Startup and shutdown control circuit
By introducing a delay control module into the power-on/off circuit, the device is ensured to automatically power on and lock into a high-level state after a power outage, solving the problem of the inability to automatically power on after a power outage in the prior art and improving the reliability and stability of the device.
Patent Information
- Application Number
- CN202520207166.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-10
- Publication Date
- 2026-01-20
- Estimated Expiration
- 2035-02-10
AI Technical Summary
The existing power-on/off circuit lacks the function of automatically turning on when power is restored after a power outage, and it is easy to shut down due to accidental button presses.
The device employs a switch module, a first delay switch module, and a second delay switch module. When the button is pressed to power on, the switch is turned on or off. The delay controls the input level of the power-on/off control module, ensuring that the device automatically powers on and locks to a high level state when power is restored after a power outage.
It enables automatic power-on after a power outage, preventing accidental button presses that could cause shutdown and improving the reliability and stability of the device.
Smart Images
Figure CN223816151U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to a power supply circuit technology, and in particular to a power on / off control circuit. Background Technology
[0002] Currently, electrical equipment (such as ventilators) generally has a D trigger power-on / off circuit with a self-resetting button. Pressing the power button turns the device on, and pressing the power button again after powering on does not automatically shut it down via hardware; the software needs to detect the button being pressed or the battery being low to control the shutdown. For example... Figure 1 As shown, when the equipment is powered, VCC is a constant 5V; when there is no power, VCC is 0V. Regardless of whether the equipment is powered on or off, VCC remains 5V when any power source is connected. When the power button is pressed, the system detects a high-level signal CHECK_POWER_SW, which is then converted to a low level by the first inverter UA and then to a high level by the second inverter UB. This inputs to the CLK pin of the D flip-flop, causing the non-Q output of the flip-flop to go high, thus powering on the equipment. When the equipment is not powered on, VDD is 0V. After powering on, VDD is 5V and locked. At this time, pressing the button will not affect the flip-flop's output state. When the power button is released, a low-level SOFT_OFF signal is output through the equipment's main control I / O port. This inputs a low-level signal to the CLK pin of the D flip-flop. Resistor R23 charges capacitors C14 and C15, causing the non-PRE output of the D flip-flop to go low, setting the D flip-flop. After being set, the non-Q output of the D flip-flop goes low, powering off the equipment. Although this power-on circuit has basic power-on and power-off control functions, it lacks the function of automatically powering on when power is restored after a power outage. Utility Model Content
[0003] In view of the shortcomings of the prior art, the purpose of this utility model is to provide a power-on / off control circuit that can restore power after a power outage.
[0004] To solve the above technical problems, the present invention adopts the following technical solution:
[0005] A switch control circuit is electrically connected with a key start module and a switch control module of an electric device, which comprises a switch module, a first delay switch module and a second delay switch module. When a start key of the key start module is pressed, the switch module is turned on, the first delay switch module is turned on after a delay, and the input of the switch control module is low. When the start key is released, the switch module is turned off, the first delay switch module is turned off after a delay, and the second delay switch module is turned on after a delay, so that the output of the switch control module is high, and the electric device is started. When the electric device is powered off, the switch module, the first delay switch module and the second delay switch module are all turned off, the output of the switch control module is low, and the electric device is powered off. When the electric device is powered on again after being powered off, the second delay switch module is turned on after a delay, the output of the switch control module is high, and the electric device is started and locked in a high level state.
[0006] In the switch control circuit, the switch module comprises a first MOS tube, one end of the gate of the first MOS tube is connected with the key start module, the drain of the first MOS tube is connected with one end of the second delay switch module and a system power supply module, and the source of the first MOS tube is grounded.
[0007] In the switch control circuit, the first delay switch module comprises a second MOS tube, a first delay unit and a second delay unit, the gate of the second MOS tube is connected with the gate of the first MOS tube and one end of the key start module through the first delay unit, the drain of the second MOS tube is connected with one end of the key start module, and the source of the second MOS tube is connected with the input end of the second delay switch module and the switch control module.
[0008] In the switch control circuit, the first delay unit comprises a first resistor and a first capacitor, one end of the first resistor is connected with the gate of the first MOS tube and one end of the key start module, and the other end of the first resistor is connected with the gate of the second MOS tube and grounded through the first capacitor.
[0009] In the switch control circuit, the second delay unit comprises a second resistor, a diode and a second capacitor, one end of the second resistor is connected with the other end of the second delay switch module, the other end of the second resistor is connected with the source of the second MOS tube, the negative electrode of the diode and the input end of the switch control module, and grounded through the second capacitor, the drain of the second MOS tube is connected with one end of the key start module, and the positive electrode of the diode is connected with a VDD power supply end.
[0010] The second delay unit further comprises a third resistor, a fourth resistor and a fifth resistor, one end of the third resistor is connected to one end of the key power-on module, and the other end of the third resistor is connected to the drain of the second MOS tube through the fourth resistor, one end of the fifth resistor is connected to the other end of the second resistor, the source of the second MOS tube, one end of the second capacitor and the input end of the power-on / off control module, and the other end of the fifth resistor is grounded.
[0011] The second delay switch module comprises a third MOS tube, a sixth resistor and a third capacitor, the gate of the third MOS tube is connected to the drain of the second MOS tube and the system power supply module, and the third MOS tube is grounded through the sixth resistor and the third capacitor, the drain of the third MOS tube is connected to the VCC power supply end, and the source of the third MOS tube is connected to one end of the second resistor.
[0012] The power-on / off control module comprises a first inverter, a second inverter, a flip-flop, a seventh resistor, a fourth capacitor and a fifth capacitor, the input end of the first inverter is connected to the source of the second MOS tube and the other end of the second resistor, the output end of the first inverter is connected to the input end of the second inverter, the output end of the second inverter is connected to the CLK end of the flip-flop, the non-PRE end of the flip-flop is connected to the VCC power supply end through the seventh resistor, and the flip-flop is grounded through the fourth capacitor and connected to the power-off control end of the powered device through the fifth capacitor.
[0013] The system power supply module comprises an eighth resistor, a ninth resistor, a tenth resistor and an eleventh resistor, one end of the eighth resistor, one end of the ninth resistor, one end of the tenth resistor and one end of the eleventh resistor are connected to the drain of the second MOS tube and the gate of the third MOS tube, the other end of the eighth resistor is connected to the VAC power supply end, the other end of the ninth resistor is connected to the VDC power supply end, the other end of the tenth resistor is connected to the VBATA power supply end, and the other end of the eleventh resistor is connected to the VBATB power supply end.
[0014] The key power-on module comprises a power-on key, a twelfth resistor and a clamping diode, the fifth pin of the power-on key is connected to the VDD power supply end through the twelfth resistor, the third pin and the fourth pin of the power-on key are connected to the third pin of the clamping diode, the other end of the first resistor, one end of the third resistor and one end of the fourth resistor, the first pin of the clamping diode is grounded, and the second pin of the clamping diode is connected to the VCC power supply end.
[0015] Compared with the prior art, the switch control circuit provided by the utility model, including switch module, first delay switch module and second delay switch module, when the power-on button of the button power-on module is pressed, the switch module is turned on, the first delay switch module is turned on after delay, and the input of the switch control module is low, when the power-on button is released, the switch module is turned off, the first delay switch module is turned off after delay, and the second delay switch module is turned on after delay, so that the switch control module outputs high level to start the electric equipment; when the electric equipment is powered off, the switch module, the first delay switch module and the second delay switch module are all disconnected, and the switch control module outputs low level to shut down the electric equipment; when the electric equipment is powered on again after power-off, the second delay switch module is turned on after delay, the switch control module outputs high level to start the electric equipment and locks the high level state, thereby realizing the function of automatic start when powered on again after power-off, and locking the high level to avoid shutdown caused by accidental pressing of the power-on button. BRIEF DESCRIPTION OF DRAWINGS
[0016] Figure 1 It is the power-on circuit schematic diagram of the electric equipment in the prior art.
[0017] Figure 2 It is the structure block diagram of the switch control circuit provided by the utility model.
[0018] Figure 3 It is the circuit principle diagram of the switch control circuit provided by the utility model.
[0019] REFERENCE SIGNS
[0020] Button power-on module 10, switch control module 20, switch module 30, first delay switch module 40, second delay switch module 50, first MOS tube Q1, second MOS tube Q2, first delay unit 41, second delay unit 42, first resistor R1, first capacitor C1, second resistor R2, diode D1, second capacitor C2, third resistor R3, fourth resistor R4, fifth resistor R5, third MOS tube Q3, sixth resistor R6, third capacitor C3, first inverter U1A, second inverter U1B, flip-flop U2, seventh resistor R7, fourth capacitor C4, fifth capacitor C5, eighth resistor R8, ninth resistor R9, tenth resistor R10, eleventh resistor R11, power-on button KW1, twelfth resistor R12, clamping diode D2, anti-reverse diode D3 DETAILED DESCRIPTION
[0021] In order to make the purpose, technical scheme and advantages of the utility model more clear and obvious, the utility model is further described in detail below by combining with the drawings and examples. It should be understood that the specific examples described here are only used to explain the utility model, and are not used to limit the utility model.
[0022] Please refer to Figure 2 and Figure 3 The utility model provides a switch control circuit, and the key start module 10 and the switch control module 20 of electric equipment are electrically connected, the electric equipment can be anesthesia machine, breathing machine, defibrillator and other equipment, and the key start module 10 of these equipment includes start key KW1, and when pressing, the electric equipment starts, and when the start key KW1 pops up, the software detects, and the software control delay shutdown is passed.
[0023] The switch control circuit includes switch module 30, first delay switch module 40 and second delay switch module 50, one end of the key start module 10 is connected with one end of the switch module 30, and one end of the first delay switch module 40 is connected, the other end of the switch module 30 is connected with one end of the second delay switch module 50, and the other end of the first delay switch module 40 and the other end of the second delay switch module 50 are connected with the switch control module 20.
[0024] When the start key KW1 of the key start module 10 is pressed, the switch module 30 is turned on, the first delay switch module 40 is turned on after delay, and the switch control module 20 outputs high level and the electric equipment starts; when the electric equipment is powered off, the switch module 30, the first delay switch module 40 and the second delay switch module 50 are disconnected, the switch control module 20 outputs low level and the electric equipment is powered off; when the electric equipment is powered on again after starting, the second delay switch module 50 is turned on after delay, the switch control module 20 outputs high level and the electric equipment starts and is locked in high level state, so that the function of automatically starting when powering on again after starting and powering off is realized, and the high level is locked to avoid the shutdown caused by accidentally pressing the start key KW1.
[0025] Please continue to refer to Figure 2 and Figure 3 The switch module 30 includes the first MOS tube Q1, the first MOS tube Q1 is N channel MOS tube, and is turned on when the gate is high level, and is cut off when the gate is low level. One end of the key start module 10 is connected with the gate of the first MOS tube Q1, one end of the second delay switch module 50 and the system power supply module are connected with the drain of the first MOS tube Q1, and the source of the first MOS tube Q1 is grounded.
[0026] The first delay switch module 40 includes the second MOS tube Q2, the first delay unit 41 and the second delay unit 42, and the second MOS tube Q2 can also adopt N channel MOS tube, and is turned on when the gate is high level, and is cut off when the gate is low level.
[0027] The gate of the second MOS tube Q2 is connected with the gate of the first MOS tube Q1 and one end of the key start module 10 through the first delay unit 41, the drain of the second MOS tube Q2 is connected with one end of the key start module 10, and the source of the second MOS tube Q2 is connected with the second delay switch module 50 and the input end of the switch start control module 20.
[0028] The first delay unit 41 is used for making the second MOS tube Q2 delay on when the first MOS tube Q1 is on, and the second delay unit 42 is used for making the output level of the switch start control module 20 delay flip when the start key KW1 of the key start module 10 is popped up, such as delay output low level, so as to realize that the software control delay shutdown is realized when the start key KW1 is popped up.
[0029] Optionally, the first delay unit 41 comprises a first resistance R1 and a first capacitance C1, one end of the first resistance R1 is connected with the gate of the first MOS tube Q1 and one end of the key start module 10, and the other end of the first resistance R1 is connected with the gate of the second MOS tube Q2 and grounded through the first capacitance C1.
[0030] The first resistance R1 and the first capacitance C1 constitute an RC delay circuit, the first capacitance C1 is charged when the start key KW1 is pressed to make the second MOS tube Q2 delay on, and the time of the delay on of the second MOS tube is set by the values of the first resistance R1 and the first capacitance C1. Optionally, the resistance value of the first resistance R1 can be 1M ohm, and the capacitance value of the first capacitance C1 can be 2.2uF.
[0031] The second delay unit 42 comprises a second resistance R2, a diode D1 and a second capacitance C2, one end of the second resistance R2 is connected with the other end of the second delay switch module 50, the other end of the second resistance R2 is connected with the source of the second MOS tube Q2, the negative electrode of the diode D1 and the input end of the switch start control module 20, and grounded through the second capacitance C2, the drain of the second MOS tube Q2 is connected with one end of the key start module 10, and the positive electrode of the diode D1 is connected with the VDD power supply end.
[0032] Wherein, the voltage VDD of the VDD power supply end is 0V before the start of the electric equipment, the resistance value of the second resistance R2 can be as small as possible (such as R2=10K) to avoid that the voltage is too large, and the capacitance value of the second capacitance C2 can also be as small as possible (such as C2=1uF) to avoid that the capacitor discharge time is too long. The diode D1 is a reverse prevention diode, after the electric equipment is started, the power supply end VDD is powered on, and the level input into the switch start control module 20 is locked as high level, so as to prevent that the user equipment is started and the start key is accidentally pressed to cause the shutdown.
[0033] The second delay unit 42 further comprises a third resistor R3, a fourth resistor R4 and a fifth resistor R5, one end of the third resistor R3 is connected to one end of the key-on module 10, and is grounded through the fourth resistor R4, the other end of the third resistor R3 is connected to the drain of the second MOS tube Q2, one end of the fifth resistor R5 is connected to the other end of the second resistor R2, the source of the second MOS tube Q2, one end of the second capacitor C2 and the input end of the switch control module 20, and the other end of the fifth resistor R5 is grounded.
[0034] In the process of the delay conduction of the second MOS tube Q2, the charge on the second capacitor C2 is discharged through the fifth resistor R5, and after the second MOS tube Q2 is turned on, the charge on the second capacitor C2 is also discharged through the third resistor R3 and the fourth resistor R4, until the level input into the input end of the switch control module 20 is low.
[0035] The second delay switch module 50 is used to make the switch control module 20 delay output low level when the key-on button KW1 is popped up or the battery power is low, so as to delay the power-off of the electric device. Please continue to refer to Figure 2 and Figure 3 The second delay switch module 50 comprises a third MOS tube Q3, a sixth resistor R6 and a third capacitor C3, the gate of the third MOS tube Q3 is connected to the drain of the second MOS tube Q2 and the system power supply module, is also grounded through the sixth resistor R6, and is further grounded through the third capacitor C3, the drain of the third MOS tube Q3 is connected to the VCC power supply end, and the source of the third MOS tube Q3 is connected to one end of the second resistor R2.
[0036] The third MOS tube Q3 is an N-channel MOS tube, and the VGS of the third MOS tube Q3 needs to be ensured to be large enough to make the third MOS tube Q3 fully conduct. The sixth resistor R6 and the third capacitor C3 also constitute an RC delay circuit, the third MOS tube Q3 is cut off when the key-on button KW1 is pressed, and the third MOS tube Q3 is delay turned on when the key-on button KW1 is released.
[0037] In this embodiment, the voltage VCC of the VCC power supply end is a constant 5V voltage, and the resistance values of the third resistor R3, the fourth resistor R4 and the fifth resistor R5 are R5>R3>R4, so as to ensure that when the key-on button KW1 is pressed, the voltage VCC is divided by the third resistor R3 and the fifth resistor R5, and the voltage on the fifth resistor R5 is high, and it also needs to be ensured that when the key-on button KW1 is released, the voltage VDD is divided by the diode D1, the parasitic diode of the second MOS tube Q2, the third resistor R3 and the fourth resistor R4, and the voltage on the fifth resistor R5 is low.
[0038] The switch control module 20 includes a first inverter U1A, a second inverter U1B, a flip-flop U2, a seventh resistor R7, a fourth capacitor C4 and a fifth capacitor C5, the input end of the first inverter U1A is connected to the source of the second MOS Q2 and the other end of the second resistor R2, the output end of the first inverter U1A is connected to the input end of the second inverter U1B, the output end of the second inverter U1B is connected to the CLK end of the flip-flop U2, the non-PRE end of the flip-flop U2 is connected to the VCC power supply end through the seventh resistor R7, is also grounded through the fourth capacitor C4, and is further connected to the power-off control end of the electrical equipment through the fifth capacitor C5. The capacitance of the fourth capacitor C4 can be 0.47uF, which is shorter than the charging time of the second capacitor C2.
[0039] The first inverter U1A and the second inverter U1B can be integrated in an inverter chip with a model of 74HC14D, and a third inverter, a fourth inverter, a fifth inverter and a sixth inverter can also be integrated in the inverter chip, which can all play a role in signal buffering, for shaping and buffering the power-on level. The flip-flop U2 can be a D flip-flop U2 with a model of 74HC74D, when the first pin (i.e. the non-CLR end) and the fourth pin (i.e. the non-PRE end) are high level, and when the third pin (i.e. the CLK end) inputs a rising edge pulse, the sixth pin (i.e. the non-Q end) generates a low level to high level flip-flop to realize system power-on.
[0040] The system power supply module includes an eighth resistor R8, a ninth resistor R9, a tenth resistor R10 and an eleventh resistor R11, one end of the eighth resistor R8, one end of the ninth resistor R9, one end of the tenth resistor R10 and one end of the eleventh resistor R11 are connected to the drain of the second MOS Q2 and the gate of the third MOS Q3, the other end of the eighth resistor R8 is connected to the VAC power supply end, the other end of the ninth resistor R9 is connected to the VDC power supply end, the other end of the tenth resistor R10 is connected to the VBAT A power supply end, and the other end of the eleventh resistor R11 is connected to the VBATB power supply end.
[0041] Among them, the eighth resistor R8, the ninth resistor R9, the tenth resistor R10 and the eleventh resistor R11 are all pull-up resistors, and an anti-reverse diode D3 can be arranged between each resistor and the corresponding power supply end to prevent current between each power supply (i.e. VAC, VDC, VBAT A and VBATB). The resistance values of the sixth resistor R6, the eighth resistor R8, the ninth resistor R9, the tenth resistor R10 and the eleventh resistor R11 can all be 1M ohms, and the capacitance of the third capacitor C3 can be 1uF, thereby setting the time for the third MOS Q3 to delay conduction.
[0042] Please refer again to Figure 2 and Figure 3The key starting module 10 comprises a starting key KW1, a twelfth resistor R12 and a clamping diode D2, the 5th pin of the starting key KW1 is connected to the VDD power supply end through the twelfth resistor R12, the 3rd pin and the 4th pin of the starting key KW1 are connected to the 3rd pin of the clamping diode D2, the other end of the first resistor R1, one end of the third resistor R3 and one end of the fourth resistor R4, the 1st pin of the clamping diode D2 is grounded, and the 2nd pin of the clamping diode D2 is connected to the VCC power supply end, and mainly serves the purpose of static protection.
[0043] Further, the third resistor R3 has a resistance of 47K ohms, and the second capacitor C2 has a capacitance of 1uF, which constitutes a delay debouncing circuit of the starting key KW1, when the starting key KW1 is pressed, the constant 5V power supply VCC charges the second capacitor C2 through the third resistor R3 and the second MOS tube Q2, and the delay debouncing time can be adjusted by changing the resistance of the third resistor R3 and the capacitance of the second capacitor C2.
[0044] It should be noted that the type, model and specification of the electronic components used in the switch control circuit are not limited, and other components with the same function can be used instead, such as the first, second and third MOS tubes can be replaced by NPN triodes, and the like, which are not limited by the utility model.
[0045] In order to better understand the technical scheme of the utility model, the following is an application example of an anesthesia machine, and the Figure 2 and Figure 3 The switch control circuit of the utility model is described in detail:
[0046] In Figure 3 , CHECK_POWER_SW is a key detection, the starting key KW1 is pressed to be high level, and the starting key KW1 is released to be low level; SOFT_OFF is a CPU control shutdown pin control signal of the anesthesia machine, and the shutdown is low level and the startup is high level; CTRL_5V is an enable control power supply of the switch circuit, high level makes the anesthesia machine start, and low level makes the anesthesia machine stop; VCC is a constant 5V LDO power supply of the anesthesia machine, which supplies power to the first inverter U1A and the flip-flop U2; VAC, VDC, VBATA and VBATB are four power input interfaces of the anesthesia machine, which are powered after being plugged in, and VAC, VDC, VBATA and VBATB all have electric voltage; VDD is a 5V output of the DC-DC power supply system of the anesthesia machine, which has VDD after the switch control circuit CTRL_5V of the utility model outputs high level, and the VDD is clamped and locked after starting, and the CLK level of the flip-flop U2 is high level, so that the flip-flop U2 still maintains the original output level even if the power key is not pressed.
[0047] After the anesthetic machine is powered off, the input end of the first inverter U1A is discharged to a low level, and then re-plugged to automatically power on; when there is no AC voltage (i.e. VAC), DC voltage (i.e. VDC), battery voltage (i.e. VBATA and VBATB), suddenly power on, i.e. plug in any power supply, the input end of the first inverter U1A jumps from 0V to 5V, which is equivalent to pressing the power-on button KW1. When there is AC voltage, DC voltage, and battery voltage, press the power-on button KW1, and the input end of the first inverter U1A is discharged through the second capacitor C2. Release the power-on button KW1, and the input end of the first inverter U1A is powered on from 0V to 5V through VCC, triggering the output of the flip-flop U2 to high level to power on.
[0048] Before the anesthetic machine is powered on, there is any one of VAC, VDC, VBATA, VBATB voltage and constant 5V power supply VCC, and the first MOS tube Q1 is off, the second MOS tube Q2 is off, and the third MOS tube Q3 is on. The voltage VCC charges the second capacitor C2 through the second resistor R2, and the voltage VCC is divided by the second resistor R2 and the fifth resistor R5 to a high level at the input end of the first inverter, and the voltage VDD is 0V before power on.
[0049] Press the power-on button KW1 to power on the process:
[0050] Press the power-on button, the first MOS tube Q1 is immediately turned on, the gate level of the third MOS tube Q3 is quickly pulled low to turn off, the VCC voltage of the power-on button charges the first capacitor C1 through the first resistor R1, and the second MOS tube Q2 is turned on with a delay. At the same time, the second capacitor C2 is discharged through the fifth resistor R5, and the second capacitor C2 is also discharged through the second MOS tube Q2, the third resistor R3, and the fourth resistor R4, until the input end of the first inverter U1A becomes low.
[0051] When the button is released (i.e. the button switch is turned off), the first MOS tube Q1 is immediately turned off, any one of VAC, VDC, VBATA, VBATB voltage charges the third capacitor to turn on the third MOS tube Q3 with a delay, and the first capacitor C1 is discharged to turn off the second MOS tube Q2 with a delay. The VCC voltage charges the second capacitor C2 through the second resistor R2, so that the input end of the first inverter U1A jumps from low to high, the second flip-flop U2 inputs a rising edge, the non-Q end of the flip-flop U2 flips, the CTRL_5V becomes high, and the machine is powered on. After the machine is powered on, VDD changes from 0V to 5V, VDD passes through the diode D1 to make U1A input always high, locking the power-on state to prevent accidental power-off. At this time, repeatedly pressing the power-on button will not cause hard power-off (i.e. will not directly power off through hardware), and software cooperation is required to power off.
[0052] Software power-off process
[0053] When the release button is detected, that is, the main control of the anesthetizing machine detects CHECK_POWER_SW as low, or detects low battery power, a low level SOFT_OFF signal is output through the IO port of the main control, at this time the VCC voltage passes through the seventh resistor R7, and the fourth capacitor C4 discharges to charge the fifth capacitor C5, the fourth pin (that is, the non-PRE end) of the flip-flop U2 presents a jump from high level to low level, so that the fourth pin changes from high level to low level, prompting the flip-flop U2 to be set, and after setting, the sixth pin (that is, the non-Q end) outputs as low level, and the anesthetizing machine is turned off. At this time, VDD becomes 0V, but since there is still any one of VAC, VDC, VBATA, VBATB power supply and the constant 5V power supply VCC, the third MOS tube Q3 is still turned on, so that the input end of the first inverter U1A is high.
[0054] After power failure, the power-on automatic start process
[0055] After the anesthetizing machine is powered off, VDD is 0 when it is not turned on. If it suddenly goes from no power to power, since any one of VAC, VDC, VBATA, VBATB power supply is connected at this time, VCC immediately supplies power to the flip-flop U2, and the VCC voltage charges the fourth capacitor C4 through the seventh resistor R7, and the fourth pin of the flip-flop U2 jumps from low level to high level, so that the first pin CLR reset pin is high at the beginning, the PRE set pin is low, and the non-Q end of the flip-flop U2 is low, and the system is in the shutdown state.
[0056] After the third MOS tube Q3 is turned on, the VCC voltage at the drain of the third MOS tube Q3 charges the second capacitor C2 through the second resistor R2 to the input end of the first inverter U1A, and the charging time is longer than that of the fourth capacitor C4 at the PRE set pin of the flip-flop U2. After the non-Q end of the flip-flop U2 initializes to low level, the input end of the first inverter U1A jumps from low level to high level, an ascending edge is input to the flip-flop U2, the non-Q end of the flip-flop U2 flips and outputs high level to make CTRL_5V high level, and the machine is turned on. After turning on, VDD locks the input end of the first inverter U1A as high level through the diode D1, and whether the button is pressed or popped up does not affect the non-Q level state of the D flip-flop U2, avoiding false touch of the button to cause hardware shutdown, and realizing shutdown in cooperation with the above software shutdown process.
[0057] In summary, the switch control circuit provided by the utility model, when the power-on button is pressed, the switch module is quickly turned on, the first delay switch module is turned on, and the switch control module outputs high level to start the electric device; when the electric device is powered off, the switch module, the first delay switch module and the second delay switch module are all disconnected, the switch control module outputs low level to turn off the electric device; when the electric device is powered on again after being powered off, the second delay switch module is turned on, the switch control module outputs high level to start the electric device and locks the high level state, thereby realizing automatic start when the electric device is powered on again after being powered off, without affecting the function of starting by pressing the button, and locking the high level to avoid turning off due to accidental pressing of the start button. Meanwhile, the utility model adds a few conventional electronic components on the basis of the existing start circuit, realizes the function of automatically starting when being powered on after being powered off for a long time, greatly improves the reliability of the electric device under the premise of low cost.
[0058] It can be understood that, for those skilled in the art, equivalent replacements or changes can be made according to the technical scheme and the utility model concept of the utility model, and all these changes or replacements shall belong to the protection scope of the claims attached to the utility model.
Claims
1. A switch control circuit, which is electrically connected with a key-on module and a switch control module of an electric appliance, characterized in that, The key start module includes a switch module, a first delay switch module and a second delay switch module. When the start key of the key start module is pressed, the switch module is turned on, the first delay switch module is turned on after a delay, and the input of the switch module control module is low. When the start key is released, the switch module is turned off, the first delay switch module is turned off after a delay, and the second delay switch module is turned on after a delay, so that the output of the switch module control module is high, and the power equipment is started. When the power equipment is powered off, the switch module, the first delay switch module and the second delay switch module are all turned off, the output of the switch module control module is low, and the power equipment is powered off. When the power equipment is powered on again after being powered off, the second delay switch module is turned on after a delay, the output of the switch module control module is high, and the power equipment is started and locked in a high level state.
2. The power-on / off control circuit according to claim 1, wherein The switch module includes a first MOS tube, the gate of the first MOS tube is connected to one end of the key start module, the drain of the first MOS tube is connected to one end of the second delay switch module and the system power supply module, and the source of the first MOS tube is grounded.
3. The power-on / off control circuit according to claim 2, wherein The first delay switch module includes a second MOS tube, a first delay unit and a second delay unit, the gate of the second MOS tube is connected to the gate of the first MOS tube and one end of the key start module through the first delay unit, the drain of the second MOS tube is connected to one end of the key start module, and the source of the second MOS tube is connected to the input end of the second delay switch module and the switch module control module.
4. The power-on / off control circuit according to claim 3, wherein The first delay unit includes a first resistor and a first capacitor, one end of the first resistor is connected to the gate of the first MOS tube and one end of the key start module, and the other end of the first resistor is connected to the gate of the second MOS tube and grounded through the first capacitor.
5. The power-on / off control circuit according to claim 3, wherein The second delay unit includes a second resistor, a diode and a second capacitor, one end of the second resistor is connected to the other end of the second delay switch module, the other end of the second resistor is connected to the source of the second MOS tube, the negative electrode of the diode and the input end of the switch module control module, and grounded through the second capacitor, the drain of the second MOS tube is connected to one end of the key start module, and the positive electrode of the diode is connected to the VDD power supply end.
6. The power-on / off control circuit according to claim 5, wherein The second delay unit further includes a third resistor, a fourth resistor and a fifth resistor, one end of the third resistor is connected to one end of the key start module and grounded through the fourth resistor, the other end of the third resistor is connected to the drain of the second MOS tube, one end of the fifth resistor is connected to the other end of the second resistor, the source of the second MOS tube, one end of the second capacitor and the input end of the switch module control module, and the other end of the fifth resistor is grounded.
7. The power-on / off control circuit according to claim 3, wherein The second delay switch module includes a third MOS tube, a sixth resistor and a third capacitor, the gate of the third MOS tube is connected to the drain of the second MOS tube and the system power supply module, grounded through the sixth resistor, and grounded through the third capacitor, the drain of the third MOS tube is connected to the VCC power supply end, and the source of the third MOS tube is connected to one end of the second resistor.
8. The power-on / off control circuit according to claim 3, wherein The switch control module comprises a first inverter, a second inverter, a flip-flop, a seventh resistor, a fourth capacitor and a fifth capacitor, the input end of the first inverter is connected with the source of the second MOS tube and the other end of the second resistor, the output end of the first inverter is connected with the input end of the second inverter, the output end of the second inverter is connected with the CLK end of the flip-flop, the non-PRE end of the flip-flop is connected with the VCC power supply end through the seventh resistor, is also grounded through the fourth capacitor, and is further connected with the power-off control end of the electric device through the fifth capacitor.
9. The power-on / off control circuit according to claim 7, wherein The system power supply module comprises an eighth resistor, a ninth resistor, a tenth resistor and an eleventh resistor, one end of the eighth resistor, one end of the ninth resistor, one end of the tenth resistor and one end of the eleventh resistor are connected with the drain of the second MOS tube and the gate of the third MOS tube, the other end of the eighth resistor is connected with the VAC power supply end, the other end of the ninth resistor is connected with the VDC power supply end, the other end of the tenth resistor is connected with the VBATA power supply end, and the other end of the eleventh resistor is connected with the VBATB power supply end.
10. The power-on / off control circuit according to claim 6, wherein The key start module comprises a start key, a twelfth resistor and a clamping diode, the 5th pin of the start key is connected with the VDD power supply end through the twelfth resistor, the 3rd pin and the 4th pin of the start key are connected with the 3rd pin of the clamping diode, the other end of the first resistor, one end of the third resistor and one end of the fourth resistor, the 1st pin of the clamping diode is grounded, and the 2nd pin of the clamping diode is connected with the VCC power supply end.