WO2022181025A1 - Control system and sensor - Google Patents

Control system and sensor Download PDF

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Publication number
WO2022181025A1
WO2022181025A1 PCT/JP2021/047783 JP2021047783W WO2022181025A1 WO 2022181025 A1 WO2022181025 A1 WO 2022181025A1 JP 2021047783 W JP2021047783 W JP 2021047783W WO 2022181025 A1 WO2022181025 A1 WO 2022181025A1
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WIPO (PCT)
Prior art keywords
circuit
power supply
voltage
output current
output
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PCT/JP2021/047783
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French (fr)
Japanese (ja)
Inventor
卓 福井
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パナソニックＩｐマネジメント株式会社
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Publication of WO2022181025A1 publication Critical patent/WO2022181025A1/en

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    • G—PHYSICS
    • G05—CONTROLLING; REGULATING
    • G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
    • G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
    • G05F1/10—Regulating voltage or current
    • G05F1/46—Regulating voltage or current wherein the variable actually regulated by the final control device is dc
    • G05F1/56—Regulating voltage or current wherein the variable actually regulated by the final control device is dc using semiconductor devices in series with the load as final control devices
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
    • G06F1/00—Details not covered by groups G06F3/00 - G06F13/00 and G06F21/00
    • G06F1/26—Power supply means, e.g. regulation thereof
    • G06F1/30—Means for acting in the event of power-supply failure or interruption, e.g. power-supply fluctuations
    • G—PHYSICS
    • G08—SIGNALLING
    • G08B—SIGNALLING OR CALLING SYSTEMS; ORDER TELEGRAPHS; ALARM SYSTEMS
    • G08B17/00—Fire alarms; Alarms responsive to explosion
    • G08B17/06—Electric actuation of the alarm, e.g. using a thermally-operated switch
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J1/00—Circuit arrangements for dc mains or dc distribution networks

Definitions

  • the present disclosure relates to control systems and sensors for embedded devices.
  • a heat sensor (see, for example, Patent Document 1) and a smoke sensor are used as fire alarm equipment.
  • the detector When the power supply from the commercial power system is interrupted due to a power failure, the detector is required to continue operating for a certain period of time (on the order of several hours) after the power failure.
  • a large-capacity electrolytic capacitor (for example, about 100 ⁇ F) is connected to the output wiring of the power supply circuit that supplies power to the load circuit including thermistors and the microcontroller (hereinafter referred to as microcomputer as appropriate).
  • a power supply circuit with an output current limit is sometimes used in order to prevent erroneous detection due to overcurrent flowing into the power supply circuit due to current being drawn from many loads at startup.
  • microcontrollers due to variations in the process, there are some that generate an indeterminate area for a moment before the internal power supply starts up, causing a large through current to flow inside the microcontroller.
  • the current drawn from the microcomputer may run short of the current to charge the large-capacity electrolytic capacitor, causing the output voltage to stop rising partway through. If the output voltage of the power supply circuit with output current limit stops below the operating lower limit voltage of the microcomputer, the microcomputer cannot be started.
  • the present disclosure has been made in view of such circumstances, and its purpose is to provide a control system capable of suppressing startup failure of a microcomputer in a power supply configuration in which a large-capacity capacitor is connected to the output wiring of a power supply circuit with an output current limit. , to provide a sensor.
  • a control system generates a constant power supply voltage based on an input voltage, and includes a power supply circuit with an output current limit that limits an output current to a predetermined value or less. a large-capacity capacitor connected between the output wiring of the power supply circuit with output current limitation and a fixed potential;
  • a microcontroller that includes a voltage circuit, an internal control circuit that generates logic signals for driving internal switching elements based on the generated internal power supply voltage, and assists the startup of the constant voltage circuit in the microcontroller. and an assist circuit unit.
  • FIG. 3 is a diagram showing a schematic circuit configuration of an embedded device according to a comparative example
  • FIGS. 2A and 2B are diagrams showing specific circuit configuration examples of embedded devices according to comparative examples.
  • FIG. 3 is a diagram showing the internal configuration of part of the microcomputer.
  • 1 is a diagram showing a schematic circuit configuration of an embedded device according to Embodiment 1
  • FIG. 5(a) and 5(b) are diagrams showing specific circuit configuration examples of the embedded device according to the first embodiment.
  • FIGS. 6A and 6B are diagrams showing transition images of voltage waveforms when the embedded device according to the comparative example starts up and when the embedded device according to the first embodiment starts up.
  • FIGS. 1 is a diagram showing a schematic circuit configuration of an embedded device according to Embodiment 1
  • FIG. 5(a) and 5(b) are diagrams showing specific circuit configuration examples of the embedded device according to the first embodiment.
  • FIGS. 6A and 6B are diagrams showing transition images of voltage waveforms when the embedded
  • FIG. 7(a) and 7(b) are diagrams showing simulation examples when the embedded device according to the first embodiment starts up.
  • 3 is a diagram showing a schematic circuit configuration of an embedded device according to Embodiment 2;
  • FIG. 10 is a diagram showing a specific circuit configuration example of an embedded device according to the second embodiment;
  • FIG. 10 is a diagram showing a transition image of voltage waveforms at the start-up of the embedded device according to the second embodiment;
  • FIG. 1 is a diagram showing a schematic circuit configuration of an embedded device 1 according to a comparative example.
  • the embedded device 1 according to the comparative example has a control system 15 and a load circuit 30 .
  • the control system 15 includes a power supply circuit 10 with output current limitation, a large-capacity capacitor C1, and a microcomputer 20.
  • FIG. 10 includes a power supply circuit 10 with output current limitation, a large-capacity capacitor C1, and a microcomputer 20.
  • the power supply circuit 10 with output current limitation is a constant voltage AC-DC power supply circuit with output current limitation.
  • the power supply circuit 10 with output current limit converts an AC voltage input from the commercial power system 2 into a DC voltage, steps down the converted DC voltage, and outputs a constant DC voltage.
  • the power supply circuit 10 with output current limit has a function of limiting the output current to a predetermined value (for example, about 100 ⁇ A) or less.
  • the power supply circuit 10 with output current limitation converts, for example, a 100V AC voltage supplied from an indoor outlet into a 24V DC voltage, and steps down the converted 24V DC voltage to a 5V DC voltage for output.
  • a DC voltage output from the power supply circuit 10 with output current limit is used as a power supply voltage for the microcomputer 20 and the load circuit 30 .
  • the large-capacity capacitor C1 is connected between the output wiring of the power supply circuit 10 with output current limit and the ground potential of the substrate.
  • an electrolytic capacitor of about 100 ⁇ F is used.
  • the microcomputer 20 controls the load circuit 30 based on the power supply voltage supplied from the power supply circuit 10 with output current limitation. If the power supply voltage of the microcomputer 20 is lower than the output voltage of the power supply circuit 10 with output current limitation, a DC-DC regulator such as an LDO (Low Dropout Linear Regulator) is placed between the power supply circuit 10 with output current limitation and the microcomputer 20. A converter is inserted. For example, when the power supply voltage of the microcomputer 20 is set to 3V, the DC-DC converter steps down the DC voltage of 5V input from the power supply circuit 10 with output current limitation to a DC voltage of 3V.
  • LDO Low Dropout Linear Regulator
  • FIGS. 2(a) and 2(b) are diagrams showing specific circuit configuration examples of the embedded device 1 according to the comparative example.
  • FIG. 2(a) shows a circuit configuration example when the embedded device 1 is a heat sensor 1a.
  • the power supply circuit 10 with output current limitation shown in FIG. 2(a) includes an AC-DC converter, a constant voltage circuit, and a current limiting circuit.
  • the AC-DC converter includes a diode bridge circuit DB and Zener diodes ZD1-ZD3.
  • Bidirectional Zener diodes ZD1-ZD2 are connected in series between two input terminals of commercial power system 2 such that their cathode terminals face each other.
  • Diode bridge circuit DB full-wave rectifies and outputs an AC voltage defined by two Zener diodes ZD1 and ZD2.
  • the Zener diode ZD3 is connected between the output wiring of the diode bridge circuit DB and the ground potential, and shapes the full-wave rectified waveform output from the diode bridge circuit DB into a constant voltage waveform.
  • the constant voltage circuit includes an NPN transistor Q1, a resistor R1, and a Zener diode ZD4.
  • the collector terminal of NPN transistor Q1 is connected to the output terminal of the AC-DC converter.
  • a resistor R1 and a reverse Zener diode ZD4 are connected in series between the output wiring of the AC-DC converter and the ground potential.
  • a connection point between the resistor R1 and the Zener diode ZD4 is connected to the base terminal of the NPN transistor Q1.
  • the NPN transistor Q1 operates as an emitter follower and outputs a voltage corresponding to the Zener voltage from the emitter terminal. Specifically, a voltage obtained by subtracting the base-emitter saturation voltage VBE from the Zener voltage input to the base terminal is output from the emitter terminal.
  • the current limiting circuit includes an NPN transistor Q2, a current limiting resistor R2, and an anti-backflow diode D1.
  • a current limiting resistor R2 and a diode D1 are connected in series to the emitter terminal of the NPN transistor Q1.
  • the emitter terminal of NPN transistor Q2 is connected to the cathode terminal of diode D1
  • the base terminal of NPN transistor Q2 is connected to the emitter terminal of NPN transistor Q1
  • the collector terminal of NPN transistor Q2 is connected to the base terminal of NPN transistor Q1. .
  • the NPN transistor Q2 When the voltage between the current limiting resistor R2 and the diode D1 becomes larger than the base-emitter saturation voltage VBE of the NPN transistor Q2, the NPN transistor Q2 turns on to bypass the base current of the NPN transistor Q1. As a result, the emitter current of NPN transistor Q1 is limited to a certain value or less.
  • the load circuit 30 is the heat sensing circuit 30a.
  • the thermal sensing circuit 30a includes a thermistor T1 and a resistor T3.
  • the thermistor T1 and the resistor 3 are connected in series between the output wiring of the power supply circuit 10 with output current limit and the ground potential.
  • the microcomputer 20 monitors the voltage dividing point of the thermistor T1 and resistor 3 .
  • the thermistor T1 is a thermosensitive element whose resistance value changes with changes in temperature. When NPC thermistors are used, their resistance decreases with increasing temperature.
  • the microcomputer 20 sends a fire signal to a fire receiver (not shown) or a repeater (not shown) when the ambient temperature rise rate exceeds a certain rate, or when the local ambient temperature rises above a certain rate. to send.
  • FIG. 2(b) shows a circuit configuration example when the embedded device 1 is the smoke sensor 1b.
  • the configuration of the power supply circuit 10 with output current limitation is the same as that of the power supply circuit 10 with output current limitation of FIG. 2(a).
  • the load circuit 30 is the smoke sensor circuit 30b.
  • Smoke sensing circuit 30b includes light emitting diode LD, photodiode PD, N-channel MOSFET (M1), resistors R4-R6, and capacitor C3.
  • a resistor R5, a light emitting diode LD, a resistor R6, and an N-channel MOSFET (M1) are connected in series between the output wiring of the power supply circuit 10 with output current limit and the ground potential.
  • a capacitor C3 is connected between the connection point between the resistor R5 and the light emitting diode LD and the ground potential. The capacitor C3 serves to supplement the current flowing through the light emitting diode LD and to remove noise.
  • the microcomputer 20 inputs a drive signal to the gate terminal of the N-channel MOSFET (M1) to control lighting/extinguishing of the light emitting diode LD. When a high level signal is input to the gate terminal of the N-channel MOSFET (M1), the light emitting diode LD is turned on, and when a low level signal is input, the light emitting diode LD is turned off.
  • a photodiode PD and a resistor R4 are connected in series between the output wiring of the power supply circuit 10 with output current limit and the ground potential.
  • the photodiode PD is arranged at a position where direct light from the light emitting diode LD does not enter.
  • the microcomputer 20 monitors the voltage dividing point of the photodiode PD and resistor R4. When smoke flows into the housing, the light emitted from the light emitting diode LD is diffusely reflected by the smoke, the amount of light received from the light emitting diode LD increases in the photodiode PD, and the amount of current flowing through the photodiode PD increases.
  • the microcomputer 20 transmits a fire signal to a fire receiver (not shown) or a repeater (not shown) when a change in smoke density estimated from a change in voltage dividing point exceeds a set value.
  • FIG. 3 is a diagram showing the internal configuration of part of the microcomputer 20.
  • the microcomputer 20 includes a constant voltage circuit 21, a logic control circuit 22, and an I/O cell 23, as shown in FIG. 3(a).
  • the constant voltage circuit 21 steps down the power supply voltage VDD input from the power supply circuit 10 with output current limitation to generate an internal power supply voltage VD1 (for example, about 1.4 V).
  • a stabilizing capacitor C2 (for example, about 1 ⁇ F) is connected between the terminal to which the output wiring of the constant voltage circuit 21 is connected and the ground potential.
  • the constant voltage circuit 21 includes one or more transistors, and uses the threshold voltage of the transistors to generate the internal power supply voltage VD1. For example, it is possible to configure the constant voltage circuit (NPN transistor Q1, resistor R1, and Zener diode ZD4) shown in FIGS. 2(a) and 2(b).
  • the logic control circuit 22 Based on the internal power supply voltage VD1 generated by the constant voltage circuit 21, the logic control circuit 22 generates a logic signal (L/O) for driving internal circuits (for example, switching elements).
  • the logic control circuit 22 generates a high level signal at 1.4V and a low level signal at 0V, for example.
  • the I/O cell 23 includes, for example, an input/output unit 23a, a pull-up circuit (not shown), and a pull-down circuit.
  • the pull-down circuit has a P-channel MOSFET (M2) and a resistor R7, and the P-channel MOSFET (M2) and the resistor R7 are connected between the power supply line to which the power supply voltage VDD is applied and the ground line connected to the ground potential. connected in series.
  • the source terminal of the P-channel MOSFET (M2) is connected to the power supply line, and the connection point between the drain terminal of the P-channel MOSFET (M2) and the resistor R7 is connected to the input/output port.
  • a logic signal from the logic control circuit 22 is input to the gate terminal of the P-channel MOSFET (M2).
  • the P-channel MOSFET (M2) turns off when a high level signal is input to the gate terminal from the logic control circuit 22 while power is supplied to the source terminal, and turns on when a low level signal is input. .
  • the logic control circuit 22 can pull up the input/output port to a high level by inputting a low level to the P-channel MOSFET (M2).
  • the logic control circuit 22 can also pull down the input/output port to a low level by controlling a pull-down circuit (not shown).
  • a pull-up circuit using a P-channel MOSFET (M2) is used in various places other than the I/O cell 23 in the microcomputer 20. FIG.
  • the constant voltage circuit 21 starts outputting the internal power supply voltage VD1.
  • the logic control circuit is connected to the gate terminal of the P-channel MOSFET (M2). 22, the P-channel MOSFET (M2) turns on. In this case, a through current flows through the P-channel MOSFET (M2) and the resistor R7.
  • the microcomputer 20 there are many circuits in which through current flows when a low level signal (0V) is input from the logic control circuit 22 to the gate terminal of the P-channel MOSFET (M2). As a result, the microcomputer 20 may start drawing current from the power supply circuit 10 with output current limitation before the constant voltage circuit 21 starts up.
  • the current limiting function of the power supply circuit 10 with output current limitation is activated, the current for charging the large-capacity capacitor C1 is insufficient, and the rise of the power supply voltage VDD may stop halfway. . If the power supply voltage VDD stops halfway and the constant voltage circuit 21 does not start up, a through current will continue to flow through the microcomputer 20 and the power supply voltage VDD will be held. If the power supply voltage VDD is held below the operating lower limit voltage (for example, about 1.2 V) of the microcomputer 20, the microcomputer 20 cannot be started.
  • an embedded device 1 equipped with an assist circuit section for assisting startup of the constant voltage circuit 21 in the microcomputer 20 will be described as a countermeasure capable of suppressing start-up failure of the microcomputer 20 .
  • FIG. 4 is a diagram showing a schematic circuit configuration of the embedded device 1 according to the first embodiment.
  • the embedded device 1 according to the first embodiment is different from the embedded device 1 according to the comparative example shown in FIG. be done.
  • the coupling capacitor Cc is connected between the output wiring of the power supply circuit 10 with output current limit and the terminal (VD1 terminal) of the microcomputer 20 connected to the output wiring of the constant voltage circuit 21 .
  • FIGS. 5(a) and 5(b) are diagrams showing specific circuit configuration examples of the embedded device 1 according to the first embodiment.
  • FIGS. 5(a) and 5(b) show circuit configuration examples when the embedded device 1 is the heat sensor 1a.
  • a Zener diode ZD6 is connected between the VD1 terminal of the microcomputer 20 and the ground potential. The Zener diode ZD6 limits the voltage rise of the VD1 terminal of the microcomputer 20 so that the voltage of the VD1 terminal of the microcomputer 20 does not exceed the withstand voltage of the logic control circuit 22 (for example, about 2.5 V).
  • FIGS. 6(a) and 6(b) are diagrams showing transition images of voltage waveforms when the embedded device 1 according to the comparative example starts up and when the embedded device 1 according to the first embodiment starts up.
  • FIG. 6A shows an example in which the power supply voltage VDD is clamped in the middle of the rise due to the consumption current of the microcomputer 20 when the embedded device 1 according to the comparative example starts up.
  • the internal power supply voltage VD1 is also clamped on the way up.
  • FIG. 6B shows that when the embedded device 1 according to the first embodiment starts up, the rise in the internal power supply voltage VD1 of the microcomputer 20 is caused by the output voltage of the power supply circuit 10 with output current limitation via the coupling capacitor Cc. It shows an example to assist.
  • the logic control circuit 22 can operate normally and the flow of through current in the microcomputer 20 can be suppressed.
  • the power supply voltage VDD and the internal power supply voltage VD1 of the microcomputer 20 rise to normal voltages.
  • FIGS. 7(a) and 7(b) are diagrams showing simulation examples when the embedded device 1 according to the first embodiment starts up.
  • FIG. 7(a) shows simulation results when the capacitance of the capacitor C2 is varied.
  • the current flowing through the current limiting resistor R2 is suppressed to about 110 ⁇ A by the current limiting function of the power supply circuit 10 with output current limitation with respect to the current drawn from the load side.
  • the power supply voltage VDD rises, the current flowing through the current limiting resistor R2 drops to about several tens of ⁇ A.
  • the internal power supply voltage VD1 of the microcomputer 20 rises by receiving the assist voltage via the coupling capacitor Cc.
  • the internal power supply voltage VD1' of the microcomputer 20 indicated by the dotted line is an example when the capacitance of the capacitor C2 is reduced to about 1/10. It can be seen that if the capacitance of the capacitor C2 is reduced, the noise resistance is lowered, but the effect of raising the internal power supply voltage VD1 at startup is enhanced.
  • FIG. 7(b) shows simulation results when the capacitance of the coupling capacitor Cc is varied.
  • the internal power supply voltage VD1' of the microcomputer 20 indicated by the dotted line is an example when the capacitance of the coupling capacitor Cc is reduced to about 2/3. It can be seen that the larger the capacitance of the coupling capacitor Cc, the stronger the effect of raising the internal power supply voltage VD1 at startup.
  • FIG. 8 is a diagram showing a schematic circuit configuration of the embedded device 1 according to the second embodiment.
  • the embedded device 1 according to the second embodiment is different from the embedded device 1 according to the comparative example shown in FIG. .
  • the switch circuit 25b is inserted between the connection point of the large-capacity capacitor C1 and the connection point of the microcomputer 20 on the output wiring of the power supply circuit 11 with output current limitation.
  • the delay circuit 25a turns on the switch circuit 25b after a predetermined time has passed since the start of charging the large-capacity capacitor C1.
  • the predetermined time is set to be longer than the time required for charging the large-capacity capacitor C1.
  • FIG. 9 is a diagram showing a specific circuit configuration example of the embedded device 1 according to the second embodiment.
  • Delay circuit 25a includes resistor R9 and capacitor C4. The resistor R9 and the capacitor C4 are connected in series between the output wiring of the power supply circuit 10 with output current limit and the ground potential.
  • the switch circuit 25b includes a P-channel MOSFET (M3), an NPN transistor Q4, and resistors R10-R11.
  • M3 P-channel MOSFET
  • NPN transistor Q4 NPN transistor
  • resistors R10-R11 resistors
  • the voltage input to the base terminal of the NPN transistor Q4 rises with a delay from the output voltage of the power supply circuit 11 with output current limitation due to the time constant of the resistor R9 and the capacitor C4.
  • the NPN transistor Q4 turns on and the P-channel MOSFET (M3) turns on.
  • a reset IC (not shown) may be used to turn on the NPN transistor Q4 after a predetermined time has passed since the output voltage of the power supply circuit 11 with output current limit rises.
  • FIG. 10 is a diagram showing a transition image of voltage waveforms at startup of the embedded device 1 according to the second embodiment.
  • the output voltage Vout of the power supply circuit 10 with output current limitation rises, but the power supply voltage VDD does not rise because the switch circuit 25b is in the off state.
  • the switch circuit 25b is turned on, the power supply voltage VDD starts to rise.
  • the output voltage Vout of the power supply circuit 10 with output current limitation once drops when the switch circuit 25b is turned on.
  • the present embodiment in a power supply configuration in which a large-capacity capacitor C1 is connected to the output wiring of the power supply circuit 10 with an output current limit, startup of the constant voltage circuit 21 in the microcomputer 20 is assisted. By providing the circuit, startup failure of the microcomputer 20 can be suppressed. Since the microcomputer 20 itself does not need to be improved, the general-purpose microcomputer 20 that consumes less power and is inexpensive can be used as it is.
  • Embodiment 1 it is sufficient to add the coupling capacitor Cc and, if necessary, the Zener diode ZD6, and the increase in the number of parts can be minimized. Therefore, increases in circuit area and cost can be minimized. The additional parts hardly increase the current consumption.
  • the start-up of the microcomputer 20 is started while the large-capacity capacitor C1 is charged, so the microcomputer 20 can be started up more reliably.
  • the embedded device 1 to which power is supplied from the commercial power system 2 is assumed.
  • the technology of the present disclosure can also be applied to the embedded device 1 to which power is supplied from a battery.
  • the output current limited power supply circuit 10 includes a DC-DC converter instead of an AC-DC converter.
  • the technology of the present disclosure can be applied to other than the sensor as long as it is an embedded device 1 equipped with a microcomputer 20 having a power supply configuration in which a large-capacity capacitor C1 is connected to the output wiring of the power supply circuit 10 with output current limitation. It is possible. In particular, it is most suitable for reducing the power consumption of the system of the embedded device 1 .
  • the embodiment may be specified by the following items.
  • the assist circuit unit including a coupling capacitor (Cc) connected between the output wiring of the power supply circuit (10) with output current limit and the terminals of the microcontroller (20) connected to the output wiring of the constant voltage circuit (21). , A control system (15) according to item 1. According to this, countermeasures for suppressing start-up failure of the microcontroller (20) can be realized with a single coupling capacitor (Cc) at low cost and without an increase in power consumption.
  • the assist circuit unit further comprising a Zener diode (ZD6) connected between the terminal of the microcontroller (20) connected to the output wiring of the constant voltage circuit (21) and the fixed potential; A control system (15) according to item 2.
  • the assist circuit unit a switch circuit (25b) inserted between the connection point of the large-capacity capacitor (C1) and the connection point of the microcontroller (20) on the output wiring of the power supply circuit (10) with output current limitation; including The switch circuit (25b) is turned on after a predetermined time has elapsed from the start of charging of the large-capacity capacitor (C1) at the rising time.
  • the present disclosure can be used for heat sensors and smoke sensors.
  • 1 Embedded device 1a Heat sensor, 1b Smoke sensor, 2 Commercial power system, 10 Power supply circuit with output current limit, 15 Control system, 20 Microcomputer, 21 Constant voltage circuit, 22 Logic control circuit, 23 I/O cell , 23a input/output unit, 25a delay circuit, 25b switch circuit, 30 load circuit, 30a heat sensing circuit, 30b smoke sensing circuit, C1 large capacity capacitor, C2-C4 capacitor, Cc coupling capacitor, R1-R11 resistor, Q1- Q4 NPN transistor, M1 N-channel MOSFET, M2 P-channel MOSFET, M3 P-channel MOSFET, DB diode bridge circuit, D1 diode, ZD1-ZD6 Zener diode, T1 thermistor, PD photodiode, LD light emitting diode.

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Abstract

An output current limiting power supply circuit (10) generates a constant power supply voltage from an input voltage, and limits the output current to a predetermined value or less. A large-capacitance capacitor (C1) is connected between the output line of the output current limiting power supply circuit (10) and a fixed potential. A microcontroller (20) includes a constant voltage circuit that reduces a power supply voltage input from the output current limiting power supply circuit (10) to generate an internal power supply voltage, and an internal control circuit that generates a logic signal for driving an internal switching element on the basis of the generated internal power supply voltage. An assist circuit unit (Cc) assists in activation of the constant voltage circuit in the microcontroller (20).

Description

制御システム、感知器control system, sensor
　本開示は、組込機器の制御システム、感知器に関する。 The present disclosure relates to control systems and sensors for embedded devices.
　火災報知設備として、熱感知器（例えば、特許文献１参照）や煙感知器が使用される。感知器は、停電により商用電力系統からの電源供給が途絶えた場合、停電から一定時間（数時間オーダー）、動作を継続することが求められる。それを実現するために、サーミスタ等を含む負荷回路、及びマイクロコントローラ（以下適宜、マイコンという）に電源を供給する電源回路の出力配線に大容量の電解コンデンサ（例えば、１００μＦ程度）が接続されることがある。 A heat sensor (see, for example, Patent Document 1) and a smoke sensor are used as fire alarm equipment. When the power supply from the commercial power system is interrupted due to a power failure, the detector is required to continue operating for a certain period of time (on the order of several hours) after the power failure. In order to achieve this, a large-capacity electrolytic capacitor (for example, about 100 μF) is connected to the output wiring of the power supply circuit that supplies power to the load circuit including thermistors and the microcontroller (hereinafter referred to as microcomputer as appropriate). Sometimes.
　また、多数の感知器が設置される場合、一つの電源回路に多数の負荷が接続されることがある。その際、起動時に多数の負荷から電流が引かれることにより、電源回路に過電流が流れたことによる誤検知を防止するため、出力電流制限付き電源回路が使用されることがある。 Also, when many sensors are installed, many loads may be connected to one power supply circuit. In this case, a power supply circuit with an output current limit is sometimes used in order to prevent erroneous detection due to overcurrent flowing into the power supply circuit due to current being drawn from many loads at startup.
特開平１０－３３４３６０号公報JP-A-10-334360
　出力電流制限付き電源回路の出力配線に大容量の電解コンデンサが接続される場合、小電流で大容量の電解コンデンサを充電する必要があるため、電源投入時の立ち上がりが遅くなる（秒オーダー）。これにより、マイコンの内部電源の立ち上がりも遅くなる。 When a large-capacity electrolytic capacitor is connected to the output wiring of a power supply circuit with an output current limit, it is necessary to charge the large-capacity electrolytic capacitor with a small current, resulting in a slow start-up when the power is turned on (on the order of seconds). As a result, the start-up of the internal power supply of the microcomputer is also delayed.
　量産化されるマイコンの中には、プロセスのバラツキ等により、内部電源が立ち上がる前に一瞬、不定領域が発生し、マイコン内に大きな貫通電流が流れるものがある。出力電流制限付き電源回路では、このマイコンから引かれる電流により、大容量の電解コンデンサに充電する電流が不足し、出力電圧の上昇が途中で停止することがある。出力電流制限付き電源回路の出力電圧が、マイコンの動作下限電圧未満で停止すると、マイコンが起動できなくなる。 Among mass-produced microcontrollers, due to variations in the process, there are some that generate an indeterminate area for a moment before the internal power supply starts up, causing a large through current to flow inside the microcontroller. In a power supply circuit with an output current limit, the current drawn from the microcomputer may run short of the current to charge the large-capacity electrolytic capacitor, causing the output voltage to stop rising partway through. If the output voltage of the power supply circuit with output current limit stops below the operating lower limit voltage of the microcomputer, the microcomputer cannot be started.
　本開示はこうした状況に鑑みなされたものであり、その目的は、出力電流制限付き電源回路の出力配線に大容量コンデンサが接続される電源構成において、マイコンの起動失敗を抑制することができる制御システム、感知器を提供することにある。 The present disclosure has been made in view of such circumstances, and its purpose is to provide a control system capable of suppressing startup failure of a microcomputer in a power supply configuration in which a large-capacity capacitor is connected to the output wiring of a power supply circuit with an output current limit. , to provide a sensor.
　上記課題を解決するために、本開示のある態様の制御システムは、入力電圧をもとに定電圧の電源電圧を生成するとともに、出力電流を所定値以下に制限する出力電流制限付き電源回路と、前記出力電流制限付き電源回路の出力配線と固定電位との間に接続される大容量コンデンサと、前記出力電流制限付き電源回路から入力される電源電圧を降圧して内部電源電圧を生成する定電圧回路と、生成された内部電源電圧をもとに内部スイッチング素子を駆動するための論理信号を生成する内部制御回路を含むマイクロコントローラと、前記マイクロコントローラ内の前記定電圧回路の立ち上がりをアシストするアシスト回路部と、を備える。 In order to solve the above problems, a control system according to one aspect of the present disclosure generates a constant power supply voltage based on an input voltage, and includes a power supply circuit with an output current limit that limits an output current to a predetermined value or less. a large-capacity capacitor connected between the output wiring of the power supply circuit with output current limitation and a fixed potential; A microcontroller that includes a voltage circuit, an internal control circuit that generates logic signals for driving internal switching elements based on the generated internal power supply voltage, and assists the startup of the constant voltage circuit in the microcontroller. and an assist circuit unit.
　本開示によれば、出力電流制限付き電源回路の出力配線に大容量コンデンサが接続される電源構成において、マイコンの起動失敗を抑制することができる。 According to the present disclosure, in a power supply configuration in which a large-capacity capacitor is connected to the output wiring of a power supply circuit with an output current limit, it is possible to suppress start-up failures of the microcomputer.
比較例に係る組込機器の概略回路構成を示す図である。FIG. 3 is a diagram showing a schematic circuit configuration of an embedded device according to a comparative example; 図２（ａ）－（ｂ）は、比較例に係る組込機器の具体的な回路構成例を示す図である。FIGS. 2A and 2B are diagrams showing specific circuit configuration examples of embedded devices according to comparative examples. 図３は、マイコンの一部の内部構成を示す図である。FIG. 3 is a diagram showing the internal configuration of part of the microcomputer. 実施の形態１に係る組込機器の概略回路構成を示す図である。1 is a diagram showing a schematic circuit configuration of an embedded device according to Embodiment 1; FIG. 図５（ａ）－（ｂ）は、実施の形態１に係る組込機器の具体的な回路構成例を示す図である。5(a) and 5(b) are diagrams showing specific circuit configuration examples of the embedded device according to the first embodiment. 図６（ａ）－（ｂ）は、比較例に係る組込機器の立ち上がり時と、実施の形態１に係る組込機器の立ち上がり時の電圧波形の遷移イメージを示した図である。FIGS. 6A and 6B are diagrams showing transition images of voltage waveforms when the embedded device according to the comparative example starts up and when the embedded device according to the first embodiment starts up. 図７（ａ）－（ｂ）は、実施の形態１に係る組込機器の立ち上がり時のシミュレーション例を示す図である。FIGS. 7(a) and 7(b) are diagrams showing simulation examples when the embedded device according to the first embodiment starts up. 実施の形態２に係る組込機器の概略回路構成を示す図である。3 is a diagram showing a schematic circuit configuration of an embedded device according to Embodiment 2; FIG. 実施の形態２に係る組込機器の具体的な回路構成例を示す図である。FIG. 10 is a diagram showing a specific circuit configuration example of an embedded device according to the second embodiment; 実施の形態２に係る組込機器の立ち上がり時の電圧波形の遷移イメージを示した図である。FIG. 10 is a diagram showing a transition image of voltage waveforms at the start-up of the embedded device according to the second embodiment;
　図１は、比較例に係る組込機器１の概略回路構成を示す図である。比較例に係る組込機器１は、制御システム１５及び負荷回路３０を備える。制御システム１５は、出力電流制限付き電源回路１０、大容量コンデンサＣ１、及びマイコン２０を含む。 FIG. 1 is a diagram showing a schematic circuit configuration of an embedded device 1 according to a comparative example. The embedded device 1 according to the comparative example has a control system 15 and a load circuit 30 . The control system 15 includes a power supply circuit 10 with output current limitation, a large-capacity capacitor C1, and a microcomputer 20. FIG.
　出力電流制限付き電源回路１０は、出力電流制限付きの定電圧ＡＣ－ＤＣ電源回路である。出力電流制限付き電源回路１０は、商用電力系統２から入力される交流電圧を直流電圧に変換し、変換した直流電圧を降圧して定電圧の直流電圧を出力する。出力電流制限付き電源回路１０は、出力電流を所定値（例えば、１００μＡ程度）以下に制限する機能を有する。出力電流制限付き電源回路１０は例えば、宅内のコンセントから供給される１００Ｖの交流電圧を２４Ｖの直流電圧に変換し、変換した２４Ｖの直流電圧を５Ｖの直流電圧に降圧して出力する。出力電流制限付き電源回路１０から出力される直流電圧は、マイコン２０及び負荷回路３０の電源電圧として使用される。 The power supply circuit 10 with output current limitation is a constant voltage AC-DC power supply circuit with output current limitation. The power supply circuit 10 with output current limit converts an AC voltage input from the commercial power system 2 into a DC voltage, steps down the converted DC voltage, and outputs a constant DC voltage. The power supply circuit 10 with output current limit has a function of limiting the output current to a predetermined value (for example, about 100 μA) or less. The power supply circuit 10 with output current limitation converts, for example, a 100V AC voltage supplied from an indoor outlet into a 24V DC voltage, and steps down the converted 24V DC voltage to a 5V DC voltage for output. A DC voltage output from the power supply circuit 10 with output current limit is used as a power supply voltage for the microcomputer 20 and the load circuit 30 .
　大容量コンデンサＣ１は、出力電流制限付き電源回路１０の出力配線と、基板のグランド電位との間に接続される。例えば、１００μＦ程度の電解コンデンサが使用される。 The large-capacity capacitor C1 is connected between the output wiring of the power supply circuit 10 with output current limit and the ground potential of the substrate. For example, an electrolytic capacitor of about 100 μF is used.
　マイコン２０は、出力電流制限付き電源回路１０から供給される電源電圧をもとに、負荷回路３０を制御する。なお、出力電流制限付き電源回路１０の出力電圧より、マイコン２０の電源電圧が低い場合、出力電流制限付き電源回路１０とマイコン２０との間に、ＬＤＯ (Low Dropout Linear Regulator)等のＤＣ－ＤＣコンバータが挿入される。例えば、マイコン２０の電源電圧が３Ｖに設定されている場合、ＤＣ－ＤＣコンバータは、出力電流制限付き電源回路１０から入力される５Ｖの直流電圧を、３Ｖの直流電圧に降圧する。 The microcomputer 20 controls the load circuit 30 based on the power supply voltage supplied from the power supply circuit 10 with output current limitation. If the power supply voltage of the microcomputer 20 is lower than the output voltage of the power supply circuit 10 with output current limitation, a DC-DC regulator such as an LDO (Low Dropout Linear Regulator) is placed between the power supply circuit 10 with output current limitation and the microcomputer 20. A converter is inserted. For example, when the power supply voltage of the microcomputer 20 is set to 3V, the DC-DC converter steps down the DC voltage of 5V input from the power supply circuit 10 with output current limitation to a DC voltage of 3V.
　図２（ａ）－（ｂ）は、比較例に係る組込機器１の具体的な回路構成例を示す図である。図２（ａ）は、組込機器１が熱感知器１ａの場合の回路構成例を示す。図２（ａ）に示す出力電流制限付き電源回路１０は、ＡＣ－ＤＣコンバータ、定電圧回路、及び電流制限回路を含む。 FIGS. 2(a) and 2(b) are diagrams showing specific circuit configuration examples of the embedded device 1 according to the comparative example. FIG. 2(a) shows a circuit configuration example when the embedded device 1 is a heat sensor 1a. The power supply circuit 10 with output current limitation shown in FIG. 2(a) includes an AC-DC converter, a constant voltage circuit, and a current limiting circuit.
　ＡＣ－ＤＣコンバータは、ダイオードブリッジ回路ＤＢ及びツェナーダイオードＺＤ１－ＺＤ３を含む。商用電力系統２の２入力端子間に、カソード端子同士が向き合うように、双方向ツェナーダイオードＺＤ１－ＺＤ２が直列に接続される。ダイオードブリッジ回路ＤＢは、２つのツェナーダイオードＺＤ１－ＺＤ２により規定された交流電圧を、全波整流して出力する。ツェナーダイオードＺＤ３は、ダイオードブリッジ回路ＤＢの出力配線とグランド電位との間に接続され、ダイオードブリッジ回路ＤＢから出力される全波整流波形を定電圧波形に整形する。 The AC-DC converter includes a diode bridge circuit DB and Zener diodes ZD1-ZD3. Bidirectional Zener diodes ZD1-ZD2 are connected in series between two input terminals of commercial power system 2 such that their cathode terminals face each other. Diode bridge circuit DB full-wave rectifies and outputs an AC voltage defined by two Zener diodes ZD1 and ZD2. The Zener diode ZD3 is connected between the output wiring of the diode bridge circuit DB and the ground potential, and shapes the full-wave rectified waveform output from the diode bridge circuit DB into a constant voltage waveform.
　定電圧回路は、ＮＰＮトランジスタＱ１、抵抗Ｒ１、及びツェナーダイオードＺＤ４を含む。ＮＰＮトランジスタＱ１のコレクタ端子はＡＣ－ＤＣコンバータの出力端子に接続される。ＡＣ－ＤＣコンバータの出力配線とグランド電位間に、抵抗Ｒ１と逆向きのツェナーダイオードＺＤ４が直列に接続される。抵抗Ｒ１とツェナーダイオードＺＤ４との接続点が、ＮＰＮトランジスタＱ１のベース端子に接続される。ＮＰＮトランジスタＱ１はエミッタフォロワとして動作し、ツェナー電圧に応じた電圧をエミッタ端子から出力する。具体的には、ベース端子に入力されるツェナー電圧から、ベース・エミッタ間飽和電圧ＶＢＥを引いた電圧をエミッタ端子から出力する。 The constant voltage circuit includes an NPN transistor Q1, a resistor R1, and a Zener diode ZD4. The collector terminal of NPN transistor Q1 is connected to the output terminal of the AC-DC converter. A resistor R1 and a reverse Zener diode ZD4 are connected in series between the output wiring of the AC-DC converter and the ground potential. A connection point between the resistor R1 and the Zener diode ZD4 is connected to the base terminal of the NPN transistor Q1. The NPN transistor Q1 operates as an emitter follower and outputs a voltage corresponding to the Zener voltage from the emitter terminal. Specifically, a voltage obtained by subtracting the base-emitter saturation voltage VBE from the Zener voltage input to the base terminal is output from the emitter terminal.
　電流制限回路は、ＮＰＮトランジスタＱ２、電流制限抵抗Ｒ２、及び逆流防止用のダイオードＤ１を含む。ＮＰＮトランジスタＱ１のエミッタ端子に、電流制限抵抗Ｒ２及びダイオードＤ１が直列に接続される。ＮＰＮトランジスタＱ２のエミッタ端子はダイオードＤ１のカソード端子に接続され、ＮＰＮトランジスタＱ２のベース端子はＮＰＮトランジスタＱ１のエミッタ端子に接続され、ＮＰＮトランジスタＱ２のコレクタ端子はＮＰＮトランジスタＱ１のベース端子に接続される。 The current limiting circuit includes an NPN transistor Q2, a current limiting resistor R2, and an anti-backflow diode D1. A current limiting resistor R2 and a diode D1 are connected in series to the emitter terminal of the NPN transistor Q1. The emitter terminal of NPN transistor Q2 is connected to the cathode terminal of diode D1, the base terminal of NPN transistor Q2 is connected to the emitter terminal of NPN transistor Q1, and the collector terminal of NPN transistor Q2 is connected to the base terminal of NPN transistor Q1. .
　電流制限抵抗Ｒ２とダイオードＤ１との間の電圧が、ＮＰＮトランジスタＱ２のベース・エミッタ間飽和電圧ＶＢＥより大きくなると、ＮＰＮトランジスタＱ２がターンオンし、ＮＰＮトランジスタＱ１のベース電流をバイパスする。これにより、ＮＰＮトランジスタＱ１のエミッタ電流が一定値以下に制限される。 When the voltage between the current limiting resistor R2 and the diode D1 becomes larger than the base-emitter saturation voltage VBE of the NPN transistor Q2, the NPN transistor Q2 turns on to bypass the base current of the NPN transistor Q1. As a result, the emitter current of NPN transistor Q1 is limited to a certain value or less.
　組込機器１が熱感知器１ａの場合、負荷回路３０は熱感知回路３０ａとなる。熱感知回路３０ａは、サーミスタＴ１及び抵抗３を含む。サーミスタＴ１と抵抗３は、出力電流制限付き電源回路１０の出力配線とグランド電位間に直列に接続される。マイコン２０は、サーミスタＴ１と抵抗３の分圧点電圧を監視する。サーミスタＴ１は、温度変化に対して抵抗値が変化する感温素子である。ＮＰＣサーミスタが使用される場合、温度上昇に応じて抵抗値が低下する。マイコン２０は例えば、周囲の温度上昇率が一定率以上になったとき、または一局所の周囲温度が一定以上になったとき、火災受信機（不図示）や中継器（不図示）に火災信号を送信する。 When the embedded device 1 is the heat sensor 1a, the load circuit 30 is the heat sensing circuit 30a. The thermal sensing circuit 30a includes a thermistor T1 and a resistor T3. The thermistor T1 and the resistor 3 are connected in series between the output wiring of the power supply circuit 10 with output current limit and the ground potential. The microcomputer 20 monitors the voltage dividing point of the thermistor T1 and resistor 3 . The thermistor T1 is a thermosensitive element whose resistance value changes with changes in temperature. When NPC thermistors are used, their resistance decreases with increasing temperature. For example, the microcomputer 20 sends a fire signal to a fire receiver (not shown) or a repeater (not shown) when the ambient temperature rise rate exceeds a certain rate, or when the local ambient temperature rises above a certain rate. to send.
　図２（ｂ）は、組込機器１が煙感知器１ｂの場合の回路構成例を示す。出力電流制限付き電源回路１０の構成は、図２（ａ）の出力電流制限付き電源回路１０と同様である。組込機器１が煙感知器１ｂの場合、負荷回路３０は煙感知回路３０ｂとなる。煙感知回路３０ｂは、発光ダイオードＬＤ、フォトダイオードＰＤ、ＮチャネルＭＯＳＦＥＴ（Ｍ１）、抵抗Ｒ４－Ｒ６、及びコンデンサＣ３を含む。 FIG. 2(b) shows a circuit configuration example when the embedded device 1 is the smoke sensor 1b. The configuration of the power supply circuit 10 with output current limitation is the same as that of the power supply circuit 10 with output current limitation of FIG. 2(a). When the embedded device 1 is the smoke sensor 1b, the load circuit 30 is the smoke sensor circuit 30b. Smoke sensing circuit 30b includes light emitting diode LD, photodiode PD, N-channel MOSFET (M1), resistors R4-R6, and capacitor C3.
　出力電流制限付き電源回路１０の出力配線とグランド電位間に、抵抗Ｒ５、発光ダイオードＬＤ、抵抗Ｒ６、ＮチャネルＭＯＳＦＥＴ（Ｍ１）が直列に接続される。抵抗Ｒ５と発光ダイオードＬＤとの接続点とグランド電位間にコンデンサＣ３が接続される。コンデンサＣ３は、発光ダイオードＬＤに流す電流を補う作用、及びノイズを除去する作用を担う。マイコン２０はＮチャネルＭＯＳＦＥＴ（Ｍ１）のゲート端子に駆動信号を入力して、発光ダイオードＬＤの点灯／消灯を制御する。ＮチャネルＭＯＳＦＥＴ（Ｍ１）のゲート端子にハイレベル信号が入力されると発光ダイオードＬＤが点灯し、ローレベル信号が入力されると発光ダイオードＬＤが消灯する。 A resistor R5, a light emitting diode LD, a resistor R6, and an N-channel MOSFET (M1) are connected in series between the output wiring of the power supply circuit 10 with output current limit and the ground potential. A capacitor C3 is connected between the connection point between the resistor R5 and the light emitting diode LD and the ground potential. The capacitor C3 serves to supplement the current flowing through the light emitting diode LD and to remove noise. The microcomputer 20 inputs a drive signal to the gate terminal of the N-channel MOSFET (M1) to control lighting/extinguishing of the light emitting diode LD. When a high level signal is input to the gate terminal of the N-channel MOSFET (M1), the light emitting diode LD is turned on, and when a low level signal is input, the light emitting diode LD is turned off.
　出力電流制限付き電源回路１０の出力配線とグランド電位間に、フォトダイオードＰＤと抵抗Ｒ４が直列に接続される。煙感知器１ｂのハウジング内において、フォトダイオードＰＤは、発光ダイオードＬＤからの直接光が入射しない位置に配置される。マイコン２０は、フォトダイオードＰＤと抵抗Ｒ４の分圧点電圧を監視する。ハウジング内に煙が流入すると、発光ダイオードＬＤの照射光が煙で拡散反射され、フォトダイオードＰＤにおける発光ダイオードＬＤからの受光量が増加し、フォトダイオードＰＤに流れる電流量が増加する。マイコン２０は例えば、分圧点電圧の変化から推定される煙濃度の変化が設定値を超えると、火災受信機（不図示）や中継器（不図示）に火災信号を送信する。 A photodiode PD and a resistor R4 are connected in series between the output wiring of the power supply circuit 10 with output current limit and the ground potential. In the housing of the smoke sensor 1b, the photodiode PD is arranged at a position where direct light from the light emitting diode LD does not enter. The microcomputer 20 monitors the voltage dividing point of the photodiode PD and resistor R4. When smoke flows into the housing, the light emitted from the light emitting diode LD is diffusely reflected by the smoke, the amount of light received from the light emitting diode LD increases in the photodiode PD, and the amount of current flowing through the photodiode PD increases. For example, the microcomputer 20 transmits a fire signal to a fire receiver (not shown) or a repeater (not shown) when a change in smoke density estimated from a change in voltage dividing point exceeds a set value.
　図３は、マイコン２０の一部の内部構成を示す図である。図３（ａ）に示すようにマイコン２０は、定電圧回路２１、ロジック制御回路２２、Ｉ／Ｏセル２３を含む。定電圧回路２１は、出力電流制限付き電源回路１０から入力される電源電圧ＶＤＤを降圧して内部電源電圧ＶＤ１（例えば、１．４Ｖ程度）を生成する。定電圧回路２１の出力配線が接続される端子とグランド電位との間に、安定化用のコンデンサＣ２（例えば、１μＦ程度）が接続される。 FIG. 3 is a diagram showing the internal configuration of part of the microcomputer 20. As shown in FIG. The microcomputer 20 includes a constant voltage circuit 21, a logic control circuit 22, and an I/O cell 23, as shown in FIG. 3(a). The constant voltage circuit 21 steps down the power supply voltage VDD input from the power supply circuit 10 with output current limitation to generate an internal power supply voltage VD1 (for example, about 1.4 V). A stabilizing capacitor C2 (for example, about 1 μF) is connected between the terminal to which the output wiring of the constant voltage circuit 21 is connected and the ground potential.
　定電圧回路２１は、１つ以上のトランジスタを含み、トランジスタの閾値電圧を利用して、内部電源電圧ＶＤ１を生成する。例えば、図２（ａ）－（ｂ）に示した定電圧回路（ＮＰＮトランジスタＱ１、抵抗Ｒ１、及びツェナーダイオードＺＤ４）のように構成することも可能である。 The constant voltage circuit 21 includes one or more transistors, and uses the threshold voltage of the transistors to generate the internal power supply voltage VD1. For example, it is possible to configure the constant voltage circuit (NPN transistor Q1, resistor R1, and Zener diode ZD4) shown in FIGS. 2(a) and 2(b).
　ロジック制御回路２２は、定電圧回路２１により生成された内部電源電圧ＶＤ１をもとに、内部回路（例えば、スイッチング素子）を駆動するための論理信号（Ｌ／Ｏ）を生成する。ロジック制御回路２２は例えば、ハイレベル信号を１．４Ｖ、ローレベル信号を０Ｖで生成する。 Based on the internal power supply voltage VD1 generated by the constant voltage circuit 21, the logic control circuit 22 generates a logic signal (L/O) for driving internal circuits (for example, switching elements). The logic control circuit 22 generates a high level signal at 1.4V and a low level signal at 0V, for example.
　マイコン２０内には、ポートごとにＩ／Ｏセル２３が設けられる。Ｉ／Ｏセル２３は一例として、入出力部２３ａ、プルアップ回路（不図示）、プルダウン回路を含む。プルダウン回路はＰチャネルＭＯＳＦＥＴ（Ｍ２）と抵抗Ｒ７を有し、ＰチャネルＭＯＳＦＥＴ（Ｍ２）と抵抗Ｒ７は、電源電圧ＶＤＤが印加される電源線と、グランド電位に接続されるグランド線との間に直列に接続される。 Within the microcomputer 20, an I/O cell 23 is provided for each port. The I/O cell 23 includes, for example, an input/output unit 23a, a pull-up circuit (not shown), and a pull-down circuit. The pull-down circuit has a P-channel MOSFET (M2) and a resistor R7, and the P-channel MOSFET (M2) and the resistor R7 are connected between the power supply line to which the power supply voltage VDD is applied and the ground line connected to the ground potential. connected in series.
　ＰチャネルＭＯＳＦＥＴ（Ｍ２）のソース端子が電源線に接続され、ＰチャネルＭＯＳＦＥＴ（Ｍ２）のドレイン端子と抵抗Ｒ７との間の接続点が入出力ポートに接続される。ＰチャネルＭＯＳＦＥＴ（Ｍ２）のゲート端子にはロジック制御回路２２からの論理信号が入力される。ＰチャネルＭＯＳＦＥＴ（Ｍ２）は、ソース端子に電源が供給された状態で、ロジック制御回路２２からゲート端子にハイレベル信号が入力されるとオフ状態、ローレベル信号が入力されるとオン状態となる。ロジック制御回路２２は、ＰチャネルＭＯＳＦＥＴ（Ｍ２）にローレベルを入力することにより、入出力ポートをハイレベルにプルアップすることができる。なお、ロジック制御回路２２は、プルダウン回路（不図示）を制御することにより、入出力ポートをローレベルにプルダウンすることもできる。なお、ＰチャネルＭＯＳＦＥＴ（Ｍ２）を用いたブルアップ回路は、マイコン２０内において、Ｉ／Ｏセル２３以外にも様々な箇所で使用される。 The source terminal of the P-channel MOSFET (M2) is connected to the power supply line, and the connection point between the drain terminal of the P-channel MOSFET (M2) and the resistor R7 is connected to the input/output port. A logic signal from the logic control circuit 22 is input to the gate terminal of the P-channel MOSFET (M2). The P-channel MOSFET (M2) turns off when a high level signal is input to the gate terminal from the logic control circuit 22 while power is supplied to the source terminal, and turns on when a low level signal is input. . The logic control circuit 22 can pull up the input/output port to a high level by inputting a low level to the P-channel MOSFET (M2). The logic control circuit 22 can also pull down the input/output port to a low level by controlling a pull-down circuit (not shown). A pull-up circuit using a P-channel MOSFET (M2) is used in various places other than the I/O cell 23 in the microcomputer 20. FIG.
　以上の回路構成において、組込機器１の起動時、電源電圧ＶＤＤが一定の電圧に到達すると、定電圧回路２１が内部電源電圧ＶＤ１の出力を開始する。 In the above circuit configuration, when the power supply voltage VDD reaches a certain voltage when the embedded device 1 is activated, the constant voltage circuit 21 starts outputting the internal power supply voltage VD1.
　マイコン２０に電源電圧ＶＤＤが印加されてから、定電圧回路２１が内部電源電圧ＶＤ１の出力を開始する前に、マイコン２０内で不定状態が発生し、マイコン２０内に電流が流れる場合がある。本来、マイコン２０の起動直後は、ＰチャネルＭＯＳＦＥＴ（Ｍ２）のゲート端子にロジック制御回路２２からハイレベル信号が入力され、ＰチャネルＭＯＳＦＥＴ（Ｍ２）はオフ状態に制御される。 After the power supply voltage VDD is applied to the microcomputer 20 and before the constant voltage circuit 21 starts outputting the internal power supply voltage VD1, an unstable state may occur within the microcomputer 20 and current may flow within the microcomputer 20. Essentially, immediately after the microcomputer 20 is started, a high level signal is input from the logic control circuit 22 to the gate terminal of the P-channel MOSFET (M2), and the P-channel MOSFET (M2) is controlled to be off.
　しかしながら、Ｉ／Ｏセル２３のプルダウン回路に電源電圧ＶＤＤが印加されてから、定電圧回路２１が内部電源電圧ＶＤ１の出力を開始する間に、ＰチャネルＭＯＳＦＥＴ（Ｍ２）のゲート端子にロジック制御回路２２からローレベル信号（０Ｖ）が入力されると、ＰチャネルＭＯＳＦＥＴ（Ｍ２）がオンしてしまう。この場合、ＰチャネルＭＯＳＦＥＴ（Ｍ２）と抵抗Ｒ７に貫通電流が流れる。 However, after the power supply voltage VDD is applied to the pull-down circuit of the I/O cell 23, during the period when the constant voltage circuit 21 starts outputting the internal power supply voltage VD1, the logic control circuit is connected to the gate terminal of the P-channel MOSFET (M2). 22, the P-channel MOSFET (M2) turns on. In this case, a through current flows through the P-channel MOSFET (M2) and the resistor R7.
　マイコン２０内には、ＰチャネルＭＯＳＦＥＴ（Ｍ２）のゲート端子にロジック制御回路２２からローレベル信号（０Ｖ）が入力されることにより貫通電流が流れてしまう回路が多数存在する。これにより、定電圧回路２１が立ち上がる前に、マイコン２０が出力電流制限付き電源回路１０から電流を引き始める場合が発生する。 In the microcomputer 20, there are many circuits in which through current flows when a low level signal (0V) is input from the logic control circuit 22 to the gate terminal of the P-channel MOSFET (M2). As a result, the microcomputer 20 may start drawing current from the power supply circuit 10 with output current limitation before the constant voltage circuit 21 starts up.
　そのマイコン２０の消費電流により、出力電流制限付き電源回路１０の電流制限機能が働き、大容量コンデンサＣ１へ充電する電流が不足し、電源電圧ＶＤＤの上昇が途中で停止してしまうことがあった。電源電圧ＶＤＤが途中で停止し、定電圧回路２１が立ち上がらないと、マイコン２０に貫通電流が流れ続けてしまい、電源電圧ＶＤＤがホールドしてしまう。電源電圧ＶＤＤがマイコン２０の動作下限電圧（例えば、１．２Ｖ程度）未満でホールドされてしまうと、マイコン２０が起動できなくなる。以下の実施の形態では、このマイコン２０の起動失敗を抑制することができる対策として、マイコン２０内の定電圧回路２１の立ち上がりをアシストするアシスト回路部を搭載した組込機器１を説明する。 Due to the current consumption of the microcomputer 20, the current limiting function of the power supply circuit 10 with output current limitation is activated, the current for charging the large-capacity capacitor C1 is insufficient, and the rise of the power supply voltage VDD may stop halfway. . If the power supply voltage VDD stops halfway and the constant voltage circuit 21 does not start up, a through current will continue to flow through the microcomputer 20 and the power supply voltage VDD will be held. If the power supply voltage VDD is held below the operating lower limit voltage (for example, about 1.2 V) of the microcomputer 20, the microcomputer 20 cannot be started. In the following embodiments, an embedded device 1 equipped with an assist circuit section for assisting startup of the constant voltage circuit 21 in the microcomputer 20 will be described as a countermeasure capable of suppressing start-up failure of the microcomputer 20 .
（実施の形態１）
　図４は、実施の形態１に係る組込機器１の概略回路構成を示す図である。実施の形態１に係る組込機器１は、図１に示した比較例に係る組込機器１に対して、定電圧回路２１のアシスト回路部としてカップリングコンデンサＣｃ（例えば、１μＦ程度）が追加される。カップリングコンデンサＣｃは、出力電流制限付き電源回路１０の出力配線と、定電圧回路２１の出力配線に接続されたマイコン２０の端子（ＶＤ１端子）間に接続される。 (Embodiment 1)
FIG. 4 is a diagram showing a schematic circuit configuration of the embedded device 1 according to the first embodiment. The embedded device 1 according to the first embodiment is different from the embedded device 1 according to the comparative example shown in FIG. be done. The coupling capacitor Cc is connected between the output wiring of the power supply circuit 10 with output current limit and the terminal (VD1 terminal) of the microcomputer 20 connected to the output wiring of the constant voltage circuit 21 .
　これにより、組込機器１の起動時に、出力電流制限付き電源回路１０からカップリングコンデンサＣｃを介して瞬時的にロジック制御回路２２に電圧を供給することができ、マイコン２０内で不定状態が発生することを防止することができる。 As a result, when the embedded device 1 is activated, voltage can be instantaneously supplied from the power supply circuit 10 with output current limitation to the logic control circuit 22 through the coupling capacitor Cc, and an unstable state occurs within the microcomputer 20. can be prevented.
　図５（ａ）－（ｂ）は、実施の形態１に係る組込機器１の具体的な回路構成例を示す図である。図５（ａ）－（ｂ）は、組込機器１が熱感知器１ａの場合の回路構成例を示す。図５（ｂ）に示す例では、マイコン２０のＶＤ１端子とグランド電位間に、ツェナーダイオードＺＤ６が接続される。ツェナーダイオードＺＤ６は、マイコン２０のＶＤ１端子の電圧が、ロジック制御回路２２の耐圧（例えば、２．５Ｖ程度）を超えないように、マイコン２０のＶＤ１端子の電圧上昇を制限する。 FIGS. 5(a) and 5(b) are diagrams showing specific circuit configuration examples of the embedded device 1 according to the first embodiment. FIGS. 5(a) and 5(b) show circuit configuration examples when the embedded device 1 is the heat sensor 1a. In the example shown in FIG. 5B, a Zener diode ZD6 is connected between the VD1 terminal of the microcomputer 20 and the ground potential. The Zener diode ZD6 limits the voltage rise of the VD1 terminal of the microcomputer 20 so that the voltage of the VD1 terminal of the microcomputer 20 does not exceed the withstand voltage of the logic control circuit 22 (for example, about 2.5 V).
　図６（ａ）－（ｂ）は、比較例に係る組込機器１の立ち上がり時と、実施の形態１に係る組込機器１の立ち上がり時の電圧波形の遷移イメージを示した図である。図６（ａ）は、比較例に係る組込機器１の立ち上がり時に、マイコン２０の消費電流により、電源電圧ＶＤＤが上昇途中でクランプされた例を示している。内部電源電圧ＶＤ１も上昇途中でクランプされる。 FIGS. 6(a) and 6(b) are diagrams showing transition images of voltage waveforms when the embedded device 1 according to the comparative example starts up and when the embedded device 1 according to the first embodiment starts up. FIG. 6A shows an example in which the power supply voltage VDD is clamped in the middle of the rise due to the consumption current of the microcomputer 20 when the embedded device 1 according to the comparative example starts up. The internal power supply voltage VD1 is also clamped on the way up.
　図６（ｂ）は、実施の形態１に係る組込機器１の立ち上がり時に、マイコン２０の内部電源電圧ＶＤ１の上昇を、カップリングコンデンサＣｃを介して出力電流制限付き電源回路１０の出力電圧でアシストする例を示している。マイコン２０の内部電源電圧ＶＤ１の上昇をアシストすることにより、ロジック制御回路２２が正常に動作し、マイコン２０内に貫通電流が流れることを抑制することができる。これにより、電源電圧ＶＤＤとマイコン２０の内部電源電圧ＶＤ１が正常な電圧まで上昇する。 FIG. 6B shows that when the embedded device 1 according to the first embodiment starts up, the rise in the internal power supply voltage VD1 of the microcomputer 20 is caused by the output voltage of the power supply circuit 10 with output current limitation via the coupling capacitor Cc. It shows an example to assist. By assisting the rise of the internal power supply voltage VD1 of the microcomputer 20, the logic control circuit 22 can operate normally and the flow of through current in the microcomputer 20 can be suppressed. As a result, the power supply voltage VDD and the internal power supply voltage VD1 of the microcomputer 20 rise to normal voltages.
　図７（ａ）－（ｂ）は、実施の形態１に係る組込機器１の立ち上がり時のシミュレーション例を示す図である。図７（ａ）は、コンデンサＣ２の容量を可変させた場合のシミュレーション結果を示している。組込機器１の立ち上がり時において、負荷側からの電流の引きに対して、出力電流制限付き電源回路１０の電流制限機能により、電流制限抵抗Ｒ２に流れる電流が１１０μＡ程度に抑えられている。電源電圧ＶＤＤが立ち上がると、電流制限抵抗Ｒ２に流れる電流は、数十μＡ程度まで低下する。 FIGS. 7(a) and 7(b) are diagrams showing simulation examples when the embedded device 1 according to the first embodiment starts up. FIG. 7(a) shows simulation results when the capacitance of the capacitor C2 is varied. When the embedded device 1 starts up, the current flowing through the current limiting resistor R2 is suppressed to about 110 μA by the current limiting function of the power supply circuit 10 with output current limitation with respect to the current drawn from the load side. When the power supply voltage VDD rises, the current flowing through the current limiting resistor R2 drops to about several tens of μA.
　マイコン２０の内部電源電圧ＶＤ１は、カップリングコンデンサＣｃを介したアシスト電圧を受けて上昇する。点線で示されるマイコン２０の内部電源電圧ＶＤ１’は、コンデンサＣ２の容量を１／１０程度に低下させた場合の例である。コンデンサＣ２の容量を小さくすると、ノイズ耐性は低下するが、起動時の内部電源電圧ＶＤ１の吊り上げ効果が強くなることが分かる。 The internal power supply voltage VD1 of the microcomputer 20 rises by receiving the assist voltage via the coupling capacitor Cc. The internal power supply voltage VD1' of the microcomputer 20 indicated by the dotted line is an example when the capacitance of the capacitor C2 is reduced to about 1/10. It can be seen that if the capacitance of the capacitor C2 is reduced, the noise resistance is lowered, but the effect of raising the internal power supply voltage VD1 at startup is enhanced.
　図７（ｂ）は、カップリングコンデンサＣｃの容量を可変させた場合のシミュレーション結果を示している。点線で示されるマイコン２０の内部電源電圧ＶＤ１’は、カップリングコンデンサＣｃの容量を２／３程度に低下させた場合の例である。カップリングコンデンサＣｃの容量が大きいほど、起動時の内部電源電圧ＶＤ１の吊り上げ効果が強くなることが分かる。 FIG. 7(b) shows simulation results when the capacitance of the coupling capacitor Cc is varied. The internal power supply voltage VD1' of the microcomputer 20 indicated by the dotted line is an example when the capacitance of the coupling capacitor Cc is reduced to about 2/3. It can be seen that the larger the capacitance of the coupling capacitor Cc, the stronger the effect of raising the internal power supply voltage VD1 at startup.
（実施の形態２）
　図８は、実施の形態２に係る組込機器１の概略回路構成を示す図である。実施の形態２に係る組込機器１は、図１に示した比較例に係る組込機器１に対して、定電圧回路２１のアシスト回路部として、遅延回路２５ａ及びスイッチ回路２５ｂが追加される。スイッチ回路２５ｂは、出力電流制限付き電源回路１１の出力配線上において、大容量コンデンサＣ１の接続点と、マイコン２０の接続点との間に挿入される。 (Embodiment 2)
FIG. 8 is a diagram showing a schematic circuit configuration of the embedded device 1 according to the second embodiment. The embedded device 1 according to the second embodiment is different from the embedded device 1 according to the comparative example shown in FIG. . The switch circuit 25b is inserted between the connection point of the large-capacity capacitor C1 and the connection point of the microcomputer 20 on the output wiring of the power supply circuit 11 with output current limitation.
　遅延回路２５ａは、組込機器１の立ち上がり時において、大容量コンデンサＣ１の充電開始後から所定時間経過後に、スイッチ回路２５ｂをターンオンさせる。所定時間は、大容量コンデンサＣ１の充電に必要な時間以上の時間に設定される。 When the embedded device 1 starts up, the delay circuit 25a turns on the switch circuit 25b after a predetermined time has passed since the start of charging the large-capacity capacitor C1. The predetermined time is set to be longer than the time required for charging the large-capacity capacitor C1.
　図９は、実施の形態２に係る組込機器１の具体的な回路構成例を示す図である。遅延回路２５ａは、抵抗Ｒ９及びコンデンサＣ４を含む。抵抗Ｒ９とコンデンサＣ４は、出力電流制限付き電源回路１０の出力配線とグランド電位間に直列に接続される。 FIG. 9 is a diagram showing a specific circuit configuration example of the embedded device 1 according to the second embodiment. Delay circuit 25a includes resistor R9 and capacitor C4. The resistor R9 and the capacitor C4 are connected in series between the output wiring of the power supply circuit 10 with output current limit and the ground potential.
　スイッチ回路２５ｂは、ＰチャネルＭＯＳＦＥＴ（Ｍ３）、ＮＰＮトランジスタＱ４、及び抵抗Ｒ１０－Ｒ１１を含む。出力電流制限付き電源回路１１の出力配線上において、ＰチャネルＭＯＳＦＥＴ（Ｍ３）のソース端子は大容量コンデンサＣ１の接続点側に接続され、ＰチャネルＭＯＳＦＥＴ（Ｍ３）のドレイン端子はマイコン２０の接続点側に接続される。ＰチャネルＭＯＳＦＥＴ（Ｍ３）のソース端子とゲート端子間に抵抗Ｒ１１が接続される。ＮＰＮトランジスタＱ４のエミッタ端子はグランド電位に接続され、ＮＰＮトランジスタＱ４のベース端子は、抵抗Ｒ１０を介して抵抗Ｒ９とコンデンサＣ４との間の接続点に接続される。ＮＰＮトランジスタＱ４のコレクタ端子はＰチャネルＭＯＳＦＥＴ（Ｍ３）のゲート端子に接続される。 The switch circuit 25b includes a P-channel MOSFET (M3), an NPN transistor Q4, and resistors R10-R11. On the output wiring of the power supply circuit 11 with output current limit, the source terminal of the P-channel MOSFET (M3) is connected to the connection point side of the large-capacity capacitor C1, and the drain terminal of the P-channel MOSFET (M3) is the connection point of the microcomputer 20. connected to the side. A resistor R11 is connected between the source terminal and the gate terminal of the P-channel MOSFET (M3). The emitter terminal of NPN transistor Q4 is connected to the ground potential, and the base terminal of NPN transistor Q4 is connected via resistor R10 to the connection point between resistor R9 and capacitor C4. The collector terminal of NPN transistor Q4 is connected to the gate terminal of P-channel MOSFET (M3).
　組込機器１の立ち上がり時、ＮＰＮトランジスタＱ４のベース端子に入力される電圧は、抵抗Ｒ９とコンデンサＣ４の時定数により、出力電流制限付き電源回路１１の出力電圧より遅れて立ち上がる。大容量コンデンサＣ１の電圧が十分に上昇した後、または大容量コンデンサＣ１の充電が完了した後、ＮＰＮトランジスタＱ４がターンオンし、ＰチャネルＭＯＳＦＥＴ(Ｍ３)がターンオンする。なお、リセットＩＣ（不図示）を使用して、出力電流制限付き電源回路１１の出力電圧の立ち上がりから所定時間後に、ＮＰＮトランジスタＱ４をターンオンさせてもよい。 When the embedded device 1 starts up, the voltage input to the base terminal of the NPN transistor Q4 rises with a delay from the output voltage of the power supply circuit 11 with output current limitation due to the time constant of the resistor R9 and the capacitor C4. After the voltage of the large-capacity capacitor C1 rises sufficiently, or after the charging of the large-capacity capacitor C1 is completed, the NPN transistor Q4 turns on and the P-channel MOSFET (M3) turns on. A reset IC (not shown) may be used to turn on the NPN transistor Q4 after a predetermined time has passed since the output voltage of the power supply circuit 11 with output current limit rises.
　図１０は、実施の形態２に係る組込機器１の立ち上がり時の電圧波形の遷移イメージを示した図である。実施の形態２に係る組込機器１の立ち上がり時において、出力電流制限付き電源回路１０の出力電圧Ｖｏｕｔが上昇するが、スイッチ回路２５ｂがオフ状態であるため、電源電圧ＶＤＤは上昇しない。スイッチ回路２５ｂがターンオンされると電源電圧ＶＤＤの上昇が開始する。出力電流制限付き電源回路１０の出力電圧Ｖｏｕｔは、スイッチ回路２５ｂがターンオンされると、一旦、降下する。 FIG. 10 is a diagram showing a transition image of voltage waveforms at startup of the embedded device 1 according to the second embodiment. When the embedded device 1 according to the second embodiment starts up, the output voltage Vout of the power supply circuit 10 with output current limitation rises, but the power supply voltage VDD does not rise because the switch circuit 25b is in the off state. When the switch circuit 25b is turned on, the power supply voltage VDD starts to rise. The output voltage Vout of the power supply circuit 10 with output current limitation once drops when the switch circuit 25b is turned on.
　スイッチ回路２５ｂがターンオンされた時点では負荷側のコンデンサに電荷が蓄積されていないため、大容量コンデンサＣ１に蓄積された電荷が負荷側のコンデンサと分配される。設計者は、スイッチ回路２５ｂのターンオン時の、出力電流制限付き電源回路１０の出力電圧Ｖｏｕｔの低下が、マイコン２０の起動に影響を与えないように、各素子の定数を設計する必要がある。 When the switch circuit 25b is turned on, no charge is accumulated in the load-side capacitor, so the charge accumulated in the large-capacity capacitor C1 is distributed to the load-side capacitor. A designer needs to design the constants of each element so that the drop in the output voltage Vout of the power supply circuit 10 with output current limit when the switch circuit 25b is turned on does not affect the startup of the microcomputer 20.
　以上説明したように本実施の形態によれば、出力電流制限付き電源回路１０の出力配線に大容量コンデンサＣ１が接続されている電源構成において、マイコン２０内の定電圧回路２１の立ち上がりをアシストする回路を設けたことにより、マイコン２０の起動失敗を抑制することができる。マイコン２０自体に改良を加える必要がないため、低消費で安価な汎用品のマイコン２０をそのまま使用することができる。 As described above, according to the present embodiment, in a power supply configuration in which a large-capacity capacitor C1 is connected to the output wiring of the power supply circuit 10 with an output current limit, startup of the constant voltage circuit 21 in the microcomputer 20 is assisted. By providing the circuit, startup failure of the microcomputer 20 can be suppressed. Since the microcomputer 20 itself does not need to be improved, the general-purpose microcomputer 20 that consumes less power and is inexpensive can be used as it is.
　実施の形態１では、カップリングコンデンサＣｃと、必要に応じてツェナーダイオードＺＤ６を追加するだけで足り、部品点数の増加を最小限に抑えることができる。したがって、回路面積やコストの上昇も最小限に抑えることができる。追加部品により消費電流は殆ど増加しない。実施の形態２では、大容量コンデンサＣ１が充電された状態でマイコン２０の立ち上げを開始するため、より確実にマイコン２０を立ち上げることができる。 In Embodiment 1, it is sufficient to add the coupling capacitor Cc and, if necessary, the Zener diode ZD6, and the increase in the number of parts can be minimized. Therefore, increases in circuit area and cost can be minimized. The additional parts hardly increase the current consumption. In the second embodiment, the start-up of the microcomputer 20 is started while the large-capacity capacitor C1 is charged, so the microcomputer 20 can be started up more reliably.
　以上、本開示を実施の形態をもとに説明した。実施の形態は例示であり、それらの各構成要素や各処理プロセスの組み合わせにいろいろな変形例が可能なこと、またそうした変形例も本開示の範囲にあることは当業者に理解されるところである。 The present disclosure has been described above based on the embodiment. It is to be understood by those skilled in the art that the embodiment is an example, and that various modifications are possible in the combination of each component and each treatment process, and such modifications are also within the scope of the present disclosure. .
　上述した実施の形態１、２では、商用電力系統２から電源が供給される組込機器１を想定した。この点、本開示の技術は、電池から電源が供給される組込機器１にも適用可能である。その場合、出力電流制限付き電源回路１０は、ＡＣ－ＤＣコンバータではなく、ＤＣ－ＤＣコンバータを含む。 In the first and second embodiments described above, the embedded device 1 to which power is supplied from the commercial power system 2 is assumed. In this regard, the technology of the present disclosure can also be applied to the embedded device 1 to which power is supplied from a battery. In that case, the output current limited power supply circuit 10 includes a DC-DC converter instead of an AC-DC converter.
　また、本開示の技術は、出力電流制限付き電源回路１０の出力配線に大容量コンデンサＣ１が接続されている電源構成のマイコン２０を搭載する組込機器１であれば、感知器以外にも適用可能である。特に組込機器１のシステムを低消費化する場合に最適である。 In addition, the technology of the present disclosure can be applied to other than the sensor as long as it is an embedded device 1 equipped with a microcomputer 20 having a power supply configuration in which a large-capacity capacitor C1 is connected to the output wiring of the power supply circuit 10 with output current limitation. It is possible. In particular, it is most suitable for reducing the power consumption of the system of the embedded device 1 .
　なお、実施の形態は、以下の項目によって特定されてもよい。 The embodiment may be specified by the following items.
［項目１］
　入力電圧をもとに定電圧の電源電圧を生成するとともに、出力電流を所定値以下に制限する出力電流制限付き電源回路（１０）と、
　前記出力電流制限付き電源回路（１０）の出力配線と固定電位との間に接続される大容量コンデンサ（Ｃ１）と、
　前記出力電流制限付き電源回路（１０）から入力される電源電圧を降圧して内部電源電圧を生成する定電圧回路（２１）と、生成された内部電源電圧をもとに内部スイッチング素子（Ｍ１）を駆動するための論理信号を生成する内部制御回路（２２）を含むマイクロコントローラ（２０）と、
　前記マイクロコントローラ（２０）内の前記定電圧回路（２１）の立ち上がりをアシストするアシスト回路部と、
　を備える制御システム（１５）。
　これによれば、マイクロコントローラ（２０）の起動失敗を抑制することができる。
［項目２］
　前記アシスト回路部は、
　前記出力電流制限付き電源回路（１０）の出力配線と、前記定電圧回路（２１）の出力配線に接続された前記マイクロコントローラ（２０）の端子間に接続されるカップリングコンデンサ（Ｃｃ）を含む、
　項目１に記載の制御システム（１５）。
　これによれば、マイクロコントローラ（２０）の起動失敗を抑制する対策を、カップリングコンデンサ（Ｃｃ）１点で低コストかつ消費電力増加無しで実現することができる。
［項目３］
　前記アシスト回路部は、
　前記定電圧回路（２１）の出力配線に接続された前記マイクロコントローラ（２０）の端子と前記固定電位との間に接続されるツェナーダイオード（ＺＤ６）をさらに含む、
　項目２に記載の制御システム（１５）。
　これによれば、マイクロコントローラ（２０）内の内部電源電圧で動作する回路を、過電圧から保護することができる。
［項目４］
　前記アシスト回路部は、
　前記出力電流制限付き電源回路（１０）の出力配線上において、前記大容量コンデンサ（Ｃ１）の接続点と、前記マイクロコントローラ（２０）の接続点との間に挿入されるスイッチ回路（２５ｂ）を含み、
　前記スイッチ回路（２５ｂ）は、立ち上がり時において前記大容量コンデンサ（Ｃ１）の充電開始から所定時間経過後に、ターンオンする、
　項目１に記載の制御システム（１５）。
　これによれば、より確実にマイクロコントローラ（２０）の起動失敗を抑制することができる。
［項目５］
　熱または煙を感知する感知回路（３０ａ、３０ｂ）と、
　前記感知回路（３０ａ、３０ｂ）を制御する項目１から４のいずれか１項に記載の制御システム（１５）と、
　を備える感知器（１ａ、１ｂ）。
　これによれば、マイクロコントローラ（２０）の起動失敗が抑制された感知器（１ａ、１ｂ）を実現することができる。 [Item 1]
a power supply circuit (10) with an output current limit that generates a constant power supply voltage based on an input voltage and limits an output current to a predetermined value or less;
a large-capacity capacitor (C1) connected between the output wiring of the power supply circuit (10) with output current limit and a fixed potential;
A constant voltage circuit (21) for stepping down the power supply voltage input from the power supply circuit (10) with output current limit to generate an internal power supply voltage, and an internal switching element (M1) based on the generated internal power supply voltage a microcontroller (20) including an internal control circuit (22) for generating logic signals to drive the
an assist circuit unit that assists the startup of the constant voltage circuit (21) in the microcontroller (20);
A control system (15) comprising:
According to this, it is possible to suppress start-up failure of the microcontroller (20).
[Item 2]
The assist circuit unit
including a coupling capacitor (Cc) connected between the output wiring of the power supply circuit (10) with output current limit and the terminals of the microcontroller (20) connected to the output wiring of the constant voltage circuit (21). ,
A control system (15) according to item 1.
According to this, countermeasures for suppressing start-up failure of the microcontroller (20) can be realized with a single coupling capacitor (Cc) at low cost and without an increase in power consumption.
[Item 3]
The assist circuit unit
further comprising a Zener diode (ZD6) connected between the terminal of the microcontroller (20) connected to the output wiring of the constant voltage circuit (21) and the fixed potential;
A control system (15) according to item 2.
According to this, the circuit operating on the internal power supply voltage in the microcontroller (20) can be protected from overvoltage.
[Item 4]
The assist circuit unit
a switch circuit (25b) inserted between the connection point of the large-capacity capacitor (C1) and the connection point of the microcontroller (20) on the output wiring of the power supply circuit (10) with output current limitation; including
The switch circuit (25b) is turned on after a predetermined time has elapsed from the start of charging of the large-capacity capacitor (C1) at the rising time.
A control system (15) according to item 1.
According to this, it is possible to more reliably suppress failures in starting the microcontroller (20).
[Item 5]
a sensing circuit (30a, 30b) for sensing heat or smoke;
a control system (15) according to any one of items 1 to 4 for controlling said sensing circuits (30a, 30b);
sensors (1a, 1b) comprising:
According to this, it is possible to realize the sensors (1a, 1b) in which activation failure of the microcontroller (20) is suppressed.
　本開示は、熱感知器や煙感知器に利用可能である。 The present disclosure can be used for heat sensors and smoke sensors.
　１　組込機器、　１ａ　熱感知器、　１ｂ　煙感知器、　２　商用電力系統、　１０　出力電流制限付き電源回路、　１５　制御システム、　２０　マイコン、　２１　定電圧回路、　２２　ロジック制御回路、　２３　Ｉ／Ｏセル、　２３ａ　入出力部、　２５ａ　遅延回路、　２５ｂ　スイッチ回路、　３０　負荷回路、　３０ａ　熱感知回路、　３０ｂ　煙感知回路、　Ｃ１　大容量コンデンサ、　Ｃ２－Ｃ４　コンデンサ、　Ｃｃ　カップリングコンデンサ、　Ｒ１－Ｒ１１　抵抗、　Ｑ１－Ｑ４　ＮＰＮトランジスタ、　Ｍ１　ＮチャネルＭＯＳＦＥＴ、　Ｍ２　ＰチャネルＭＯＳＦＥＴ、　Ｍ３　ＰチャネルＭＯＳＦＥＴ、　ＤＢ　ダイオードブリッジ回路、　Ｄ１　ダイオード、　ＺＤ１－ＺＤ６　ツェナーダイオード、　Ｔ１　サーミスタ、　ＰＤ　フォトダイオード、　ＬＤ　発光ダイオード。 1 Embedded device, 1a Heat sensor, 1b Smoke sensor, 2 Commercial power system, 10 Power supply circuit with output current limit, 15 Control system, 20 Microcomputer, 21 Constant voltage circuit, 22 Logic control circuit, 23 I/O cell , 23a input/output unit, 25a delay circuit, 25b switch circuit, 30 load circuit, 30a heat sensing circuit, 30b smoke sensing circuit, C1 large capacity capacitor, C2-C4 capacitor, Cc coupling capacitor, R1-R11 resistor, Q1- Q4 NPN transistor, M1 N-channel MOSFET, M2 P-channel MOSFET, M3 P-channel MOSFET, DB diode bridge circuit, D1 diode, ZD1-ZD6 Zener diode, T1 thermistor, PD photodiode, LD light emitting diode.

Claims (5)

  1. 　入力電圧をもとに定電圧の電源電圧を生成するとともに、出力電流を所定値以下に制限する出力電流制限付き電源回路と、
    　前記出力電流制限付き電源回路の出力配線と固定電位との間に接続される大容量コンデンサと、
    　前記出力電流制限付き電源回路から入力される電源電圧を降圧して内部電源電圧を生成する定電圧回路と、生成された内部電源電圧をもとに内部スイッチング素子を駆動するための論理信号を生成する内部制御回路を含むマイクロコントローラと、
    　前記マイクロコントローラ内の前記定電圧回路の立ち上がりをアシストするアシスト回路部と、
    　を備える制御システム。     a power supply circuit with an output current limit that generates a constant power supply voltage based on the input voltage and limits the output current to a predetermined value or less;
    a large-capacity capacitor connected between the output wiring of the power supply circuit with output current limit and a fixed potential;
    A constant voltage circuit that steps down the power supply voltage input from the power supply circuit with output current limit to generate an internal power supply voltage, and a logic signal for driving an internal switching element is generated based on the generated internal power supply voltage. a microcontroller containing internal control circuitry for
    an assist circuit unit that assists the startup of the constant voltage circuit in the microcontroller;
    A control system with
  2. 　前記アシスト回路部は、
    　前記出力電流制限付き電源回路の出力配線と、前記定電圧回路の出力配線に接続された前記マイクロコントローラの端子間に接続されるカップリングコンデンサを含む、
    　請求項１に記載の制御システム。     The assist circuit unit
    a coupling capacitor connected between the output wiring of the power supply circuit with output current limit and the terminal of the microcontroller connected to the output wiring of the constant voltage circuit;
    A control system according to claim 1 .
  3. 　前記アシスト回路部は、
    　前記定電圧回路の出力配線に接続された前記マイクロコントローラの端子と前記固定電位との間に接続されるツェナーダイオードをさらに含む、
    　請求項２に記載の制御システム。     The assist circuit unit
    further comprising a Zener diode connected between a terminal of the microcontroller connected to the output wiring of the constant voltage circuit and the fixed potential;
    3. A control system according to claim 2.
  4. 　前記アシスト回路部は、
    　前記出力電流制限付き電源回路の出力配線上において、前記大容量コンデンサの接続点と、前記マイクロコントローラの接続点との間に挿入されるスイッチ回路を含み、
    　前記スイッチ回路は、立ち上がり時において前記大容量コンデンサの充電開始から所定時間経過後に、ターンオンする、
    　請求項１に記載の制御システム。     The assist circuit unit
    a switch circuit inserted between a connection point of the large-capacity capacitor and a connection point of the microcontroller on the output wiring of the power supply circuit with output current limitation,
    The switch circuit is turned on after a predetermined time has elapsed from the start of charging of the large-capacity capacitor at the rising time.
    A control system according to claim 1 .
  5. 　熱または煙を感知する感知回路と、
    　前記感知回路を制御する請求項１から４のいずれか１項に記載の制御システムと、
    　を備える感知器。     a sensing circuit for sensing heat or smoke;
    a control system according to any one of claims 1 to 4 for controlling the sensing circuit;
    sensor with
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10334360A (en) * 1997-05-27 1998-12-18 Matsushita Electric Works Ltd Digital heat sensor and digital heat sensor for house
JPH11213261A (en) * 1998-01-27 1999-08-06 Hochiki Corp Fire sensor

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH10334360A (en) * 1997-05-27 1998-12-18 Matsushita Electric Works Ltd Digital heat sensor and digital heat sensor for house
JPH11213261A (en) * 1998-01-27 1999-08-06 Hochiki Corp Fire sensor

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