CN210898570U - Lithium battery under-voltage charging processing circuit - Google Patents

Abstract

The utility model discloses an under-voltage charging processing circuit of lithium cell is applied to in the lithium cell that has battery management system, battery management system has under-voltage protection signal output part UVP, reference voltage end VCC, under-voltage charging processing circuit is including charging MOS pipe MC1, discharging MOS pipe MD1, first switch tube Q1, second switch tube Q2, third switch tube Q3, switch S1 and delay circuit. Utilize the utility model provides an under-voltage charging processing circuit can realize that the lithium cell also can charge for the charger that has voltage detection function under the under-voltage state to normal charge protection function has when charging, avoided causing the permanent condition of becoming invalid of lithium cell under-voltage protection function to appear because misoperation or because the switch damages, effectively solve prior art and do not have the problem of overcharging protect function and having very big potential safety hazard with the negative output end when directly regard as emergent charging port with the positive output of lithium cell.

Description

Lithium battery under-voltage charging processing circuit

Technical Field

The utility model relates to an under-voltage charging processing circuit of lithium cell.

Background

Part lithium cell charger need detect the group battery and have output voltage just can charge, leads to the lithium cell group to be unable to charge after undervoltage. In the prior art, the positive output terminal BATT + and the negative output terminal BATT-of the battery are directly led out to be used as emergency charging ports, so that when the charger is connected with the emergency charging port of the battery pack for charging, the BMS (battery management system) is directly skipped, and therefore, the battery has no over-charging protection function and has great potential safety hazard.

SUMMERY OF THE UTILITY MODEL

For the problem of overcoming prior art not enough and existence, the utility model provides an under-voltage charging processing circuit of lithium cell utilizes this pressure charging processing circuit, can realize also can charge under the state that has normal charge protection function at the lithium cell under the under-voltage state.

The utility model discloses a realize through following technical scheme: a lithium battery under-voltage charging processing circuit is applied to a lithium battery with a battery management system, the battery management system is provided with an under-voltage protection signal output end UVP and a reference voltage end VCC, the under-voltage charging processing circuit comprises a charging MOS tube MC1, a discharging MOS tube MD1 and a first switch tube Q1, grids of the charging MOS tube MC1 and the discharging MOS tube MD1 are respectively connected with the reference voltage VCC through a resistor R6 and a resistor R5, a drain of the charging MOS tube MC1 is connected with a drain of the discharging MOS tube MD1, a positive output end of the lithium battery is connected with a first connecting end of a load, a negative output end of the lithium battery is connected with a source of the discharging MOS tube MD1, a source of the charging MOS tube MC1 is connected with a second connecting end of the load, a control end of the first switch tube Q1 is connected with the UVP through the resistor R1, an input end of the first switch tube Q1 is connected with the grid of the discharging MOS tube MD1, the output end of the first switching tube Q1 is connected with the source electrode of the discharge MOS tube MD 1;

the undervoltage charging processing circuit further comprises a second switch tube Q2, a third switch tube Q3, a switch S1 and a time delay circuit, wherein an input end of the second switch tube Q2 is connected with the undervoltage protection signal output end UVP through a resistor R1, an output end of the second switch tube Q2 is connected with a source electrode of the discharge MOS tube MD1, a control end of the second switch tube Q2 is connected with an output end of the third switch tube Q3 through a resistor R2, an input end of the third switch tube Q3 is connected with the reference voltage end VCC, the reference voltage end VCC is connected with one end of the switch S1 through a resistor R4 and a second capacitor C2 in sequence, the other end of the switch S1 is connected with a negative output end of the lithium battery, one end of the resistor R4 and the second capacitor C2 which are connected with a control end of the third switch tube Q3, and one end of the second capacitor and the switch S1 which are connected with each other is connected with a control end of the third switch tube Q3 through a resistor R7, one end of the delay circuit is connected with the control end of the second switch tube Q2, and the other end of the delay circuit is connected with the output end of the second switch tube Q2.

Preferably, the delay circuit is an RC delay circuit; the switch S1 is a tact switch.

Preferably, the first switch transistor Q1, the second switch transistor Q2 and the third switch transistor Q3 are MOS transistors.

Compared with the prior art, the utility model provides an under-voltage charging treatment circuit can realize that the lithium cell also can charge for the charger that has voltage detection function under the under-voltage state to have normal charge protection function when charging, avoided because misoperation or because the switch damages the condition that causes the permanent inefficacy of lithium cell under-voltage protection function to appear, effectively solve the problem that does not have the overcharge protection function and have very big potential safety hazard when directly regard as emergent charging port with the positive output of lithium cell and negative output among the prior art.

Drawings

Fig. 1 is a circuit structure diagram of the under-voltage charging processing circuit of the present invention.

Detailed Description

To facilitate understanding of those skilled in the art, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

As shown in fig. 1, 1. a lithium battery under-voltage charging processing circuit, applied to a lithium battery having a battery management system, the battery management system has an under-voltage protection signal output terminal UVP and a reference voltage terminal VCC, the under-voltage charging processing circuit includes a charging MOS transistor MC1, a discharging MOS transistor MD1 and a first switch Q1, gates of the charging MOS transistor MC1 and the discharging MOS transistor MD1 are connected to the reference voltage VCC through a resistor R6 and a resistor R5, respectively, a drain of the charging MOS transistor MC1 is connected to a drain of the discharging MOS transistor MD1, a positive output terminal of the lithium battery is connected to a first connection terminal of a load, a negative output terminal of the lithium battery is connected to a source of the discharging MOS transistor MD1, a source of the charging MOS transistor MC1 is connected to a second connection terminal of the load, a control terminal of the first switch Q1 is connected to the under-voltage protection signal output terminal UVP through a resistor R1, an input terminal of the first switch Q1 is connected to a gate of the discharging MOS transistor MD1, the output end of the first switching tube Q1 is connected with the source electrode of the discharge MOS tube MD 1; the undervoltage charging processing circuit further comprises a second switch tube Q2, a third switch tube Q3, a switch S1 and a delay circuit, wherein the input end of the second switch tube Q2 is connected with the undervoltage protection signal output end UVP through a resistor R1, the output end of the second switch tube Q2 is connected with the source electrode of the discharge MOS tube MD1, the control end of the second switch tube Q2 is connected with the output end of the third switch tube Q3 through a resistor R2, the input end of the third switch tube Q3 is connected with the reference voltage end VCC, the reference voltage end VCC is connected with one end of the switch S1 through a resistor R4 and a second capacitor C2 in sequence, the other end of the switch S1 is connected with the negative output end of the lithium battery, the end of the resistor R4 connected with the second capacitor C2 is connected with the control end of the third switch tube Q3, and the end of the second capacitor S1 connected with the control end of the third switch tube Q67 3 through a resistor R7, one end of the delay circuit is connected with the control end of the second switch tube Q2, and the other end of the delay circuit is connected with the output end of the second switch tube Q2.

In the present embodiment, the terms "first", "second", "third", and the like are used only for descriptive distinction and have no special meaning. In addition, in fig. 1, P1 is a positive output terminal of the lithium battery, P2 is a negative output terminal of the lithium battery, P3 is a first connection terminal of the load, and P4 is a second connection terminal of the load.

In this embodiment, the first switch transistor Q1, the second switch transistor Q2, and the third switch transistor Q3 are MOS transistors. The first switch transistor Q1 and the second switch transistor Q2 are N-channel MOS transistors, and the third switch transistor Q3 is a P-channel MOS transistor. When the switching tube is an N-channel MOS tube, the input end of the switching tube is a drain electrode, the output end of the switching tube is a source electrode, and the control end of the switching tube is a grid electrode; when the switching tube is a P-channel MOS tube, the input end is a source electrode, the output end is a drain electrode, and the control end is a grid electrode. In addition, the undervoltage protection signal in the undervoltage protection signal output terminal UVP is a high level signal, that is, in a normal state, when no undervoltage protection occurs, the undervoltage protection signal output terminal UVP is a low level signal, and when undervoltage protection occurs, the undervoltage protection signal output terminal UVP is a high level signal.

In a preferred embodiment, the delay circuit is an RC delay circuit. Specifically, the RC delay circuit comprises a first capacitor C1 and a resistor R3 connected in parallel, and a specific connection structure of the first capacitor C1 and the resistor R3 is shown in fig. 1. Preferably, the switch S1 is a tact switch, which is a non-self-locking tact switch in this embodiment.

The working principle or the working process of the under-voltage charging processing circuit provided by the embodiment is briefly described as follows:

when the lithium battery is in an undervoltage state and the charger with the voltage detection function needs to be charged temporarily, the light touch switch S1 is used as an emergency starting switch, the light touch switch S1 is pressed to be loosened or pressed all the time, the voltage of the reference voltage end VCC charges the second capacitor C2 through the resistor R4, and the third switch tube Q3 is conducted, so that the reference voltage end VCC charges the first capacitor C1 through the resistor R2, then the second switch tube Q2 is conducted to remove the undervoltage protection function, the discharging MOS tube MD1 is conducted, and the lithium battery also has the function of charging the charger with the voltage detection function in the undervoltage state. As the voltage across the second capacitor C2 increases, the third switch Q3 turns to off state, but since the first capacitor C1 is already charged with voltage (about 10V in this embodiment), the second switch Q2 remains on, and the second switch Q2 turns to off state only after the charge stored in the first capacitor C1 slowly discharges through the resistor R3 to a voltage below the turn-on voltage of the second switch Q2. At this time, if the charger is connected, normal charging is performed (the charger with voltage detection detects whether the battery has output or not only in the case of no charging current); if the charger is not connected and the undervoltage protection signal output end UVP is still at a high level, the discharge MOS tube MD1 is recovered to be in an off state.

Therefore, utilize the undervoltage charging processing circuit that this embodiment type provided, realized that the lithium cell also can charge for the charger that has voltage detection function under the undervoltage condition to normal charge protect function has when charging, avoided causing the permanent condition that becomes invalid of lithium cell undervoltage protect function to appear because misoperation or because the switch damages, effectively solved prior art with the positive output of lithium cell and the negative output do not have the problem of overcharging protect function and have very big potential safety hazard when directly regard as emergent charging port.

The above embodiments are preferred implementations of the present invention, and are not intended to be limiting, and any obvious replacement is within the scope of the present invention without departing from the inventive concept of the present invention.

Claims (6)

1. The utility model provides a lithium cell under-voltage charging treatment circuit, is applied to in the lithium cell that has battery management system, its characterized in that: the battery management system is provided with an undervoltage protection signal output end UVP and a reference voltage end VCC, the undervoltage charging processing circuit comprises a charging MOS tube MC1, a discharging MOS tube MD1 and a first switching tube Q1, the grids of the charging MOS tube MC1 and the discharging MOS tube MD1 are respectively connected with the reference voltage VCC through a resistor R6 and a resistor R5, the drain of the charging MOS tube MC1 is connected with the drain of the discharging MOS tube MD1, the positive output end of the lithium battery is connected with a first connecting end of a load, the negative output end of the lithium battery is connected with the source of the discharging MOS tube MD1, the source of the charging MOS tube MC1 is connected with a second connecting end of the load, the control end of the first switching tube Q1 is connected with the undervoltage protection signal output end UVP through a resistor R1, the input end of the first switch tube Q1 is connected with the gate of the discharge MOS tube MD1, the output end of the first switching tube Q1 is connected with the source electrode of the discharge MOS tube MD 1; the undervoltage charging processing circuit further comprises a second switch tube Q2, a third switch tube Q3, a switch S1 and a delay circuit, wherein an input end of the second switch tube Q2 is connected with the undervoltage protection signal output end UVP through a resistor R1, an output end of the second switch tube Q2 is connected with a source electrode of the discharge MOS tube MD1, a control end of the second switch tube Q2 is connected with an output end of the third switch tube Q3 through a resistor R2, an input end of the third switch tube Q3 is connected with the reference voltage terminal VCC, the reference voltage terminal VCC is connected with one end of the switch S1 through a resistor R4 and a second capacitor C2 in sequence, the other end of the switch S1 is connected with a negative output end of the lithium battery, one end of the resistor R4 and the second capacitor C2 which are connected with the control end of the third switch tube Q3, and one end of the second capacitor and the switch S1 which are connected with each other is connected with a control end of the third switch tube Q3 through a resistor R7, one end of the delay circuit is connected with the control end of the second switch tube Q2, and the other end of the delay circuit is connected with the output end of the second switch tube Q2.

2. The under-voltage charge handling circuit of claim 1, wherein: the delay circuit is an RC delay circuit.

3. The under-voltage charge handling circuit of claim 2, wherein: the RC time delay circuit comprises a first capacitor C1 and a resistor R3 which are connected in parallel.

4. The under-voltage charge handling circuit of claim 3, wherein: the first switch transistor Q1, the second switch transistor Q2 and the third switch transistor Q3 are MOS transistors.

5. The under-voltage charge handling circuit of claim 1, wherein: and the undervoltage protection signal in the undervoltage protection signal output end UVP is a high level signal.

6. The under-voltage charge handling circuit of claim 1, wherein: the switch S1 is a tact switch.

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