Wide voltage switching circuit

Abstract

The invention provides a wide voltage switching circuit. Comprising a direct current input end, a direct current output end, a first voltage control switch, a second voltage control switch, a voltage reduction module, a first controllable precision voltage stabilization source, a second controllable precision voltage stabilization source, a third controllable precision voltage stabilization source, a fourth controllable precision voltage stabilization source, a first voltage division circuit, a second voltage division circuit, a third voltage division circuit and an overvoltage protection device. The voltage input to the reference ends of the first, second, third and fourth controllable precision voltage stabilization sources is adjusted by setting the voltage division ratios of the first, second and third voltage division circuits, so as to control whether the cathode to the anode are conducted or not, and further control the on-off of the first voltage control switch and the second voltage control switch. Different input voltages are switched to be output through the first voltage control switch or the second voltage control switch, and the adapter is maintained to work in a safe voltage range.

Description

Technical Field

[0001] The present invention relates to the technical field of voltage regulating circuits, and in particular to a wide voltage switching circuit. Background Art

[0002] The adapter is an interface converter, which usually needs to work within a specific voltage range. The standard working voltage is generally around 12V. In actual use, a certain range of voltage fluctuations is allowed, such as 9V~14V. However, if the input voltage is lower than 9V, the adapter will trigger the low voltage protection mechanism and stop working; if the input voltage exceeds 14V, the voltage may be too high, causing unstable operation and even damage to the device. Therefore, when using the adapter in daily life, make sure it works within the safe voltage range. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a voltage transmission circuit capable of maintaining an adapter within a safe voltage range.

[0004] In order to solve the above technical problems, the present invention provides a wide voltage switching circuit, including a DC input terminal, a DC output terminal, a first voltage control switch, a second voltage control switch, a step-down module, a first controllable precision voltage stabilizing source, a second controllable precision voltage stabilizing source, a third controllable precision voltage stabilizing source, a fourth controllable precision voltage stabilizing source, a first voltage divider circuit, a second voltage divider circuit, a third voltage divider circuit and an overvoltage protection device; the first voltage control switch is connected in series with the step-down module and then connected between the DC input terminal and the DC output terminal, and the second voltage control switch is connected between the DC input terminal and the DC output terminal; the first voltage divider circuit, the second voltage divider circuit, the third voltage divider circuit and the overvoltage protection device The overvoltage protection devices are each connected in series between the DC input terminal and the ground terminal; the reference end of the first controllable precision voltage-stabilizing source is connected to the voltage dividing point of the first voltage-dividing circuit, the anode is grounded, and the cathode is connected to the voltage dividing point of the second voltage-dividing circuit; the reference end of the second controllable precision voltage-stabilizing source is connected to the voltage dividing point of the second voltage-dividing circuit, the anode is grounded, and the cathode is connected to the control end of the first voltage-controlled switch; the reference end of the third controllable precision voltage-stabilizing source is connected to the voltage dividing point of the second voltage-dividing circuit, the anode is grounded, and the cathode is connected to the voltage dividing point of the third voltage-dividing circuit; the reference end of the fourth controllable precision voltage-stabilizing source is connected to the voltage dividing point of the third voltage-dividing circuit, the anode is grounded, and the cathode is connected to the control end of the second voltage-controlled switch.

[0005] Furthermore, the breakdown voltage of the overvoltage protection device is 28V.

[0006] Furthermore, the voltage division ratios of the first, second and third voltage division circuits are set as: When the input voltage is less than 9V, the voltage divided by the first voltage-dividing circuit is less than the reference voltage of the first controllable precision voltage-stabilizing source, the voltage divided by the second voltage-dividing circuit is less than the reference voltages of the second controllable precision voltage-stabilizing source and the third controllable precision voltage-stabilizing source, and the voltage divided by the third voltage-dividing circuit is less than the reference voltage of the fourth controllable precision voltage-stabilizing source; When the input voltage is not less than 9V but less than 14V, the voltage divided by the first voltage-dividing circuit is less than the reference voltage of the first controllable precision voltage-stabilizing source, the voltage divided by the second voltage-dividing circuit is less than the reference voltages of the second controllable precision voltage-stabilizing source and the third controllable precision voltage-stabilizing source, and the voltage divided by the third voltage-dividing circuit is not less than the reference voltage of the fourth controllable precision voltage-stabilizing source; When the input voltage is not less than 14V but less than 28V, the voltage after voltage division by the first voltage divider circuit is less than the reference voltage of the first controllable precision voltage regulator, and the voltage after voltage division by the second voltage divider circuit is not less than the reference voltages of the second controllable precision voltage regulator and the third controllable precision voltage regulator, and the voltage after voltage division by the third voltage divider circuit is not less than the reference voltage of the fourth controllable precision voltage regulator.

[0007] Furthermore, the reference voltage of the first controllable precision voltage-stabilizing source, the second controllable precision voltage-stabilizing source, the third controllable precision voltage-stabilizing source and the fourth controllable precision voltage-stabilizing source is 2.5V.

[0008] Further, the voltage division ratio of the first voltage division circuit is set to 10.2:1, the voltage division ratio of the second voltage division circuit is set to 4.6:1, and the voltage division ratio of the third voltage division circuit is set to 2.6:1.

[0009] Further, the first voltage-controlled switch includes two P-type MOS tubes, whose sources are connected to the DC input terminal, whose drains are connected to the step-down module, and whose gates are connected as the control terminal and connected to the cathode of the second controllable precision voltage-stabilizing source; the second voltage-controlled switch includes a P-type MOS tube, whose sources are connected to the DC input terminal, whose drains are connected to the DC output terminal, and whose gates are connected as the control terminal and connected to the cathode of the fourth controllable precision voltage-stabilizing source.

[0010] Furthermore, a first anti-backflow diode is connected in series to the branch where the first voltage control switch and the step-down module are located, and a second anti-backflow diode is connected in series to the branch where the second voltage control switch is located.

[0011] Furthermore, a surge protection module is connected in series between the DC input terminal and the ground terminal, and the surge protection module includes a surge protection resistor and a surge protection capacitor connected in series with each other.

[0012] Furthermore, the step-down module includes an NDP2450KC step-down chip.

[0013] Furthermore, a connection point between the first voltage control switch and the voltage reduction module is connected to an energy storage filter capacitor.

[0014] The present invention has the following beneficial effects: among the four controllable precision voltage-stabilizing sources, if the reference terminal voltage is less than the reference voltage, the cathode to the anode is not conductive, and if the reference terminal voltage is not less than the reference voltage, the cathode to the anode is conductive. Since the reference terminal of the first controllable precision voltage-stabilizing source is connected to the voltage dividing point of the first voltage-dividing circuit, the reference terminals of the second controllable precision voltage-stabilizing source and the third controllable precision voltage-stabilizing source are connected to the voltage dividing point of the second voltage-dividing circuit, and the reference terminal of the fourth controllable precision voltage-stabilizing source is connected to the voltage dividing point of the third voltage-dividing circuit, the voltage input to the reference terminals of the first, second, third, and fourth controllable precision voltage-stabilizing sources can be adjusted by setting the voltage dividing ratio of the first, second, and third voltage-dividing circuits, thereby controlling whether the cathode to the anode is conductive, and then controlling the on and off of the first voltage-controlled switch and the second voltage-controlled switch, so as to realize switching to output through the first voltage-controlled switch or the second voltage-controlled switch under different input voltages.

[0015] Specifically, the voltage division ratio of the first, second and third voltage division circuits is set as follows: when the input voltage is less than 9V, the voltages divided by the first, second and third voltage division circuits are all less than the reference voltage of the controllable precision voltage regulator; when the input voltage is not less than 9V but less than 14V, the voltages divided by the first and second voltage division circuits are less than the reference voltage of the controllable precision voltage regulator, while the voltage divided by the third voltage division circuit is not less than the reference voltage of the controllable precision voltage regulator; when the input voltage is not less than 14V but less than 28V, the voltage divided by the first voltage division circuit is less than the reference voltage of the controllable precision voltage regulator, while the voltage divided by the second voltage division circuit is not less than the reference voltage of the controllable precision voltage regulator. In this way: When the input voltage is less than 9V, the reference terminal voltage of the first controllable precision voltage-stabilizing source is obtained by dividing the voltage of the first voltage-dividing circuit. If the voltage is less than the reference voltage, the cathode to anode of the first controllable precision voltage-stabilizing source is not conductive, so that the second voltage-dividing circuit can divide the voltage normally. The reference terminal voltage of the second controllable precision voltage-stabilizing source is obtained by dividing the voltage of the second voltage-dividing circuit. If the voltage is less than the reference voltage, the cathode to anode of the second controllable precision voltage-stabilizing source is not conductive. Since the cathode of the second controllable precision voltage-stabilizing source is connected to the control end of the first voltage-controlled switch, the first voltage-controlled switch is also not conductive when the cathode to anode of the second controllable precision voltage-stabilizing source is not conductive, and the input voltage cannot be output to the DC output end through the first voltage-controlled switch and the step-down module.

[0016] At the same time, the reference end voltage of the third controllable precision voltage-stabilizing source is obtained by dividing the voltage of the second voltage-dividing circuit. If the voltage is less than the reference voltage, the cathode to anode of the third controllable precision voltage-stabilizing source is not conductive, so that the third voltage-dividing circuit divides the voltage normally. The reference end voltage of the fourth controllable precision voltage-stabilizing source is obtained by dividing the voltage of the third voltage-dividing circuit. If the voltage is less than the reference voltage, the cathode to anode of the fourth controllable precision voltage-stabilizing source is not conductive. Since the cathode of the fourth controllable precision voltage-stabilizing source is connected to the control end of the second voltage-controlled switch, the second voltage-controlled switch is also not conductive when the cathode to anode of the fourth controllable precision voltage-stabilizing source is not conductive, and the input voltage cannot be output to the DC output end through the second voltage-controlled switch.

[0017] When the input voltage is not less than 9V but less than 14V, the reference terminal voltage of the first controllable precision voltage-stabilizing source is obtained by dividing the voltage of the first voltage-dividing circuit. If the voltage is less than the reference voltage, the cathode to anode of the first controllable precision voltage-stabilizing source is not conductive, so that the second voltage-dividing circuit can divide the voltage normally. The reference terminal voltage of the second controllable precision voltage-stabilizing source is obtained by dividing the voltage of the second voltage-dividing circuit. If the voltage is less than the reference voltage, the cathode to anode of the second controllable precision voltage-stabilizing source is not conductive. Since the cathode of the second controllable precision voltage-stabilizing source is connected to the control end of the first voltage-controlled switch, the first voltage-controlled switch is also not conductive when the cathode to anode of the second controllable precision voltage-stabilizing source is not conductive, and the input voltage cannot be output to the DC output end through the first voltage-controlled switch and the step-down module.

[0018] At the same time, the reference end voltage of the third controllable precision voltage-stabilizing source is obtained by dividing the voltage of the second voltage-dividing circuit. If the voltage is less than the reference voltage, the cathode to anode of the third controllable precision voltage-stabilizing source is not conductive, so that the third voltage-dividing circuit divides the voltage normally. The reference end voltage of the fourth controllable precision voltage-stabilizing source is obtained by dividing the voltage of the third voltage-dividing circuit. If the voltage is not less than the reference voltage, the cathode to anode of the fourth controllable precision voltage-stabilizing source is conductive. Since the cathode of the fourth controllable precision voltage-stabilizing source is connected to the control end of the second voltage-controlled switch, when the cathode to anode of the fourth controllable precision voltage-stabilizing source is conductive, the second voltage-controlled switch is also conductive, and the input voltage can be output to the DC output end via the second voltage-controlled switch.

[0019] When the input voltage is not less than 14V but less than 28V, the reference terminal voltage of the first controllable precision voltage-stabilizing source is obtained by dividing the voltage of the first voltage-dividing circuit. If the voltage is less than the reference voltage, the cathode to anode of the first controllable precision voltage-stabilizing source is not conductive, so that the second voltage-dividing circuit can divide the voltage normally. The reference terminal voltage of the second controllable precision voltage-stabilizing source is obtained by dividing the voltage of the second voltage-dividing circuit. If the voltage is not less than the reference voltage, the cathode to anode of the second controllable precision voltage-stabilizing source is conductive. Since the cathode of the second controllable precision voltage-stabilizing source is connected to the control end of the first voltage-controlled switch, when the cathode to anode of the second controllable precision voltage-stabilizing source is conductive, the first voltage-controlled switch is also conductive. The input voltage can be output through the first voltage-controlled switch and the step-down module. The input voltage is reduced to 9V~14V by the step-down module and then output to the DC output end.

[0020] At the same time, the reference end voltage of the third controllable precision voltage-stabilizing source is obtained by dividing the voltage of the second voltage-dividing circuit. If the voltage is not less than the reference voltage, the cathode to anode of the third controllable precision voltage-stabilizing source is turned on, so that the reference end voltage of the fourth controllable precision voltage-stabilizing source is pulled down. If the voltage is less than the reference voltage, the cathode to anode of the fourth controllable precision voltage-stabilizing source is not turned on. Since the cathode of the fourth controllable precision voltage-stabilizing source is connected to the control end of the second voltage-controlled switch, the second voltage-controlled switch is also not turned on when the cathode to anode of the fourth controllable precision voltage-stabilizing source is not turned on, and the input voltage cannot be output to the DC output end through the second voltage-controlled switch.

[0021] When the input voltage is not less than 28V, the overvoltage protection device breaks down and conducts, and the input voltage at the DC input end is output to the ground end through the overvoltage protection device, and cannot be output to the DC output end through the first voltage control switch or the second voltage control switch.

[0022] In summary, when the input voltage is less than 9V or not less than 28V, the input voltage cannot be output to the DC output terminal; when the input voltage is not less than 9V but less than 14V, the input voltage is directly output to the DC output terminal through the second voltage control switch; when the input voltage is not less than 14V but less than 28V, the input voltage is output through the first voltage control switch and the step-down module, and the input voltage is reduced to 9V~14V by the step-down module and then output to the DC output terminal. In this way, the wide voltage switching circuit can achieve the output of only 9V~14V voltage, which can maintain the adapter working within the safe voltage range. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a partial circuit diagram of the voltage-controlled switch portion of the wide-voltage switching circuit.

[0024] Figure 2 It is a partial circuit diagram of the buck module part of the wide voltage switching circuit. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below in conjunction with specific implementation methods.

[0026] This embodiment provides a wide voltage switching circuit, such as Figure 1 , 2 As shown, the wide voltage switching circuit includes a DC input terminal Vin, a DC output terminal Vout, a first voltage control switch, a second voltage control switch, a step-down module DCDC, a first controllable precision voltage regulator U1, a second controllable precision voltage regulator U2, a third controllable precision voltage regulator U3, a fourth controllable precision voltage regulator U4, a first voltage divider circuit, a second voltage divider circuit, a third voltage divider circuit and an overvoltage protection device D1. Among them, the DC output terminal Vout is used to connect the power supply terminal of the adapter.

[0027] The first voltage control switch includes a P-type MOS transistor Q1 and a P-type MOS transistor Q2. The gates of the two MOS transistors Q1 and Q2 are connected as the control end of the first voltage control switch. The sources are connected and connected to the DC input terminal Vin. A resistor R7 and a capacitor C1 are connected in series between the source and the gate. The drains are connected and connected to the input end of the step-down module DCDC via the contact VIN14V_28V. The output end of the step-down module DCDC is connected to the DC output terminal Vout. The first voltage control switch is connected in series with the step-down module DCDC and connected between the DC input terminal Vin and the DC output terminal Vout. The second voltage control switch includes a P-type MOS transistor Q3 and a P-type MOS transistor Q4. The gates of the two MOS transistors Q3 and Q4 are connected and used as the control end of the second voltage control switch. The sources are connected and connected to the DC input terminal Vin. A resistor R8 and a capacitor C2 are connected in series between the source and the gate. The drains are connected and connected to the DC output terminal Vout. The second voltage control switch is connected between the DC input terminal Vin and the DC output terminal Vout.

[0028] The first voltage-dividing circuit includes a resistor R1 and a resistor R2 connected in series, the second voltage-dividing circuit includes a resistor R3 and a resistor R4 connected in series, and the third voltage-dividing circuit includes a resistor R5 and a resistor R6 connected in series. The first voltage-dividing circuit, the second voltage-dividing circuit, the third voltage-dividing circuit and the overvoltage protection device D1 are each connected in series between the DC input terminal Vin and the ground terminal.

[0029] The reference end R of the first controllable precision voltage-stabilizing source U1 is connected to the voltage-dividing point of the first voltage-dividing circuit (i.e., the connection point between resistors R1 and R2), the anode A is grounded, and the cathode K is connected to the voltage-dividing point of the second voltage-dividing circuit (i.e., the connection point between resistors R3 and R4). The reference end R of the second controllable precision voltage-stabilizing source U2 is connected to the voltage-dividing point of the second voltage-dividing circuit (i.e., the connection point between resistors R3 and R4), the anode A is grounded, and the cathode K is connected to the control end of the first voltage-controlled switch (i.e., the gate of MOS tube Q1 and MOS tube Q2) via resistor R9. The reference end R of the third controllable precision voltage-stabilizing source U3 is connected to the voltage-dividing point of the second voltage-dividing circuit (i.e., the connection point between resistors R3 and R4) via the connection point 14V_ON / OFF, the anode A is grounded, and the cathode K is connected to the voltage-dividing point of the third voltage-dividing circuit (i.e., the connection point between resistors R5 and R6). The reference end R of the fourth controllable precision voltage-stabilizing source U4 is connected to the voltage dividing point of the third voltage dividing circuit (i.e., the connection point between the resistor R5 and the resistor R6), the anode A is grounded, and the cathode K is connected to the control end of the second voltage-controlled switch (i.e., the gates of the MOS tube Q3 and the MOS tube Q4) via the resistor R10.

[0030] In this embodiment, the reference voltages of the first controllable precision voltage regulator U1, the second controllable precision voltage regulator U2, the third controllable precision voltage regulator U3 and the fourth controllable precision voltage regulator U4 are all 2.5V. When the voltage at the reference end R of these four controllable precision voltage regulators U1, U2, U3, and U4 is less than 2.5V, the cathode K to the anode A is not conductive, and when the voltage at the reference end R is not less than 2.5V, the cathode K to the anode A is conductive.

[0031] In this embodiment, the voltage division ratio of the first voltage division circuit is set to 10.2:1, specifically, the resistance value of the resistor R1 is set to 102kΩ, and the resistance value of the resistor R2 is set to 10kΩ; the voltage division ratio of the second voltage division circuit is set to 4.6:1, specifically, the resistance value of the resistor R3 is set to 46kΩ, and the resistance value of the resistor R4 is set to 10 kΩ; the voltage division ratio of the third voltage division circuit is set to 2.6:1, specifically, the resistance value of the resistor R5 is set to 26kΩ, and the resistance value of the resistor R6 is set to 10 kΩ. In this way, based on the voltage division ratios of the first voltage division circuit, the second voltage division circuit, and the third voltage division circuit, the voltage magnitude of the reference end R input to the first controllable precision voltage stabilizing source U1, the second controllable precision voltage stabilizing source U2, the third controllable precision voltage stabilizing source U3, and the fourth controllable precision voltage stabilizing source U4 can be adjusted, thereby controlling whether the cathode K is turned on to the anode A, and then controlling the on and off of the first voltage control switch and the second voltage control switch, so as to achieve switching through the first voltage control switch or the second voltage control switch for output under different input voltages.

[0032] When the input voltage of the DC input terminal Vin is less than 9V, the output voltage after the input voltage is divided by the first voltage divider circuit is Vin*10 / (102+10)<2.5V. The voltage of the reference terminal R of the first controllable precision voltage-stabilizing source U1 is obtained by the voltage division of the first voltage-dividing circuit. If the voltage is less than 2.5V, that is, less than the reference voltage of the first controllable precision voltage-stabilizing source U1, the cathode K to the anode A of the first controllable precision voltage-stabilizing source U1 is not conductive, so that the second voltage-dividing circuit divides the voltage normally. The voltage of the input voltage after being divided by the second voltage divider circuit is Vin*10 / (46+10)<2.5V. The voltage of the reference terminal R of the second controllable precision voltage regulator U2 is obtained by the voltage division of the second voltage divider circuit. The voltage is less than 2.5V, that is, less than the reference voltage of the second controllable precision voltage regulator U2. Then, the cathode K to the anode A of the second controllable precision voltage regulator U2 is not conductive. Since the cathode K of the second controllable precision voltage regulator U2 is connected to the control terminal of the first voltage control switch, when the cathode K to the anode A of the second controllable precision voltage regulator U2 is not conductive, the control terminal of the first voltage control switch cannot be grounded through the second controllable precision voltage regulator U2. Then, the voltage of the control terminal of the first voltage control switch will not be pulled down, that is, the source voltage of the MOS tube Q1 and the MOS tube Q2 of the first voltage control switch is not higher than the gate voltage, so that the first voltage control switch is not conductive, and the input voltage of the DC input terminal Vin cannot be output to the DC output terminal Vout through the first voltage control switch and the step-down module DCDC.

[0033] At the same time, the voltage at the reference terminal R of the third controllable precision voltage-stabilizing source U3 is also obtained by dividing the voltage of the second voltage-dividing circuit. If the voltage is less than 2.5V, that is, less than the reference voltage of the third controllable precision voltage-stabilizing source U3, the cathode K to the anode A of the third controllable precision voltage-stabilizing source U3 is not conductive, so that the third voltage-dividing circuit can divide the voltage normally. The voltage of the input voltage after being divided by the third voltage-dividing circuit is Vin*10 / (26+10)<2.5V. The voltage of the reference terminal R of the fourth controllable precision voltage-regulating source U4 is obtained by dividing the voltage of the third voltage-dividing circuit. The voltage is less than 2.5V, that is, less than the reference voltage of the fourth controllable precision voltage-regulating source U4. Then, the cathode K to the anode A of the fourth controllable precision voltage-regulating source U4 is not conductive. Since the cathode K of the fourth controllable precision voltage-regulating source U4 is connected to the control terminal of the second voltage-controlled switch, when the cathode K to the anode A of the fourth controllable precision voltage-regulating source U4 is not conductive, the control terminal of the second voltage-controlled switch cannot be grounded through the fourth controllable precision voltage-regulating source U4. Then, the voltage of the control terminal of the second voltage-controlled switch will not be pulled down, that is, the source voltage of the MOS tube Q3 and the MOS tube Q4 of the second voltage-controlled switch is not higher than the gate voltage, so that the second voltage-controlled switch is not conductive, and the input voltage cannot be output to the DC output terminal Vout through the second voltage-controlled switch.

[0034] When the input voltage of the DC input terminal Vin is not less than 9V but less than 14V, the voltage of the input voltage after being divided by the first voltage divider circuit is Vin*10 / (102+10)<2.5V, and the voltage of the reference terminal R of the first controllable precision voltage-regulating source U1 is obtained by the voltage division of the first voltage-dividing circuit. If the voltage is less than 2.5V, that is, less than the reference voltage of the first controllable precision voltage-regulating source U1, the cathode K to the anode A of the first controllable precision voltage-regulating source U1 is not conductive, so that the second voltage-dividing circuit divides the voltage normally. The voltage of the input voltage after being divided by the second voltage divider circuit is Vin*10 / (46+10)<2.5V. The voltage of the reference terminal R of the second controllable precision voltage regulator U2 is obtained by the voltage division of the second voltage divider circuit. The voltage is less than 2.5V, that is, less than the reference voltage of the second controllable precision voltage regulator U2. Then, the cathode K to the anode A of the second controllable precision voltage regulator U2 is not conductive. Since the cathode K of the second controllable precision voltage regulator U2 is connected to the control terminal of the first voltage control switch, when the cathode K to the anode A of the second controllable precision voltage regulator U2 is not conductive, the control terminal of the first voltage control switch cannot be grounded through the second controllable precision voltage regulator U2. Then, the voltage of the control terminal of the first voltage control switch will not be pulled down, that is, the source voltage of the MOS tube Q1 and the MOS tube Q2 of the first voltage control switch is not higher than the gate voltage, so that the first voltage control switch is not conductive, and the input voltage of the DC input terminal Vin cannot be output to the DC output terminal Vout through the first voltage control switch and the step-down module DCDC.

[0035] At the same time, the voltage at the reference terminal R of the third controllable precision voltage-stabilizing source U3 is also obtained by dividing the voltage of the second voltage-dividing circuit. If the voltage is less than 2.5V, that is, less than the reference voltage of the third controllable precision voltage-stabilizing source U3, the cathode K to the anode A of the third controllable precision voltage-stabilizing source U3 is not conductive, so that the third voltage-dividing circuit can divide the voltage normally. The voltage of the input voltage after being divided by the third voltage-dividing circuit is Vin*10 / (26+10)≥2.5V. The voltage of the reference terminal R of the fourth controllable precision voltage-regulating source U4 is obtained by dividing the voltage of the third voltage-dividing circuit. The voltage is not less than 2.5V, that is, not less than the reference voltage of the fourth controllable precision voltage-regulating source U4. Then, the cathode K of the fourth controllable precision voltage-regulating source U4 is turned on to the anode A. Since the cathode K of the fourth controllable precision voltage-regulating source U4 is connected to the control terminal of the second voltage-controlled switch, when the cathode K of the fourth controllable precision voltage-regulating source U4 is turned on to the anode A, the control terminal of the second voltage-controlled switch is grounded via the second controllable precision voltage-regulating source U2. Then, the voltage of the control terminal of the second voltage-controlled switch is pulled down, that is, the source voltage of the MOS tube Q3 and the MOS tube Q4 of the second voltage-controlled switch is higher than the gate voltage, so that the second voltage-controlled switch is turned on, and the input voltage of the DC input terminal Vin can be output to the DC output terminal Vout via the second voltage-controlled switch.

[0036] When the input voltage of the DC input terminal Vin is not less than 14V and less than 28V, the voltage of the input voltage after being divided by the first voltage divider circuit is Vin*10 / (102+10)<2.5V, and the voltage of the reference terminal R of the first controllable precision voltage-stabilizing source U1 is obtained by the voltage division of the first voltage divider circuit. If the voltage is less than 2.5V, that is, less than the reference voltage of the first controllable precision voltage-stabilizing source U1, the cathode K to the anode A of the first controllable precision voltage-stabilizing source U1 is not conductive, so that the second voltage divider circuit divides the voltage normally. The input voltage after being divided by the second voltage divider circuit is Vin*10 / (46+10)≥2.5V. The voltage of the reference terminal R of the second controllable precision voltage regulator U2 is obtained by the voltage division of the second voltage divider circuit. The voltage is not less than 2.5V, that is, not less than the reference voltage of the second controllable precision voltage regulator U2. Then, the cathode K of the second controllable precision voltage regulator U2 is connected to the anode A. Since the cathode K of the second controllable precision voltage regulator U2 is connected to the control terminal of the first voltage control switch, the cathode K of the second controllable precision voltage regulator U2 is connected to the anode A. When the control end of the first voltage control switch is grounded via the second controllable precision voltage regulator U2, the voltage at the control end of the first voltage control switch is pulled down, that is, the source voltage of the MOS tube Q1 and the MOS tube Q2 of the first voltage control switch is higher than the gate voltage, so that the first voltage control switch is turned on, and the input voltage of the DC input terminal Vin can be output through the first voltage control switch and the step-down module DCDC, and the input voltage of the DC input terminal Vin is reduced to 9V~14V by the step-down module DCDC and then output to the DC output terminal Vout.

[0037] In this embodiment, the buck module DCDC includes the NDP2450KC buck chip, which is a synchronous buck converter that converts a high input voltage into a stable low output voltage through PWM control and synchronous rectification technology. The specific output voltage is sampled by the feedback resistor Rup and the feedback resistor Rdown of the feedback network, and then set after comparison with the internal reference voltage Vref. By adjusting the ratio of the feedback resistor Rup and the feedback resistor Rdown, the output voltage can be accurately set. The formula is as follows: Vout=Vref*(1+Rup / Rdown); The internal reference voltage Vref is set to 1V, the feedback resistor Rup is 115 kΩ, and the feedback resistor Rdown is 10 kΩ. Thus, the specific output voltage Vout after being stepped down by the step-down module DCDC is 12.5V.

[0038] At the same time, the voltage at the reference terminal R of the third controllable precision voltage-stabilizing source U3 is also obtained by the voltage division of the second voltage-dividing circuit. This voltage is not less than 2.5V, that is, not less than the reference voltage of the third controllable precision voltage-stabilizing source U3. Then, the cathode K of the third controllable precision voltage-stabilizing source U3 is turned on to the anode A, so that the voltage division point of the third voltage-dividing circuit is grounded through the third controllable precision voltage-stabilizing source U3. Since the reference terminal R of the fourth controllable precision voltage-stabilizing source U4 is connected to the voltage division point of the third voltage-dividing circuit, the voltage at the reference terminal R of the fourth controllable precision voltage-stabilizing source U4 is pulled down, so that this voltage is less than the reference voltage of the fourth controllable precision voltage-stabilizing source U4. Then, the voltage of the fourth controllable precision voltage-stabilizing source U4 is The cathode K is not conducting to the anode A. Since the cathode K of the fourth controllable precision voltage-stabilizing source U4 is connected to the control end of the second voltage-controlled switch, when the cathode K of the fourth controllable precision voltage-stabilizing source U4 is not conducting to the anode A, the control end of the second voltage-controlled switch cannot be grounded through the fourth controllable precision voltage-stabilizing source U4, and the control end voltage of the second voltage-controlled switch will not be pulled down, that is, the source voltage of the MOS tube Q3 and the MOS tube Q4 of the second voltage-controlled switch is not higher than the gate voltage, so that the second voltage-controlled switch is also not conducting, and the input voltage of the DC input terminal Vin cannot be output to the DC output terminal Vout through the second voltage-controlled switch.

[0039] When the input voltage of the DC input terminal Vin is not less than 28V, the overvoltage protection device D1 breaks down and conducts, and the input voltage of the DC input terminal Vin is output to the ground through the overvoltage protection device D1, and will not be output to the DC output terminal Vout through the first voltage control switch or the second voltage control switch.

[0040] In summary, when the input voltage of the DC input terminal Vin is less than 9V or not less than 28V, the input voltage cannot be output to the DC output terminal Vout; when the input voltage of the DC input terminal Vin is not less than 9V but less than 14V, the input voltage is directly output to the DC output terminal Vout through the second voltage control switch; when the input voltage is not less than 14V but less than 28V, the input voltage is output through the first voltage control switch and the step-down module DCDC, and the input voltage of the DC input terminal Vin is reduced to 9V~14V through the step-down module DCDC and then output to the DC output terminal Vout. In this way, the wide voltage switching circuit realizes the output of only 9V~14V voltage, which can maintain the adapter working within the safe voltage range.

[0041] In this embodiment, a first anti-backflow diode D2 is connected in series to the branch where the first voltage control switch and the step-down module DCDC are located, and a second anti-backflow diode D3 is connected in series to the branch where the second voltage control switch is located. In this way, when the output is switched through the first voltage control switch or the second voltage control switch under different input voltages, the current is prevented from flowing in reverse, thereby protecting the safety of the circuit and the equipment.

[0042] In this embodiment, a surge protection module is connected in series between the DC input terminal Vin and the ground terminal. The surge protection module includes a surge protection resistor R11 and a surge protection capacitor C3 connected in series. When the circuit is disturbed by the outside world and a power surge occurs, the surge protection module can quickly conduct the shunt, thereby clamping the voltage within a safe range to prevent the surge from damaging other devices in the circuit.

[0043] In this embodiment, the contact VIN14V_28V between the first voltage control switch and the step-down module DCDC is connected to energy storage filter capacitors C4, C5, and C6, which play the role of smoothing voltage, storing energy, filtering, reducing electromagnetic interference, and improving transient response in the wide voltage switching circuit to ensure stable operation of the circuit.

[0044] The above is only an implementation method of the invention, and does not limit the scope of patent protection. Those skilled in the art can make non-substantial changes or substitutions based on the invention, which still fall within the scope of patent protection.

Claims

1. A wide voltage switching circuit, characterized in that: The invention comprises a DC input terminal, a DC output terminal, a first voltage control switch, a second voltage control switch, a voltage step-down module, a first controllable precision voltage stabilizing source, a second controllable precision voltage stabilizing source, a third controllable precision voltage stabilizing source, a fourth controllable precision voltage stabilizing source, a first voltage divider circuit, a second voltage divider circuit, a third voltage divider circuit and an overvoltage protection device; the first voltage control switch is connected in series with the voltage step-down module and then connected between the DC input terminal and the DC output terminal, and the second voltage control switch is connected between the DC input terminal and the DC output terminal; the first voltage divider circuit, the second voltage divider circuit, the third voltage divider circuit and the overvoltage protection device are each connected in series. Between the DC input terminal and the ground terminal; the reference end of the first controllable precision voltage-stabilizing source is connected to the voltage dividing point of the first voltage-dividing circuit, the anode is grounded, and the cathode is connected to the voltage dividing point of the second voltage-dividing circuit; the reference end of the second controllable precision voltage-stabilizing source is connected to the voltage dividing point of the second voltage-dividing circuit, the anode is grounded, and the cathode is connected to the control end of the first voltage-controlled switch; the reference end of the third controllable precision voltage-stabilizing source is connected to the voltage dividing point of the second voltage-dividing circuit, the anode is grounded, and the cathode is connected to the voltage dividing point of the third voltage-dividing circuit; the reference end of the fourth controllable precision voltage-stabilizing source is connected to the voltage dividing point of the third voltage-dividing circuit, the anode is grounded, and the cathode is connected to the control end of the second voltage-controlled switch.

2. The wide voltage switching circuit according to claim 1, characterized in that: The breakdown voltage of the overvoltage protection device is 28V.

3. The wide voltage switching circuit according to claim 2, characterized in that: The voltage division ratios of the first, second and third voltage division circuits are set as: When the input voltage is less than 9V, the voltage divided by the first voltage-dividing circuit is less than the reference voltage of the first controllable precision voltage-stabilizing source, the voltage divided by the second voltage-dividing circuit is less than the reference voltages of the second controllable precision voltage-stabilizing source and the third controllable precision voltage-stabilizing source, and the voltage divided by the third voltage-dividing circuit is less than the reference voltage of the fourth controllable precision voltage-stabilizing source; When the input voltage is not less than 9V but less than 14V, the voltage divided by the first voltage-dividing circuit is less than the reference voltage of the first controllable precision voltage-stabilizing source, the voltage divided by the second voltage-dividing circuit is less than the reference voltages of the second controllable precision voltage-stabilizing source and the third controllable precision voltage-stabilizing source, and the voltage divided by the third voltage-dividing circuit is not less than the reference voltage of the fourth controllable precision voltage-stabilizing source; When the input voltage is not less than 14V but less than 28V, the voltage after voltage division by the first voltage divider circuit is less than the reference voltage of the first controllable precision voltage regulator, and the voltage after voltage division by the second voltage divider circuit is not less than the reference voltages of the second controllable precision voltage regulator and the third controllable precision voltage regulator, and the voltage after voltage division by the third voltage divider circuit is not less than the reference voltage of the fourth controllable precision voltage regulator.

4. The wide voltage switching circuit according to claim 3, characterized in that: The reference voltage of the first controllable precision voltage-stabilizing source, the second controllable precision voltage-stabilizing source, the third controllable precision voltage-stabilizing source and the fourth controllable precision voltage-stabilizing source is 2.5V.

5. The wide voltage switching circuit according to claim 4, characterized in that: The voltage division ratio of the first voltage division circuit is set to 10.2:1, the voltage division ratio of the second voltage division circuit is set to 4.6:1, and the voltage division ratio of the third voltage division circuit is set to 2.6:

1.

6. The wide voltage switching circuit according to claim 1, characterized in that: The first voltage-controlled switch includes two P-type MOS tubes, whose sources are connected to the DC input terminal, whose drains are connected to the step-down module, and whose gates are connected as the control terminal and connected to the cathode of the second controllable precision voltage-stabilizing source; the second voltage-controlled switch includes a P-type MOS tube, whose sources are connected to the DC input terminal, whose drains are connected to the DC output terminal, and whose gates are connected as the control terminal and connected to the cathode of the fourth controllable precision voltage-stabilizing source.

7. The wide voltage switching circuit according to claim 1, characterized in that: A first anti-backflow diode is connected in series on the branch where the first voltage control switch and the step-down module are located, and a second anti-backflow diode is connected in series on the branch where the second voltage control switch is located.

8. The wide voltage switching circuit according to claim 1, characterized in that: An anti-surge module is connected in series between the DC input terminal and the ground terminal. The anti-surge module includes an anti-surge resistor and an anti-surge capacitor connected in series.

9. The wide voltage switching circuit according to claim 1, characterized in that: The step-down module includes an NDP2450KC step-down chip.

10. The wide voltage switching circuit according to claim 1, characterized in that: The junction between the first voltage control switch and the voltage reduction module is connected with an energy storage filter capacitor.

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