JP2014137353A - Constant voltage generation circuit, semiconductor device, and electronic timepiece - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce power consumption.SOLUTION: A constant voltage generation circuit 100 includes: a differential circuit 130 provided with an input terminal 131, to which a reference potential is input, and an input terminal 132 connected to an output terminal 110, that generates and outputs a control signal on the basis of a result of comparison between the reference potential and the potential of the output terminal 110; an output control switch element 150 that is connected between a VDD power supply line 101 and the output terminal 110, and that controls the state of conduction between the VDD power supply line 101 and the output terminal 110 on the basis of the control signal which is output by the differential circuit 130; and an input control switch element 160 connected between the input terminal 131 and a supply terminal to which a fixed potential is supplied, that causes conduction between the input terminal 131 and supply terminal when the constant voltage generation circuit 100 is in a stop state, and that causes non-conduction between the input terminal 131 and supply terminal when the constant voltage generation circuit 100 is in an operation state.

Description

  The present invention relates to a constant voltage generation circuit, a semiconductor device having a constant voltage generation circuit, and an electronic timepiece having a constant voltage generation circuit.

  Some electronic timepieces have a constant voltage generation circuit that supplies a constant voltage to a load circuit such as a motor driver that drives a step motor. For example, Patent Document 1 discloses a constant voltage circuit that supplies a constant voltage to an output load circuit.

One constant voltage generation circuit of an electronic timepiece is a constant voltage generation circuit 200 shown in FIG. The constant voltage generation circuit 200 includes a VDD power supply line 201 to which VDD is supplied, a VSS power supply line 202 to which VSS is supplied, an output terminal 210, a differential circuit 220, and an output control switch element 230.
A load circuit 21 such as an external motor driver and a capacitor 22 are connected in parallel to the output terminal 210. The differential circuit 220 includes an input terminal 221 to which a reference potential is input and an input terminal 222 connected to the output terminal 210, and generates a control signal based on a comparison result between the reference potential and the potential of the output terminal 210. And output. The output control switch element 230 is connected between the VDD power supply line 201 and the output terminal 210, and controls the conduction state between the VDD power supply line 201 and the output terminal 210 based on the control signal output by the differential circuit 220. To do. Here, when the control signal output from the differential circuit 220 is at a low level, the output control switch element 230 is turned on and conducts between the VDD power supply line 201 and the output terminal 210.

  Here, in an electronic timepiece having a constant voltage generating circuit, the constant voltage generating circuit is normally always in an operating state.

JP-A-10-214121

  A portable electronic timepiece such as a wristwatch needs to reduce power consumption as much as possible due to the fact that it is difficult to mount a large capacity battery or a secondary battery. Under such circumstances, the present inventor has attempted a method for stopping the operation of the constant voltage generating circuit when the load circuit is stopped, for example, in order to reduce the power consumption of the electronic timepiece having the constant voltage circuit. It was.

However, in the electronic timepiece having the constant voltage generation circuit 200, when the constant voltage generation circuit 200 is stopped, the reference potential input to the input terminal 221 of the differential circuit 220 becomes unstable (floating state), and the input terminal The potential of 221 may rise to the VDD side.
When the constant voltage generating circuit 200 shifts from this state to the operating state, the current I21 flows through the path on the input terminal 221 side in the differential circuit 220, and the potential of the control signal output from the differential circuit 220 decreases to the VSS side. The output control switch element 230 is turned on. As a result, a current flows from the VDD power line 201 to the capacitor 22 via the output terminal 210, and the potential (constant voltage output) of the output terminal 210 may increase excessively.

  In this case, the power consumption of the load circuit 21 increases. That is, while the constant voltage generation circuit 200 is turned on and off to reduce power consumption, the power consumption of the load circuit 21 increases with the on / off control of the constant voltage generation circuit 200, and the electronic The power consumption of the watch cannot be reduced sufficiently.

  An object of the present invention is to provide a constant voltage generation circuit, a semiconductor device, and an electronic timepiece that can reduce power consumption.

  The constant voltage generation circuit according to the present invention is a constant voltage generation circuit for supplying a constant voltage to a load circuit, wherein a first power supply line to which a first potential is supplied and a second potential lower than the first potential are supplied. A second power supply line, an output terminal connected to the load circuit, a first input terminal to which a reference potential is input, and a second input terminal connected to the output terminal, the reference potential and the A differential circuit that generates and outputs a control signal based on a comparison result with the potential of the output terminal, and is connected between the first power supply line and the output terminal, and is connected between the first power supply line and the output terminal. A constant voltage generator connected between an output control switch element for controlling a conduction state between the first input terminal and a supply terminal to which a fixed potential is supplied; When the circuit is in a stopped state, the first input terminal and the An input control switch element that conducts between the first supply terminal and the supply terminal when the constant voltage generating circuit is in an operating state. .

According to the present invention, when the constant voltage generation circuit is in a stopped state, the input control switch element is electrically connected between the first input terminal of the differential circuit and the supply terminal to which a fixed potential is supplied, A fixed potential is input to the first input terminal. Thereby, it is possible to prevent the potential of the first input terminal from becoming unstable (floating state) and the potential of the first input terminal from rising to the first potential side.
Thereby, when the constant voltage generating circuit shifts from the stopped state to the operating state, the differential circuit can correctly output the control signal based on the comparison result between the reference potential and the potential of the output terminal. That is, the output control switch element is appropriately controlled so that the potential of the output terminal is maintained at a predetermined potential. As a result, it can be prevented that a current flows from the first power supply line to the output terminal and the potential (constant voltage output) of the output terminal rises excessively, and the power consumption of the load circuit can be suppressed. For this reason, the on / off control of the constant voltage generation circuit can sufficiently reduce the power consumption of the electronic device in which the constant voltage generation circuit is mounted.

  In the constant voltage generation circuit of the present invention, the load circuit is a motor driver that drives a step motor that rotates a pointer of an electronic timepiece, and the constant voltage generation circuit shifts to an operation state every operation cycle of the step motor. It is preferable to shift to the stop state when detecting that the step motor operates normally.

According to the present invention, the constant voltage generation circuit can be controlled on and off in accordance with the operation of the step motor. That is, while the load for operating the step motor is applied to the motor driver, the constant voltage generation circuit is in an operating state, and while the load for operating the step motor is not applied to the motor driver, the constant voltage generation circuit is It can be in a stopped state.
Thereby, the power consumption of the electronic timepiece can be sufficiently reduced without affecting the operation of the motor driver.

In the constant voltage generation circuit of the present invention, it is preferable that the supply terminal is connected to one of the first power supply line and the second power supply line.
According to the present invention, since the potential of the supply terminal is fixed to the first potential or the second potential, it is not necessary to provide a new circuit for supplying a fixed potential to the supply terminal. For this reason, the constant voltage generating circuit is not complicated.

A semiconductor device of the present invention includes the constant voltage generation circuit described above and a control circuit that controls the constant voltage generation circuit, and the control circuit switches between a stop state and an operation state of the constant voltage generation circuit. And controlling the switch operation of the input control switch element of the constant voltage generation circuit.
According to the present invention, the power consumption of the load circuit is suppressed as in the above-described invention of the constant voltage generation circuit, and the power consumption of the electronic device on which the semiconductor device is mounted can be sufficiently reduced.

  The electronic timepiece of the present invention generates the reference voltage generation circuit, the step motor for rotating the pointer, a load circuit, a control circuit for controlling the constant voltage generation circuit, and a reference signal for measuring time. And the load circuit is a motor driver that drives the step motor, and the control circuit generates the constant voltage based on the reference signal output from the reference signal generation circuit. The circuit is shifted to an operation state every operation cycle of the step motor, and the constant voltage generation circuit is shifted to a stop state based on a detection signal indicating that the step motor output from the motor driver is operating normally. The switch operation of the input control switch element is controlled.

  According to the present invention, the power consumption of the load circuit is suppressed as in the above-described invention of the constant voltage generation circuit, and the power consumption of the electronic timepiece can be sufficiently reduced. In addition, the power consumption of the electronic timepiece can be reduced without affecting the operation of the motor driver.

It is a circuit diagram which shows the electronic timepiece which concerns on this embodiment. It is a figure which shows the state of the constant voltage output which concerns on this embodiment. It is a circuit diagram which shows the conventional constant voltage generation circuit.

Hereinafter, an electronic timepiece according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a circuit diagram showing an electronic timepiece according to the present embodiment.
[Outline of electronic watch]
The electronic timepiece 1 is an analog electronic timepiece driven by a solar cell or the like. The electronic timepiece 1 includes a step motor 14 that rotates a hand, a motor driver 11 that drives the step motor 14, a capacitor 12, a constant voltage generation circuit 100 that supplies a constant voltage to the motor driver 11, and a control that controls the constant voltage generation circuit 100. A circuit 10 and a reference signal generation circuit 13 that generates and outputs a reference signal for measuring time are provided.
Here, the constant voltage generation circuit 100, the motor driver 11, the control circuit 10, and the reference signal generation circuit 13 are formed on a semiconductor substrate and constitute a semiconductor device. The capacitor 12 is an external capacitor that stabilizes the constant voltage supplied to the motor driver 11.

[Configuration of constant voltage generation circuit]
The constant voltage generation circuit 100 includes a VDD power supply line 101 to which a first potential VDD is supplied, a VSS power supply line 102 to which a second potential VSS lower than VDD is supplied, an output terminal 110, a differential circuit 120, 130, constant current sources 141, 142, and 143, an output control switch element 150, and an input control switch element 160. VDD is, for example, 5V, and VSS is, for example, 0V.

  A motor driver 11 and a capacitor 12 are connected in parallel between the output terminal 110 and the VSS power supply line 102. That is, the motor driver 11 forms a load circuit.

  The first-stage differential circuit 120 is connected to the VDD power supply line 101 and further connected to the VSS power supply line 102 via the constant current source 141. The differential circuit 120 generates and outputs a reference potential based on an input signal (not shown).

The differential circuit 130 at the second stage is connected to the VDD power supply line 101 and further connected to the VSS power supply line 102 via the constant current source 142.
The differential circuit 130 has an input terminal 131 to which the reference potential output from the differential circuit 120 is input, and an input terminal 132 connected to the output terminal 110. Then, the differential circuit 130 generates and outputs a control signal based on the comparison result between the reference potential and the potential of the output terminal 110.

The output control switch element 150 is configured by a P-type channel MOS (Metal Oxide Semiconductor) field effect transistor. The output control switch element 150 is connected between the VDD power supply line 101 and the output terminal 110, and establishes a conduction state between the VDD power supply line 101 and the output terminal 110 in accordance with a control signal output from the differential circuit 130. Control.
Specifically, the output control switch element 150 conducts between the VDD power supply line 101 and the output terminal 110 when the control signal output from the differential circuit 130 is at a low level, and the control output from the differential circuit 130. When the signal is at high level, the VDD power supply line 101 and the output terminal 110 are made non-conductive.
That is, the differential circuit 130 controls on / off of the output control switch element 150 by the control signal so that the potential of the output terminal 110 (constant voltage output) becomes a predetermined potential (for example, 3.5 V).
A constant current source 143 is connected between the output terminal 110 and the VSS power supply line 102.

The input control switch element 160 is composed of an N-type channel MOS field effect transistor. The input control switch element 160 is connected between the input terminal 131 of the differential circuit 130 and the VSS power supply line 102, and is connected between the input terminal 131 and the VSS power supply line 102 according to a control signal output from the control circuit 10. Control the conduction state between. That is, the connection terminal between the input control switch element 160 and the VSS power supply line 102 constitutes a supply terminal to which the fixed potential VSS is supplied.
Specifically, the input control switch element 160 is turned on when the control signal is at a high level to conduct between the input terminal 131 and the VSS power supply line 102, and is turned off and input when the control signal is at a low level. The terminal 131 and the VSS power supply line 102 are made non-conductive.

[Configuration of control circuit]
The control circuit 10 is connected to the constant voltage generation circuit 100, the motor driver 11, and the reference signal generation circuit 13.
Here, the motor driver 11 drives the step motor 14, detects that the step motor 14 has operated normally, and outputs a detection signal. The reference signal generation circuit 13 divides an oscillation signal of a crystal resonator (not shown) to generate and output a reference signal. The reference signal is, for example, a 1 Hz signal.

Based on the reference signal output from the reference signal generation circuit 13, the control circuit 10 shifts the constant voltage generation circuit 100 to an operation state every operation cycle of the step motor 14.
For example, since the operation cycle of the step motor 14 for driving the second hand is 1 second, the control circuit 10 shifts the constant voltage generation circuit 100 to the operation state every second. Further, since the operation cycle of the minute hand and hour hand step motor 14 is, for example, 20 seconds, the control circuit 10 shifts the constant voltage generation circuit 100 to the operation state every 20 seconds.
In addition, when receiving the detection signal output from the motor driver 11, the control circuit 10 shifts the constant voltage generation circuit 100 to a stopped state.
Here, the stopped state is a state in which power supply to at least the differential circuits 120 and 130 of the constant voltage generation circuit 100 is interrupted.

The control circuit 10 also outputs a control signal that controls the input control switch element 160 of the constant voltage generation circuit 100.
Specifically, the control circuit 10 outputs a control signal (low level) for turning off the input control switch element 160 when the constant voltage generation circuit 100 is in an operating state, and the constant voltage generation circuit 100 is in a stop state. At this time, a control signal (high level) for turning on the input control switch element 160 is output.

[Operation of constant voltage generator]
First, an operation when the constant voltage generation circuit 100 is in a stopped state will be described.
In this case, a high level control signal is output from the control circuit 10, and the input control switch element 160 is turned on. Thereby, the input terminal 131 of the differential circuit 130 and the VSS power supply line 102 are electrically connected, and the input terminal 131 is fixed to VSS.
At this time, the control signal output from the differential circuit 130 becomes a high level, and the output control switch element 150 is turned off.

Next, the operation when the constant voltage generation circuit 100 shifts from the stopped state to the operating state will be described.
In this case, a low level control signal is output from the control circuit 10, and the input control switch element 160 is turned off. As a result, the input terminal 131 of the differential circuit 130 and the VSS power supply line 102 are rendered non-conductive, and the reference potential output from the differential circuit 120 is input to the input terminal 131.
Then, on / off of the output control switch element 150 is appropriately controlled according to the comparison result between the reference potential and the potential of the output terminal 110, and the potential of the output terminal 110 (constant voltage output) is maintained at a predetermined potential. The

[Constant voltage output status]
FIG. 2 is a diagram illustrating a state of constant voltage output according to the present embodiment.
FIG. 2 shows the potential (constant voltage output) VDM of the output terminal 110 of the constant voltage generation circuit 100, the on / off state of the constant voltage generation circuit 100, and the motor pulses output by the motor driver 11.
Here, the motor pulse 11A is an AC magnetic field detection pulse, the motor pulse 11B is a main drive pulse that mainly drives the step motor 14, and the motor pulse 11C is a rotation detection pulse of the step motor 14, and the motor pulse 11D and 11E are auxiliary driving pulses for driving the step motor 14 in an auxiliary manner, and the motor pulse 11F is a demagnetizing pulse.
When rotation detection is performed with the rotation detection pulse, it can be confirmed that the step motor 14 has operated normally. If rotation cannot be detected, an auxiliary drive pulse and a demagnetizing pulse are output. When an alternating magnetic field is detected, the auxiliary drive pulse and the demagnetization pulse are directly output without outputting the main drive pulse and the rotation detection pulse.
FIG. 2 shows a case where the auxiliary drive pulse and the demagnetizing pulse are output without rotation detection by the rotation detection pulse. In this case, as shown in FIG. 2, the constant voltage generation circuit 100 stops after the degaussing pulse is output. When the rotation can be detected by the rotation detection pulse and the auxiliary drive pulse and the demagnetization pulse are not output, the constant voltage generation circuit 100 stops immediately after the rotation is detected.

In the constant voltage generation circuit 100, when the constant voltage generation circuit 100 shifts from the stop state (OFF) to the operation state (ON), the constant voltage output VDM has a predetermined potential (for example, 3.5V) as indicated by a solid line. ) Is maintained.
Since the constant voltage generation circuit 100 is in an operating state while the motor pulse is being output, the constant voltage output VDM is maintained at a predetermined potential. On the other hand, since the constant voltage generation circuit 100 is in a stopped state while the motor pulse is not output, the constant voltage output VDM falls to the VSS side.
On the other hand, in the case of the conventional constant voltage generation circuit 200, when the constant voltage generation circuit shifts from the stop state to the operation state, a current flows from the VDD power line 201 to the capacitor 22 via the output terminal 210, and the constant voltage output VDM. May rise significantly from a predetermined potential to the VDD side as indicated by a dotted line.

According to this embodiment, there are the following effects.
(1) In the present embodiment, when the constant voltage generation circuit 100 is in a stopped state, the input control switch element 160 establishes conduction between the input terminal 131 of the differential circuit 130 and the VSS power supply line 102. Therefore, the fixed potential VSS is input to the input terminal 131. Accordingly, it is possible to prevent the potential of the input terminal 131 from becoming unstable (floating state) and the potential of the input terminal 131 from rising to the VDD side.
Thereby, when the constant voltage generating circuit 100 shifts from the stopped state to the operating state, the differential circuit 130 can correctly output a control signal based on the comparison result between the reference potential and the potential of the output terminal 110. As a result, it is possible to prevent current from flowing from the VDD power supply line 101 to the capacitor 12 via the output terminal 110 and excessively increasing the potential (constant voltage output) of the output terminal 110, thereby reducing the power consumption of the motor driver 11. Can be suppressed. For this reason, the power consumption of the electronic timepiece 1 can be sufficiently reduced by the on / off control of the constant voltage generation circuit 100.
Furthermore, since it is possible to prevent the constant voltage output from rising excessively, it is possible to suppress the generation of a magnetic field stronger than usual in the step motor 14, and to prevent the electronic component of the electronic timepiece 1 from being affected by this magnetic field. Can be suppressed. Furthermore, the step motor 14 can be stably driven by the motor driver 11.
(2) The constant voltage generation circuit 100 shifts to an operation state every operation cycle of the step motor 14, and shifts to a stop state when it detects that the step motor 14 operates normally.
As a result, the constant voltage generation circuit 100 can be on / off controlled in accordance with the operation of the step motor 14. For this reason, the power consumption of the electronic timepiece 1 can be reduced without affecting the operation of the motor driver 11.
(3) The input terminal 131 of the differential circuit 130 is connected to the VSS power supply line 102 when the constant voltage generation circuit 100 is in a stopped state.
Thereby, since the input terminal 131 is fixed to VSS, it is not necessary to provide a new circuit for inputting a fixed potential to the input terminal 131. For this reason, the constant voltage generation circuit 100 is not complicated.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, the input control switch element 160 is connected between the input terminal 131 of the differential circuit 130 and the VSS power supply line 102, but may be connected between the input terminal 131 and the VDD power supply line 101. . In this case, the connection terminal between the input control switch element 160 and the VDD power supply line 102 constitutes a supply terminal to which the fixed potential VDD is supplied. Further, in this case, the differential circuit 130 and the output control switch element 150 are configured so that the output control switch element 150 is turned off when the input terminal 131 and the VDD power supply line 101 become conductive.
The input control switch element 160 also has a terminal (supply terminal) to which an input terminal 131 and a fixed potential such as an intermediate potential generated based on VDD and VSS supplied from the VDD power supply line 101 and the VSS power supply line 102 are supplied. ).
Further, the reference potential supplied to the input terminal 131 of the differential circuit 130 is generated by the differential circuit 120, but is another circuit in which the supply of power is cut off when the constant voltage generation circuit 100 is in a stopped state. The same effect as that of the present embodiment can be obtained even when the above is generated.
Further, the load circuit connected to the output terminal 110 is not limited to the motor driver 11.
Further, the device on which the constant voltage generation circuit 100 is mounted is not limited to a semiconductor device.
The constant voltage generation circuit 100 can be applied not only to an electronic timepiece but also to various electronic devices having a load circuit driven by a constant voltage. For example, the present invention can be applied to various electronic devices such as a portable blood pressure monitor, a mobile phone, a pager, a pedometer, a calculator, a portable personal computer, an electronic notebook, a portable radio, a music box, a metronome, and an electric razor. In particular, it is suitable for a portable electronic device in which it is difficult to mount a large-capacity battery or a secondary battery.

  DESCRIPTION OF SYMBOLS 1 ... Electronic timepiece, 10 ... Control circuit, 11 ... Motor driver, 12 ... Condenser, 13 ... Reference signal generation circuit, 14 ... Step motor, 100 ... Constant voltage generation circuit, 101 ... VDD power supply line, 102 ... VSS power supply line, DESCRIPTION OF SYMBOLS 110 ... Output terminal, 120, 130 ... Differential circuit, 131, 132 ... Input terminal, 141-143 ... Constant current source, 150 ... Output control switch element, 160 ... Input control switch element

Claims (5)

A constant voltage generation circuit for supplying a constant voltage to a load circuit,
A first power supply line to which a first potential is supplied;
A second power supply line to which a second potential lower than the first potential is supplied;
An output terminal connected to the load circuit;
A first input terminal to which a reference potential is input and a second input terminal connected to the output terminal are provided, and a control signal is generated and output based on a comparison result between the reference potential and the potential of the output terminal. Differential circuit,
An output control switch element that is connected between the first power supply line and the output terminal and controls a conduction state between the first power supply line and the output terminal based on a control signal output from the differential circuit. When,
A constant voltage is connected between the first input terminal and a supply terminal to which a fixed potential is supplied, and when the constant voltage generating circuit is in a stopped state, the first input terminal and the supply terminal are electrically connected. An input control switch element for non-conducting between the first input terminal and the supply terminal when the generating circuit is in an operating state;
A constant voltage generation circuit comprising: The constant voltage generation circuit according to claim 1,
The load circuit is a motor driver that drives a step motor that rotates the hands of an electronic timepiece,
The constant voltage generation circuit shifts to an operation state every operation cycle of the step motor, and shifts to a stop state when detecting that the step motor operates normally.
A constant voltage generation circuit characterized by that. In the constant voltage generation circuit according to claim 1 or 2,
The supply terminal is connected to one of the first power line and the second power line.
A constant voltage generation circuit characterized by that. A constant voltage generation circuit according to any one of claims 1 to 3, and a control circuit that controls the constant voltage generation circuit,
The control circuit controls switching between a stopped state and an operating state in the constant voltage generation circuit, and controls a switch operation of the input control switch element of the constant voltage generation circuit.
A semiconductor device. A constant voltage generation circuit according to any one of claims 1 to 3, a step motor for rotating a pointer, a load circuit, a control circuit for controlling the constant voltage generation circuit, and a reference for measuring time A reference signal generation circuit that generates and outputs a signal,
The load circuit is a motor driver that drives the step motor,
The control circuit shifts the constant voltage generation circuit to an operation state for each operation cycle of the step motor based on the reference signal output from the reference signal generation circuit, and the step motor output by the motor driver is operated normally. The constant voltage generation circuit is shifted to a stop state based on a detection signal indicating that it has been operated, and the switch operation of the input control switch element is controlled.
An electronic timepiece characterized by that.

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