CN212114765U - Undervoltage protection circuit with hysteresis function applied to products in power industry - Google Patents

Abstract

The utility model discloses an under-voltage protection circuit of area hysteresis function for electric power industry product, including stabilivolt VD1, MOS pipe VT1, VT2, resistance R1, R2, R3, R4, R5, R6, R7, its connection is: the source electrode of the MOS transistor VT1 is connected with the standby voltage, the drain electrode is connected with the voltage of the standby voltage, and the grid electrode is connected with the resistors R4 and R5; the source of the MOS transistor VT2 is electrically connected with GND, the drain is connected with the resistors R2 and R3, and the gate is connected with the resistors R6 and R7; the reference voltage end of the voltage regulator tube VD1 is connected with resistors R1 and R2, the anode end is connected with GND, and the cathode end is connected with resistors R5 and R6. This standby power system under-voltage protection circuit of hysteresis function, when its power failure disconnection standby power end, through the hysteresis circuit, solve standby power system voltage "virtual high" or voltage fluctuation and cause many times to go on and off the electricity abnormal problem, avoid P MOS pipe work at the linear region simultaneously, improve devices such as standby power end battery and switch life-span, the circuit is simple, reliable, stability is good.

Description

Undervoltage protection circuit with hysteresis function applied to products in power industry

Technical Field

The utility model relates to a hysteresis circuit, especially an under-voltage protection circuit who is applied to area hysteresis function of electric power industry product.

Background

The battery or super capacitor has a certain service life when in use, and the service life of the battery is greatly influenced particularly in the charging and discharging stage. Particularly, after the batteries such as lithium batteries and lead storage batteries are discharged, the voltage of the batteries rises slowly for a period of time, which is called as the phenomenon of virtual high of the batteries, and in the period of time, a rear-stage electric system is frequently switched on and off, so that the loss of the batteries is accelerated. The utility model discloses a circuit design can prevent effectively that the frequent switch of back stage circuit to reach the purpose of protection battery.

SUMMERY OF THE UTILITY MODEL

In order to solve the problem, the utility model provides a be applied to under-voltage protection circuit of area hysteresis function of electric power industry product. The technical scheme of the utility model is that: the voltage regulator comprises a voltage regulator VD1, MOS transistors VT1 and VT2, resistors R1, R2, R3, R4, R5, R6 and R7, wherein a source electrode of the MOS transistor VT1 is in voltage connection with a standby voltage, a drain electrode is in voltage connection with a voltage, and a grid electrode is connected with the resistors R4 and R5; the source of the MOS transistor VT2 is electrically connected with GND, the drain is connected with the resistors R2 and R3, and the gate is connected with the resistors R6 and R7; the reference voltage end of the voltage-regulator tube VD1 is connected with the resistors R1 and R2, the anode end is connected with GND, and the cathode end is connected with the resistors R5 and R6.

The utility model has the advantages that: the undervoltage protection circuit increases a hysteresis function, can not cause frequent switching of the PMOS switch when the voltage of the standby power system is 'virtual high' or fluctuates, and cuts off a rear-stage circuit to achieve the purpose of protecting the battery. The PMOS tube of the control back stage switch can be effectively prevented from working in an online state, the conduction loss of the MOS tube is greatly reduced, the service life of the device is prolonged, and the market utilization value is good.

Drawings

In order to more clearly understand how the present invention is implemented, the technical solution of the present invention is briefly described with reference to the accompanying drawings, wherein the drawings only illustrate the comparison between the embodiments of the present invention and the conventional solution, and actually can also extend other drawings through the drawings.

FIG. 1 is a schematic diagram of the protection of an under-voltage circuit with hysteresis interval;

FIG. 2 is a schematic diagram of under-voltage circuit protection without hysteresis.

Detailed Description

The technical solution implemented is further described below with reference to the accompanying drawings, wherein the drawings only illustrate the comparison between the embodiments of the present invention and the conventional solutions, and mainly specifically illustrate the advantages of the present invention: as shown in fig. 1, the schematic diagram of the under-voltage circuit protection with hysteresis interval of the present invention includes a voltage regulator VD1, MOS transistors VT1, VT2, resistors R1, R2, R3, R4, R5, R6, and R7, wherein the source of the MOS transistor VT1 is connected to the voltage of the backup power supply, the drain is connected to the voltage of the power supply, and the gate is connected to the resistors R4 and R5; the source of the MOS transistor VT2 is electrically connected with GND, the drain is connected with the resistors R2 and R3, and the gate is connected with the resistors R6 and R7; the reference voltage end of the voltage-regulator tube VD1 is connected with the resistors R1 and R2, the anode end is connected with GND, and the cathode end is connected with the resistors R5 and R6.

The working principle is as follows: the voltage of the standby power supply can generate two voltage reference points, namely a high voltage VH and a low voltage VL through VT 2. The high voltage value relationship is VH × R2/(R1+ R2) ═ 2.5V, and the low voltage value relationship is VL × (R2+ R3)/(R1+ R2+ R3) ═ 2.5V. The voltage of the standby power supply in the initial state is higher than that of VH, at the moment, the voltage of the standby power supply is divided by resistors R1, R2 and R3 to obtain a comparison voltage of VD1, which is larger than 2.5V, so that the triode in TL431 is conducted, and VD1 is in a saturation state. The current is connected to GND from the standby power end through R4, R5 resistor and VD1, the voltage of the grid end of VT1 is equal to the voltage of the cathode end of VD1, the voltage of the source end of VT1 is the voltage of a battery at the standby power end, the voltage of the grid end of VT1 is lower than the voltage of the source end, the PMOS tube is conducted, and the battery supplies power to the rear stage. When the voltage of the standby power supply is gradually reduced until the voltage is lower than VL voltage, the voltage of the cathode of the VD1 is gradually increased, but the voltage does not reach the linear state of VT1, at the moment, the resistance voltage division of R6 and R7 meets the grid source electrode conduction condition of VT2, so that VT2 is conducted, the reference pin voltage of VD1 is changed into two resistance voltage division of R1 and R2, the reference voltage is rapidly reduced, VD1 is rapidly turned off, and the circuit enters an undervoltage locking state, so that the condition that the VT1 switching tube works in the linear state due to the slow reduction of the voltage of the battery at the standby power supply is avoided. When the battery voltage is in a virtual high state, due to the arrangement of a hysteresis interval, only when the voltage of the standby power end is higher than VH, VD1 works in a saturated state again, and the VT1 switching tube is conducted again.

As shown in fig. 2, the schematic diagram of under-voltage circuit protection without hysteresis interval includes a TL431 voltage-stabilizing circuit, a first MOS transistor VT1, a cathode of the TL431 voltage-stabilizing circuit is connected to a gate of the first MOS transistor VT1, an anode of the TL431 voltage-stabilizing circuit is electrically connected to a GND, a reference voltage end of the TL431 voltage-stabilizing circuit is connected to a first resistor R1, a second resistor R2 and a third resistor R3, a gate of the first MOS transistor VT1 is connected to a cathode of the TL431 through a fourth resistor R4, a source and a drain of the first MOS transistor VT1 are respectively connected to a standby terminal and a power terminal, and the purpose of adding the diagram is to facilitate comparison of effectiveness brought by hysteresis interval of the present invention, and a connection relationship shown in fig. 2 is: the standby battery controls the reference voltage of VD1 through the resistance voltage of R1 and R2, and when the reference voltage of VD1 is more than 2.5V, VT1 conducts the energy of the front stage and transmits the energy to the rear stage through the PMOS tube; when the voltage of VD1 slowly drops from 2.5V, the voltage of VD1 cathode slowly rises, when a certain voltage range is reached, the VT1 switching tube is in a linear conduction state, and the conduction loss of VT1 is increased until VT1 is turned off. When the battery voltage at the standby power end is in a virtual high state or the battery voltage fluctuates, the VT1 is in a frequent switching state, the service life of the battery and the service life of devices of the switching tube are greatly reduced, and a better protection effect is not achieved.

The above only is the embodiment of the present invention, not limiting the patent scope of the present invention, all the equivalent structures or equivalent processes that are used in the specification and the attached drawings or directly or indirectly applied to other related technical fields are included in the patent protection scope of the present invention.

Claims (1)

1. The utility model provides an under-voltage protection circuit who takes hysteresis function that is applied to electric power industry product which characterized in that includes stabilivolt VD1, MOS pipe VT1, VT2, resistance R1, R2, R3, R4, R5, R6, R7, its relation of connection is: the source electrode of the MOS transistor VT1 is connected with the standby voltage, the drain electrode is connected with the voltage of the standby voltage, and the grid electrode is connected with the resistors R4 and R5; the source of the MOS transistor VT2 is electrically connected with GND, the drain is connected with the resistors R2 and R3, and the gate is connected with the resistors R6 and R7; the reference voltage end of the voltage-regulator tube VD1 is connected with the resistors R1 and R2, the anode end is connected with GND, and the cathode end is connected with the resistors R5 and R6.

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