Constant-current and constant-voltage output control circuit and charger

Abstract

The utility model relates to the technical field of chargers, and discloses a constant-current constant-voltage output control circuit, which comprises a reference voltage unit, a constant-voltage control unit and a constant-current control unit, the constant voltage control unit and the constant current control unit output corresponding voltage feedback signals or current feedback signals according to the output voltage of the charger and the reference voltage. And the duty ratio of a PWM control circuit of the charger is adjusted through the voltage feedback signal or the current feedback signal so as to stabilize the output voltage value or the current value of the charger. The constant-voltage and constant-current control circuit is simple in structure, constant-voltage and constant-current control of charging of the charger can be realized without using a single chip microcomputer, the production cost of the charger can be reduced, and the complicated mounting process and burning process of the single chip microcomputer can be saved, so that the production efficiency of the charger can be improved.

Description

Technical Field

[0001] The utility model relates to the technical field of chargers, in particular to a constant current and constant voltage output control circuit and a charger. Background Art

[0002] With the continuous development of power supply industry technology, there are many types of battery chargers. However, for high-power current groups, many manufacturers only have constant voltage function but no constant current function. They all rely on the current limiting of the primary IC to control the circuit. However, this control method has a large difference in the output current when the input voltage is high or low, and the current accuracy is not enough to achieve the constant current effect required by the charger. At present, some manufacturers use single-chip microcomputer control to solve this problem, but the high price of single-chip microcomputer will increase the cost, and the use of single-chip microcomputer requires burning the program. It cannot be output without the program, which requires an additional manufacturing process. In addition, the installation process of the circuit using the single-chip microcomputer is also more complicated. For example, some can only use the reflow process but cannot realize the wave peak process, resulting in low production efficiency of the charger.

[0003] Therefore, in order to solve the above problems, the utility model provides a constant current and constant voltage output control circuit and a charger which can improve production efficiency and have low cost. Utility Model Content

[0004] The utility model provides a constant current and constant voltage output control circuit and a charger, aiming to solve the problems of high production cost and low production efficiency of the existing charger.

[0005] In order to solve the above technical problems, the utility model provides a constant current and constant voltage output control circuit, which includes: a reference voltage unit, which is used to output a reference voltage; a constant voltage control unit, one end of which is used to be connected to the output end of the charger, and the other end is connected to the reference voltage unit, and the constant voltage control unit is used to output a voltage feedback signal according to the reference voltage and the output voltage of the charger; a constant current control unit, which includes a current limiting module and a constant current comparison module, one end of the current limiting module is used to be connected to the output end of the charger, and the other end is connected to one end of the constant current comparison module, and the other end of the constant current comparison module is connected to the reference voltage unit, and the constant current control unit is used to output a current feedback signal according to the reference voltage and the output voltage; wherein, the duty cycle of the PWM control circuit of the charger is adjusted by the voltage feedback signal to stabilize the voltage value output by the charger; or the duty cycle is adjusted by the current feedback signal to stabilize the current value output by the charger.

[0006] Furthermore, the current limiting module includes a first resistor and a second resistor, one end of the first resistor is used to be connected to the output end of the charger, and the other end is connected to one end of the second resistor, and the other end of the second resistor is connected to the constant current comparison module.

[0007] Furthermore, the constant current comparison module includes a first comparator, a first capacitor, and a first diode, the inverting input terminal of the first comparator is connected to the second resistor, the non-inverting input terminal of the first comparator is connected to the reference voltage unit, the output terminal of the first comparator is connected to the cathode of the first diode, and the anode of the first diode is used to be connected to the feedback circuit of the charger; one end of the first capacitor is connected to the inverting input terminal of the first comparator, and the other end is connected to the output terminal of the first comparator.

[0008] Furthermore, the constant voltage control unit includes a voltage divider module and a constant voltage comparison module, the first end of the voltage divider module is used to be connected to the output end of the charger, the second end of the voltage divider module is connected to the constant voltage comparison module, and the third end of the voltage divider module is grounded; one end of the constant voltage comparison module is connected to the voltage divider module and the reference voltage unit, and the other end is used to output the voltage feedback signal.

[0009] Furthermore, the constant voltage comparison module includes a second comparator, a third resistor, a second capacitor and a second diode, the inverting input terminal of the second comparator is connected to the voltage divider module, the non-inverting input terminal of the second comparator is connected to the reference voltage unit, the output terminal of the second comparator is connected to the cathode of the second diode, and the anode of the second diode is used to be connected to the feedback circuit of the charger; one end of the third resistor is connected to the inverting input terminal of the second comparator, and the other end is connected to one end of the second capacitor, and the other end of the second capacitor is connected to the output terminal of the second comparator.

[0010] Furthermore, the reference voltage unit includes a TL431 regulator and a fourth resistor, the cathode of the TL431 regulator is connected to one end of the fourth resistor, the other end of the fourth resistor is used to be connected to the output end of the charger, the reference end of the TL431 regulator is connected to the constant voltage control unit and the constant current control unit, and the anode of the TL431 regulator is grounded.

[0011] Furthermore, the constant current and constant voltage output control circuit also includes a light control unit and a fan control unit, one end of the light control unit is used to be connected to the output end of the charger, and the other end is connected to one end of the fan control unit, the other end of the fan control unit is used to be connected to the fan, the light control unit is used to indicate the charging status of the charger, and the fan control unit is used to control the fan to dissipate heat from the charger when it is charging.

[0012] Further, the light control unit includes a third comparator, a fourth comparator, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a first LED and a second LED, one end of the fifth resistor is connected to the reference voltage unit, and the other end is connected to one end of the sixth resistor, the other end of the sixth resistor is connected to the non-inverting input end of the third comparator and one end of the seventh resistor, the other end of the seventh resistor is grounded, the inverting input end of the third comparator is connected to the output end of the charger, the output end of the third comparator is connected to the cathode of the first LED and the inverting input end of the fourth comparator, the anode of the first LED is connected to one end of the eighth resistor, the non-inverting input end of the fourth comparator is connected to the reference voltage unit, the output end of the fourth comparator is connected to the cathode of the second LED and the fan control unit, the anode of the second LED is connected to one end of the eighth resistor, and the other end of the eighth resistor is connected to the fan control unit.

[0013] Further, the fan control unit includes a voltage stabilizing diode, a ninth resistor, a transistor, a voltage stabilizing chip, a third capacitor and a fourth capacitor, the cathode of the voltage stabilizing diode is connected to the output end of the fourth comparator, the anode of the voltage stabilizing diode is connected to one end of the ninth resistor, the other end of the ninth resistor is connected to the base of the transistor, the collector of the transistor is connected to the anodes of the first LED and the second LED, the emitter of the transistor is connected to the first end of the voltage stabilizing chip, the second end of the voltage stabilizing chip is used to be connected to the anode of the fan, and the third end of the voltage stabilizing chip is used to be connected to the cathode of the fan; the anode of the third capacitor is connected to the second end of the voltage stabilizing chip, the cathode of the third capacitor is connected to the third end of the voltage stabilizing chip, and the fourth capacitor is connected between the second end and the third end of the voltage stabilizing chip.

[0014] On the other hand, the utility model also provides a charger, which includes a rectifier and filter circuit, a transformer, a feedback circuit, a PWM control circuit, an auxiliary power supply circuit and the above-mentioned constant current and constant voltage output control circuit, wherein one end of the rectifier and filter circuit is used to receive alternating current, and the other end is connected to the primary coil of the transformer, the secondary coil of the transformer is connected to one end of the constant current and constant voltage output control circuit, the other end of the constant current and constant voltage output control circuit is connected to one end of the feedback circuit, the other end of the feedback circuit is connected to one end of the PWM control circuit, the other end of the PWM control circuit is connected to one end of the auxiliary power supply circuit, and the other end of the auxiliary power supply circuit is connected to the PWM control circuit.

[0015] The constant current and constant voltage output control circuit and charger disclosed in the utility model include a reference voltage unit, a constant voltage control unit and a constant current control unit, wherein the constant voltage control unit and the constant current control unit output a voltage feedback signal or a current feedback signal corresponding to the output voltage of the charger and the reference voltage, and then adjust the duty cycle of the PWM control circuit of the charger through the voltage feedback signal or the current feedback signal to achieve a stable output voltage value or current value of the charger. The utility model has a simple structure and can achieve constant voltage and constant current control of the charger without using a single-chip microcomputer, which can not only reduce the production cost of the charger, but also save the complex installation process and burning process of the single-chip microcomputer, thereby improving the production efficiency of the charger. The constant current and constant voltage output control circuit and charger disclosed in the utility model solve the problems of high cost and low production efficiency of existing chargers. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 It is a structural block diagram of a constant current and constant voltage output control circuit provided by an embodiment of the utility model;

[0018] Figure 2 This is a circuit schematic diagram of a constant current and constant voltage output control circuit provided by an embodiment of the utility model;

[0019] Figure 3 It is a structural block diagram of a charger provided by an embodiment of the utility model;

[0020] Figure 4 The utility model provides a circuit diagram of a charger according to an embodiment of the present invention.

[0021] Reference numerals:

[0022] 10. Constant current and constant voltage output control circuit; 11. Reference voltage unit; 12. Constant voltage control unit; 121. Voltage divider module; 122. Constant voltage comparison module; 13. Constant current control unit; 131. Current limiting module; 132. Constant current comparison module; 14. Light control unit; 15. Fan control unit; 20. Rectification and filtering circuit; 30. Transformer; 40. Feedback circuit; 50. PWM control circuit; 60. Auxiliary power supply circuit; 100. Charger. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments of the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0024] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0025] It should also be understood that the terms used in this utility model specification are only for the purpose of describing specific embodiments and are not intended to limit the utility model. As used in this utility model specification and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0026] It should be further understood that the term “and / or” used in the present specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0027] Figures 1 to 4 An embodiment of the constant current and constant voltage output control circuit provided by the utility model is shown. Figure 1 , Figure 1A structural block diagram of a constant current and constant voltage output control circuit provided by an embodiment of the utility model. The constant current and constant voltage output control circuit 10 of this embodiment includes a reference voltage unit 11, which is used to output a reference voltage; a constant voltage control unit 12, one end of which is used to be connected to the output end of the charger 100, and the other end is connected to the reference voltage unit 11, and the constant voltage control unit 12 is used to output a voltage feedback signal according to the reference voltage and the output voltage of the charger 100; a constant current control unit 13, which includes a current limiting module 131 and a constant current comparison module 132, one end of the current limiting module 131 is used to be connected to the output end of the charger 100, and the other end is connected to one end of the constant current comparison module 132, and the other end of the constant current comparison module 132 is connected to the reference voltage unit 11, and the constant current control unit 13 is used to output a current feedback signal according to the reference voltage and the output voltage; wherein the duty cycle of the PWM control circuit 50 of the charger 100 is adjusted by the voltage feedback signal to stabilize the voltage value output by the charger 100; or the duty cycle is adjusted by the current feedback signal to stabilize the current value output by the charger 100. The utility model has a simple structure and can realize constant voltage and constant current control of charging of the charger 100 without using a single chip microcomputer, which can not only reduce the production cost of the charger 100, but also save the complicated installation process and burning process of the single chip microcomputer, thereby improving the production efficiency of the charger 100.

[0028] In one embodiment, such as this embodiment, see Figure 2 , Figure 2 1 is a circuit diagram of a constant current and constant voltage output control circuit provided by an embodiment of the present utility model. The current limiting module 131 includes a first resistor RS1 and a second resistor R8, one end of the first resistor RS1 is used to connect to the output end of the charger 100, and the other end is connected to one end of the second resistor R8, and the other end of the second resistor R8 is connected to the constant current comparison module 132. It should be noted that, please refer to Figure 2 In this embodiment, the first resistor RS1 and the second resistor R8 are both current limiting resistors, and the output end of the charger 100 includes pins 9, 7 and 10 of the secondary coil of the charger transformer 30, wherein pins 9 and 7 are respectively connected to Figure 2 The A1 and A2 nodes in the circuit are connected to the positive output terminal VO+ and the negative output terminal VO-, and the 10th pin is connected to the Figure 2 The A3 node in is connected, and what is connected is the fan F, specifically the positive pole F+ of the fan.

[0029] Furthermore, if Figure 2As shown, the reference voltage unit 11 includes a TL431 voltage regulator IC2 and a fourth resistor R6, the cathode of the TL431 voltage regulator IC2 is connected to one end of the fourth resistor R6, the other end of the fourth resistor R6 is used to connect to the output end of the charger 100, the reference end of the TL431 voltage regulator IC2 is connected to the constant voltage control unit 12 and the constant current control unit 13, and the anode of the TL431 voltage regulator IC2 is grounded. It should be noted that, in this embodiment, the TL431 voltage regulator IC2 can provide a reference voltage of 2.5V, which is output from its reference end, and the output reference voltage is input to the constant voltage control unit 12 and the constant current control unit 13.

[0030] Specifically, Figure 2 As shown, the constant current comparison module 132 includes a first comparator IC3D, a first capacitor C7, and a first diode D4. The inverting input terminal of the first comparator IC3D is connected to the second resistor R8, the non-inverting input terminal of the first comparator IC3D is connected to the reference voltage unit 11, the output terminal of the first comparator IC3D is connected to the cathode of the first diode D4, and the anode of the first diode D4 is used to connect to the feedback circuit 40 of the charger 100; one end of the first capacitor C7 is connected to the inverting input terminal of the first comparator IC3D, and the other end is connected to the output terminal of the first comparator IC3D. Among them, the non-inverting input terminal of the first comparator IC3D is pin 3, which is connected to the reference voltage; the inverting input terminal of the first comparator IC3D is pin 2, which is connected to the negative output terminal VO- of the charger 100 through the second resistor R8.

[0031] In this embodiment, the working principle of the constant current control unit 13 is as follows: when the output end of the transformer 30 is connected to a load, an output loop is formed, the first resistor RS1 and the second resistor R8 detect the voltage connected to the inverting input end of the first comparator IC3D, and the voltage of the inverting input end is compared with the 2.5V reference voltage of the non-inverting input end to output a low level, which is fed back to the PWM control circuit 50 of the charger 100 through the feedback circuit 40 of the charger 100, so that the PWM duty cycle can be adjusted to stabilize the current value of the output end of the charger 100. It should be noted that, in this embodiment, the feedback circuit 40 includes an optical coupler U1, the cathode of the light-emitting diode of the optical coupler U1 is connected to the constant voltage control unit 12 and the constant current control unit 13, and the anode of the light-emitting diode of the optical coupler U1 is connected to the 10th pin of the secondary coil of the transformer 30 through the resistor R2. Among them, the cathode of the light-emitting diode of the optocoupler U1 is connected to the anode of the first diode D4. When the first comparator IC3D outputs a low level, the light-emitting diode of the optocoupler U1 is turned on, so that the signal can be fed back to the PWM control circuit 50, and the first diode D4 can prevent the voltage from flowing back to the optocoupler U1 to ensure the stability of the current loop. In the PWM control circuit 50, the PWM duty cycle can be adjusted according to the feedback signal to adjust the switching frequency of the MOS tube in the PWM control circuit 50 to stabilize the current value at the output end. Among them, the constant current control formula is: Io = (R11 + R10 / R11 + R10 + R7) * 2.5 / RS1.

[0032] In one embodiment, such as the present embodiment, the constant voltage control unit 12 includes a voltage divider module 121 and a constant voltage comparison module 122, the first end of the voltage divider module 121 is used to connect to the output end of the charger 100, the second end of the voltage divider module 121 is connected to the constant voltage comparison module 122, and the third end of the voltage divider module 121 is grounded; one end of the constant voltage comparison module 122 is connected to the voltage divider module 121 and the reference voltage unit 11, and the other end is used to output the voltage feedback signal. Specifically, the voltage divider module 121 includes resistors R3 and R4, one end of the resistor R3 is used to connect to the positive output terminal VO+ of the charger 100, and the other end is connected to the constant voltage comparison module 122 and one end of the resistor R4, and the other end of the resistor R4 is grounded. The constant voltage comparison module 122 includes a second comparator IC3A, a third resistor R9, a second capacitor C6 and a second diode D3. The inverting input terminal of the second comparator IC3A is connected to the second end of the voltage divider module 121, the non-inverting input terminal of the second comparator IC3A is connected to the reference voltage unit 11, the output terminal of the second comparator IC3A is connected to the cathode of the second diode D3, and the anode of the second diode D3 is used to connect to the feedback circuit 40 of the charger 100; one end of the third resistor R9 is connected to the inverting input terminal of the second comparator IC3A, and the other end is connected to one end of the second capacitor C6, and the other end of the second capacitor C6 is connected to the output terminal of the second comparator IC3A. It should be noted that in this embodiment, the non-inverting input terminal of the second comparator IC3A is pin 12, which is connected to the reference voltage; the inverting input terminal of the second comparator IC3A is pin 13, which is connected between the resistor R3 and the resistor R4.

[0033] In this embodiment, the working principle of the constant voltage control unit 12 is as follows: the output terminal VO+ of the charger 100 is connected to the inverting input terminal of the second comparator IC3A through the resistor R3 and the resistor R4 to GND for voltage division, and the voltage of the inverting input terminal is compared with the 2.5V reference voltage of the non-inverting input terminal to output a low level, which is fed back to the PWM control circuit 50 of the charger 100 through the feedback circuit 40 of the charger 100, so that the PWM duty cycle can be adjusted to stabilize the voltage value of the output terminal of the charger 100. It should be noted that in the constant voltage control unit 12, the cathode of the light-emitting diode of the optocoupler U1 is connected to the anode of the second diode D3. When the second comparator IC3A outputs a low level, the light-emitting diode of the optocoupler U1 is turned on, so that the signal can be fed back to the PWM control circuit 50, and the second diode D3 can prevent the voltage from flowing back to the optocoupler U1 to ensure the stability of the voltage loop. In the PWM control circuit 50, the PWM duty cycle is adjusted according to the feedback signal to adjust the switching frequency of the MOS tube in the PWM control circuit 50 to stabilize the voltage value at the output end. The constant voltage control formula is: VO = (R13 / R4+1)*2.5.

[0034] In one embodiment, such as this embodiment, the constant current and constant voltage output control circuit 10 further includes a light control unit 14 and a fan control unit 15, one end of the light control unit 14 is used to be connected to the output end of the charger 100, and the other end is connected to one end of the fan control unit 15, and the other end of the fan control unit 15 is used to be connected to a fan, the light control unit 14 is used to indicate the charging state of the charger 100, and the fan control unit 15 is used to control the fan to dissipate heat for the charger 100 when it is charging. Among them, one end of the light control unit 14 is used to be connected to the negative output terminal VO- of the charger 100.

[0035] Specifically, Figure 2As shown, the light control unit 14 includes a third comparator IC3B, a fourth comparator IC3C, a fifth resistor R7, a sixth resistor R10, a seventh resistor R11, an eighth resistor R12, a first LED and a second LED, one end of the fifth resistor R7 is connected to the reference voltage unit 11, and the other end is connected to one end of the sixth resistor R10, the other end of the sixth resistor R10 is connected to the non-inverting input end of the third comparator IC3B and one end of the seventh resistor R11, the other end of the seventh resistor R11 is grounded, and the inverting input end of the third comparator IC3B is connected to the charging The output end of the third comparator IC3B is connected to the cathode of the second LED and the inverting input end of the fourth comparator IC3C, the anode of the second LED is connected to one end of the eighth resistor R12, the non-inverting input end of the fourth comparator IC3C is connected to the reference voltage unit 11, the output end of the fourth comparator IC3C is connected to the cathode of the first LED and the fan control unit 15, the anode of the first LED is connected to one end of the eighth resistor R12, and the other end of the eighth resistor R12 is connected to the fan control unit 15. Figure 2 LED1 is the first LED, which displays green light; LED2 is the second LED, which displays red light.

[0036] Furthermore, if Figure 2 As shown, the fan control unit 15 includes a voltage stabilizing diode ZD1, a ninth resistor R13, a transistor Q2, a voltage stabilizing chip IC1, a third capacitor EC4 and a fourth capacitor C5, the cathode of the voltage stabilizing diode ZD1 is connected to the output end of the fourth comparator IC3C, the anode of the voltage stabilizing diode ZD1 is connected to one end of the ninth resistor 13, the other end of the ninth resistor R13 is connected to the base of the transistor Q2, the collector of the transistor Q2 is connected to the anodes of the first LED and the second LED, the emitter of the transistor Q2 is connected to the first end of the voltage stabilizing chip IC1, the second end of the voltage stabilizing chip IC1 is used to be connected to the positive electrode F+ of the fan, and the third end of the voltage stabilizing chip IC1 is used to be connected to the negative electrode F- of the fan; the anode of the third capacitor EC4 is connected to the second end of the voltage stabilizing chip IC1, the cathode of the third capacitor EC4 is connected to the third end of the voltage stabilizing chip IC1, and the fourth capacitor C5 is connected between the second end and the third end of the voltage stabilizing chip IC1.

[0037] In this embodiment, the working principles of the light control unit 14 and the fan control unit 15 are as follows:

[0038] When unloaded, the second resistor R8 is connected to the negative output terminal VO- of the charger 100, and the other end is connected to the inverting input terminal of the third comparator IC3B, so the inverting input terminal of the third comparator IC3B is at a low level at this time, and the voltage of the non-inverting input terminal of the third comparator IC3B is compared with the reference voltage of the inverting input terminal, and the output terminal of the third comparator IC3B outputs a high level. Since the output terminal of the third comparator IC3B is connected to the inverting input terminal of the fourth comparator IC3C and the cathode of LED2, and LED2 is connected to the output terminal of the charger 100 through the eighth resistor R12, that is, the anode of LED2 is at a high level, so both the positive and negative ends of LED2 are high levels, and LED2 does not emit light at this time. The non-inverting input of the fourth comparator IC3C is connected to the reference voltage. The reference voltage of the non-inverting input of the fourth comparator IC3C is compared with the voltage of the inverting input, and the output outputs a low level. At this time, the cathode of LED1 is at a low level, and LED1 is connected to the output of the charger 100 through the eighth resistor R12, that is, the anode of LED1 is at a high level, and LED1 is on. The light control formula is: (R11 / R11+R10+R7) / RS1. When the LED1 light is on and displayed as a green light, in the fan control unit 15, the low level output by the output of the fourth comparator IC3C is transmitted to the base of the transistor Q2 through the voltage stabilizing diode ZD1 and the ninth resistor R13. Since when the base of the transistor Q2 is at a low level, the transistor Q2 is cut off and does not conduct, so the fan control unit 15 has no output, and the fan stops working, thereby solving the no-load loss and noise problems.

[0039] When the charger 100 is charging, the output end of the charger 100 is connected to the load to form a loop, and a voltage is generated on the first resistor RS1, which is connected to the inverting input end of the third comparator IC3B through the second resistor R8. At this time, the voltage of the inverting input end of the third comparator IC3B is higher than the reference voltage of the inverting input end, and a low level will be output at the output end, that is, the cathode of LED2 is a low level. Since the anode of LED2 is a high level, the LED2 light is on and displays a red light. Then, the voltage of the inverting input end of the fourth comparator IC3C is compared with the reference voltage of the inverting input end, and its output end outputs a high level, then both the positive and negative ends of LED1 are high levels, so it does not emit light. In the fan control unit 15, the high level output by the fourth comparator IC3C is connected to the ninth resistor R13 after being turned on by the voltage stabilizing diode ZD1, then the base of the transistor Q2 is turned on at a high level, and the output end of the charger 100 supplies power to the voltage stabilizing chip IC1, which is stabilized to 12V by the voltage stabilizing chip IC1 to power the fan. Therefore, when the charger 100 is charging, the LED 2 lights up and displays a red light, and the fan is started to solve the heating problem of the charger 100.

[0040] In an embodiment, such as this embodiment, a charger 100 is also provided. Figure 3 and Figure 4 , Figure 4 It is a structural block diagram of a charger provided by an embodiment of the utility model; Figure 4 This is a circuit schematic diagram of a charger provided in one embodiment of the utility model. The charger 100 includes a rectifier and filter circuit 20, a transformer 30, a feedback circuit 40, a PWM control circuit 50, an auxiliary power supply circuit 60 and the above-mentioned constant current and constant voltage output control circuit 10, wherein one end of the rectifier and filter circuit 20 is used to receive alternating current, and the other end is connected to the primary coil of the transformer 30, the secondary coil of the transformer 30 is connected to one end of the constant current and constant voltage output control circuit 10, the other end of the constant current and constant voltage output control circuit 10 is connected to one end of the feedback circuit 40, the other end of the feedback circuit 40 is connected to one end of the PWM control circuit 50, the other end of the PWM control circuit 50 is connected to one end of the auxiliary power supply circuit 60, and the other end of the auxiliary power supply circuit 60 is connected to the PWM control circuit 50. It should be noted that in this embodiment, Figure 4 In the figure, the transformer 30 and the feedback circuit 40 only show part of the circuit connected to the constant voltage and constant current output control circuit of the utility model. For example, the transformer 30 mainly shows part of the circuit schematic diagram of the connection between the secondary coil and the constant current and constant voltage output control circuit 10; the feedback circuit 40 mainly shows the optocoupler U1 connected to the constant current and constant voltage output circuit for feeding back a voltage feedback signal or a current feedback signal. The other circuits of the charger 100 are existing commonly used circuits. In order to save circuit diagram space and facilitate display, they are omitted, but it does not affect the technical solution and effect to be achieved by the utility model.

[0041] In summary, the constant current and constant voltage output control circuit and charger of the utility model output a voltage feedback signal or a current feedback signal corresponding to the output voltage of the charger and the reference voltage, and then adjust the duty cycle of the PWM control circuit of the charger through the voltage feedback signal or the current feedback signal to achieve a stable output voltage value or current value of the charger. In addition, the light control unit can realize the charging light control to indicate the working status of the charger; and the fan control unit can cooperate with the light control unit to control the start and stop of the fan to reduce heat generation and no-load noise. The utility model has a simple structure and can realize constant voltage and constant current control of the charger without the use of a single-chip microcomputer. It can not only reduce the production cost of the charger, but also save the complex installation process and burning process of the single-chip microcomputer, thereby improving the production efficiency of the charger. The constant current and constant voltage output control circuit and charger disclosed in the utility model solve the problems of high cost and low production efficiency of existing chargers.

[0042] The above is only a specific implementation of the utility model, but the protection scope of the utility model is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the utility model, and these modifications or replacements should be included in the protection scope of the utility model. Therefore, the protection scope of the utility model should be based on the protection scope of the claims.

Claims

1. A constant current and constant voltage output control circuit, used in a charger, characterized in that: include: A reference voltage unit, which is used to output a reference voltage; a constant voltage control unit, one end of which is used to be connected to the output end of the charger, and the other end of which is connected to the reference voltage unit, and the constant voltage control unit is used to output a voltage feedback signal according to the reference voltage and the output voltage of the charger; A constant current control unit, comprising a current limiting module and a constant current comparison module, wherein one end of the current limiting module is connected to the output end of the charger, and the other end is connected to one end of the constant current comparison module, and the other end of the constant current comparison module is connected to the reference voltage unit, and the constant current control unit is used to output a current feedback signal according to the reference voltage and the output voltage; Wherein, the duty cycle of the PWM control circuit of the charger is adjusted by the voltage feedback signal to stabilize the voltage value output by the charger; or The duty cycle is adjusted by the current feedback signal to stabilize the current value output by the charger.

2. The constant current and constant voltage output control circuit according to claim 1, characterized in that: The current limiting module includes a first resistor and a second resistor, one end of the first resistor is used to be connected to the output end of the charger, and the other end is connected to one end of the second resistor, and the other end of the second resistor is connected to the constant current comparison module.

3. The constant current and constant voltage output control circuit according to claim 2, characterized in that: The constant current comparison module includes a first comparator, a first capacitor, and a first diode. The inverting input terminal of the first comparator is connected to the second resistor, the non-inverting input terminal of the first comparator is connected to the reference voltage unit, the output terminal of the first comparator is connected to the cathode of the first diode, and the anode of the first diode is used to be connected to the feedback circuit of the charger; one end of the first capacitor is connected to the inverting input terminal of the first comparator, and the other end is connected to the output terminal of the first comparator.

4. The constant current and constant voltage output control circuit according to claim 1, characterized in that: The constant voltage control unit includes a voltage divider module and a constant voltage comparison module, the first end of the voltage divider module is used to be connected to the output end of the charger, the second end of the voltage divider module is connected to the constant voltage comparison module, and the third end of the voltage divider module is grounded; one end of the constant voltage comparison module is connected to the voltage divider module and the reference voltage unit, and the other end is used to output the voltage feedback signal.

5. The constant current and constant voltage output control circuit according to claim 4, characterized in that: The constant voltage comparison module includes a second comparator, a third resistor, a second capacitor and a second diode, the inverting input of the second comparator is connected to the voltage divider module, the non-inverting input of the second comparator is connected to the reference voltage unit, the output of the second comparator is connected to the cathode of the second diode, and the anode of the second diode is used to be connected to the feedback circuit of the charger; one end of the third resistor is connected to the inverting input of the second comparator, and the other end is connected to one end of the second capacitor, and the other end of the second capacitor is connected to the output of the second comparator.

6. The constant current and constant voltage output control circuit according to claim 1, characterized in that: The reference voltage unit includes a TL431 regulator and a fourth resistor, the cathode of the TL431 regulator is connected to one end of the fourth resistor, the other end of the fourth resistor is used to be connected to the output end of the charger, the reference end of the TL431 regulator is connected to the constant voltage control unit and the constant current control unit, and the anode of the TL431 regulator is grounded.

7. The constant current and constant voltage output control circuit according to claim 1, characterized in that: The constant current and constant voltage output control circuit also includes a light control unit and a fan control unit. One end of the light control unit is used to be connected to the output end of the charger, and the other end is connected to one end of the fan control unit. The other end of the fan control unit is used to be connected to a fan. The light control unit is used to indicate the charging status of the charger, and the fan control unit is used to control the fan to dissipate heat from the charger when it is charging.

8. The constant current and constant voltage output control circuit according to claim 7, characterized in that: The light control unit includes a third comparator, a fourth comparator, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a first LED and a second LED, one end of the fifth resistor is connected to the reference voltage unit, and the other end is connected to one end of the sixth resistor, the other end of the sixth resistor is connected to the non-inverting input end of the third comparator and one end of the seventh resistor, the other end of the seventh resistor is grounded, the inverting input end of the third comparator is connected to the output end of the charger, the output end of the third comparator is connected to the cathode of the first LED and the inverting input end of the fourth comparator, the anode of the first LED is connected to one end of the eighth resistor, the non-inverting input end of the fourth comparator is connected to the reference voltage unit, the output end of the fourth comparator is connected to the cathode of the second LED and the fan control unit, the anode of the second LED is connected to one end of the eighth resistor, and the other end of the eighth resistor is connected to the fan control unit.

9. The constant current and constant voltage output control circuit according to claim 8, characterized in that: The fan control unit includes a voltage stabilizing diode, a ninth resistor, a transistor, a voltage stabilizing chip, a third capacitor and a fourth capacitor. The cathode of the voltage stabilizing diode is connected to the output end of the fourth comparator, the anode of the voltage stabilizing diode is connected to one end of the ninth resistor, the other end of the ninth resistor is connected to the base of the transistor, the collector of the transistor is connected to the anodes of the first LED and the second LED, the emitter of the transistor is connected to the first end of the voltage stabilizing chip, the second end of the voltage stabilizing chip is used to be connected to the anode of the fan, and the third end of the voltage stabilizing chip is used to be connected to the cathode of the fan; the anode of the third capacitor is connected to the second end of the voltage stabilizing chip, the cathode of the third capacitor is connected to the third end of the voltage stabilizing chip, and the fourth capacitor is connected between the second end and the third end of the voltage stabilizing chip.

10. A charger, characterized in that: The charger includes a rectifier and filter circuit, a transformer, a feedback circuit, a PWM control circuit, an auxiliary power supply circuit and a constant current and constant voltage output control circuit as described in any one of claims 1 to 9, wherein one end of the rectifier and filter circuit is used to receive alternating current, and the other end is connected to the primary coil of the transformer, the secondary coil of the transformer is connected to one end of the constant current and constant voltage output control circuit, the other end of the constant current and constant voltage output control circuit is connected to one end of the feedback circuit, the other end of the feedback circuit is connected to one end of the PWM control circuit, the other end of the PWM control circuit is connected to one end of the auxiliary power supply circuit, and the other end of the auxiliary power supply circuit is connected to the PWM control circuit.

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