A kind of short-circuit protection circuit of lithium battery
Technical field
The utility model relates to short circuit protection field, particularly a kind of short-circuit protection circuit of lithium battery.
Background technology
At present, when meeting power output end short circuit in the short-circuit protection circuit of lithium battery, then have very large electric current in circuit and flow through, easily cause burning of element; If use market there is the voltage stabilizing IC of the integrated circuit of specialty, also can realize protecting output short-circuit, but if because price is higher and need to need when exporting different magnitudes of voltage to change different voltage stabilizing IC.Therefore, how to provide a kind of structure simple, cheap, and the concern of manufacturer and research staff can be enjoyed by available protecting output power supply circuit.
Utility model content
In view of this, the utility model provides a kind of and carries out real-time guard to lithium battery output circuit and the short-circuit protection circuit of the low lithium battery of cost.
The design that the utility model is taked is: a kind of short-circuit protection circuit of lithium battery, comprise power input Vcc_IN and power output end Vcc_OUT, connect a field effect transistor Q1 between power input Vcc_IN with power output end Vcc_OUT, the source electrode of field effect transistor Q1 is connected with power input Vcc_IN, the drain electrode of field effect transistor Q1 is connected with power output end Vcc_OUT, source electrode and the node between power input Vcc_IN of scene effect pipe Q1 are connected the negative electrode of a resistance R1 and voltage-stabiliser tube Z1 successively, the plus earth of voltage-stabiliser tube, the grid of field effect transistor Q1 is connected with the node between resistance R1 and voltage-stabiliser tube Z1, the source electrode of scene effect pipe Q1 is in parallel with the two ends of drain electrode accesses a series circuit be made up of resistance R2 and resistance R3, node between resistance R1 and voltage-stabiliser tube Z1 in parallel with the two ends of the drain electrode of field effect transistor Q1 one makes the field effect transistor Q2 that switch uses, the source electrode of field effect transistor Q2 is connected with the node between resistance R1 and voltage-stabiliser tube Z1, the drain electrode of field effect transistor Q2 is connected with power output end Vcc_OUT with the drain electrode of field effect transistor Q1, and the grid of field effect transistor Q2 is connected with the node between resistance R2 and resistance R3.
Wherein, described field effect transistor Q1 and field effect transistor Q2 is NPN type field effect transistor.
Compared with prior art; the conducting that the utility model utilizes the voltage difference between field effect transistor Q2 grid voltage and drain electrode to realize field effect transistor controls with disconnecting, and can avoid the damage of field effect transistor, realizes the protection of output circuit short circuit; reduce potential safety hazard; and this short-circuit protection circuit principle is simple, circuit element amount is few, and cost is low; can be applicable to various electrical appliance carries out real-time guard to output circuit; reliability is high, safety and stability, and range of application is wide.
Accompanying drawing explanation
Fig. 1 is circuit theory diagrams of the present utility model.
Embodiment
In order to allow those skilled in the art understand the technical solution of the utility model better, below in conjunction with accompanying drawing, the utility model is further elaborated.
As shown in Figure 1, a kind of short-circuit protection circuit power input Vcc_IN of lithium battery one uses field effect transistor Q1 as switch with connecting between power output end Vcc_OUT, the source electrode of field effect transistor Q1 is connected with power input Vcc_IN, the drain electrode of field effect transistor Q1 is connected with power output end Vcc_OUT, source electrode and the node between power input Vcc_IN of scene effect pipe Q1 are connected the negative electrode of a resistance R1 and voltage-stabiliser tube Z1 successively, the plus earth of voltage-stabiliser tube, the grid of field effect transistor Q1 is connected with the node between resistance R1 and voltage-stabiliser tube Z1; The source electrode of scene effect pipe Q1 is in parallel with the two ends of drain electrode accesses a series circuit be made up of resistance R2 and resistance R3; Node between resistance R1 and voltage-stabiliser tube Z1 in parallel with the two ends of the drain electrode of field effect transistor Q1 one makes the field effect transistor Q2 that switch uses, the source electrode of field effect transistor Q2 is connected with the node between resistance R1 and voltage-stabiliser tube Z1, the drain electrode of field effect transistor Q2 is connected with power output end Vcc_OUT with the drain electrode of field effect transistor Q1, and the grid of field effect transistor Q2 is connected with the node between resistance R2 and resistance R3.Selected field effect transistor Q1 and field effect transistor Q2 is NPN type field effect transistor.
The short-circuit protection circuit course of work of a kind of lithium battery provided by the utility model is as follows: when output circuit normally works, field effect transistor Q2 is in cut-off state, and field effect transistor Q1 saturation conduction, be then in conducting state between power input Vcc_IN and power output end Vcc_OUT; When there is short circuit in the power output end Vcc_OUT in output circuit; field effect transistor Q2 is in saturation conduction state; and field effect transistor Q1 is in cut-off state; then locate off-state between power input Vcc_IN and power output end Vcc_OUT; thus play protective circuit effect, prevent field effect transistor Q1 from burning.
It is more than the utility model preferably implementation; it should be noted that; when not deviating from the utility model spirit and essence thereof; those of ordinary skill in the art are when making various corresponding change and distortion according to the utility model, but these change and are out of shape the protection range that all should belong to the claim appended by the utility model.