A constant temperature and constant current control system, circuit and linear charger

Abstract

The application discloses a constant temperature and constant current control system, comprising a sampling circuit, a first power tube and a constant temperature control circuit. The drain electrode of the first power tube is connected with an electric device, and the gate electrode is connected with the constant temperature control circuit. The sampling circuit is connected with the drain electrode of the first power tube and the first input end of the constant temperature control circuit, and is also used for collecting the current and voltage of the first power tube when charging the electric device, determining the power of the first power tube according to the current and voltage, and determining the relationship between the power and temperature, and controlling the change of the voltage of the first input end according to the relationship between the temperature and a preset temperature threshold. The constant temperature control circuit adjusts the gate voltage of the first power tube according to the change of the voltage of the first input end, and controls the charging current of the first power tube. Through the sampling circuit and the constant temperature control loop, the temperature of the first power tube is fed back to the constant temperature control circuit in the form of an electric signal, the first current value is controlled, the temperature of the system can be kept at a preset temperature, and the influence of the performance caused by the excessively high temperature is avoided.

Description

Technical Field

[0001] This application relates to the field of power control, and in particular to a constant temperature and constant current control system, circuit, and linear charger. Background Technology

[0002] With the development of various electronic technologies, the control chips inside various electronic devices have also been developed. Chips need to operate within a certain temperature range to function properly, but when there are high-power loads in electronic devices, the chip temperature will continue to rise, leading to damage to the equipment.

[0003] In current technology, to prevent equipment damage, the load is automatically cut off when the chip temperature reaches a set value. However, cutting off the load will affect the normal operation of the equipment. Summary of the Invention

[0004] This application provides a constant temperature and constant current control system, circuit, and linear charger, which adjusts the voltage supplied by the first power transistor to the electrical device according to the temperature of the first power transistor without affecting the power supply to the electrical device, so as to ensure the normal operation of the device.

[0005] The technical solution is as follows:

[0006] In a first aspect, a constant temperature and constant current control system is provided, characterized in that the system includes a sampling circuit, a first power transistor and a constant temperature control circuit, wherein the drain of the first power transistor is connected to an electrical device, the sampling circuit is connected to the drain of the first power transistor and a first input terminal of the constant temperature control circuit, and a second output terminal of the constant temperature control circuit is connected to a DC voltage source.

[0007] The gate of the first power transistor is connected to the output terminal of the constant temperature control circuit;

[0008] The sampling circuit is used to collect the first current value and the first voltage value when the first power transistor charges the electrical device, to determine the power of the first power transistor based on the first current value and the voltage value of the first power transistor, wherein the magnitude of the power affects the temperature of the first power transistor, and to control the change of the voltage at the first input terminal of the constant temperature control circuit based on the relationship between the temperature of the first power transistor and a preset temperature threshold.

[0009] The constant temperature control circuit is used to adjust the gate voltage of the first power transistor according to the change in voltage at the first input terminal, so as to change the current value when the first power transistor charges the electrical device.

[0010] This application utilizes a sampling circuit and a constant temperature control loop. It acquires the first current value when a first power transistor charges the device, reflecting the temperature change of the first power transistor. By using the relationship between the first power transistor's temperature and a preset temperature threshold, it controls the voltage change at the first input terminal of the constant temperature control circuit. Since the output terminal of the constant temperature control circuit is also connected to the gate of the first power transistor, and the second input terminal is connected to a DC voltage source, changes in the voltage at the first input terminal of the constant temperature control circuit cause a voltage change at the output terminal. This changes the voltage at the gate of the first power transistor, which in turn affects the current value of the first power transistor charging the device. This allows the temperature of the constant temperature and constant current control system to be maintained at the preset temperature, preventing excessively high temperatures from affecting device performance. Furthermore, this solution does not affect the power supply to the device during use.

[0011] Optionally, the sampling circuit is used to control the voltage change of the first input terminal of the constant temperature control circuit according to the relationship between the temperature of the first power transistor and the preset temperature threshold, including: the sampling circuit is used to reduce the voltage supplied to the first input terminal of the constant temperature control circuit when the temperature of the first power transistor is higher than or equal to the preset temperature threshold.

[0012] Accordingly, the constant temperature control circuit is used to adjust the gate voltage of the first power transistor according to the change in the voltage of the first input terminal, so as to change the current value of the first power transistor when charging the electrical device, including: the constant temperature control circuit is used to increase the gate voltage of the first power transistor when the voltage of the first input terminal decreases, so as to trigger the first power transistor to decrease the current value when charging the electrical device.

[0013] Optionally, the sampling circuit is used to control the voltage change of the first input terminal of the constant temperature control circuit according to the relationship between the temperature of the first power transistor and the preset temperature threshold, including: the sampling circuit is used to increase the voltage supplied to the first input terminal of the constant temperature control circuit when the temperature of the first power transistor is lower than the preset temperature threshold.

[0014] Accordingly, the constant temperature control circuit is used to adjust the gate voltage of the first power transistor according to the control signal to change the voltage supplied by the first power transistor to the electrical device, including: the constant temperature control circuit is used to reduce the gate voltage of the first power transistor when the voltage at the first input terminal increases, so as to increase the current value when the first power transistor charges the electrical device.

[0015] Optionally, the sampling circuit includes: a sampling module connected to the drain of the first power transistor for acquiring the current and voltage output from the drain; a conversion module connected to the sampling module for converting the current and voltage values ​​acquired by the sampling module into a voltage reflecting the thermal power of the first power transistor; and a control module for controlling the voltage change at the first input terminal of the constant temperature control circuit according to the voltage reflecting the thermal power of the first power transistor.

[0016] Optionally, the sampling module includes a first voltage-controlled current source and a first resistor; the conversion module includes a second voltage-controlled current source; and the control module includes a second resistor, a capacitor, and a first voltage-controlled voltage source.

[0017] The first terminal of the first voltage-controlled current source is connected to the drain of the first power transistor, and the second terminal is connected to the first terminal of the first resistor. The second terminal of the first resistor is connected to ground. The first terminal of the first resistor is connected to the first terminal of the second voltage-controlled current source, and the second terminal of the second voltage-controlled current source is connected to the first terminal of the second resistor. The capacitor is connected in parallel with the second resistor. The first terminal of the second resistor is connected to the negative terminal of the first voltage-controlled voltage source. The negative terminal of the first voltage-controlled voltage source is connected to the temperature control module through a diode. The positive terminal of the first voltage-controlled voltage source is connected to ground. The negative terminal of the diode is connected to the negative terminal of the first voltage-controlled voltage source, and the positive terminal of the diode is connected to the temperature control module.

[0018] Optionally, the constant temperature and constant current control system further includes a constant current control circuit and a constant voltage control circuit. In constant current mode, the constant current control circuit is used to adjust the gate voltage of the first power transistor according to the change in the drain current of the second power transistor, so as to change the current value when the first power transistor charges the electrical device; the second power transistor is used to transmit a sampling current to the constant current control circuit, and the current value of the sampling current is proportional to the current value when the first power transistor charges the electrical device.

[0019] In constant voltage mode, the constant voltage control circuit is used to adjust the gate voltage of the first power transistor to the power supply voltage according to the voltage change of the electrical device, so as to turn off the first power transistor and stop the charging voltage to the electrical device.

[0020] Optionally, the constant current module includes: a second error amplifier, a first sampling transistor, a third resistor, and a second power supply. The inverting input of the second error amplifier is connected to the second power supply, the non-inverting input of the second error amplifier is connected to the drain of the first sampling transistor, the drain of the first sampling transistor is connected to the first end of the third resistor, the second end of the third resistor is connected to ground, and the output of the second error amplifier is connected to the gate of the first power transistor.

[0021] Optionally, the constant voltage module comprises a third error amplifier, a fourth resistor, a fifth resistor, and a third power supply. One end of the fourth resistor is connected to the first power transistor, and the second end is connected to the first end of the fifth resistor. The second end of the fifth resistor is connected to ground. The inverting input of the third error amplifier is connected to the third power supply, and the non-inverting input of the third error amplifier is connected to the second end of the fourth resistor. The output of the third error amplifier is connected to the gate of the first power transistor.

[0022] Secondly, a constant temperature and constant current control circuit is provided, wherein the above-mentioned constant temperature and constant current control system is used in the circuit.

[0023] Thirdly, a linear charger is provided, wherein the charger employs the aforementioned constant temperature and constant current control system or the aforementioned constant temperature and constant current control circuit.

[0024] Fourthly, a constant temperature and constant current control method is provided. The method is applied to a constant temperature and constant current control system. The system includes a sampling circuit, a first power transistor and a constant temperature control circuit of the constant temperature and constant current control system. The drain of the first power transistor is connected to the electrical device. The sampling circuit is connected to the drain of the first power transistor and the first input terminal of the constant temperature control circuit. The second output terminal of the constant temperature control circuit is connected to a DC voltage source. The gate of the first power transistor is connected to the output terminal of the constant temperature control circuit.

[0025] The sampling circuit collects the first current value and voltage value when the first power transistor charges the electrical device, determines the power of the first power transistor based on the first current value and voltage value, the power affects the temperature of the first power transistor, and controls the change of voltage at the first input terminal of the constant temperature control circuit based on the relationship between the temperature of the first power transistor and a preset temperature threshold.

[0026] The constant temperature control circuit adjusts the gate voltage of the first power transistor according to the change in voltage at the first input terminal, thereby changing the current value when the first power transistor charges the electrical device.

[0027] Optionally, the sampling circuit controls the voltage change of the first input terminal of the constant temperature control circuit according to the relationship between the temperature of the first power transistor and the preset temperature threshold, including: when the temperature of the first power transistor is higher than or equal to the preset temperature threshold, the sampling circuit reduces the voltage supplied to the first input terminal of the constant temperature control circuit.

[0028] Accordingly, the constant temperature control circuit adjusts the gate voltage of the first power transistor according to the change in the voltage of the first input terminal to change the current value of the first power transistor when charging the electrical device, including: when the voltage of the first input terminal decreases, the constant temperature control circuit increases the gate voltage of the first power transistor to trigger the first power transistor to decrease the current value when charging the electrical device.

[0029] Optionally, the sampling circuit controls the voltage change at the first input terminal of the constant temperature control circuit according to the relationship between the temperature of the first power transistor and the preset temperature threshold, including: the sampling circuit increases the voltage supplied to the first input terminal of the constant temperature control circuit when the temperature of the first power transistor is lower than the preset temperature threshold.

[0030] Accordingly, the constant temperature control circuit adjusts the gate voltage of the first power transistor according to the control signal to change the voltage supplied by the first power transistor to the electrical device, including: when the voltage at the first input terminal increases, the constant temperature control circuit decreases the gate voltage of the first power transistor to increase the current value when the first power transistor charges the electrical device.

[0031] It is understood that the beneficial effects of the second, third, and fourth aspects mentioned above can be found in the relevant descriptions in the first aspect above, and will not be repeated here. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram of a constant temperature control circuit provided in an embodiment of this application;

[0034] Figure 2 This is a constant temperature control circuit diagram provided in an embodiment of this application;

[0035] Figure 3 This is a circuit diagram of a constant temperature and constant current control system provided in an embodiment of this application. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be described in further detail below with reference to the accompanying drawings.

[0037] It should be understood that "multiple" as mentioned in this application refers to two or more. In the description of this application, unless otherwise stated, " / " indicates "or," for example, A / B can mean A or B; "and / or" in this document is merely a description of the relationship between related objects, indicating that three relationships can exist, for example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Furthermore, to facilitate a clear description of the technical solutions of this application, the terms "first," "second," etc., are used to distinguish identical or similar items with essentially the same function and effect. Those skilled in the art will understand that the terms "first," "second," etc., do not limit the quantity or execution order, and that "first," "second," etc., do not necessarily imply differences.

[0038] Before providing a detailed explanation of the embodiments of this application, the application scenarios of these embodiments will be described first.

[0039] In some electronic devices, such as linear chargers, chips can overheat under heavy loads if the current is not limited, leading to performance degradation, reduced lifespan, and potential safety hazards. This invention provides a constant temperature and current control system, circuit, and linear charger that maintains the temperature within the linear charger within a preset range, enabling real-time temperature regulation to ensure continued normal operation.

[0040] The protection system provided in the embodiments of this application will be explained in detail below.

[0041] This application provides a constant temperature and constant current control system, such as... Figure 1 As shown, the system includes a sampling circuit 101, a first power transistor PM0, and a temperature control loop. The drain of the first power transistor PM0 is connected to the device 103 (e.g., a battery). The sampling circuit 101 is connected to the drain of the first power transistor PM0 and the first input terminal of the temperature control loop. The gate of the first power transistor PM0 is connected to the temperature control loop. The sampling circuit 101 is used to acquire the first current value and voltage when the first power transistor PM0 charges the device 103, to determine the power of the first power transistor PM0 based on the first current value and voltage (the power of the first power transistor PM0 affects its temperature, i.e., the higher the power, the higher the temperature), and to control the voltage change at the first input terminal of the temperature control loop based on the relationship between the temperature of the first power transistor PM0 and a preset temperature threshold. The temperature control loop is used to adjust the gate voltage of the first power transistor PM0 according to the change in the voltage at the first input terminal, thereby changing the current value when the first power transistor PM0 charges the device 103.

[0042] It is worth noting that in this embodiment, the constant temperature and constant current control system is applied to the linear charger. During operation, the temperature of the linear charger will rise. The reason for the temperature rise is the heating of the first power transistor PMO. The heat power can be expressed as the product of current and voltage. Since the temperature change is not an electrical signal, that is, the temperature characteristics cannot be directly represented by electrical characteristics, the temperature change is first converted into an electrical signal through the sampling circuit 101 to complete the constant temperature control loop.

[0043] In one embodiment of this application, such as Figure 2 As shown, the constant temperature and constant current control system is applied in a linear charger. When the linear charger is connected to the adapter, it starts working, and the first power transistor PM0 is turned on, transmitting charging current from the drain of the first power transistor PM0 to the device 103. The sampling circuit 101 is connected to the drain of the first power transistor PM0 to collect the charging current, i.e., the first current value and the voltage at the sampling point. The sampling circuit 101 reflects the temperature signal as an electrical signal by collecting the first current value and voltage value, and sends the electrical signal to the constant temperature control loop, where the electrical signal is the change in voltage. The temperature control loop is a first error amplifier CT COMP, and the first input terminal is the inverting input terminal of the first error amplifier CT COMP. The voltage change controls the output voltage of the first error amplifier CT COMP through the inverting input terminal of the first error amplifier CT COMP, i.e., controls the voltage of the gate of the first power transistor PM0, thereby changing the current value of the first power transistor PM0 when charging the device 103.

[0044] This application uses a sampling circuit 101 and a constant temperature control loop to collect the first current value when the first power transistor charges the electrical device 103. The first current value reflects the temperature change of the first power transistor PMO. By using the relationship between the temperature of the first power transistor and a preset temperature threshold, the voltage change of the first input terminal of the constant temperature control circuit 102 is controlled. Since the output terminal of the constant temperature control circuit 102 is also connected to the gate of the first power transistor, and the second input terminal is connected to a DC voltage source, the voltage change of the first input terminal of the constant temperature control circuit 102 will cause the voltage change of the output terminal of the constant temperature control circuit 102. This will change the voltage of the gate of the first power transistor PMO. The change in the voltage of the gate of the first power transistor PMO will affect the change in the current value of the drain of the first power transistor PMO charging the electrical device 103. This allows the temperature of the constant temperature and constant current control system to be sampled and fed back to the constant temperature control circuit, controlling the output current of the power transistor to maintain the preset temperature. This avoids the performance of the equipment being affected by excessively high temperatures, and also avoids the reliability risks to electronic devices (such as Bluetooth headsets and charging cases) that use the constant temperature and constant current control system due to excessively high temperatures. Moreover, this solution will not affect the power supply to the electrical device 103 during use.

[0045] In one embodiment of this application, the sampling circuit 101 is used to control the voltage change of the first input terminal of the constant temperature control loop according to the relationship between the temperature of the first power transistor PM0 and a preset temperature threshold. The sampling circuit 101 is used to output a first control signal to the constant temperature control loop when the temperature of the first power transistor PM0 is higher than or equal to the preset temperature threshold. The first control signal is used to indicate an increase in the gate voltage of the first power transistor PM0.

[0046] Correspondingly, the constant temperature control loop is used to adjust the gate voltage of the first power transistor PM0 according to the change of the voltage at the first input terminal, so as to change the current value of the first power transistor PM0 when charging the electrical device 103. The constant temperature control loop is used to increase the gate voltage of the first power transistor PM0 according to the first control signal, so as to trigger the first power transistor PM0 to reduce the current value when charging the electrical device 103.

[0047] It is understood that, in the embodiments of this application, the first power transistor PM0 reduces the current value when charging the electrical device 103 to at least 0.

[0048] It is understood that the constant temperature control loop is used to increase the gate voltage of the first power transistor PM0 according to the first control signal, so as to trigger the first power transistor PM0 to reduce the current value when charging the electrical device 103 to a first target current value. The first target current value is greater than 0, and the first target current value is the current value corresponding to the temperature of the first power transistor PM0 within a preset temperature threshold. The first target current value can be obtained from conventional experience, and this application embodiment does not limit it.

[0049] Understandably, the sampling circuit 101 sends a first control signal to the temperature control loop by reducing the voltage value supplied to the first input terminal of the temperature control loop. In other words, if the temperature control loop detects a decrease in the voltage at the first input terminal of the temperature control loop, it can increase the gate voltage of the first power transistor PM0 to trigger the first power transistor PM0 to reduce the current value when charging the electrical device 103.

[0050] The preset temperature threshold can be understood as the maximum temperature at which a linear charger using a constant temperature and current control system can operate normally. Exceeding this temperature will cause the linear charger's performance to degrade, affecting its lifespan and posing safety hazards. The reason for the temperature increase may be a high-power external load that requires the linear charger to continuously increase the current, thus leading to a temperature rise.

[0051] In one possible implementation of this application, when the constant temperature and constant current control system charges a high-power charging device, the sampling circuit 101 detects an increase in the charging current output by the first power transistor PM0, i.e., a gradual increase in the first current value, which leads to a gradual increase in temperature. The sampling circuit 101 converts this temperature change into a voltage change through the first current value it detects, and sends a first control signal to the first input terminal of the constant temperature control circuit 102. The first control signal is used to instruct an increase in the gate voltage of the first power transistor PM0. According to the first control signal, the first power transistor PM0 increases its gate voltage, causing the first power transistor PM0 to reduce the current value it uses to charge the device 103.

[0052] It is worth noting that the temperature control circuit 102 in this embodiment has two input terminals (e.g., a first input terminal and a second input terminal) and one output terminal. The first input terminal is connected to the output terminal of the sampling circuit 101, and the second input terminal is connected to the DC voltage source VDC1. Taking the temperature control circuit 102 as a first error amplifier CT COMP as an example, the inverting input terminal of the first error amplifier CT COMP is the first output terminal, and the non-inverting input terminal of the first error amplifier CT COMP is the second output terminal. The output terminal of the temperature control circuit 102 is connected to the gate of the first power transistor PMO. Since the second input terminal is grounded through the DC voltage source VDC1, and the voltage of VDC1 is fixed, a change in the voltage at the first input terminal will cause a change in the voltage at the output terminal of the temperature control circuit 102, thereby affecting the voltage at the gate of the first power transistor PMO connected to the output terminal of the temperature control circuit 102.

[0053] In another embodiment of this application, the sampling circuit 101 is used to control the voltage change at the first input terminal of the constant temperature control loop based on the relationship between the temperature of the first power transistor PM0 and a preset temperature threshold. This includes: the sampling circuit 101 outputting a second control signal to the constant temperature control loop when the temperature of the first power transistor PM0 is lower than the preset temperature threshold. Correspondingly, the constant temperature control loop is used to adjust the gate voltage of the first power transistor based on the voltage change at the first input terminal, thereby changing the current value when the first power transistor charges the electrical device 103. This includes: the constant temperature control loop reducing the gate voltage of the first power transistor PM0 based on the second control signal, thereby increasing the current value provided by the first power transistor PM0 to the electrical device 103.

[0054] Specifically, the sampling circuit 101 is used to output a second control signal to the constant temperature control loop through the first input terminal when the temperature of the first power transistor PMO is lower than the preset temperature threshold.

[0055] Understandably, the sampling circuit 101 sends a second control signal to the thermostatic control loop by increasing the voltage value supplied to the first input terminal of the thermostatic control loop. In other words, if the thermostatic control loop detects an increase in the voltage at the first input terminal of the thermostatic control loop, it can reduce the gate voltage of the first power transistor PM0 to trigger the first power transistor PM0 to increase the current value when charging the electrical device 103.

[0056] The second control signal is used to reduce the output voltage of the constant temperature control loop, thereby lowering the gate voltage of the first power transistor PM0 and increasing the current value of the first power transistor PM0 charging the electrical device 103.

[0057] In one embodiment of this application, the sampling circuit 101 includes: a sampling module connected to the drain of a first power transistor PMO, used to collect the current and voltage output from the drain; a conversion module connected to the sampling module, used to convert the first current value into a voltage reflecting the thermal power of the first power transistor PMO based on the first current value collected by the sampling module and the voltage value at the sampling point; and a control module used to control the change of the voltage at the first input terminal of the constant temperature control loop based on the voltage reflecting the thermal power of the first power transistor PMO.

[0058] In one embodiment of this application, the sampling module, such as Figure 2 As shown, it includes a first voltage-controlled current source VCCS1 and a first resistor RSENCE. The second end of the first resistor RSENCE is connected to ground GND. The input end of the first voltage-controlled current source VCCS1 is connected to the drain of the first power transistor PM0, and the second end is connected to the conversion module, which converts the product of the voltage and the first current value on the first power transistor into a voltage and transmits it to the conversion module.

[0059] In one embodiment of this application, the conversion module, such as Figure 2 As shown, this includes a second voltage-controlled current source (VCCS2). The first terminal of VCCS2 is connected to the first terminal of the first resistor RSENCE. When a second current flows through RSENCE, a voltage VP is generated. This voltage VP acts on VCCS2, which in turn generates a third current that flows to the control module. The positive terminal of the power supply VDD is connected to the source of the first power transistor, and the negative terminal is grounded to GND.

[0060] In one embodiment of this application, the control module includes a second resistor Rhot, a capacitor Chot, a first voltage-controlled voltage source VCVS1, and a diode D0. The second terminal of the second voltage-controlled current source VCCS2 is connected to the first terminal of the second resistor Rhot. The capacitor Chot is connected in parallel with the second resistor Rhot. The first terminal of the second resistor Rhot is connected to the negative terminal of the first voltage-controlled voltage source VCVS1. When a third current flows through the second resistor Rhot, a voltage VD is generated due to the voltage division. This voltage VD is transmitted to the first voltage-controlled voltage source VCVS1, and the change in voltage VD causes a change in the first voltage-controlled voltage source VCVS1. The negative terminal of the first voltage-controlled voltage source VCVS1 is connected to the temperature control circuit 102 through the diode D0, and the positive terminal of the first voltage-controlled voltage source VCVS1 is connected to ground GND. Specifically, the negative terminal of diode D0 is connected to the negative terminal of the first voltage-controlled voltage source VCVS1, and the positive terminal of diode D0 is connected to the temperature control circuit 102.

[0061] It's worth noting that the current generated by the second voltage-controlled current source VCCS2 flows to capacitor Chot, increasing the amount of charge stored in Chot. This increased charge is equivalent to Chot storing the heat generated by the first power transistor PM0. The current flows through the second resistor Rhot, which impedes current changes, effectively hindering the dissipation of heat from the first power transistor PM0. Therefore, when the voltage VD rises, it acts on the first voltage-controlled voltage source VCVS1, causing its voltage to increase. This can be understood as the voltage of the first voltage-controlled voltage source VCVS1 increasing as the temperature of the first power transistor PM0 rises.

[0062] In this circuit, the voltage across diode D0 is VBE. Since the positive terminal of VCVS1 is grounded and its negative terminal is connected to the negative terminal of VBE, and the positive terminal of VBE is connected to the first input terminal of the temperature control circuit 102, and because the polarity of the first voltage-controlled voltage source VCVS1 is opposite to the polarity of the voltage VBE across diode D0—meaning that when the temperature of the first power transistor PM0 rises, the voltage of the first voltage-controlled voltage source VCVS1 increases in the opposite direction—the voltage VT, which actually characterizes the temperature, decreases. VT can be considered as the voltage provided by the sampling circuit 101 to the first input terminal of the temperature control circuit 102. This voltage reflects the characteristic that the voltage across the diode decreases as the temperature increases.

[0063] In one embodiment of this application, the constant temperature and constant current control system further includes a constant current control circuit and a constant voltage control circuit, which can be understood as having two modes.

[0064] Mode 1:

[0065] In constant current mode, the constant current control circuit adjusts the gate voltage of the first power transistor PM0 according to the change in the drain current of the second power transistor PM1, thereby changing the current value of the first power transistor PM0 when charging the device 103. The second power transistor PM1 is used to transmit a sampling current to the constant current control circuit, and the current value of the sampling current is proportional to the current value of the first power transistor PM0 when charging the device 103.

[0066] The proportional relationship allows the current of the first power transistor PM0 to replicate the current of the second power transistor PM1 according to a preset ratio. Furthermore, given a fixed specification for the first power transistor, the second power transistor will be reduced proportionally, resulting in a smaller volume and thus saving space.

[0067] In one embodiment of this application, the constant current control circuit includes: a second error amplifier CC COMP, a second power transistor PM1, a third resistor RS, and a second power supply VDC2. The inverting input terminal of the second error amplifier CC COMP is connected to the second power supply VDC2, the non-inverting input terminal of the second error amplifier CC COMP is connected to the drain of the second power transistor PM1, the drain of the second power transistor PM1 is connected to the first terminal of the third resistor RS, the second terminal of the third resistor RS is connected to ground GND, and the output terminal of the second error amplifier CC COMP is connected to the gate of the first power transistor PM0.

[0068] When the output current of the first power transistor PM0 increases to a level greater than the preset current, the output current of the second power transistor PM1 also increases proportionally, with a ratio of 1:1000. The third resistor RS divides the voltage, generating a current ISEN, which is input to the non-inverting input of the second error amplifier CC COMP. The inverting input of the second error amplifier CC COMP is connected to the second power supply VDC2. When the current ISEN increases, the input voltage of the second error amplifier CC COMP rises, controlling the first field-effect transistor PM0 to decrease its output current. When the output current of the first power transistor PM0 decreases to a level less than the preset current, the current ISEN decreases, the input voltage of the second error amplifier CC COMP decreases, controlling the first power transistor PM0 to increase its output current, thus maintaining a stable fluctuation in the output current.

[0069] Mode 2:

[0070] In constant voltage mode, the constant voltage control circuit is used to adjust the gate voltage of the first power transistor PM0 to the power supply voltage according to the voltage change of the electrical device 103, so as to turn off the first power transistor PM0 and stop charging the electrical device 103.

[0071] Specifically, when the voltage of the electrical device 103 is close to the preset voltage, the constant voltage control circuit is used to adjust the gate voltage of the first power transistor PM0 to the power supply voltage in order to turn off the first power transistor PM0.

[0072] In one embodiment of this application, such as Figure 3 As shown, the constant voltage control circuit consists of a third error amplifier CV COMP, a fourth resistor RH, a fifth resistor RL, and a third power supply VDC3. One end of the fourth resistor RH is connected to the first power transistor PM0, and the second end is connected to the first end of the fifth resistor RL. The second end of the fifth resistor RL is connected to ground (GND). The inverting input of the third error amplifier CV COMP is connected to the positive terminal of the third power supply VDC3, the negative terminal of the third power supply VDC3 is grounded, the non-inverting input of the third error amplifier CV COMP is connected to the second end of the fourth resistor RH, and the output of the third error amplifier CV COMP is connected to the gate of the first power transistor PM0.

[0073] When the first power transistor PM0 charges the device 103, and the charging voltage approaches the preset full battery voltage (i.e., the FB voltage equals the voltage of the third power supply VDC3), the output voltage of the third error amplifier CV COMP increases the gate voltage of the first power transistor PM0, thus turning off the first power transistor PM0. This can be understood as stopping charging the device 103 once it is fully charged.

[0074] This application provides a constant temperature and constant current control circuit, which uses the above-mentioned constant temperature and constant current control system.

[0075] This application provides a linear charger that uses the above-described constant temperature and constant current control system or the above-described constant temperature and constant current control circuit.

[0076] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0077] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of this application.

[0078] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A constant temperature and constant current control system, characterized by, The system comprises a sampling circuit, a first power tube and a constant temperature control circuit, The drain of the first power tube is connected to an electrical device, the sampling circuit is connected to the drain of the first power tube and the first input end of the constant temperature control circuit, and the second output end of the constant temperature control circuit is connected to a direct current voltage source; The gate of the first power tube is connected to the output end of the constant temperature control circuit; The sampling circuit is used to collect a first current value and a first voltage value when the first power tube charges the electrical device, to determine the power of the first power tube according to the first current value and the first voltage value, to affect the temperature of the first power tube, and to control the change of the voltage of the first input end of the constant temperature control circuit according to the relationship between the temperature of the first power tube and a preset temperature threshold; The constant temperature control circuit is used to adjust the gate voltage of the first power tube according to the change of the voltage of the first input end, so as to change the current value when the first power tube charges the electrical device.

2. The system of claim 1, wherein, The sampling circuit is used to control the change of the voltage of the first input end of the constant temperature control circuit according to the relationship between the temperature of the first power tube and a preset temperature threshold, comprising: The sampling circuit is used to reduce the voltage provided to the first input end of the constant temperature control circuit when the temperature of the first power tube is higher than or equal to the preset temperature threshold; Correspondingly, the constant temperature control circuit is used to adjust the gate voltage of the first power tube according to the change of the voltage of the first input end, so as to change the current value when the first power tube charges the electrical device, comprising: The constant temperature control circuit is used to increase the gate voltage of the first power tube when the voltage of the first input end is reduced, so as to trigger the first power tube to reduce the current value when charging the electrical device.

3. The system of claim 1, wherein, The sampling circuit is used to control the change of the voltage of the first input end of the constant temperature control circuit according to the relationship between the temperature of the first power tube and a preset temperature threshold, comprising: The sampling circuit is used to increase the voltage provided to the first input end of the constant temperature control circuit when the temperature of the first power tube is lower than the preset temperature threshold; Correspondingly, the constant temperature control circuit is used to adjust the gate voltage of the first power tube according to the control signal to change the voltage provided by the first power tube to the electrical device, comprising: The constant temperature control circuit is used to reduce the gate voltage of the first power tube when the voltage of the first input end is increased, so as to increase the current value when the first power tube charges the electrical device.

4. The system of any one of claims 1 to 3, wherein, The sampling circuit comprises: A sampling module connected to the drain of the first power tube, used to collect the current output from the drain and the voltage on the power tube; A conversion module connected to the sampling module, used to convert the current value and voltage value collected by the sampling module into a voltage reflecting the thermal power of the first power tube; The control module is configured to control a change in voltage of the first input end of the constant temperature control circuit according to a voltage reflecting a thermal power of the first power tube.

5. The system of claim 4, wherein, The sampling module comprises a first voltage-controlled current source and a first resistor. The conversion module comprises a second voltage-controlled current source. The control module comprises a second resistor, a capacitor and a first voltage-controlled voltage source. The first end of the first voltage-controlled current source is connected to the drain of the first power tube, the second end of the first voltage-controlled current source is connected to the first end of the first resistor, the second end of the first resistor is connected to the ground, the first end of the first resistor is connected to the first end of the second voltage-controlled current source, the second end of the second voltage-controlled current source is connected to the first end of the second resistor, the capacitor is connected in parallel with the second resistor, the first end of the second resistor is connected to the negative electrode of the first voltage-controlled voltage source, the negative electrode of the first voltage-controlled voltage source is connected to the constant temperature control circuit through a diode, and the positive electrode of the first voltage-controlled voltage source is connected to the ground.

6. The system of any one of claims 1-3, wherein, The constant temperature and constant current control system further comprises a constant current control circuit and a constant voltage control circuit. In the constant current mode, the constant current control circuit is configured to adjust the gate voltage of the first power tube according to a change in drain current of the second power tube, so as to change the current value when the first power tube charges the electrical device. The second power tube is configured to transmit a sampling current to the constant current control circuit, and the current value of the sampling current is in proportional relationship with the current value when the first power tube charges the electrical device. In the constant voltage mode, the constant voltage control circuit is configured to adjust the gate voltage of the first power tube to the power supply voltage according to a change in voltage of the electrical device, so as to close the first power tube and stop the charging voltage to the electrical device.

7. The system of claim 6, wherein, The constant current control circuit comprises a second error amplifier, a second power tube, a third resistor and a second power supply, the inverting input end of the second error amplifier is connected to the second power supply, the non-inverting input end of the second error amplifier is connected to the drain of the second power tube, the drain of the second power tube is connected to the first end of the third resistor, the second end of the third resistor is connected to the ground, and the output end of the second error amplifier is connected to the gate of the first power tube.

8. The system of claim 6, wherein, The constant voltage control circuit comprises a third error amplifier, a fourth resistor, a fifth resistor and a third power supply, one end of the fourth resistor is connected to the first power tube, the second end of the fourth resistor is connected to the first end of the fifth resistor, the second end of the fifth resistor is connected to the ground, the inverting input end of the third error amplifier is connected to the third power supply, the non-inverting input end of the third error amplifier is connected to the second end of the fourth resistor, and the output end of the third error amplifier is connected to the gate of the first power tube.

9. A constant temperature and constant current control circuit, characterized by comprising: The circuit adopts the constant temperature and constant current control system according to any one of claims 1-8.

10. A linear charger, comprising: The charger adopts the constant temperature and constant current control system according to any one of claims 1-8 or the circuit according to claim 9.

11. A constant temperature and constant current control method, characterized by, The method is applied to a constant temperature and constant current control system, the system comprises a sampling circuit, and a first power tube and a constant temperature control circuit of the constant temperature and constant current control system, The drain electrode of the first power tube is connected with an electrical equipment, the sampling circuit is connected with the drain electrode of the first power tube, and the first input end of the constant temperature control circuit, the second output end of the constant temperature control circuit is connected with a direct current voltage source, and the gate electrode of the first power tube is connected with the output end of the constant temperature control circuit; The sampling circuit collects a first current value and a voltage on the first power tube when the first power tube charges the electrical equipment, reflects a temperature change on the first power tube according to a product of the first current value and the voltage on the first power tube, and controls a voltage change of the first input end of the constant temperature control circuit according to a relationship between the temperature of the first power tube and a preset temperature threshold value; The constant temperature control circuit adjusts the gate voltage of the first power tube according to the voltage change of the first input end, so as to change the current value when the first power tube charges the electrical equipment.

12. The method of claim 11, wherein, The sampling circuit controls the voltage change of the first input end of the constant temperature control circuit according to the relationship between the temperature of the first power tube and the preset temperature threshold value, including: The sampling circuit reduces the voltage provided to the first input end of the constant temperature control circuit when the temperature of the first power tube is higher than or equal to the preset temperature threshold value; Correspondingly, the constant temperature control circuit adjusts the gate voltage of the first power tube according to the voltage change of the first input end, so as to change the current value when the first power tube charges the electrical equipment, including: The constant temperature control circuit increases the gate voltage of the first power tube when the voltage of the first input end is reduced, so as to trigger the first power tube to reduce the current value when charging the electrical equipment.

13. The method of claim 11, wherein, The sampling circuit controls the voltage change of the first input end of the constant temperature control circuit according to the relationship between the temperature of the first power tube and the preset temperature threshold value, including: The sampling circuit increases the voltage provided to the first input end of the constant temperature control circuit when the temperature of the first power tube is lower than the preset temperature threshold value; Correspondingly, the constant temperature control circuit adjusts the gate voltage of the first power tube according to the control signal to change the voltage provided by the first power tube to the electrical equipment, including: The constant temperature control circuit reduces the gate voltage of the first power tube when the voltage of the first input end is increased, so as to increase the current value when the first power tube charges the electrical equipment.

Images