A kind of overcurrent lock-in circuit of lithium battery protection circuit
Technical field
The utility model relates to battery charge discharge technology field, especially relates to a kind of overcurrent lock-in circuit that N-channel MOS FET cuts off anode type lithium battery protection circuit that is used for.
Background technology
Lithium ion battery generally all is equipped with protective circuit in use, overcharges for lithium battery provides, defencive function such as overdischarge, overcurrent.Wherein overcurrent protection is to cut off electric current when load abnormal guiding discharge electric current is excessive, and the function of protection battery and protective circuit also can recover normal according to the design automatic or manual after protection.If it is unreasonable that restore funcitons is provided with, might be under the situation that abnormal load does not remove, restoring electricity of mistake causes battery or protective circuit to damage even burning.Therefore the appropriate design of this overcurrent restore funcitons is one of lithium battery important leverage safe in utilization.At present, this kind function is generally taked following mode: 1. load removes back protective circuit overcurrent protection releasing, restores electricity; 2. remove overcurrent protection behind the time-delay certain hour; 3. hand-reset or charging are removed protection.First kind of mode resume speed is fast, but may occur the phenomenon of interface sparking when removing load, the influence safe handling; The second way has time of delay for removing load, also can not restore electricity but remove load in time-delay, causes abnormal load work and causes that overcurrent protection takes place protective circuit once more, may damage protective circuit if take place repeatedly for a long time; The third mode can not be finished automatically, needs extra operation or equipment.
The utility model content
In view of this, the purpose of this utility model is to overcome the defective of prior art, and a kind of overcurrent lock-in circuit of lithium battery protection circuit is provided, and improves the lithium battery safety in utilization, and design easy, take up room little, cost is low, battery protection system is not had influence.
For achieving the above object, the utility model is by the following technical solutions: the overcurrent lock-in circuit of lithium battery protection circuit of the present utility model, this overcurrent lock-in circuit comprise first control end (1), second control end (2), the 3rd control end (3), N-channel MOS FET, voltage-stabiliser tube, diode, resistance and electric capacity; Wherein, N-channel MOS FET source electrode links to each other with first control end (1), and drain electrode links to each other with second control end (2), and grid links to each other with the voltage-stabiliser tube anode; The voltage-stabiliser tube negative terminal links to each other with the diode negative terminal, and the diode anode links to each other with first control end (1); Resistance one end links to each other with N-channel MOS FET grid, and the other end links to each other with the 3rd control end (3); Electric capacity one end links to each other with first control end (1), and the other end links to each other with N-channel MOS FET grid.
The beneficial effects of the utility model are: after the lithium battery protection circuit generation overcurrent protection, can recover automatically according to the connection situation locking guard mode or the time-delay of load; That the utility model takes up room is little, cost is low, design is easy, is applicable to that conveniently N-channel MOS FET cuts off anode type lithium battery protection circuit, has improved the performance of battery protection system, and battery protection system is not had influence.Having following beneficial effect comprises: simplicity of design, be convenient in product design, use; Improved the performance of protection system; Do not increase assembling parts, convenient production; Adopting enhancement mode MOSFET is driven, does not also increase the original system power consumption during work substantially; Adopt device to be the switching controls device, specific (special) requirements such as no high-power, high pressure, cost is low.
Other advantages of the present utility model, target and feature will be set forth to a certain extent in the following description, and to a certain extent, based on being conspicuous to those skilled in the art, perhaps can from practice of the present utility model, obtain instruction to investigating hereinafter.Target of the present utility model and other advantages can realize and obtain by specifically noted structure in following specification and the accompanying drawing.
Description of drawings
Fig. 1 is a circuit diagram of the present utility model.
Embodiment
Below in conjunction with drawings and Examples the utility model is further described.
As shown in Figure 1; the overcurrent lock-in circuit of lithium battery protection circuit of the present utility model comprises first control end 1; second control end 2; the 3rd control end 3; N channel field-effect pipe Q1; voltage-stabiliser tube Z1; diode D1; resistance R 1 and capacitor C 1; wherein; N channel field-effect pipe Q1 source electrode links to each other with first control end 1; drain electrode links to each other with second control end 2; grid links to each other with voltage-stabiliser tube Z1 anode; voltage-stabiliser tube Z1 negative terminal links to each other with diode D1 negative terminal; diode D1 anode links to each other with first control end 1; resistance R 1 one ends link to each other with N channel field-effect pipe Q1 grid; the other end links to each other with the 3rd control end 3; capacitor C 1 one ends link to each other with first control end 1, and the other end links to each other with N channel field-effect pipe Q1 grid.
During enforcement; above-mentioned overcurrent lock-in circuit is connected to N-channel MOS FET to cut off in the anode type lithium battery protection circuit; specifically be connected to: described overcurrent lock-in circuit first control end 1 is connected with the lithium battery protection circuit anode; second control end 2 is connected with lithium battery protection circuit anode discharge control N-channel MOS FET grid, and the 3rd control end 3 is connected with the 3.3V power supply of master control IC in the lithium battery protection circuit.When system's operate as normal, if load current is excessive, after the protective circuit generation overcurrent protection, the source electrode of N channel field-effect pipe Q1 in the overcurrent lock-in circuit is pulled to 0V by load, thereby the capacitor C 1 in the overcurrent lock-in circuit is recharged, voltage in that grid and the source electrode of N channel field-effect pipe Q1 just produces a 3.3V makes field effect transistor Q1 conducting; The voltage that field effect transistor Q1 conducting then makes the discharge in the lithium battery protection circuit control between N-channel MOS FET grid and the source electrode is 0V, guarantees that the discharge control N-channel MOS FET in the lithium battery protection circuit closes.For removing the protective circuit that load just recovers, because the effect of capacitor C 1 in the overcurrent lock-in circuit, N channel field-effect pipe Q1 can not close immediately when removing load, has guaranteed to load on fully to disconnect the back protection system and just restore electricity, thereby has avoided the generation of spark phenomenon; Protective circuit for the overcurrent delay recovery; when load does not remove; N channel field-effect pipe Q1 in the overcurrent lock-in circuit just is in opening all the time; guaranteed that the discharge control N-channel MOS FET in the lithium battery protection circuit is in closed condition always, thereby avoided not removing the situation that overcurrent protection that load causes recovers.
Explanation is at last, above embodiment is only unrestricted in order to the explanation the technical solution of the utility model, other modifications that those of ordinary skills make the technical solution of the utility model or be equal to replacement, only otherwise break away from the spirit and scope of technical solutions of the utility model, all should be encompassed in the middle of the claim scope of the present utility model.