly performed.

JP 2000-111590 A

  By the way, as a power source for portable electronic devices, various power sources such as a solar cell and a generator using a rotating weight are used in addition to a button battery. For this reason, the power supply voltage is various, such as 1.5V and 3V, and even if the power supply voltage is the same, the characteristics of the change may be different. It is required to provide a selection voltage value corresponding to the type or the like.

In addition, as a kind of battery, secondary batteries, such as primary batteries, such as manganese, lithium, silver oxide, manganese carbon lithium, manganese titanium lithium, cobalt titanium lithium, are mentioned as an example.
Examples of portable electronic devices include watches, mobile phones, notebook computers, and the like in addition to the above-described watches.

For example, in Patent Document 1, a plurality of voltage values are selected for one selection voltage value by changing a wiring pattern in order to provide a selection voltage value corresponding to the type of each battery or portable electronic device. A method is conceivable in which an integrated circuit is designed as much as possible and options for a plurality of semiconductor masks having different wiring patterns are prepared.
As a result, the integrated circuit is manufactured by selecting an option according to the type of each battery or portable electronic device, etc., so that the voltage detection circuit can select the selected voltage value according to the type of each battery or portable electronic device. Can be provided.

However, according to such a method, since the selection voltage value cannot be newly changed after the integrated circuit is manufactured, a different integrated circuit is required depending on the type of each battery or portable electronic device. The versatility of the detection circuit is lacking.
Furthermore, for example, when an integrated circuit is designed so that ten voltage values can be selected with respect to one selection voltage value, the number of options of semiconductor masks to be prepared becomes very large, and space is secured. It is not realistic because it is difficult.

For example, when an integrated circuit is designed so that two to three voltage values can be selected with respect to one selection voltage value, the comparison voltage is included in the selectable two to three voltage values. When there is no voltage value to be set as the value, the selected voltage value cannot be used, and the selection voltage value options are reduced.
Furthermore, if there are two or more voltage values that are to be set as comparison voltage values among the selectable voltage values, only one of the voltage values can be selected as the selection voltage value. Cannot be used as a comparison voltage value.

  Further, when inspecting the integrated circuit, it is necessary to manufacture the same number of integrated circuits as the number of options of the prepared semiconductor masks, and it is necessary to inspect all of them, which reduces the manufacturing efficiency.

  The present invention has been made in view of the above-described problems, and the selection voltage value can be newly changed even after manufacturing, and the selection voltage value can be set according to the type of battery or portable electronic device. An object of the present invention is to provide a voltage detection circuit having a high degree of freedom and high versatility and a timepiece including the voltage detection circuit.

  The voltage detection circuit according to the present invention includes a selection candidate voltage storage unit that stores a plurality of voltage values as selection candidates, a voltage selection unit that selects a predetermined number of voltage values from the plurality of voltage values, and the voltage A selection voltage allocating unit that allocates a predetermined number of voltage values selected by the selection unit as a selection voltage value; a comparison voltage setting unit that sets a comparison voltage value to be compared with a voltage value to be detected from the selection voltage value; It is characterized by comprising voltage comparison means for comparing the detection target voltage value with the comparison voltage value.

According to such a configuration, the voltage selection means can be set by setting a flag in the program from among a plurality of voltage values stored in the selection candidate voltage storage means (hereinafter referred to as selection candidate voltage values). A predetermined number of voltage values can be selected. The selection voltage assigning unit can assign a predetermined number of voltage values selected by the voltage selection unit as the selection voltage value.
Therefore, the selection voltage value can be newly changed even after manufacture, and a highly versatile voltage detection circuit can be provided.

Further, the selection candidate voltage value is stored in the selection candidate voltage storage means, and the voltage selection means can select a predetermined number, for example, eight voltage values to be used as the comparison voltage value from the selection candidate voltage values. The selection voltage assigning means can assign these eight voltage values as the selection voltage values. That is, unlike the method of preparing a plurality of semiconductor mask options, a voltage value to be used as a comparison voltage value can be appropriately selected from selection candidate voltage values to be a selection voltage value without excess or deficiency. Furthermore, it is only necessary to prepare one semiconductor mask, and the manufacturing efficiency can be increased.
Therefore, it is possible to provide a highly versatile voltage detection circuit with a high degree of freedom in setting a selection voltage value according to the type of battery or portable electronic device.

In the present invention, it is preferable that the selection voltage allocating unit arranges a predetermined number of voltage values selected by the voltage selecting unit in ascending or descending order and allocates the selected voltage values as selection voltage values.
For example, when the selection voltage allocating unit allocates a predetermined number of voltage values selected by the voltage selection unit as selection voltage values in random order, the comparison voltage value is sequentially changed from a low voltage value to a high voltage value to supply voltage value In a program for detecting which power supply voltage value is in which region between the selected voltage values by comparing with the above, it is necessary to change the order of the voltage values by a macro or the like. Furthermore, such a program must be created separately according to the type of battery, portable electronic device, and the like, and is not efficient.

  However, according to such a configuration, the selection voltage assigning means arranges a predetermined number of voltage values selected by the voltage selection means in ascending order or descending order and assigns them as selection voltage values. The number of instructions can be reduced without having to change the order of voltage values by using a macro or the like. Furthermore, even if the types of batteries and portable electronic devices are different, the same program can be used, and an efficient program can be created.

  In the present invention, the selection voltage allocating means divides the plurality of voltage values in half to select a high voltage group and a low voltage group as a selection candidate voltage dividing unit, and among the voltage values belonging to the high voltage group, A high voltage group allocating unit that allocates voltage values selected by the voltage selection unit as selection voltage values in descending order, and a voltage value selected by the voltage selection unit among the voltage values belonging to the low voltage group is small. A low voltage group allocating unit that sequentially allocates as a selected voltage value, and the high voltage group allocating unit arranges voltage values belonging to the high voltage group in descending order, and sets an initial position according to the sequence, When assigning each voltage value, among the voltage values larger than the assigned voltage value, the number of voltage values not selected by the voltage selection means is shifted to a position shifted from the initial position toward the larger voltage value. The low voltage group assigning unit arranges the voltage values belonging to the low voltage group in ascending order, sets an initial position according to the order, and assigns each voltage value to the assigned voltage value. Of the small voltage values, the number of voltage values not selected by the voltage selection means is preferably allocated to positions shifted from the initial position in the direction of small voltage values.

According to such a configuration, the high voltage group allocating unit and the low voltage group allocating unit can be realized by the same algorithm. For example, the voltage selection unit can efficiently select the voltage using the same circuit. The voltage values belonging to the high voltage group and the low voltage group can be assigned as selection voltage values, and the circuit scale can be reduced.
In addition, since the selection candidate voltage dividing unit divides the selection candidate voltage value in half to obtain a high voltage group and a low voltage group, the initial position is compared with the case where the selection candidate voltage value is not divided in half. The number of shifts from can be reduced, and the circuit scale can be reduced.

  In the present invention, the selection candidate voltage storage means stores the plurality of voltage values for each voltage system to which the plurality of voltage values belong, and the voltage selection means includes a plurality of voltage values belonging to each voltage system. A predetermined number of voltage values are selected for each voltage system, and the selection voltage allocating unit allocates a predetermined number of voltage values for each voltage system selected by the voltage selection unit as a selection voltage value, and the comparison voltage The setting means preferably selects one voltage system from the voltage systems and sets a comparison voltage value to be compared with the voltage value to be detected from the selected voltage values belonging to the voltage system.

  According to such a configuration, for example, when the selection candidate voltage values belonging to the 1.5V system and 3V system voltage systems are stored in the selection candidate voltage storage unit, the comparison voltage setting unit has 1 Any one of the voltage systems can be selected from the 5V system and the 3V system. That is, even when the power supply voltage differs depending on the type of battery or portable electronic device, the voltage system can be selected according to the power supply voltage, and a more versatile voltage detection circuit can be provided. it can.

The timepiece of the present invention includes the voltage detection circuit described above and a control unit that performs control based on the detection result of the voltage detection circuit.
According to such a configuration, since the timepiece includes the voltage detection circuit described above, the same voltage detection circuit can be configured even if the types of batteries and timepieces are different. For example, the structure design of the watch, the peripheral circuit design, the software design, and the like can be facilitated.

For example, in a timepiece that receives radio waves, such as a radio-controlled timepiece, it is preferable to use a power supply voltage that is about 3 V higher than that of a normal timepiece in order to increase reception sensitivity. On the other hand, in the case of a normal timepiece, an easily available power supply voltage of about 1.5V may be used.
Even in such a case, since the timepiece includes the voltage detection circuit described above, even a timepiece that preferably uses a high power supply voltage such as a radio-controlled timepiece is an ordinary timepiece. The same voltage detection circuit can be provided.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram showing a microcomputer mounted on a timepiece according to an embodiment of the present invention.
The microcomputer 1 includes a CPU (Central Processing Unit) 2 as a processing device, a ROM (Read Only Memory) 3 and a RAM (Random Access Memory) 4 as storage devices, a peripheral circuit 5, and a power source for the microcomputer 1. The battery 6 for supplying the power, the crystal resonator 7, and various ports 8 serving as an input / output device for connecting the microcomputer 1 to an external device.
Examples of ROM 3 include mask ROM, EEPROM (Electrically Erasable Programmable ROM), flash ROM, and the like.

The CPU 2, the ROM 3, and the RAM 4 execute a program to operate the peripheral circuit 5.
In the present embodiment, the control means is constituted by the CPU 2, ROM 3, and RAM 4.
The peripheral circuit 5 is connected to a peripheral circuit control register 51 that stores information for controlling each circuit of the peripheral circuit 5, an SVD (Supply Voltage Detector) circuit 52 as a voltage detection circuit, and a crystal resonator 7. An oscillation circuit 53 that generates a clock for operating the microcomputer 1 and supplies the generated clock to each circuit of the peripheral circuit 5 is provided.
The CPU 2 writes and reads data to and from the peripheral circuit control register 51 via the data bus 9 according to the program.

The peripheral circuit 5 includes a constant voltage generating circuit, a frequency dividing circuit, an input port circuit, an output port circuit, an input / output port circuit, a motor circuit, an LCD circuit, a stopwatch circuit, a timer circuit, a buzzer, in addition to the circuits described above. Various circuits such as a circuit are provided.
In the present embodiment, operations of the peripheral circuit control register 51 and the SVD circuit 52 are mainly described, and descriptions of operations of other circuits are omitted.

Next, operations of the peripheral circuit control register 51 and the SVD circuit 52 will be described with reference to FIGS.
In the present embodiment, the voltage detection circuit includes a peripheral circuit control register 51 and an SVD circuit 52.
As shown in FIG. 2, the peripheral circuit control register 51 includes SVDDT 511, SVDON 512, SVDSX 513, SVDCHG 514, and S15VXXX515 and S3VXXX516 as selection candidate voltage storage means.

In SVDDT 511, the result of the comparison between the comparison voltage value and the detection target voltage value by the voltage comparison unit is latched. In the present embodiment, the power supply voltage of the battery 6 is detected as the detection target voltage value.
The SVDON 512 causes the voltage comparison unit to compare the power supply voltage value with the comparison voltage value.
The SVDSX 513 stores setting information for setting a comparison voltage value to be compared with the detection target voltage value from among the selection voltage values.
The SVDCHG 514 stores selection information for selecting a selection voltage value belonging to the 1.5V system voltage system and a selection voltage value belonging to the 3V system voltage system.

S15VXXX515 stores selection candidate voltage values belonging to the 1.5V system voltage system.
S3VXXX 516 stores selection candidate voltage values belonging to the 3V system voltage system.
Note that data bit numbers 0 to 2 are attached to X of SVDSX 513, and numbers excluding the decimal point of the selection candidate voltage value are attached to XXX of S15VXXX515 and S3VXXX516.

Each data bit of the peripheral circuit control register 51 is associated with data bits D0 to D3 of addresses FF04H to FF65H as shown in the register map of FIG.
FIG. 3 is a register map of a portion related to the SVD circuit of the peripheral circuit control register 51, in which each address value is displayed in the vertical direction, and each data bit of the register and an annotation are displayed in the horizontal direction.

At the lower position of each data bit, the attribute of each data bit (R: read enabled, W: write enabled) is described.
Also, in the annotation, the data bit name, Init (initial value of the data bit value), the state when the data bit value is 1, the state when the data bit value is 0, and the comment are described from the left in FIG. ing.

  For example, the data bit D3 of the address FF04H is a data bit whose name is SVDCHG and can be read and written. SVDCHG is a data bit for selecting the SVD voltage system. When the data bit value is 0, the selection voltage value belonging to the 1.5V system voltage system is selected, and when the data bit value is 1, A selection voltage value belonging to the 3V system voltage system is selected. The initial value of the data bit value is 0.

  On the register map shown in FIG. 3, SVDDT511 is D1 of FF05H, SVDON512 is D0 of FF05H, SVDCSX513 is D0 to D2 of FF04H, SVDCHG514 is D3 of FF04H, S15VXXX515 is D0 to D3 of FF60H to FF61H, S3VXXX516 corresponds to D2 to D3 of FF62H and D0 to D3 of FF63H to FF65H, respectively.

Here, the selection candidate voltage values belonging to the 1.5V system voltage system are stored in ascending order from D0 of FF60H of S15VXXX515 to D1 of FF62H. The selection candidate voltage values belonging to the 3V system voltage system are stored in ascending order from D2 of FF62H of S3VXXX516 to D3 of FF65H.
In the present embodiment, description of other data bits is omitted.

As shown in FIG. 2, the SVD circuit 52 includes a voltage selection circuit 521 as voltage selection means, a selection voltage assignment circuit 522 as selection voltage assignment means, a comparison voltage setting circuit 523 as comparison voltage setting means, and a voltage A voltage comparison circuit 524 as a comparison means and a transistor 525 are provided.
The voltage selection circuit 521 selects a predetermined number of voltage values from the selection candidate voltage values stored in S15VXXX515 and S3VXXX516. Specifically, the voltage selection circuit 521 selects a voltage value having a data bit value of 1 in S15VXXX515 and S3VXXX516. In the present embodiment, the predetermined number is “8”, and the number of voltage values with the data bit value of 1 in S15VXXX515 and S3VXXX516 needs to be 8 each.

  For example, if the data bit value remains the initial value, the voltage selection circuit 521 uses 1.05V, 1.1V, 1.15V, and 1.2V as voltage values belonging to the 1.5V system. , 1.25V, 1.3V, 1.4V, and 1.5V. Similarly, the voltage selection circuit 521 has 1.7V, 1.8V, 1.9V, 2.0V, 2.1V, 2.3V, 2.6V, and voltage values belonging to the 3V system. Select 2.7V.

  On the other hand, when a predetermined number of voltage values other than the initial value are selected, the program causes the CPU 2 to set 1 to each data bit value corresponding to the voltage value selected by the S15VXXX515 and S3VXXX516 via the data bus 9, By writing 0 to each data bit value corresponding to a voltage value that is not selected, the voltage value selected by the voltage selection circuit 521 can be changed. That is, a predetermined number of voltage values can be selected by a program according to the type of the battery 6 or the timepiece.

The selection voltage allocation circuit 522 includes a selection candidate voltage division unit 5221, a high voltage group allocation unit 5222, and a low voltage group allocation unit 5223.
Hereinafter, the operation of the selection voltage allocation circuit 522 will be described in detail by taking a selection candidate voltage value belonging to the 3V system voltage system as an example. Here, as shown in the data bit value column of FIG. 4, 1.8 V, 2.0 V, 2.2 V, 2.3 V, among the selection candidate voltage values belonging to the voltage system of 3 V system by the voltage selection circuit 521, Assume that voltage values of 2.35V, 2.5V, 2.6V, and 2.7V are selected.

The selection candidate voltage dividing unit 5221 divides the selection candidate voltage value by half to obtain a high voltage group and a low voltage group. That is, as shown in FIG. 4, when the selection candidate voltage values belonging to the 3V system voltage system are divided, the 14 selection candidate voltage values are divided into 7 pieces, and 2.7V to 2.3V are divided. The high voltage group, 2.25V to 1.7V, is divided as the low voltage group.
Here, for explanation, as shown in the symbol column of FIG. 4, symbols A to G are assigned to the high voltage group from the higher voltage value, and a to The symbol g is attached.

The high voltage group allocating unit 5222 first arranges the voltage values belonging to the high voltage group in descending order, sets an initial position according to the order, and assigns the voltage values selected by the voltage selection circuit 521 in descending order.
Here, in the present embodiment, the voltage values selected by the voltage selection circuit 521 are assigned in the descending order as the selection voltage value in the descending order of the bit value (position) of the SVDSX 513. That is, as shown in FIG. 5, the initial position of each voltage value from 2.7 V to 2.3 V is the bit value 7-1 of SVDSX 513 (indicated by white circles in FIG. 5).

  Note that the arrows shown in FIG. 5 indicate ranges that can be assigned as selection voltage values to SVDSX 513 at each voltage value. For example, the voltage value of 2.5 V indicates that the bit value 4 of the SVDSX 513 is the initial position and can be assigned as the selection voltage value to the bit values 4 to 7 of the SVDSX 513.

FIG. 6 is a diagram illustrating an example of assignment by the selection voltage assignment circuit 522. Here, the numerical value of the voltage value selected by the voltage selection circuit 521 is surrounded by a frame. In addition, the bit value of SVDSX 513 to which each voltage value is assigned as a selection voltage value is indicated by a black circle in FIG.
As shown in FIG. 6, the high voltage group allocating unit 5222 has an initial position equal to the number of voltage values that are not selected by the voltage selection circuit 521 among the voltage values larger than the allocated voltage values. To a position shifted in the direction of a larger voltage value from.

As shown in FIG. 4, half adders are connected between AB, DE, ab, and de. From this half adder, the number of 1s included in each of the two data bit values is as follows. Is output.
A full adder is connected between A and C, between D and F, between a and c, and between d and f. From this full adder, the number of 1s included in each of three data bit values Is output.

  Therefore, since the number of data bit values input to the half adder and the full adder is known, the number of 0s included in the data bit value input to the half adder and the full adder, that is, the voltage The number of voltage values not selected by the selection circuit 521 can be obtained.

Hereinafter, a procedure in which the high voltage group assignment unit 5222 assigns a voltage value belonging to the high voltage group selected by the voltage selection circuit 521 as the selection voltage value will be described in detail.
First, when 2.7V is assigned, since there is no voltage value larger than 2.7V, it is assigned as it is to the bit value 7 of SVDSX 513 as the initial position.

Next, when allocating a voltage value of 2.6V, the number of voltage values not selected by the voltage selection circuit 521 among the voltage values larger than 2.6V is obtained by the output of the half adder between AB, and (2.65V).
Therefore, the bit value 5 of SVDSX 513, which is the initial position of the 2.6V voltage value, is shifted by one in the direction of a larger voltage value and assigned to bit value 6 of SVDSX 513.

Next, when allocating a voltage value of 2.5 V, the number of voltage values not selected by the voltage selection circuit 521 among the voltage values greater than 2.5 V is obtained from the output of the full adder between A and C. One (2.65V).
Accordingly, the bit value 4 of the SVDSX 513, which is the initial position of the voltage value of 2.5V, is shifted by one in the direction of a larger voltage value and assigned to the bit value 5 of the SVDSX 513.

Next, when allocating a voltage value of 2.35V, among the voltage values larger than 2.35V, the number of voltage values not selected by the voltage selection circuit 521 is the output of the full adder between A and C, and between DE 2 (2.65V and 2.4V).
Therefore, the bit value 2 of SVDSX 513, which is the initial position of the voltage value of 2.35 V, is shifted by two in the direction of a larger voltage value and assigned to bit value 4 of SVDSX 513.

Next, when allocating a voltage value of 2.3 V, among the voltage values greater than 2.3 V, the number of voltage values not selected by the voltage selection circuit 521 is the output of the full adder between A and C, and D to It is obtained by the output of the full adder between F and is two (2.65V and 2.4V).
Therefore, the bit value 1 of SVDSX 513, which is the initial position of the voltage value of 2.3V, is shifted from the bit value 1 in the direction of a larger voltage value and assigned to bit value 3 of SVDSX 513.

The low voltage group assignment unit 5223 first arranges voltage values belonging to the low voltage group in ascending order, sets an initial position according to the order, and assigns voltage values selected by the voltage selection circuit 521 in ascending order.
Here, in the present embodiment, the voltage values selected by the voltage selection circuit 521 are allocated in ascending order of the bit value (position) of the SVDSX 513 as the selection voltage value. That is, as shown in FIG. 5, the initial position of each voltage value from 1.7 V to 2.25 V is the bit value 0 to 6 of SVDSX 513 (indicated by white circles in FIG. 5).

  As shown in FIG. 6, the low voltage group assigning unit 5223 assigns the initial position by the number of voltage values that are not selected by the voltage selection circuit 521 among the voltage values smaller than the assigned voltage values. Is assigned to the position shifted in the direction of smaller voltage value.

Hereinafter, a procedure in which the low voltage group assignment unit 5223 assigns the voltage value belonging to the low voltage group selected by the voltage selection circuit 521 as the selection voltage value will be described in detail.
First, when allocating a voltage value of 1.8 V, the number of voltage values not selected by the voltage selection circuit 521 among the voltage values smaller than 1.8 V is obtained from the output of the half adder between ab, and is 1 ( 1.7V).
Therefore, the bit value 1 of SVDSX 513, which is the initial position of the 1.8V voltage value, is shifted by one in the direction of a smaller voltage value and assigned to bit value 0 of SVDSX 513.

Next, when assigning a voltage value of 2.0 V, the number of voltage values not selected by the voltage selection circuit 521 among the voltage values smaller than 2.0 V is obtained from the output of the full adder between a and c. Two (1.7V and 1.9V).
Therefore, the bit value 3 of the SVDSX 513, which is the initial position of the voltage value of 2.0 V, is shifted by two in the direction of the smaller voltage value and assigned to the bit value 1 of the SVDSX 513.

Next, when assigning a voltage value of 2.2V, among the voltage values smaller than 2.2V, the number of voltage values not selected by the voltage selection circuit 521 is the output of the full adder between a and c, and between de 3 (1.7V, 1.9V, and 2.1V).
Accordingly, the bit value 5 of the SVDSX 513, which is the initial position of the voltage value of 2.2V, is shifted from the bit value 5 in the direction of the smaller voltage value and assigned to the bit value 2 of the SVDSX 513.

  Therefore, the selection voltage allocation circuit 522 causes the selection values of 1.8V, 2.0V, 2.2V, 2.3V, 2.35V, 2.5V, and 2.7V to be applied to the bit values 0 to 7 of the SVDSX 513. Values are assigned in ascending order.

The comparison voltage setting circuit 523 sets a comparison voltage value based on the data bit values of SVDSX 513 and SVDCHG 514.
For example, if the data bit value remains the initial value, the voltage selection circuit 521 and the selection voltage allocation circuit 522 change the bit value 0 to 7 of the SVDSX 513 to a voltage value belonging to the 1.5V voltage system. 1.05V, 1.1V, 1.15V, 1.2V, 1.25V, 1.3V, 1.4V, and 1.5V are assigned in ascending order, and 3V system voltage As voltage values belonging to the system, the selection voltage values of 1.7V, 1.8V, 1.9V, 2.0V, 2.1V, 2.3V, 2.6V, and 2.7V are allocated in ascending order.

  Then, since the data bit value of SVDCHG 514 is 0, the comparison voltage setting circuit 523 selects the selection voltage value belonging to the 1.5V system voltage system, and D0 to D2 of FF04H are all 0, so that the SVDSX 513 The bit value is 0, and 1.05 V corresponding to the bit value 0 of the SVDSX 513 is set as the comparison voltage value from the selection voltage values belonging to the 1.5 V system.

When 1 is written to the SVDON 512, the voltage comparison circuit 524 compares the power supply voltage value of the battery 6 with the comparison voltage value (1.05 V) set by the comparison voltage setting circuit 523 when the transistor 525 is turned on. To do. Then, the voltage comparison circuit 524 latches the comparison result in SVDDT 511. In this embodiment, SVDDT 511 is latched to 1 when the power supply voltage value is less than the comparison voltage value, and SVDDT 511 is latched to 0 when the power supply voltage value is greater than or equal to the comparison voltage value.
Therefore, the CPU 2 can detect the result of comparing the power supply voltage value and the comparison voltage value by reading SVDDT 511 by a program.

The microcomputer 1 according to the embodiment has the following effects.
(1) The voltage selection circuit 521 can select eight voltage values from the selection candidate voltage values stored in S15VXXX515 and S3VXXX516 by a program. Since the selection voltage allocation circuit 522 can allocate a predetermined number of voltage values selected by the voltage selection circuit 521 as the selection voltage value, the selection voltage value can be newly changed even after manufacturing. A highly reliable voltage detection circuit can be provided. Further, unlike the method of preparing a plurality of semiconductor mask options, a voltage value desired to be a comparison voltage value can be appropriately selected from selection candidate voltage values to be a selection voltage value without excess or deficiency. Furthermore, it is only necessary to prepare one semiconductor mask, and the manufacturing efficiency can be increased. Therefore, it is possible to provide a highly versatile voltage detection circuit with a high degree of freedom in setting a selection voltage value according to the type of battery or portable electronic device.

(2) The selection voltage assignment circuit 522 can arrange a predetermined number of voltage values selected by the voltage selection circuit 521 in ascending order and assign them to the SVDSX 513 as selection voltage values. As a result, even in a program for detecting which of the selection voltage values the power supply voltage value is in, the number of instructions can be reduced without having to change the order of the voltage values using a macro or the like. Furthermore, even if the types of batteries and portable electronic devices are different, the same program can be used, and an efficient program can be created.

(3) Since the high voltage group allocation unit 5222 and the low voltage group allocation unit 5223 can be realized by the same algorithm, for example, the voltage selection circuit 521 efficiently selects the same circuit using the same circuit. Voltage values belonging to the high voltage group and the low voltage group can be assigned to the SVDSX 513 as selection voltage values, and the circuit scale can be reduced.
(4) Since the selection candidate voltage dividing unit 5221 divides the selection candidate voltage value in half to obtain a high voltage group and a low voltage group, compared to the case where the selection candidate voltage value is not divided in half, The number of shifts can be reduced, and the circuit scale can be reduced.

(5) The comparison voltage setting circuit 523 can select one of the voltage systems from the 1.5V system and the 3V system. That is, even when the power supply voltage differs depending on the type of battery or portable electronic device, the voltage system can be selected according to the power supply voltage, and a more versatile voltage detection circuit can be provided. it can.

(6) Since the microcomputer 1 includes the voltage detection circuit, even if the power supply voltage of the battery mounted on the watch is different, the same microcomputer can be mounted by mounting the microcomputer 1 on the watch. For example, a clock structure design, peripheral circuit design, software design, and the like can be facilitated. Furthermore, even a timepiece that preferably uses a high power supply voltage such as a radio-controlled timepiece or a normal timepiece can be configured with the same voltage detection circuit.

It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.
For example, in the present embodiment, the selection candidate voltage values stored by S15VXXX515 and S3VXXX516 are 10 voltage values for the 1.5V system and 14 voltage values for the 3V system. However, there may be more than this, and in short, it may be stored according to the type of each battery or portable electronic device.

  In addition, the selection voltage allocation circuit 522 arranges the voltage values of 1.5V system and 3V system selected by the voltage selection circuit 521 in ascending order and allocates them to the SVDSX 513 of the peripheral circuit control register 51 as the selection voltage value. They may be arranged in descending order. In short, it is not necessary to change the order of voltage values by a macro or the like, and it is only necessary to reduce the number of instructions and to create an efficient program.

Further, the selection voltage assignment circuit 522 may assign the 1.5V system voltage value and the 3V system voltage value selected by the voltage selection circuit 521 in any order, in other words, a predetermined number of voltage values from a plurality of voltage values. It is only necessary that a value can be selected and assigned as a selected voltage value.
In addition, the selection voltage allocation circuit 522 assigns each voltage value in ascending order or descending order by a macro or the like when the 1.5V system and 3V system voltage values selected by the voltage selection circuit 521 are allocated in any order. In short, for example, it is only necessary to create a program that detects which of the selection voltage values the power supply voltage value is in.

  The selection voltage allocation circuit 522 is configured by the selection candidate voltage division unit 5221, the high voltage group allocation unit 5222, and the low voltage group allocation unit 5223, but may be realized by other configurations. It is sufficient that a predetermined number of voltage values selected by the voltage selection means can be assigned as the selection voltage value.

Further, although the voltage system is only 1.5V system and 3V system, other voltage systems may be stored in the peripheral circuit control register 51, and more voltage systems may be stored in the peripheral circuit control register 51. In other words, it is sufficient that the voltage system can be selected.
Further, the voltage system may not be selectable. In short, even if there is only one power supply system, a predetermined number of voltage values are selected and selected from among a plurality of voltage values belonging to this power supply system. What is necessary is just to be able to allocate as a voltage value.

  Further, the voltage detection circuit is built in the microcomputer mounted on the watch, but may be mounted on other electronic devices. In short, any electronic device that can mount the voltage detection circuit may be used.

It is a figure which shows the microcomputer mounted in the timepiece in embodiment of this invention. It is a block diagram of a SVD circuit. It is a register map of the part regarding the SVD circuit of the peripheral circuit control register. It is a figure which shows the example of a setting of the data bit value in each selection candidate voltage value of 3V type | system | group. It is a figure which shows the range which can be allocated as an initial position of each selection candidate voltage value, and a selection voltage value. It is a figure which shows the example of allocation by the selection voltage allocation circuit.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Microcomputer, 2 ... CPU, 3 ... ROM, 4 ... RAM, 5 ... Peripheral circuit, 6 ... Battery, 8 ... Various ports, 51 ... Peripheral circuit control register, 52 ... SVD circuit, 511 ... SVDDT, 512 ... SVDON 513 ... SVDSSX, 514 ... SVDCHG, 515 ... S15VXXX, 516 ... S3VXXX, 521 ... Voltage selection circuit, 522 ... Selection voltage allocation circuit, 523 ... Comparison voltage setting circuit, 524 ... Voltage comparison circuit, 5221 ... Selection candidate voltage divider , 5222... High voltage group allocation unit, 5223. Low voltage group allocation unit.

Claims (5)

Selection candidate voltage storage means in which a plurality of voltage values to be selection candidates are stored;
Voltage selection means for selecting a predetermined number of voltage values from the plurality of voltage values;
Selection voltage assigning means for assigning a predetermined number of voltage values selected by the voltage selection means as selection voltage values;
Comparison voltage setting means for setting a comparison voltage value to be compared with the voltage value to be detected from the selected voltage value;
A voltage detection circuit comprising voltage comparison means for comparing the detection target voltage value with the comparison voltage value. The voltage detection circuit according to claim 1,
The selection voltage allocating unit arranges a predetermined number of voltage values selected by the voltage selection unit in ascending or descending order and allocates the selected voltage values as selection voltage values. The voltage detection circuit according to claim 2,
The selection voltage allocating means divides the plurality of voltage values into half to select a high-voltage group and a low-voltage group as a selection candidate voltage dividing unit;
Among the voltage values belonging to the high voltage group, a high voltage group allocating unit that allocates the voltage values selected by the voltage selecting means as the selected voltage value in descending order;
Among the voltage values belonging to the low voltage group, a voltage value selected by the voltage selection means is configured to include a low voltage group allocating unit that allocates the selected voltage value in ascending order.
The high voltage group allocating unit arranges voltage values belonging to the high voltage group in descending order, sets an initial position according to the order, and assigns each voltage value to a voltage value larger than the assigned voltage value. Of these, the number of voltage values not selected by the voltage selection means is allocated to a position shifted from the initial position toward a larger voltage value,
The low voltage group allocating unit arranges voltage values belonging to the low voltage group in ascending order, sets an initial position according to the order, and assigns each voltage value to a voltage value smaller than the assigned voltage value. Among these, the voltage detection circuit is assigned to positions shifted from the initial position toward a smaller voltage value by the number of voltage values not selected by the voltage selection means. The voltage detection circuit according to any one of claims 1 to 3,
In the selection candidate voltage storage means, the plurality of voltage values are stored for each voltage system to which the plurality of voltage values belong,
The voltage selection means selects a predetermined number of voltage values for each voltage system from a plurality of voltage values belonging to each voltage system,
The selection voltage allocation means allocates a predetermined number of voltage values for each voltage system selected by the voltage selection means as selection voltage values,
The comparison voltage setting means selects one voltage system from each of the voltage systems, and sets a comparison voltage value to be compared with a voltage value to be detected from selected voltage values belonging to the voltage system. A characteristic voltage detection circuit. A voltage detection circuit according to any one of claims 1 to 4,
A timepiece comprising control means for performing control based on a detection result of the voltage detection circuit.

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