An LED lamp switching control circuit and a charging device

Abstract

The present invention discloses an LED lamp switching control circuit and a charging device. Among them, the LED lamp switching control circuit is connected to a first LED lamp and a second LED lamp, and includes a current detection module, a setting module, and a switching control module; the current detection module is connected to the setting module and the switching control module, and is used to detect the magnitude of the charging current, convert it into a detection voltage, and compare it with the reference voltage output by the current setting module, and output the comparison result to the setting module and the switching control module; the setting module is used to set the corresponding reference voltage according to the current comparison result; the switching control module is used to control the on / off states of the first LED lamp and the second LED lamp according to the current comparison result. The corresponding reference voltage can be set according to the current magnitude of the charging current, so that the current hysteresis function can be realized during switching control. When the charging current fluctuates near the switching current, the two-way LED lamps will not flicker, providing a more stable and accurate charging indication.

Description

Technical Field

[0001] The present invention relates to the field of charging indicator lights, and particularly to an LED lamp switching control circuit and a charging device. Background Art

[0002] In applications such as portable mobile phone chargers and lithium battery protection, LED charging indicator lights are increasingly widely used. In such applications, it is often required to use two LED lights to distinguish different charging states. Currently, in such applications, usually only a general operational amplifier circuit plus an LED lamp driving circuit is adopted. As Figure 1 shown, it is a schematic diagram of a commonly used LED lamp switching in the prior art. SET is the operational amplifier gain setting terminal, and CS is the current detection terminal. According to the detected charging current, a corresponding control level is output to the LED lamp driving circuit, and then the states of the two LED lights are controlled. Since there is no hysteresis value for the switching current in this scheme, when the charging current is close to the switching current, it is easy to cause the two LED lights to flicker, which is not conducive to the popularization and use of charging devices.

[0003] Therefore, the prior art still needs to be improved and enhanced. Summary of the Invention

[0004] In view of the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide an LED lamp switching control circuit and a charging device, which can set a corresponding reference voltage according to the magnitude of the current charging current, so that a current hysteresis function can be realized during switching control. When the charging current fluctuates near the switching current, the two LED lights will not flicker, providing a more stable and accurate charging indication.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] An LED lamp switching control circuit is connected to a first LED lamp and a second LED lamp. The LED lamp switching control circuit includes a current detection module, a setting module, and a switching control module; the current detection module is connected to the setting module and the switching control module, and is used to detect the magnitude of the charging current, convert it into a detection voltage, and compare it with the reference voltage output by the current setting module, and output the comparison result to the setting module and the switching control module; the setting module is used to set a corresponding reference voltage according to the current comparison result; the switching control module is used to control the on and off states of the first LED lamp and the second LED lamp according to the current comparison result.

[0007] In the described LED lamp switching control circuit, the setting module is specifically configured to output a first reference voltage to the current detection module in the initial state, output a second reference voltage to the current detection module when the detected voltage is greater than the first reference voltage after starting charging, and re-output the first reference voltage to the current detection module when the detected voltage is less than the second reference voltage, where the first reference voltage is greater than the second reference voltage.

[0008] In the described LED lamp switching control circuit, the switching control module is specifically configured to control the first LED lamp to turn off and the second LED lamp to turn on when the detected voltage is greater than the first reference voltage; control the first LED lamp to turn on and the second LED lamp to turn off when the detected voltage is less than the second reference voltage.

[0009] In the described LED lamp switching control circuit, the current detection module includes a first resistor, a second resistor, a first operational amplifier, and a second operational amplifier; the non-inverting input terminal of the first operational amplifier is connected to the gain setting terminal, the inverting input terminal of the first operational amplifier is connected to the current detection terminal and one end of the first resistor, the other end of the first resistor is grounded, and the output terminal of the first operational amplifier is connected to the inverting input terminal of the second operational amplifier; the non-inverting input terminal of the second operational amplifier is connected to the setting module, the output terminal of the second operational amplifier is connected to the switching control module and one end of the second resistor, and the other end of the second resistor is grounded.

[0010] In the described LED lamp switching control circuit, the setting module includes a third resistor, a fourth resistor, and a first triode; one end of the third resistor is connected to the power supply terminal, the other end of the third resistor is connected to one end of the fourth resistor, the non-inverting input terminal of the second operational amplifier, and the collector of the first triode; the other end of the fourth resistor is grounded; the base of the first triode is connected to the switching control module, and the emitter of the first triode is grounded.

[0011] In the described LED lamp switching control circuit, the switching control module includes a second triode, a third triode, a fourth triode, a fifth triode, a sixth triode, a seventh triode, an eighth triode, a ninth triode, a thirteenth triode, and an eleventh triode; the bases of the second triode and the third triode are both connected to the output terminal of the second operational amplifier, the emitters of the second triode and the third triode are both grounded, and the collector of the second triode is connected to the base of the fourth triode, the base of the first triode, and the collector of the seventh triode; the collector of the third triode is connected to the base of the sixth triode and the collector of the eighth triode; the emitter of the fourth triode is grounded, and the collector of the fourth triode is connected to the base of the fifth triode and the collector of the ninth triode; the emitter of the fifth triode is connected to the first LED lamp, and the collector of the fifth triode is connected to the collector of the thirteenth triode; the emitter of the sixth triode is connected to the second LED lamp, and the collector of the sixth triode is connected to the collector of the eleventh triode; the emitters of the seventh triode, the eighth triode, the ninth triode, the thirteenth triode, and the eleventh triode are all connected to the VCC power supply terminal, and the bases of the seventh triode, the eighth triode, the ninth triode, the thirteenth triode, and the eleventh triode are all connected to the bias voltage terminal.

[0012] In the described LED lamp switching control circuit, the first triode is an NPN type triode.

[0013] In the described LED lamp switching control circuit, the second triode, the third triode, the fourth triode, the fifth triode, and the sixth triode are all NPN type triodes, and the seventh triode, the eighth triode, the ninth triode, the thirteenth triode, and the eleventh triode are all PNP type triodes.

[0014] A charging device includes the LED lamp switching control circuit described above.

[0015] Compared with the prior art, in the LED lamp switching control circuit and charging device provided by the present invention, the LED lamp switching control circuit is connected to a first LED lamp and a second LED lamp, and includes a current detection module, a setting module, and a switching control module; the current detection module is connected to the setting module and the switching control module, and is configured to detect the magnitude of the charging current, convert it into a detection voltage, and compare it with the reference voltage output by the current setting module, and output the comparison result to the setting module and the switching control module; the setting module is configured to set a corresponding reference voltage according to the current comparison result; the switching control module is configured to control the on / off states of the first LED lamp and the second LED lamp according to the current comparison result. A corresponding reference voltage can be set according to the magnitude of the current charging current, so that a current hysteresis function can be realized during switching control, and the two LED lamps will not flicker when the charging current fluctuates near the switching current, providing a more stable and accurate charging indication. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 FIG. is a schematic diagram of LED lamp switching control in the prior art;

[0017] Figure 2 FIG. is a circuit diagram of the LED lamp switching control circuit provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The present invention provides an LED lamp switching control circuit and a charging device, which can set a corresponding reference voltage according to the magnitude of the current charging current, so that a current hysteresis function can be realized during switching control, and the two LED lamps will not flicker when the charging current fluctuates near the switching current, providing a more stable and accurate charging indication.

[0019] In order to make the objectives, technical solutions and effects of the present invention clearer and more definite, the following further describes the present invention in detail with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0020] Please refer to Figure 2, the LED lamp switching control circuit provided by the present invention is connected to the first LED lamp LED1 and the second LED lamp LED2, and includes a current detection module 10, a setting module 20 and a switching control module 30. The current detection module 10 is connected to the setting module 20 and the switching control module 30, and the switching control module 30 is connected to the first LED lamp LED1 and the second LED lamp LED2. Among them, the current detection module 10 is used to detect the magnitude of the charging current, convert it into a detection voltage, and compare it with the reference voltage output by the current setting module 20, and output the comparison result to the setting module 20 and the switching control module 30; the setting module 20 is used to set the corresponding reference voltage according to the current comparison result; the switching control module 30 is used to control the on-off states of the first LED lamp LED1 and the second LED lamp LED2 according to the current comparison result.

[0021] The LED lamp switching control circuit provided by the present invention can set the corresponding reference voltage according to the detection and comparison results of the current detection module 10 by adding a setting module 20, that is, the switching current magnitude of the LED lamp corresponding to the reference voltage is not fixed, and the corresponding reference value can be adjusted according to the magnitude of the current charging current, so that the current hysteresis function can be realized during switching control, and the two LED lamps will not flicker when the charging current fluctuates near the switching current, providing a more stable and accurate charging indication. At the same time, all the functional modules of the present invention can be integrated on the same chip, with a small PCB occupied area and low cost, which is more conducive to popularization and application in small charging devices.

[0022] Further, the setting module 20 is specifically configured to output a first reference voltage to the current detection module 10 in the initial state. After starting charging, when the detected voltage is greater than the first reference voltage, a second reference voltage is output to the current detection module 10. When the detected voltage is less than the second reference voltage, the first reference voltage is output to the current detection module 10 again, where the first reference voltage is greater than the second reference voltage. In this embodiment, the setting module 20 outputs a first reference voltage (e.g., 400 mV) to the current detection module 10 in the initial state. When starting charging, the current detection module 10 detects the magnitude of the charging current and converts it into a detected voltage, and compares the detected voltage with the first reference voltage. If the detected voltage is greater than the first reference voltage, a second reference voltage (e.g., 300 mV) is output to the current detection module 10. When the detected voltage is less than the second reference voltage, the first reference voltage is output to the current detection module 10 again. Since the charging current is generally large at the initial stage of charging, the reference voltage value is reduced after starting charging. Then, as the charging progresses, the charging current gradually decreases. However, if the decrease amplitude of the corresponding detected voltage is less than 100 mV, that is, the difference between the first reference voltage and the second reference voltage, at this time, since the comparison result does not change, the states of the two LED lights also remain unchanged. Only when the charging current further decreases until the decrease amplitude of the corresponding detected voltage is greater than 100 mV, at this time, the detected voltage is less than the second reference voltage, the comparison result changes, and then the working states of the two LED lights are switched correspondingly, leaving a current hysteresis space for the LED light switching control, so that when there is only a weak change in the charging current, the phenomenon of the two LED lights flashing will not occur.

[0023] Specifically, the switching control module 30 is specifically configured to control the first LED lamp LED1 to turn off and the second LED lamp LED2 to turn on when the detected voltage is greater than the first reference voltage; and control the first LED lamp LED1 to turn on and the second LED lamp LED2 to turn off when the detected voltage is less than the second reference voltage. That is, when the charging current is large and the detected voltage is greater than the first reference voltage, the first LED lamp LED1 is controlled to turn off and the second LED lamp LED2 is controlled to turn on. As the charging continues, the charging current continues to decrease. At this time, the setting module 20 has switched to output the second reference voltage to the switching control module 30. When the charging current decreases until the detected voltage is less than the second reference voltage, the first LED lamp LED1 is controlled to turn on and the second LED lamp LED2 is controlled to turn off, so that the user can know the current charging current state according to the on / off states of different LED lights. The first LED lamp LED1 and the second LED lamp LED2 are preferably lights of different colors to clearly indicate different charging states.

[0024] During specific implementation, such as Figure 2As shown, the current detection module 10 includes a first resistor R1, a second resistor R2, a first operational amplifier OP1, and a second operational amplifier OP2. The non-inverting input terminal of the first operational amplifier OP1 is connected to the gain setting terminal. The inverting input terminal of the first operational amplifier OP1 is connected to the current detection terminal and one end of the first resistor R1. The other end of the first resistor R1 is grounded. The output terminal of the first operational amplifier OP1 is connected to the inverting input terminal of the second operational amplifier OP2. The non-inverting input terminal of the second operational amplifier OP2 is connected to the setting module 20. The output terminal of the second operational amplifier OP2 is connected to the switching control module 30 and one end of the second resistor R2. The other end of the second resistor R2 is grounded.

[0025] The setting module 20 includes a third resistor R3, a fourth resistor R4, and a first triode Q1. One end of the third resistor R3 is connected to the power supply terminal. The other end of the third resistor R3 is connected to one end of the fourth resistor R4, the non-inverting input terminal of the second operational amplifier OP2, and the collector of the first triode Q1. The other end of the fourth resistor R4 is grounded. The base of the first triode Q1 is connected to the switching control module 30. The emitter of the first triode Q1 is grounded. In this embodiment, the first triode Q1 is an NPN type triode.

[0026] The switching control module 30 includes a second triode Q2, a third triode Q3, a fourth triode Q4, a fifth triode Q5, a sixth triode Q6, a seventh triode Q7, an eighth triode Q8, a ninth triode Q9, a tenth triode Q10 and an eleventh triode Q11; the bases of the second triode Q2 and the third triode Q3 are both connected to the output terminal of the second operational amplifier OP2, the emitters of the second triode Q2 and the third triode Q3 are both grounded, and the collector of the second triode Q2 is connected to the base of the fourth triode Q4, the base of the first triode Q1 and the collector of the seventh triode Q7; the collector of the third triode Q3 is connected to the base of the sixth triode Q6 and the collector of the eighth triode Q8; the emitter of the fourth triode Q4 is grounded, and the collector of the fourth triode Q4 is connected to the base of the fifth triode Q5 and the collector of the ninth triode Q9; the emitter of the fifth triode Q5 is connected to the first LED lamp LED1, and the collector of the fifth triode Q5 is connected to the collector of the tenth triode Q10; the emitter of the sixth triode Q6 is connected to the second LED lamp LED2, and the collector of the sixth triode Q6 is connected to the collector of the eleventh triode Q11; the emitters of the seventh triode Q7, the eighth triode Q8, the ninth triode Q9, the tenth triode Q10 and the eleventh triode Q11 are all connected to the VCC power supply terminal, and the bases of the seventh triode Q7, the eighth triode Q8, the ninth triode Q9, the tenth triode Q10 and the eleventh triode Q11 are all connected to the bias voltage terminal. In this embodiment, the second triode Q2, the third triode Q3, the fourth triode Q4, the fifth triode Q5 and the sixth triode Q6 are all NPN-type triodes, and the seventh triode Q7, the eighth triode Q8, the ninth triode Q9, the tenth triode Q10 and the eleventh triode Q11 are all PNP-type triodes.

[0027] Specifically, as Figure 2As shown, CS is the current detection terminal, which is the pin for detecting the charging current signal. SET is the gain setting terminal, which is used to set the gain of the first operational amplifier OP1. By setting the gain of the first operational amplifier OP1, the magnitude of the switching current can be set. When the charging current is detected at the CS terminal, it is converted into a voltage signal on the first resistor R1. After being amplified by the first operational amplifier OP1, it is output to the inverting input terminal of the second operational amplifier OP2. The non-inverting input terminal of the second operational amplifier is connected to VREF, that is, the reference voltage. The VREF voltage is generated by dividing the internal 1.25V power supply by the third resistor R3 and the fourth resistor R4. Its value is related to the on-off state of the first triode Q1. When the first triode Q1 is cut off, VREF1 = 1.25 * R4 / (R3 + R4), which is usually designed to be 400mV. When the first triode Q1 is conducting, there is a current I1 at the collector of the first triode Q1. At this time, VREF becomes: VREF2 = (1.25 - I1 * R3) * R4 / (R3 + R4), which is usually designed to be 300mV.

[0028] Pbias is the internal bias, which provides bias current for the seventh triode Q7 to the eleventh triode Q11. The seventh triode Q7 to the eleventh triode Q11 are the active loads of the second triode Q2 to the sixth triode Q6 respectively. The second triode Q2 to the sixth triode Q6 and the first triode Q1 to the fifth triode Q5 are the driving transistors of two LEDs. Among them, the first LED lamp LED1 is driven by the second triode Q2, the fourth triode Q4 and the fifth triode Q5, and the second LED lamp LED2 is driven by the third triode Q3 and the sixth triode Q6.

[0029] In the initial state, the first triode Q1 is cut off. At this time, the reference voltage is the first reference voltage VREF1 = 400mV. After starting to charge, at the initial stage of charging, the charging current is relatively large, and the signal at the CS terminal is also relatively large. After being amplified by the first operational amplifier OP1, the output signal is also relatively large (greater than the VREF1 voltage). Therefore, after being compared with VREF1 by the second operational amplifier OP2, a low level is output, that is, the bases of the second triode Q2 and the third triode Q3 are low, the base of the fourth triode Q4 is high, the base of the fifth triode Q5 is low, and the base of the sixth triode Q6 is high. At this time, the emitter of the fifth triode Q5 is low, turning off the first LED lamp LED1, and the emitter of the sixth triode Q6 is high, turning on the second LED lamp LED2. In this state, the base of the first triode Q1 is high, and the first triode Q1 is conducting. Therefore, the reference voltage is switched to the second reference voltage VREF2 = 300mV.

[0030] When the charging current becomes smaller, the signal at the CS terminal and the output of the first operational amplifier OP1 also become smaller. However, if the decrease is less than 100 mV, that is, if the output of the first operational amplifier OP1 is not smaller than VREF2 = 300 mV, the output state of the second operational amplifier OP2 will not change and will remain low. Therefore, the states of the first LED lamp LED1 and the second LED lamp LED2 also remain unchanged.

[0031] When the charging current becomes even smaller, the output of the first operational amplifier OP1 is lower than 300 mV. At this time, the output of the second operational amplifier OP2 will become high, causing the on-off states of the second transistor Q2 to the sixth transistor Q6 to change accordingly. At this time, the first LED lamp LED1 will light up, and the second LED lamp LED2 will go out. Since the output of the second operational amplifier OP2 becomes high, the base of the first transistor Q1 becomes low, and the first transistor Q1 is cut off. Therefore, the reference voltage rises back to 400 mV. Therefore, in the present invention, not only can a single-chip LED switching control function be realized with low cost, but also a current hysteresis function is provided, effectively avoiding the problem of simultaneous flashing of the two LED lamps.

[0032] Based on the above LED lamp switching control circuit, the present invention also correspondingly provides a charging device, which includes the above-mentioned LED lamp switching control circuit. Since the LED lamp switching control circuit has been described in detail above, it will not be elaborated here.

[0033] In summary, in the LED lamp switching control circuit and the charging device provided by the present invention, the LED lamp switching control circuit is connected to the first LED lamp and the second LED lamp, and includes a current detection module, a setting module, and a switching control module; the current detection module is connected to the setting module and the switching control module, and is used to detect the magnitude of the charging current, convert it into a detection voltage, and compare it with the reference voltage output by the current setting module, and output the comparison result to the setting module and the switching control module; the setting module is used to set the corresponding reference voltage according to the current comparison result; the switching control module is used to control the on-off states of the first LED lamp and the second LED lamp according to the current comparison result. The corresponding reference voltage can be set according to the magnitude of the current charging current, so that a current hysteresis function can be realized during switching control. When the charging current fluctuates near the switching current, the two-way LED lamps will not flash, providing a more stable and accurate charging indication.

[0034] It can be understood that for those of ordinary skill in the art, equivalent substitutions or changes can be made according to the technical solutions and inventive concepts of the present invention, and all such changes or substitutions should fall within the protection scope of the claims appended to the present invention.

Claims

1. An LED lamp switching control circuit is connected to a first LED lamp and a second LED lamp. Characterized in that, the LED lamp switching control circuit includes a current detection module, a setting module and a switching control module; the current detection module is connected to the setting module and the switching control module, and is used to detect the magnitude of the charging current, convert it into a detection voltage, and compare it with the reference voltage output by the current setting module, and output the comparison result to the setting module and the switching control module; the setting module is used to set the corresponding reference voltage according to the current comparison result; the switching control module is used to control the on and off states of the first LED lamp and the second LED lamp according to the current comparison result; the setting module is specifically used to output a first reference voltage to the current detection module in the initial state, output a second reference voltage to the current detection module when the detection voltage is greater than the first reference voltage after starting charging, and re-output the first reference voltage to the current detection module when the detection voltage is less than the second reference voltage, wherein the first reference voltage is greater than the second reference voltage; the first LED lamp and the second LED lamp are lamps of different colors to clearly indicate different charging states; the switching control module is specifically used to control the first LED lamp to turn off and the second LED lamp to turn on when the detection voltage is greater than the first reference voltage; control the first LED lamp to turn on and the second LED lamp to turn off when the detection voltage is less than the second reference voltage; Set the corresponding reference voltage according to the current magnitude of the charging current, so as to realize the current hysteresis function during switching control. When the charging current fluctuates near the switching current, the two-way LED lamps will not flicker, providing a more stable and accurate charging indication.

2. The LED lamp switching control circuit according to claim 1, Characterized in that, the current detection module includes a first resistor, a second resistor, a first operational amplifier and a second operational amplifier; the non-inverting input terminal of the first operational amplifier is connected to the gain setting terminal, the inverting input terminal of the first operational amplifier is connected to the current detection terminal and one end of the first resistor, the other end of the first resistor is grounded, and the output terminal of the first operational amplifier is connected to the inverting input terminal of the second operational amplifier; the non-inverting input terminal of the second operational amplifier is connected to the setting module, and the output terminal of the second operational amplifier is connected to the switching control module and one end of the second resistor, and the other end of the second resistor is grounded.

3. The LED lamp switching control circuit according to claim 2, Characterized in that, the setting module includes a third resistor, a fourth resistor and a first triode; one end of the third resistor is connected to the power supply terminal, the other end of the third resistor is connected to one end of the fourth resistor, the non-inverting input terminal of the second operational amplifier and the collector of the first triode; the other end of the fourth resistor is grounded; the base of the first triode is connected to the switching control module, and the emitter of the first triode is grounded.

4. The LED lamp switching control circuit according to claim 3, Characterized in that, The switching control module includes a second triode, a third triode, a fourth triode, a fifth triode, a sixth triode, a seventh triode, an eighth triode, a ninth triode, a thirteenth triode, and an eleventh triode; the bases of the second triode and the third triode are both connected to the output terminal of the second operational amplifier, the emitters of the second triode and the third triode are both grounded, and the collector of the second triode is connected to the base of the fourth triode, the base of the first triode, and the collector of the seventh triode; the collector of the third triode is connected to the base of the sixth triode and the collector of the eighth triode; the emitter of the fourth triode is grounded, and the collector of the fourth triode is connected to the base of the fifth triode and the collector of the ninth triode; the emitter of the fifth triode is connected to the first LED lamp, and the collector of the fifth triode is connected to the collector of the thirteenth triode; the emitter of the sixth triode is connected to the second LED lamp, and the collector of the sixth triode is connected to the collector of the eleventh triode; the emitters of the seventh triode, the eighth triode, the ninth triode, the thirteenth triode, and the eleventh triode are all connected to the VCC power supply terminal, and the bases of the seventh triode, the eighth triode, the ninth triode, the thirteenth triode, and the eleventh triode are all connected to the bias voltage terminal.

5. The LED lamp switching control circuit according to claim 3, characterized in that, the first triode is an NPN type triode.

6. The LED lamp switching control circuit according to claim 4, characterized in that, the second triode, the third triode, the fourth triode, the fifth triode, and the sixth triode are all NPN type triodes, and the seventh triode, the eighth triode, the ninth triode, the thirteenth triode, and the eleventh triode are all PNP type triodes.

7. A charging device, characterized in that, it includes the LED lamp switching control circuit according to any one of claims 1-6.

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