Single-key on-off circuit and chip

Abstract

The utility model discloses a single-key on-off circuit and a chip. The single-key on-off circuit comprises a connection point; a pull-up circuit; one end of the key is connected with the connection point, and the other end is grounded; the input end of the state detection input circuit is connected with the connection point; the output end of the amplitude limiting output circuit is connected with the connection point; the amplitude limiting output circuit comprises a switch and a voltage stabilizing circuit which are connected in series; the input end of the control unit is connected with the state detection input circuit, and the output end is connected with the switch; and a power switch circuit with a driving end connected with the connection point, an input end connected with a power supply and an output end outputting a controlled power supply. The circuit is simple in structure, high in integration level, small in size and low in cost, and saves standby power consumption and the number of pins.

Description

Technical Field

[0001] The utility model relates to the technical field of electronic product on / off switches, and in particular to a single-button on / off switch circuit and a chip. Background Art

[0002] For electronic products with relatively large static power consumption, a power on / off circuit is usually designed to take battery life into consideration. In order to save resources and reduce size, a single-button power on / off circuit is preferred. Press once to turn on the device, and press again to turn it off. Of course, the time factor can also be added to design short press and long press to distinguish between power on and off. Common single-button power on / off circuits include: Figure 1 As shown, it usually takes up two I / O pins of the microcontroller (MCU), one PIN1 is used to detect key input, and one PIN2 is used to self-lock output to control the power switch tube. Occupying two I / O pins is relatively costly for a microcontroller with a small number of pins, and it also has many peripheral components and a large size. Summary of the invention

[0003] Purpose of the invention: In order to solve the problem in the prior art that the single-button power on / off circuit is complex and occupies more chip pins, the utility model provides a single-button power on / off circuit and chip.

[0004] Technical solution: A single-button power on / off circuit, comprising:

[0005] Connect the dots;

[0006] A pull-up circuit, one end of which is connected to the connection point, and the other end is connected to the power supply, and the power supply voltage is VDD;

[0007] A button, one end of which is connected to the connection point and the other end is grounded;

[0008] A state detection input circuit, the input terminal is connected to the connection point, and the state threshold voltage is VI;

[0009] The limiting output circuit has an output end connected to the connection point, and the limiting voltage is VOL when the low level output is performed; the limiting output circuit includes a switch and a voltage stabilizing circuit, and the switch and the voltage stabilizing circuit are connected in series;

[0010] A control unit, the input end of which is connected to a state detection input circuit, and the output end of which is connected to the switch;

[0011] A power switch circuit, wherein the driving end is connected to the connection point, the input end is connected to the power supply, and the output end outputs the controlled power supply, and the start-up voltage of the power switch circuit is VTH;

[0012] Among them, VDD-VOL>VTH, and VOL>VI.

[0013] Furthermore, it also includes a capacitor, one end of which is connected to the connection point, and the other end of which is connected to a power supply or a ground.

[0014] Furthermore, the state detection input circuit adopts a Schmitt input structure, and a rising edge threshold voltage and a falling edge threshold voltage of the Schmitt input are both lower than VOL.

[0015] Furthermore, the pull-up circuit is a pull-up resistor or a pull-up current.

[0016] Furthermore, the voltage stabilizing circuit includes one or more voltage stabilizing devices or equivalent voltage stabilizing devices, and multiple voltage stabilizing devices or equivalent voltage stabilizing devices are connected in series. The equivalent voltage stabilizing device includes one or more of a diode, a triode, a resistor, and a MOS tube with a gate and a drain short-circuited.

[0017] Furthermore, the power switch circuit includes a switch tube, and the switch tube is a P-type MOSFET device or a PMOS tube integrated in a chip.

[0018] Furthermore, the control unit is a submodule of a hardware logic circuit or a microcontroller.

[0019] A chip integrates the pull-up circuit, state detection input circuit, amplitude limiting output circuit and control unit in the above-mentioned single-button switch circuit; and also includes a pin, and the connection point is connected to the pin.

[0020] Furthermore, the chip is a microcontroller chip, the pins are I / O pins, and the control unit is a submodule of the microcontroller.

[0021] Furthermore, the pull-up circuit, state detection input circuit, and limiting output circuit respectively reuse the pin pull-up unit, pin input unit, and pin output unit on the I / O pin of the microcontroller chip, and the limiting output circuit is connected in series on the low-level output path of the I / O pin.

[0022] Compared with the prior art, the single-button on / off circuit and chip provided by the present invention have the following effects:

[0023] The single-button switch circuit has a simple structure, high integration, and simplified peripheral components.

[0024] Only one I / O pin of the chip is needed, saving the number of I / O pins.

[0025] No static current is consumed in shutdown state, saving standby power consumption;

[0026] The single-button power on / off circuit can be built into a microcontroller (MCU), supports I / O pin multiplexing, and can reuse the pin pull-up unit, pin input unit, and pin output unit on the MCU pin. It has a small size and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A schematic diagram of a single-button power on / off circuit in the prior art;

[0028] Figure 2 This is a schematic diagram of a single-button power on / off circuit in Embodiment 1;

[0029] Figure 3 This is a schematic diagram of a single-button power on / off circuit in Embodiment 2;

[0030] Figure 4 This is a schematic diagram of the structure of the chip of Example 3;

[0031] Figure 5 This is a schematic diagram of the structure of the microcontroller chip of Example 4. DETAILED DESCRIPTION

[0032] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments.

[0033] Embodiment 1

[0034] A single button switch circuit, such as Figure 2 As shown, it includes a connection point A, a pull-up circuit, a button, a state detection input circuit, a limiting output circuit, a control unit, and a power switch circuit.

[0035] The pull-up circuit has one end connected to the connection point A and the other end connected to the power supply, the power supply voltage is VDD, and in this embodiment, it is 4 V. The pull-up circuit can be a pull-up resistor or a pull-up current, and in this embodiment, a pull-up resistor Rpu is used.

[0036] One end of the button K is connected to the connection point A, and the other end is grounded.

[0037] The state detection input circuit has an input end connected to the connection point A, and the state threshold voltage is VI. The state detection input circuit can be implemented using a comparator, or a common I / O pin input circuit, and its flip voltage only needs to be set to VI. When the voltage at the connection point A is lower than VI, the key valid state is input to the control unit. Preferably, the state detection input circuit can adopt a Schmitt input structure, and the rising edge threshold voltage and the falling edge threshold voltage of the Schmitt input are both lower than the limiting voltage VOL of the connection point A. The voltage disturbance at the connection point A can be filtered through voltage hysteresis. For example, in this embodiment, the rising edge threshold voltage VIR is set to 1.2V, the falling edge threshold voltage VIF is set to 0.8V, and VOL is designed to be 1.4V.

[0038] The limiting output circuit has an output end connected to the connection point A, and the limiting voltage is VOL when the low level output is performed; the limiting output circuit includes a switch M1 and a voltage stabilizing circuit, and the switch M1 is connected in series with the voltage stabilizing circuit. The voltage stabilizing circuit includes one or more voltage stabilizing devices D1 or equivalent voltage stabilizing devices. If there are multiple voltage stabilizing devices or equivalent voltage stabilizing devices, multiple devices are connected in series. The equivalent voltage stabilizing device can be a diode, a triode, a MOS tube with a short circuit between the gate and the drain, etc. For applications where the power supply voltage VDD is relatively certain, the voltage stabilizing circuit can also be implemented by a series resistor, which forms a voltage divider with the pull-up resistor Rpu, or forms a voltage drop with the pull-up current. The voltage stabilizing circuit here does not need precise voltage stabilization, but only needs to roughly limit the output voltage VOL so that VOL is higher than the state threshold voltage VI of the state detection input circuit.

[0039] A control unit, wherein the input end is connected to the state detection input circuit, and the output end is connected to the switch. The control unit is implemented by a hardware logic circuit or a submodule of a microcontroller. Its function is: when a signal of a key valid state input by the state detection input circuit is received, the state of the switch in the limiting output circuit is switched. The state detection received here can be a single key press or a key press of different durations, such as a long press or a short press. When the state detection only detects a key press without distinguishing the duration, no matter how long the key is pressed, the key state is considered valid, and the control unit triggers the switch action. When the duration of the key press is distinguished, the control unit switches the state of the switch according to the duration of the key press, such as a long press of the key to turn on the switch, a short press of the key to turn off the switch, etc.

[0040] The power switch circuit has a driving end connected to the connection point A, an input end connected to the power supply, and an output end outputting a controlled power supply, which is used to power the target device. The start voltage of the power switch circuit is VTH, and VTH is 1V in this embodiment. The power switch circuit includes a switch tube P1, such as Figure 2 As shown, the switch tube adopts a P-type MOSFET device, and can also be a PMOS tube integrated in the chip.

[0041] Among them, VDD-VOL>VTH, and VOL>VI. VDD-VOL>VTH can ensure that when the switch M1 is closed, the voltage at the connection point A can continuously turn on the switch tube in the power switch circuit. VOL>VI can ensure that when the key is not pressed, no valid signal is detected.

[0042] Working process: After the circuit is powered on, under the pull-up effect, the voltage at connection point A is VDD, and the switch tube P1 is turned off. When the button is pressed, the voltage at connection point A is close to 0V, and the switch tube P1 is turned on. Since 0V is much lower than the state threshold voltage VI of the state detection input circuit, the state detection input circuit outputs the key valid state to the control unit, and the control unit turns on switch M1, and the voltage at connection point A is limited to no higher than VOL. While the button is being pressed, the voltage at connection point A is close to 0 V. When the button is released, the voltage at connection point A rises from 0V to VOL (limited to VOL by the limit output circuit). Since the voltage difference of VDD-VOL is still greater than the turn-on voltage VTH of the switch tube, the switch tube remains on after the button is released, thereby achieving one-key startup and self-locking.

[0043] When the key is pressed again, the voltage at connection point A is close to 0V, and the state detection input circuit outputs the key valid state to the control unit, and the control unit turns off the switch in the limit output circuit to cancel the limit effect. When the key is released, the voltage at connection point A rises from 0 to VDD, and the switch tube P1 is turned off, thus achieving one-key shutdown.

[0044] Embodiment 2

[0045] Compared with the first embodiment, the single-button switch circuit further includes a capacitor C1, one end of the capacitor C1 is connected to the connection point A, and the other end is connected to the power supply VDD. Figure 3 As shown. Capacitor C1 can further filter the external interference when the key is connected for a long time, and C1 can form an additional delay for switching on and off with the pull-up current or pull-up resistor. In addition, capacitor C1 can also be connected in parallel between connection point A and ground. The effect is that when power is turned on, since C1 needs to be charged, there will be a process of turning on the power switch tube P1, which is equivalent to pressing the key once when powering on.

[0046] Embodiment 3

[0047] A chip such as Figure 4 As shown, the pull-up circuit, state detection input circuit, limit output circuit and control unit in the single-button switch circuit described in Example 1 are integrated; it also includes a pin, and the connection point A is connected to the pin. The switch M1 in the limit output unit is implemented by an NMOS tube M1 integrated in the chip, and the voltage stabilizing circuit is implemented by two diodes in series. When used, the chip is connected to the pin with a button K, a switch tube P1 and an optional capacitor C1. The switch tube P1 can also be implemented by a PMOS tube integrated inside the chip.

[0048] Embodiment 4:

[0049] Embodiment 4 is a microcontroller chip, which integrates the pull-up circuit, state detection input circuit, limit output circuit and control unit in the single-button switch circuit described in Embodiment 1; it also includes an I / O pin, and the connection point A is connected to the I / O pin. In order to save and share resources, the I / O pin can reuse the existing I / O pins of the microcontroller, and add a mode selection for selecting the single-button switch pin mode or the ordinary I / O pin mode. Figure 5 As shown, the pull-up circuit, the state detection input circuit, and the limit output circuit can reuse the pin pull-up unit, the pin input unit, and the pin output unit on the I / O pin of the microcontroller chip, respectively, and the limit output circuit is connected in series to the low-level output path of the I / O pin, so that the voltage of the pin when the low level is output is not lower than the voltage regulation value of the voltage regulation circuit. In this embodiment, the switch M1 in the limit output unit is implemented by an NMOS tube M1, and the voltage regulation circuit is composed of two diodes in series, and a MOS tube with a gate and a drain short circuit can also be used. This limit mode can be selected, such as Figure 5 As shown, an NMOS tube M2 is connected in parallel to the limiting output circuit to replace M1 to output a low level in the normal I / O pin function mode, or M2 is connected in parallel to the voltage stabilization circuit only, and when it is turned on, it corresponds to the normal I / O pin function mode. When M2 is turned off, it corresponds to the limiting mode. The control unit is implemented by a submodule of the microcontroller.

[0050] When in application, a key K and a P-type MOSFET are connected to the I / O pin of the microcontroller chip, and a capacitor C1 can also be connected externally. When the switch tube P1 is a PMOS tube integrated in the chip, only the key K and the optional capacitor C1 need to be connected to the I / O pin.

Claims

1. A single-button power on / off circuit, characterized in that: include: Connect the dots; A pull-up circuit, one end of which is connected to the connection point, and the other end is connected to the power supply, and the power supply voltage is VDD; A button, one end of which is connected to the connection point and the other end is grounded; A state detection input circuit, the input terminal is connected to the connection point, and the state threshold voltage is VI; The limiting output circuit has an output end connected to the connection point, and the limiting voltage is VOL when the low level output is performed; the limiting output circuit includes a switch and a voltage stabilizing circuit, and the switch and the voltage stabilizing circuit are connected in series; A control unit, the input end of which is connected to a state detection input circuit, and the output end of which is connected to the switch; A power switch circuit, wherein the driving end is connected to the connection point, the input end is connected to the power supply, and the output end outputs the controlled power supply, and the start-up voltage of the power switch circuit is VTH; Among them, VDD-VOL>VTH, and VOL>VI.

2. The single-button on / off circuit according to claim 1, characterized in that: A capacitor is also included, one end of the capacitor is connected to the connection point, and the other end is connected to the power supply or the ground.

3. The single-button on / off circuit according to claim 1 or 2, characterized in that: The state detection input circuit adopts a Schmitt input structure, and the rising edge threshold voltage and the falling edge threshold voltage of the Schmitt input are both lower than VOL.

4. The single-button on / off circuit according to claim 1 or 2, characterized in that: The pull-up circuit is a pull-up resistor or a pull-up current.

5. The single-button on / off circuit according to claim 1 or 2, characterized in that: The voltage stabilizing circuit includes one or more voltage stabilizing devices or equivalent voltage stabilizing devices, and multiple voltage stabilizing devices or equivalent voltage stabilizing devices are connected in series. The equivalent voltage stabilizing device includes one or more of a diode, a triode, a resistor, and a MOS tube with a gate and a drain short-circuited.

6. The single-button on / off circuit according to claim 1 or 2, characterized in that: The power switch circuit includes a switch tube, and the switch tube is a P-type MOSFET device or a PMOS tube integrated in a chip.

7. The single-button on / off circuit according to claim 1 or 2, characterized in that: The control unit is a hardware logic circuit or a submodule of a microcontroller.

8. A chip, characterized in that: The pull-up circuit, state detection input circuit, amplitude limiting output circuit and control unit in the single-button switch circuit as described in any one of claims 1 to 7 are integrated; and a pin is also included, and the connection point is connected to the pin.

9. The chip according to claim 8, characterized in that: The chip is a microcontroller chip, the pins are I / O pins, and the control unit is a submodule of the microcontroller.

10. The chip according to claim 9, characterized in that: The pull-up circuit, state detection input circuit and amplitude limiting output circuit respectively reuse the pin pull-up unit, pin input unit and pin output unit on the I / O pin of the microcontroller chip, and the amplitude limiting output circuit is connected in series on the low level output path of the I / O pin.

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