Battery under-voltage shutdown circuit and lithium battery

Abstract

The utility model provides a battery under-voltage shutdown circuit and a lithium battery. The circuit comprises an under-voltage acquisition circuit and a series voltage stabilizing circuit. The under-voltage acquisition circuit comprises a first electronic switch tube, a first resistor and a second resistor, and the second end of the first resistor is also connected with the control end of the first electronic switch tube; the series voltage stabilizing circuit comprises a series voltage stabilizing diode, a series Darlington tube and a third resistor, and the second end of the series Darlington tube is used for being connected with the input end of the low dropout regulator. When the battery is under-voltage, the voltage loaded on the second resistor is reduced, so that the bias voltage of the control end of the first electronic switch tube is reduced, the first electronic switch tube is turned off, the series Darlington tube is turned off synchronously, voltage is not output to the low dropout linear voltage regulator any more, and the service life of the low dropout linear voltage regulator is prolonged. Therefore, the voltage provided by the low dropout linear regulator for the battery management chip is cut off, the shutdown of the battery management system is realized, and the accurate shutdown under the condition of battery undervoltage is effectively improved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of lithium batteries, and in particular to a battery undervoltage shutdown circuit and a lithium battery. Background Art

[0002] In the existing battery management system, a linear series voltage regulator circuit is used to first reduce the total battery voltage to 12V, and then reduce the 12V to 3.3V through LDO as the power supply for the MCU. It is found in actual use that in a battery management system on a 24V platform, when the total battery voltage is between 9V and 11V, the voltage regulator diode in the linear series voltage regulator circuit cannot reversely break down to achieve voltage regulation due to the low voltage, and the transistor working in the amplification area has a low base current, so the amplified current is also very small, for example, the patent application with application number CN201910655361.2.

[0003] Although the output voltage of the series stabilizer circuit is within the working range of the LDO, the output current capacity is insufficient, and voltage jitter will occur during operation, causing the MCU to be unable to enter the shutdown state through software. Moreover, after the battery is left for a long time, the voltage will also drop to an extremely low level. At this voltage level, for safety reasons, the battery management system should enter the shutdown state normally and no longer allow charging. However, in the BMS system that uses a series voltage regulator circuit for voltage reduction at the front end, when the battery voltage is lower than the regulated output voltage, the MCU can no longer control the normal shutdown of the system due to the insufficient load capacity of the voltage regulator circuit. Utility Model Content

[0004] The purpose of the present invention is to overcome the deficiencies in the prior art and provide a battery undervoltage shutdown circuit and a lithium battery that effectively improve the undervoltage shutdown stability.

[0005] The purpose of this disclosure is achieved through the following technical solutions:

[0006] A battery undervoltage shutdown circuit comprises: an undervoltage acquisition circuit and a series voltage stabilization circuit; the undervoltage acquisition circuit comprises a first electronic switch tube, a first resistor and a second resistor, the first end of the first electronic switch tube is used to be connected to the positive electrode of the battery, the first end of the first electronic switch tube is also connected to the first end of the first resistor, the second end of the first resistor is grounded through the second resistor, and the second end of the first resistor is also connected to the control end of the first electronic switch tube; the series voltage stabilization circuit comprises a series voltage stabilization diode, a series Darlington tube and a third resistor, the second end of the first electronic switch tube is connected to the first end of the series Darlington tube, the second end of the series Darlington tube is used to be connected to the input end of a low voltage difference linear regulator, the second end of the first electronic switch tube is also connected to the first end of the third resistor, the second end of the third resistor is connected to the control end of the series Darlington tube, the second end of the third resistor is also connected to the negative electrode of the series voltage stabilization diode, and the positive electrode of the series voltage stabilization diode is grounded.

[0007] In one embodiment, the undervoltage acquisition circuit further includes a fourth resistor, and the second end of the first resistor is connected to the control end of the first electronic switch tube through the fourth resistor.

[0008] In one embodiment, the series voltage stabilization circuit further includes a fifth resistor, the second end of the first electronic switch tube is connected to the first end of the fifth resistor, and the second end of the fifth resistor is connected to the first end of the series Darlington tube.

[0009] In one embodiment, the series voltage stabilizing circuit further includes a series conducting diode, the second end of the fifth resistor is connected to the positive electrode of the series conducting diode, and the negative electrode of the series conducting diode is connected to the first end of the series Darlington tube.

[0010] In one embodiment, the series Darlington tube includes a second electronic switch tube and a third electronic switch tube, the second end of the first electronic switch tube is respectively connected to the first end of the second electronic switch tube and the first end of the third electronic switch tube, the second end of the second electronic switch tube is connected to the input end of the low voltage difference linear regulator, the second end of the third electronic switch tube is connected to the control end of the second electronic switch tube, and the control end of the third electronic switch tube is connected to the cathode of the series voltage regulator diode.

[0011] In one embodiment, the series voltage stabilization circuit further includes a sixth resistor, and the second end of the first electronic switch tube is connected to the first end of the second electronic switch tube through the sixth resistor.

[0012] In one embodiment, the series voltage stabilization circuit further includes a seventh resistor, and the second end of the first electronic switch tube is connected to the first end of the third electronic switch tube through the seventh resistor.

[0013] In one embodiment, the series voltage stabilization circuit further includes a first capacitor, and the first end of the third resistor is grounded through the first capacitor.

[0014] In one embodiment, the series voltage stabilization circuit further includes a second capacitor, and the second end of the series Darlington transistor is grounded through the second capacitor.

[0015] A lithium battery comprises the battery undervoltage shutdown circuit described in any one of the above embodiments.

[0016] Compared with the prior art, the present invention has at least the following advantages:

[0017] When the battery is under-voltage, the voltage loaded on the second resistor decreases, causing the bias voltage of the control end of the first electronic switch tube to decrease, thereby turning off the first electronic switch tube, and then causing the series Darlington tube to be synchronously turned off, and no longer outputting voltage to the low-voltage difference linear regulator, so that the voltage provided by the low-voltage difference linear regulator to the battery management chip is powered off, thereby shutting down the battery management system, effectively improving the precise shutdown under battery under-voltage conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1 is a circuit diagram of a battery undervoltage shutdown circuit in one embodiment;

[0020] Figure 2 for Figure 1 The circuit diagram of the undervoltage acquisition circuit in the battery undervoltage shutdown circuit shown;

[0021] Figure 3 for Figure 1 The circuit diagram of the series voltage regulator circuit in the battery undervoltage shutdown circuit is shown. DETAILED DESCRIPTION

[0022] In order to facilitate the understanding of the present disclosure, the present disclosure will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present disclosure are given in the drawings. However, the present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present disclosure more thoroughly and comprehensively understood.

[0023] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0024] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present disclosure. The terms used herein in the specification of the present disclosure are only for the purpose of describing specific embodiments and are not intended to limit the present disclosure. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0025] The present disclosure relates to a battery undervoltage shutdown circuit. In one embodiment, the battery undervoltage shutdown circuit includes an undervoltage acquisition circuit and a series voltage stabilization circuit; the undervoltage acquisition circuit includes a first electronic switch tube, a first resistor and a second resistor, the first end of the first electronic switch tube is used to connect to the positive electrode of the battery, the first end of the first electronic switch tube is also connected to the first end of the first resistor, the second end of the first resistor is grounded through the second resistor, and the second end of the first resistor is also connected to the control end of the first electronic switch tube; the series voltage stabilization circuit includes a series voltage stabilization diode, a series Darlington tube and a third resistor, the second end of the first electronic switch tube is connected to the first end of the series Darlington tube, the second end of the series Darlington tube is used to connect to the input end of a low voltage difference linear regulator, the second end of the first electronic switch tube is also connected to the first end of the third resistor, the second end of the third resistor is connected to the control end of the series Darlington tube, the second end of the third resistor is also connected to the negative electrode of the series voltage stabilization diode, and the positive electrode of the series voltage stabilization diode is grounded. When the battery is under-voltage, the voltage loaded on the second resistor decreases, causing the bias voltage of the control end of the first electronic switch tube to decrease, thereby turning off the first electronic switch tube, and then causing the series Darlington tube to be synchronously turned off, and no longer outputting voltage to the low-voltage difference linear regulator, so that the voltage provided by the low-voltage difference linear regulator to the battery management chip is powered off, thereby shutting down the battery management system, effectively improving the precise shutdown under battery under-voltage conditions.

[0026] See also Figure 1 , which is a circuit diagram of a battery undervoltage shutdown circuit according to an embodiment of the present disclosure.

[0027] The battery undervoltage shutdown circuit 10 of one embodiment includes an undervoltage acquisition circuit 100 and a series voltage stabilization circuit 200. Please refer to Figure 2 The undervoltage acquisition circuit 100 includes a first electronic switch tube Q1, a first resistor R1 and a second resistor R2. The first end of the first electronic switch tube Q1 is used to connect to the positive electrode B+ of the battery, the first end of the first electronic switch tube Q1 is also connected to the first end of the first resistor R1, and the second end of the first resistor R1 is grounded through the second resistor R2. The second end of the first resistor R1 is also connected to the control end of the first electronic switch tube Q1. Please refer to Figure 3 The series voltage regulator circuit 200 includes a series voltage regulator diode DZ3, a series Darlington transistor and a third resistor R7. The second end of the first electronic switch tube Q1 is connected to the first end of the series Darlington transistor, and the second end of the series Darlington transistor is used to connect to the input end of the low voltage difference linear regulator. The second end of the first electronic switch tube Q1 is also connected to the first end of the third resistor R7, the second end of the third resistor R7 is connected to the control end of the series Darlington transistor, the second end of the third resistor R7 is also connected to the cathode of the series voltage regulator diode DZ3, and the anode of the series voltage regulator diode DZ3 is grounded.

[0028] In this embodiment, when the battery is under-voltage, the voltage loaded on the second resistor R2 is reduced, so that the bias voltage of the control end of the first electronic switch tube Q1 is reduced, so that the first electronic switch tube Q1 is turned off, and then the series Darlington tube is synchronously turned off, and no voltage is output to the low-voltage difference linear regulator, so that the voltage provided by the low-voltage difference linear regulator to the battery management chip is powered off, and the battery management system is shut down, which effectively improves the precise shutdown under the condition of battery under-voltage.

[0029] In one embodiment, see Figure 2 The undervoltage acquisition circuit 100 further includes a fourth resistor R3, and the second end of the first resistor R1 is connected to the control end of the first electronic switch tube Q1 through the fourth resistor R3. In this embodiment, the fourth resistor R3 is connected to the first electronic switch tube Q1. Specifically, the fourth resistor R3 is connected in series to the control end of the first electronic switch tube Q1 to limit the current on the control end of the first electronic switch tube Q1 to avoid excessive current impacting the first electronic switch tube Q1, thereby ensuring the normal operation of the first electronic switch tube Q1.

[0030] In one embodiment, see Figure 3 The series voltage stabilizing circuit 200 further includes a fifth resistor R4, the second end of the first electronic switch tube Q1 is connected to the first end of the fifth resistor R4, and the second end of the fifth resistor R4 is connected to the first end of the series Darlington tube. In this embodiment, the fifth resistor R4 is connected to the first electronic switch tube Q1 and the series Darlington tube respectively. Specifically, the fifth resistor R4 is connected in series to the second end of the first electronic switch tube Q1, and the fifth resistor R4 is also connected in series to the first end of the series Darlington tube. The fifth resistor R4 limits the current flowing from the second end of the first electronic switch tube Q1 to the first end of the series Darlington tube, so as to ensure the normal operation of the series Darlington tube.

[0031] Furthermore, the series voltage stabilizing circuit 200 further includes a series conducting diode D15, the second end of the fifth resistor R4 is connected to the positive electrode of the series conducting diode D15, and the negative electrode of the series conducting diode D15 is connected to the first end of the series Darlington transistor. In this embodiment, the series conducting diode D15 is connected to the fifth resistor R4, that is, the series conducting diode D15 is connected in series with the fifth resistor R4, so that the current on the second end of the first electronic switch tube Q1 is unidirectionally introduced into the first end of the series Darlington tube, thereby preventing the current on the series Darlington tube from flowing back and impacting the first electronic switch tube Q1.

[0032] In one embodiment, see Figure 3 The series Darlington tube includes a second electronic switch tube Q2 and a third electronic switch tube Q3, the second end of the first electronic switch tube Q1 is connected to the first end of the second electronic switch tube Q2 and the first end of the third electronic switch tube Q3 respectively, the second end of the second electronic switch tube Q2 is connected to the input end of the low voltage difference linear regulator, the second end of the third electronic switch tube Q3 is connected to the control end of the second electronic switch tube Q2, and the control end of the third electronic switch tube Q3 is connected to the cathode of the series voltage regulator diode DZ3. In this embodiment, the second electronic switch tube Q2 and the third electronic switch tube Q3 form a Darlington tube, so that the series Darlington tube has a multi-stage amplification function, improves the current amplification of the second end of the first electronic switch tube Q1, and thus stabilizes the input voltage of the low voltage difference linear regulator.

[0033] Further, the series voltage stabilizing circuit 200 further includes a sixth resistor R5, and the second end of the first electronic switch tube Q1 is connected to the first end of the second electronic switch tube Q2 through the sixth resistor R5. In this embodiment, the sixth resistor R5 is connected to the second electronic switch tube Q2, specifically, the sixth resistor R5 is connected in series between the second end of the first electronic switch tube Q1 and the first end of the second electronic switch tube Q2, and the sixth resistor R5 limits the current flowing into the first end of the second electronic switch tube Q2 to ensure the normal operation of the second electronic switch tube Q2.

[0034] In another embodiment, the series voltage stabilizing circuit 200 further includes a seventh resistor R6, and the second end of the first electronic switch tube Q1 is connected to the first end of the third electronic switch tube Q3 through the seventh resistor R6. In this embodiment, the seventh resistor R6 is connected to the third electronic switch tube Q3, specifically, the seventh resistor R6 is connected in series between the second end of the first electronic switch tube Q1 and the first end of the third electronic switch tube Q3, and the seventh resistor R6 limits the current flowing into the first end of the third electronic switch tube Q3 to ensure the normal operation of the third electronic switch tube Q3.

[0035] In one embodiment, see Figure 3 , the series voltage stabilizing circuit 200 further includes a first capacitor C1, and the first end of the third resistor R7 is grounded through the first capacitor C1. In this embodiment, the first capacitor C1 is connected to the third resistor R7, that is, the control end of the series Darlington transistor is grounded through the first capacitor C1, and the signal at the control end of the series Darlington transistor is filtered through the first capacitor C1, so that the control signal at the control end of the series Darlington transistor is more accurate.

[0036] In one embodiment, see Figure 3 The series voltage stabilization circuit 200 further includes a second capacitor C2, and the second end of the series Darlington transistor is grounded through the second capacitor C2. In this embodiment, the second capacitor C2 is connected to the second end of the series Darlington transistor, and the second capacitor C2 filters the output voltage signal of the second end of the series Darlington transistor, so that the input voltage of the low voltage difference linear regulator is more stable.

[0037] In one embodiment, the present disclosure also relates to a lithium battery, including the battery undervoltage shutdown circuit described in any of the above embodiments. In this embodiment, the battery undervoltage shutdown circuit includes an undervoltage acquisition circuit and a series voltage stabilization circuit; the undervoltage acquisition circuit includes a first electronic switch tube, a first resistor and a second resistor, the first end of the first electronic switch tube is used to connect to the positive electrode of the battery, the first end of the first electronic switch tube is also connected to the first end of the first resistor, the second end of the first resistor is grounded through the second resistor, and the second end of the first resistor is also connected to the control end of the first electronic switch tube; the series voltage stabilization circuit includes a series voltage stabilization diode, a series Darlington tube and a third resistor, the second end of the first electronic switch tube is connected to the first end of the series Darlington tube, the second end of the series Darlington tube is used to connect to the input end of the low voltage difference linear regulator, the second end of the first electronic switch tube is also connected to the first end of the third resistor, the second end of the third resistor is connected to the control end of the series Darlington tube, the second end of the third resistor is also connected to the negative electrode of the series voltage stabilization diode, and the positive electrode of the series voltage stabilization diode is grounded. When the battery is under-voltage, the voltage loaded on the second resistor decreases, causing the bias voltage of the control end of the first electronic switch tube to decrease, thereby turning off the first electronic switch tube, and then causing the series Darlington tube to be synchronously turned off, and no longer outputting voltage to the low-voltage difference linear regulator, so that the voltage provided by the low-voltage difference linear regulator to the battery management chip is powered off, thereby shutting down the battery management system, effectively improving the precise shutdown under battery under-voltage conditions.

[0038] The above-described embodiments only express several implementation methods of the present disclosure, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present disclosure. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present disclosure, and these all belong to the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the attached claims.

Claims

1. A battery undervoltage shutdown circuit, characterized in that: include: An undervoltage acquisition circuit, the undervoltage acquisition circuit comprising a first electronic switch tube, a first resistor and a second resistor, wherein the first end of the first electronic switch tube is used to be connected to the positive electrode of the battery, the first end of the first electronic switch tube is also connected to the first end of the first resistor, the second end of the first resistor is grounded through the second resistor, and the second end of the first resistor is also connected to the control end of the first electronic switch tube; A series voltage stabilizing circuit, the series voltage stabilizing circuit comprising a series voltage stabilizing diode, a series Darlington tube and a third resistor, the second end of the first electronic switch tube is connected to the first end of the series Darlington tube, the second end of the series Darlington tube is used to be connected to the input end of a low voltage difference linear regulator, the second end of the first electronic switch tube is also connected to the first end of the third resistor, the second end of the third resistor is connected to the control end of the series Darlington tube, the second end of the third resistor is also connected to the negative electrode of the series voltage stabilizing diode, and the positive electrode of the series voltage stabilizing diode is grounded.

2. The battery undervoltage shutdown circuit according to claim 1, characterized in that: The undervoltage acquisition circuit further includes a fourth resistor, and the second end of the first resistor is connected to the control end of the first electronic switch tube through the fourth resistor.

3. The battery undervoltage shutdown circuit according to claim 1, characterized in that: The series voltage stabilization circuit further includes a fifth resistor, the second end of the first electronic switch tube is connected to the first end of the fifth resistor, and the second end of the fifth resistor is connected to the first end of the series Darlington tube.

4. The battery undervoltage shutdown circuit according to claim 3, characterized in that: The series voltage stabilization circuit further includes a series conducting diode, the second end of the fifth resistor is connected to the positive electrode of the series conducting diode, and the negative electrode of the series conducting diode is connected to the first end of the series Darlington transistor.

5. The battery undervoltage shutdown circuit according to claim 1, characterized in that: The series Darlington tube includes a second electronic switch tube and a third electronic switch tube, the second end of the first electronic switch tube is respectively connected to the first end of the second electronic switch tube and the first end of the third electronic switch tube, the second end of the second electronic switch tube is connected to the input end of the low voltage difference linear regulator, the second end of the third electronic switch tube is connected to the control end of the second electronic switch tube, and the control end of the third electronic switch tube is connected to the cathode of the series voltage regulator diode.

6. The battery undervoltage shutdown circuit according to claim 5, characterized in that: The series voltage stabilization circuit further includes a sixth resistor, and the second end of the first electronic switch tube is connected to the first end of the second electronic switch tube through the sixth resistor.

7. The battery undervoltage shutdown circuit according to claim 5, characterized in that: The series voltage stabilization circuit further includes a seventh resistor, and the second end of the first electronic switch tube is connected to the first end of the third electronic switch tube through the seventh resistor.

8. The battery undervoltage shutdown circuit according to claim 1, characterized in that: The series voltage stabilization circuit further includes a first capacitor, and the first end of the third resistor is grounded through the first capacitor.

9. The battery undervoltage shutdown circuit according to claim 1, characterized in that: The series voltage stabilization circuit further includes a second capacitor, and the second end of the series Darlington transistor is grounded via the second capacitor.

10. A lithium battery, characterized in that: The invention comprises a battery undervoltage shutdown circuit as claimed in any one of claims 1 to 9.

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