CN108768364A - A kind of power switch button circuit - Google Patents

Abstract

The present invention proposes a power switch button circuit. The circuit is provided with a button module, a power supply module and a detection module, which reduces the use of buttons and switches, reduces the production cost of the button circuit, and combines with a single-chip microcomputer to enable one button to start, shut down and automatically Define functions.

Description

A power switch button circuit

technical field

The present invention relates to the technical field of circuit control, and more specifically, relates to a power switch button circuit.

Background technique

At present, the power switch and function keys of most embedded electronic products are separated and independent from each other, and will not affect each other. This design has the following problems: 1. The power switch adopts a mechanical switch such as a rocker switch or a toggle switch. After turning on the power, it must be manually turned off. If you forget to turn off the power, the product will continue to work until the battery is exhausted. The voltage is monitored, but there is no way to actively turn off the power; second, the power switch is in an idle state during normal operation of the product, and cannot provide multiplexing functions. To achieve the required functions, additional buttons can only be added; third, it is impossible to realize long-press power on and off With this function of preventing user misoperation, once some products are turned on, users may not want the user to suddenly shut down due to misoperation, which will lead to measurement interruption or data not being saved in time.

Contents of the invention

The technical problem to be solved by the present invention is to provide a power switch button circuit for the deficiencies and defects of the prior art.

To achieve the above object, the present invention adopts the following technical solutions:

A power switch button circuit, including a button module, a power supply module, and a detection module, the specific structure is as follows:

The button module includes a first port for electrical connection with the power supply module and the detection module.

The power supply module is specifically that the power chip (U1) is connected to the drain of the first field effect transistor (Q1), the first capacitor (C1) is connected between the gate of the first field effect transistor (Q1) and the ground, and the first field effect transistor (Q1) ) The first resistor (R1) is connected between the gate and the source, the source of the first field effect transistor (Q1) is connected to the second resistor (R2), the collector of the second field effect transistor (Q2) in turn, and the second field effect transistor (Q2) The emitter of the tube (Q2) is grounded, the base of the second field effect tube (Q2) is connected to the fourth resistor (R4) and the third resistor (R3) in turn, and the other end of the third resistor (R3) is connected to the positive power supply, the second field The base of the effect tube (Q2) is also connected to the fifth resistor (R5), the other end of the fifth resistor (R5) is grounded, and the wiring between the third resistor (R3) and the fourth resistor (R4) is connected to the switch signal pin of the microcontroller (ON-OFF), the first port of the button module is connected to the collector of the second field effect transistor (Q2).

The detection module is specifically that the emitter of the third field effect transistor (Q3) is connected in series with the sixth resistor (R6) to the first port of the button module, and the seventh resistor (R7) is connected between the emitter and the collector of the third field effect transistor (Q3). ), the collector of the third field effect transistor (Q3) is connected to the eighth resistor (R8) and grounded, and the connection between the collector of the third field effect transistor (Q3) and the eighth resistor (R8) is connected to the detection pin of the microcontroller ( KEY_CPW).

Further, the button module further includes a button (S1) and a second port, the second port is grounded, and the button (S1) is used to control the connection state of the first port and the second port.

Furthermore, the first field effect transistor is a P-channel MOS transistor, the second field effect transistor is an NPN transistor, and the third field effect transistor is a PNP transistor.

Furthermore, if the detection level signal of the detection pin of the single-chip microcomputer is high level and lasts for a certain period of time, the switch pin of the single-chip microcomputer is controlled to output a high level signal, otherwise the switch pin outputs a low level signal.

Furthermore, it also includes a first diode (D1) and a second diode (D2), the first diode (D1) is connected in series with the first port of the button module and the collector of the NPN transistor (Q2) Between, the second diode (D2) is connected in series between the first port of the key module and the sixth resistor (R6).

Furthermore, the working voltage provided by the power supply chip is +3.3V.

The power switch button circuit of the present invention is provided with a button module, a power supply module and a detection module, which reduces the use of buttons and switches, reduces the manufacturing cost of the button circuit, and combines with a single-chip microcomputer to enable one button to realize power-on, power-off and self-defined functions.

Description of drawings

Figure 1 is a schematic diagram of the circuit in the embodiment.

Detailed ways

The present invention will be further described below in combination with specific embodiments.

A power switch button circuit, the specific structure is as follows:

The button module includes a button S1, a first port and a second port, and the second port is grounded, wherein the button S1 is used to control the connection state of the first port and the second port; the power chip U1 is connected to the drain of the P-channel MOS transistor Q1, The capacitor C1 is connected between the gate of the P-channel MOS transistor Q1 and the ground, the resistor R1 is connected between the gate and the source of the P-channel MOS transistor Q1, the source of the P-channel MOS transistor Q1 is sequentially connected to the resistor R2, and the NPN transistor Q2 The collector, the emitter of the NPN transistor Q2 is grounded, the base of the NPN transistor Q2 is connected to the resistor R4 and the resistor R3 in turn, the other end of the resistor R3 is connected to the positive power supply, the base of the NPN transistor Q2 is also connected to the resistor R5, and the other end of the resistor R5 is connected to the ground , the leading wiring between resistor R3 and resistor R4 is connected to the ON-OFF switch signal pin of the single chip microcomputer, the first port of the button module is connected to the collector of NPN transistor Q2; Connect the resistor R7 between the emitter and collector of the PNP transistor Q3, connect the collector of the PNP transistor Q3 to the resistor R8 and then ground, and connect the lead wire between the collector of the PNP transistor Q3 and the resistor R8 to the detection pin KEY_CPW of the microcontroller.

The circuit also includes a diode D1 and a diode D2, the diode D1 is connected in series between the first port of the button module and the collector of the NPN transistor Q2, and the diode D2 is connected in series between the first port of the button module and the resistor R6. The reverse setting of the diode D1 and the diode D2 is used to ensure that the detection level signal of the pin KEY_CPW and the level signal between the pin ON-OFF do not affect each other.

The specific working principle of this circuit is: Q1 uses a P-channel MOS tube. When it is not powered on, due to the existence of R1, its gate is always in a high level state, and the entire subsequent circuit is in a power-off state. Once the button S1 is pressed, the gate of Q1 is in a low-level state, at this time, the source and drain of Q1 are in a conductive state, and VIN is almost equal to VBAT. The power supply chip U1 immediately provides +3.3V working voltage to make the microcontroller start to work. When the microcontroller pin ON_OFF is not yet initialized, because the resistor R3 is forced to be pulled up by +3.3V, even if S1 is released immediately at this time, the entire circuit is still in the power supply state. The KEY_CPW pin of the microcontroller detects a high level. If the duration exceeds the specified long-press time (for example, 3s), ON_OFF will output a high level to maintain the power supply state, otherwise it will continue to output a low level until the S1 button is released. At this time, due to the function of Q2, the gate of Q1 is in the high level state again, so that the source and drain of Q1 are no longer in the conduction state, and the subsequent circuit enters the power-off state again at this time. When the product is running normally, as long as it detects a short press of the S1 button, it will respond to it. If it is detected that S1 has been pressed for a long time, it is determined whether to shut down immediately according to the situation. If it is necessary to shut down, it is only necessary to continuously output a low level to the ON_OFF pin as described above.

Claims (6)

1. A power switch button circuit, comprising a button module, a power supply module, and a detection module, characterized in that: the button module includes a first port for being electrically connected with the power supply module and the detection module; The power supply module is specifically that the power chip (U1) is connected to the drain of the first field effect transistor (Q1), the first capacitor (C1) is connected between the gate of the first field effect transistor (Q1) and the ground, and the first field effect transistor (Q1) ) The first resistor (R1) is connected between the gate and the source, the source of the first field effect transistor (Q1) is connected to the second resistor (R2), the collector of the second field effect transistor (Q2) in turn, and the second field effect transistor (Q2) The emitter of the tube (Q2) is grounded, the base of the second field effect tube (Q2) is connected to the fourth resistor (R4) and the third resistor (R3) in turn, and the other end of the third resistor (R3) is connected to the positive power supply, the second field The base of the effect tube (Q2) is also connected to the fifth resistor (R5), the other end of the fifth resistor (R5) is grounded, and the wiring between the third resistor (R3) and the fourth resistor (R4) is connected to the switch signal pin of the microcontroller (ON-OFF), the first port of the button module is connected to the collector of the second field effect transistor (Q2); The detection module is specifically that the emitter of the third field effect transistor (Q3) is connected in series with the sixth resistor (R6) to the first port of the button module, and the seventh resistor (R7) is connected between the emitter and the collector of the third field effect transistor (Q3). ), the collector of the third field effect transistor (Q3) is connected to the eighth resistor (R8) and grounded, and the connection between the collector of the third field effect transistor (Q3) and the eighth resistor (R8) is connected to the detection pin of the microcontroller ( KEY-CPW). 2. A power switch button circuit according to claim 1, characterized in that: the button module also includes a button (S1) and a second port, the second port is grounded, and the button (S1) is used to control the first port and the connectivity status of the second port. 3. A power switch button circuit according to claim 2, characterized in that: the first field effect transistor is a P-channel MOS transistor, the second field effect transistor is an NPN triode, and the third field effect transistor is PNP type transistor. 4. A kind of power switch key circuit according to claim 3, it is characterized in that: the single-chip microcomputer detection pin detection level signal is high level and lasts for a certain period of time, then controls the single-chip microcomputer switch pin to output high level signal, otherwise The switch pin outputs a low level. 5. A power switch button circuit according to claim 4, characterized in that it further comprises a first diode (D1) and a second diode (D2), the first diode (D1) The second diode (D2) is connected in series between the first port of the key module and the sixth resistor (R6). 6. A power switch button circuit according to claim 5, characterized in that: the working voltage provided by the power chip is +3.3V.