CN212305723U

CN212305723U - Constant current control and over-discharge protection circuit of lithium battery LED lamp

Info

Publication number: CN212305723U
Application number: CN202022110276.9U
Authority: CN
Inventors: 王黎; 吕新明; 管邦淋; 何兵
Original assignee: Zhejiang Huafeng Electric Tools Co Ltd
Current assignee: Zhejiang Huafeng Electric Tools Co Ltd
Priority date: 2020-09-23
Filing date: 2020-09-23
Publication date: 2021-01-05
Anticipated expiration: 2030-09-23

Abstract

The utility model discloses protection control circuit to lithium cell power supply's LED lamp among the prior art adopts single chip microcomputer control, and the shortcoming that comprehensive cost is high provides a constant current control and overdischarge protection circuit of lithium electricity LED lamp, and this circuit includes voltage stabilizing circuit, LED lamp control circuit and overdischarge protection circuit, and this circuit has replaced the corresponding function of singlechip through ordinary electronic components's design combination, has reduced manufacturing cost.

Description

Constant current control and over-discharge protection circuit of lithium battery LED lamp

Technical Field

The utility model belongs to the technical field of the illumination, concretely relates to constant current control and overdischarge protection circuit of lithium electricity LED lamp.

Background

The LED lamp is low in energy consumption, long in service life and high in illumination, although the LED light source is more expensive than the traditional light source, the LED light source is enabled to have higher and higher market acceptance and huge market capacity and potential due to the excellent energy-saving performance. The constant current source drive is the best LED drive mode, the constant current source drive is adopted, a current-limiting resistor is not required to be connected in series with an output circuit, and the current flowing through the LED is not influenced by the external power supply voltage change, the environment temperature change and the LED parameter discreteness, so that the constant current can be maintained, and various excellent characteristics of the LED can be fully exerted. Particularly in the field of movable lighting, the combination of the lithium battery and the LED lamp gives full play to the characteristics of light weight, long lighting duration and good lighting brightness of the lighting lamp. For example, patent publication No. CN207320918U entitled lithium battery charging and discharging circuit and LED lamp control device provides a constant voltage and constant current driving power supply for LED lamp, and has a lithium battery overcharge and overdischarge protection circuit to protect the service life of the lithium battery.

However, the protection circuit of the lithium battery in the above scheme adopts the single chip microcomputer to realize the control function, so that the comprehensive cost is high, and the marketization of the LED lamp is not facilitated. Further reducing the production cost of the LED lamp powered by the lithium battery has great significance for market occupation.

Disclosure of Invention

The utility model discloses protection control circuit to prior art lithium cell powered's LED lamp adopts single chip microcomputer control, and the shortcoming that comprehensive cost is high provides a constant current control and overdischarge protection circuit of lithium electricity LED lamp, and this circuit has replaced the corresponding function of singlechip through ordinary electronic components's design combination, has reduced manufacturing cost.

The invention aims to be realized by the following technical scheme: the constant-current control and over-discharge protection circuit of the lithium battery LED lamp comprises a voltage stabilizing circuit, an LED lamp control circuit and an over-discharge protection circuit, wherein the voltage stabilizing circuit comprises a voltage stabilizing chip U1, the input end of the voltage stabilizing chip U1 is connected with the voltage of a lithium battery, the output end of the voltage stabilizing chip U1 outputs a control voltage with constant voltage, the output end of the voltage stabilizing chip U1 is further connected with a resistor R1 and a resistor R2 which are connected in series, and the other end of the resistor R2 connected with the resistor R1 is grounded; the LED lamp control circuit comprises an LED lamp, one end of the LED lamp is connected with the voltage of a lithium battery, the other end of the LED lamp is connected with an inductor L, the other end of the inductor L is connected with the drain electrode of a power tube M1, the source electrode of the power tube M1 is connected with a sampling resistor R3, and the other end of the sampling resistor R3 is grounded; the over-discharge protection circuit comprises an N-type triode Q1 and a P-type triode Q2, wherein an emitter of the triode Q1 and an emitter of the triode Q2 are connected with a gate of a power tube M1, a collector of the triode Q2 is grounded, a collector of the triode Q1 is connected with a control voltage, a base of the triode Q1 and a base of the triode Q2 are connected with an output end of an AND gate, one input end of the AND gate is connected with an output end of a comparator B1, the other input end of the AND gate is connected with an output end of a comparator B2, a negative input end of the comparator B1 is connected with the control voltage, a positive input end of the comparator B1 is connected with a resistor R4, the other end of the resistor R4 is connected with a lithium battery voltage, one end of the resistor R4 connected with a positive input end of the comparator B1 is also connected with a resistor R5 in series, and the other; the negative input end of the comparator B2 is connected with one end of the sampling resistor R3 connected with the source electrode of the power tube M1, and the positive input end of the comparator B2 is connected with one end of the resistor R1 connected with the resistor R2.

In the scheme, the power tube M1 controls the LED lamp, when the M1 is turned on, the current flows from the voltage of the lithium battery at the anode to the cathode of the battery through the LED lamp, the inductor L, the power tube M1 and the resistor R3, and the LED lamp is on; otherwise the lamp goes out. The output end of the voltage stabilizing chip U1 outputs a stable control voltage, and the voltage generates a constant current control reference voltage with the series-connected voltage dividing resistors R1 and R2 on one hand, and is used as a gate driving voltage of the power tube M1 on the other hand. The switch of power transistor M1 is controlled by an and gate and transistor Q1 and transistor Q2. When the AND gate outputs high level, Q1 is conducted, Q2 is closed, the grid voltage of the power tube M1 is higher than the source electrode, and the power tube M1 is conducted; the input of the and gate is two signals: an over-discharge protection signal and a constant current control signal. The over-discharge protection signal is input from the output terminal of the comparator B1, and the constant current control signal is input from the output terminal of the comparator B2. When the electric quantity of the lithium battery is sufficient, the overdischarge protection signal is at a high level, the output of the AND gate depends on the constant current control signal, and the system works in a constant current control state; when the electric quantity of the lithium battery is insufficient, the overdischarge protection signal is at a low level, the output of the AND gate is at a low level, the power tube M1 is turned off, and the system works in an overdischarge protection state. The negative input end of the comparator B1 is connected with the control voltage, the voltage of the lithium battery is connected with the positive input end of the comparator B1 through the series connection of the resistor R4 and the resistor R5 and the partial voltage, when the voltage of the lithium battery is higher than the control voltage (R4 + R5)/R5, the comparator B1 outputs high level, and the system works normally. On the contrary, when the voltage of the lithium battery is lower than the value, the comparator B1 outputs a low level, and the system enters an overdischarge protection state. Different over-discharge protection voltages can be obtained by changing the values of the resistor R4 and the resistor R5 so as to adapt to different lithium battery discharge characteristics. The constant current control signal is generated by a comparator B2 for keeping the lamp brightness stable. The working current I flowing through the LED lamp generates a sampling voltage through a sampling resistor R3 and is connected to the negative input end of a comparator B2; the control voltage is serially connected with a resistor R1 and a resistor R2 for voltage division to obtain a constant current control reference voltage, and the constant current control reference voltage is connected to the positive input end of a comparator B2. When the working current I is less than or equal to the control voltage R2/[ R3 (R1+ R2) ], the comparator B2 outputs high level, and the power tube M1 is switched on; when the working current is larger than the value, the comparator B2 outputs low level, and the power tube M1 is turned off; thus, the working current is always kept at the level of I = control voltage R2/[ R3 (R1+ R2) ], and constant current control is realized.

Preferably, the input end and the output end of the voltage regulation chip U1 are further connected with a capacitor C1 and a capacitor C2, respectively, and the capacitor C1 and the capacitor C2 are grounded after being connected with the input end and the output end of the voltage regulation chip U1, respectively, so as to perform a filtering function.

Preferably, a diode D is connected in parallel in the reverse direction between the voltage connection end of the LED lamp and the lithium battery and the drain connection end of the inductor L and the power tube M1. The inductor L is an energy storage inductor and is used for supplying power to the LED lamp through the freewheeling diode D when the chopping signal is at a low level within a millisecond transient moment so as to keep the lamp light continuously bright and eliminate the stroboscopic effect.

Preferably, an RC oscillator is further connected between the negative input terminal of the comparator B2 and the sampling resistor R3, the RC oscillator includes a resistor R7 and a capacitor C3, one end of the resistor R7 and one end of the capacitor C3 are both connected to the negative input terminal of the comparator B2, the other end of the resistor R7 is connected to the source of the power transistor M1, and the other end of the capacitor C3 is grounded. The constant current control signal generated by the comparator B2 is a high-frequency chopping signal, the frequency of the signal is too high or too low, and the proper working frequency of the signal is within the range of 3-10 KHz. In order to limit the chopping frequency, an RC oscillator connected with the sampling resistor R3 in parallel is designed, and the desired chopping frequency can be obtained by selecting the values of the resistor R7 and the capacitor C3.

Preferably, the power transistor M1 is an N-channel power transistor.

Compared with the prior art, the utility model discloses following beneficial effect has: the circuit replaces the corresponding function of a singlechip by the design combination of common electronic components, thereby reducing the production cost; the combined use of the inductor L and the diode D eliminates the stroboscopic effect of the LED lamp.

Drawings

Fig. 1 is a circuit structure diagram of the present invention.

Detailed Description

The invention will be further described with reference to the embodiments shown in the drawings to which:

example 1

As shown in fig. 1, the constant current control and over-discharge protection circuit for the lithium battery LED lamp includes a voltage stabilizing circuit, an LED lamp control circuit, and an over-discharge protection circuit, where the voltage stabilizing circuit includes a voltage stabilizing chip U1, the model of the voltage stabilizing chip is a three-terminal voltage stabilizing chip 78M12, an input terminal of the voltage stabilizing chip U1 is connected to a voltage of a lithium battery, an output terminal of the voltage stabilizing chip U1 outputs a control voltage with a constant voltage of +12V, an input terminal and an output terminal of the voltage stabilizing chip U1 are further connected to a capacitor C1 and a capacitor C2, and the capacitor C1 and the capacitor C2 are connected to an input terminal and an output terminal of the voltage stabilizing chip U1, respectively. The output end of the voltage stabilizing chip U1 is also connected with a resistor R1 and a resistor R2 which are connected in series, and the other end of the resistor R2 is grounded; LED lamp control circuit includes the LED lamp, lithium cell voltage is connected to the one end of LED lamp, inductance L is connected to the other end of LED lamp, still reverse parallel connection has diode D between LED lamp and lithium cell voltage link and inductance L and power tube M1's the drain electrode link. The inductor L is an energy storage inductor and is used for supplying power to the LED lamp through the freewheeling diode D when the chopping signal is at a low level within a millisecond transient moment so as to keep the lamp light continuously bright and eliminate the stroboscopic effect. The other end of the inductor L is connected with the drain electrode of an N-channel power tube M1, the source electrode of the power tube M1 is connected with a sampling resistor R3, and the other end of the sampling resistor R3 is grounded; the over-discharge protection circuit comprises an N-type triode Q1 and a P-type triode Q2, wherein an emitter of the triode Q1 and an emitter of the triode Q2 are connected with a gate of a power tube M1, a collector of the triode Q2 is grounded, a collector of the triode Q1 is connected with a control voltage, a base of the triode Q1 and a base of the triode Q2 are connected with an output end of an AND gate, one input end of the AND gate is connected with an output end of a comparator B1, the other input end of the AND gate is connected with an output end of a comparator B2, a negative input end of the comparator B1 is connected with the control voltage, a positive input end of the comparator B1 is connected with a resistor R4, the other end of the resistor R4 is connected with a lithium battery voltage, one end of the resistor R4 connected with a positive input end of the comparator B1 is also connected with a resistor R5 in series, and the other; the negative input end of the comparator B2 is connected with one end of a sampling resistor R3 connected with the source electrode of the power tube M1, an RC oscillator is further connected between the negative input end of the comparator B2 and the sampling resistor R3, the RC oscillator comprises a resistor R7 and a capacitor C3, one end of the resistor R7 and one end of the capacitor C3 are both connected with the negative input end of the comparator B2, the other end of the resistor R7 is connected with the source electrode of the power tube M1, and the other end of the capacitor C3 is grounded. The constant current control signal generated by the comparator B2 is a high-frequency chopping signal, the frequency of the signal is too high or too low, and the proper working frequency of the signal is within the range of 3-10 KHz. In order to limit the chopping frequency, an RC oscillator connected with the sampling resistor R3 in parallel is designed, and the desired chopping frequency can be obtained by selecting the values of the resistor R7 and the capacitor C3. The positive input end of the comparator B2 is connected with one end connected with the resistor R1 and the resistor R2.

The power tube M1 controls the LED lamp, when the power tube M1 is turned on, the current flows from the voltage of the lithium battery at the anode through the LED lamp, the inductor L, the power tube M1 and the resistor R3 to the cathode of the battery, and the LED lamp is on; otherwise the lamp goes out. The output end of the voltage stabilizing chip U1 outputs a stable +12V control voltage, which generates a constant-current control reference voltage with the series-connected voltage dividing resistors R1 and R2 and serves as a gate driving voltage of the power tube M1. The switch of power transistor M1 is controlled by an and gate and transistor Q1 and transistor Q2. When the AND gate outputs high level, Q1 is conducted, Q2 is closed, the grid voltage of the power tube M1 is higher than the source electrode, and the power tube M1 is conducted; the input of the and gate is two signals: an over-discharge protection signal and a constant current control signal. The over-discharge protection signal is input from the output terminal of the comparator B1, and the constant current control signal is input from the output terminal of the comparator B2. When the electric quantity of the lithium battery is sufficient, the overdischarge protection signal is at a high level, the output of the AND gate depends on the constant current control signal, and the system works in a constant current control state; when the electric quantity of the lithium battery is insufficient, the overdischarge protection signal is at a low level, the output of the AND gate is at a low level, the power tube M1 is turned off, and the system works in an overdischarge protection state. The negative input end of the comparator B1 is connected with the control voltage, the voltage of the lithium battery is connected to the positive input end of the comparator B1 through the series connection of the resistor R4 and the resistor R5, and the comparator B1 outputs high level when the voltage of the lithium battery is higher than 12 x (R4 + R5)/R5, so that the system works normally. On the contrary, when the voltage of the lithium battery is lower than the value, the comparator B1 outputs a low level, and the system enters an overdischarge protection state. Different over-discharge protection voltages can be obtained by changing the values of the resistor R4 and the resistor R5 so as to adapt to different lithium battery discharge characteristics. The constant current control signal is generated by a comparator B2 for keeping the lamp brightness stable. The working current I flowing through the LED lamp generates a sampling voltage through a sampling resistor R3 and is connected to the negative input end of a comparator B2; the control voltage is serially connected with a resistor R1 and a resistor R2 for voltage division to obtain a constant current control reference voltage, and the constant current control reference voltage is connected to the positive input end of a comparator B2. When the working current I is less than or equal to 12 × R2/[ R3 (R1+ R2) ], the comparator B2 outputs high level, and the power tube M1 is switched on; when the working current is larger than the value, the comparator B2 outputs low level, and the power tube M1 is turned off; thus, the working current is always kept at the level of I = 12R 2/[ R3 (R1+ R2) ], and constant-current control is realized.

The specific embodiments described herein are merely illustrative of the spirit of the invention. Various modifications, additions and substitutions for the specific embodiments described herein may be made by those skilled in the art without departing from the spirit of the invention or exceeding the scope of the invention as defined in the accompanying claims.

Claims

1. The constant-current control and over-discharge protection circuit of the lithium battery LED lamp is characterized by comprising a voltage stabilizing circuit, an LED lamp control circuit and an over-discharge protection circuit, wherein the voltage stabilizing circuit comprises a voltage stabilizing chip U1, the input end of the voltage stabilizing chip U1 is connected with the voltage of a lithium battery, the output end of the voltage stabilizing chip U1 outputs a control voltage with constant voltage, the output end of the voltage stabilizing chip U1 is further connected with a resistor R1 and a resistor R2 which are connected in series, and the other end of the resistor R2 connected with the resistor R1 is grounded; the LED lamp control circuit comprises an LED lamp, one end of the LED lamp is connected with the voltage of a lithium battery, the other end of the LED lamp is connected with an inductor L, the other end of the inductor L is connected with the drain electrode of a power tube M1, the source electrode of the power tube M1 is connected with a sampling resistor R3, and the other end of the sampling resistor R3 is grounded; the over-discharge protection circuit comprises an N-type triode Q1 and a P-type triode Q2, wherein an emitter of the triode Q1 and an emitter of the triode Q2 are connected with a gate of a power tube M1, a collector of the triode Q2 is grounded, a collector of the triode Q1 is connected with a control voltage, a base of the triode Q1 and a base of the triode Q2 are connected with an output end of an AND gate, one input end of the AND gate is connected with an output end of a comparator B1, the other input end of the AND gate is connected with an output end of a comparator B2, a negative input end of the comparator B1 is connected with the control voltage, a positive input end of the comparator B1 is connected with a resistor R4, the other end of the resistor R4 is connected with a lithium battery voltage, one end of the resistor R4 connected with a positive input end of the comparator B1 is also connected with a resistor R5 in series, and the other; the negative input end of the comparator B2 is connected with one end of the sampling resistor R3 connected with the source electrode of the power tube M1, and the positive input end of the comparator B2 is connected with one end of the resistor R1 connected with the resistor R2.

2. The constant-current control and over-discharge protection circuit of the lithium battery LED lamp as claimed in claim 1, wherein the input end and the output end of the voltage stabilization chip U1 are further connected with a capacitor C1 and a capacitor C2 respectively, and the capacitor C1 and the capacitor C2 are connected with the input end and the output end of the voltage stabilization chip U1 respectively and then grounded.

3. The constant-current control and over-discharge protection circuit of the lithium battery LED lamp as claimed in claim 1, wherein a diode D is connected in parallel in a reverse direction between a voltage connection end of the LED lamp and the lithium battery and a drain connection end of the inductor L and the power tube M1.

4. The constant current control and over-discharge protection circuit of the lithium battery LED lamp as claimed in claim 1, wherein an RC oscillator is further connected between the negative input end of the comparator B2 and the sampling resistor R3, the RC oscillator comprises a resistor R7 and a capacitor C3, one end of the resistor R7 and one end of the capacitor C3 are both connected with the negative input end of the comparator B2, the other end of the resistor R7 is connected with the source of the power tube M1, and the other end of the capacitor C3 is grounded.

5. The constant current control and over-discharge protection circuit of the lithium battery LED lamp as claimed in claim 1, wherein the power transistor M1 is an N-channel power transistor.