CN214543716U

CN214543716U - Charging and discharging protection circuit of mobile terminal

Info

Publication number: CN214543716U
Application number: CN202120718693.3U
Authority: CN
Inventors: 董晓倩; 徐乐; 宋寒栋; 刘军生
Original assignee: Ningbo Maidu Zhilian Technology Co ltd
Current assignee: Ningbo Maidu Zhilian Technology Co ltd
Priority date: 2021-04-08
Filing date: 2021-04-08
Publication date: 2021-10-29
Anticipated expiration: 2031-04-08

Abstract

The utility model discloses a charge-discharge protection circuit of mobile terminal, it includes power source, switch circuit connects between power source and load, power source includes positive power interface and power negative pole interface, the last a plurality of nodes that are equipped with of switch circuit, the node includes first node, second node, third node, fourth node, fifth node, switch circuit includes electric capacity C1, resistance R1, resistance R2, resistance R3, resistance R4, NMOS pipe Q1, PMOS pipe Q2, NMOS pipe Q3. The utility model discloses the charge-discharge protection circuit of mobile terminal who obtains utilizes the very little characteristic of the voltage drop that switches on of MOS pipe, and the voltage loss of each charging path after switching on is minimum, has promoted the availability factor of power, realizes under the charging condition, if the power connects then can stop charging to the load to and the effectual MOS pipe of having protected in the circuit, the circuit is simple, and the function is reliable, and is with low costs.

Description

Charging and discharging protection circuit of mobile terminal

Technical Field

The utility model relates to a charge-discharge protection circuit, especially a mobile terminal's charge-discharge protection circuit.

Background

In the existing charge and discharge protection circuit, diodes are added in the whole path of a part of the charge and discharge protection circuit to realize charge and discharge protection, and the use efficiency of a power supply is reduced during charge and discharge due to the voltage drop characteristic and the unidirectional conductivity of the diodes; the charging and discharging protection circuit is characterized in that a MOS tube is only added in a path, the charging and discharging protection circuit can only protect a load when a power supply is in positive and negative reverse connection, when the power supply is in positive and negative reverse connection and a charger is inserted, the output voltage of the charger and the power supply voltage are superposed together and added to a drain electrode and a source electrode of the MOS tube, after the MOS tube is conducted, the MOS tube generates heat seriously due to overlarge power, and the MOS tube is burnt down for a long time to cause the problem of the whole circuit; and a part of circuits is added into a logic control chip, and the circuits cause excessive circuit cost.

SUMMERY OF THE UTILITY MODEL

The utility model aims at solving the not enough of above-mentioned prior art and providing one kind and can realize under the charging condition, detect the trouble and stop the charge mobile terminal's that charges charge and discharge protection circuit.

In order to achieve the above object, the present invention provides a charge/discharge protection circuit for a mobile terminal, including a power interface, a switch circuit, the switch circuit is connected between the power interface and a load, the power interface includes a power source positive interface and a power source negative interface, the switch circuit is provided with a plurality of nodes, the nodes include a first node, a second node, a third node, a fourth node and a fifth node, the switch circuit includes a capacitor C1, a resistor R1, a resistor R2, a resistor R3, a resistor R4, an NMOS Q1, a PMOS Q2 and an NMOS Q3, and the power source positive interface, the first end of the resistor R1, the first end of the capacitor C1 and the gate of the PMOS Q2 are all connected to the first node; the second end of the resistor R1, the first end of the resistor R2, the second end of the capacitor C1, the drain of the NMOS transistor Q1 and the gate of the NMOS transistor Q3 are all connected to a second node; the second end of the resistor R2, the first end of the resistor R4, the source of the NMOS transistor Q1, the source of the NMOS transistor Q3 and the ground are all connected to a third node; the first end of the resistor R3, the second end of the resistor R4 and the gate of the NMOS transistor Q1 are connected to a fourth node; the drain of the PMOS transistor Q2 is connected with the second end of the resistor R3, and the drain of the NMOS transistor Q3, the source of the PMOS transistor Q2 and the power supply cathode interface are all connected to the fifth node.

In order to facilitate charging of the load in various ways, the charge and discharge protection circuit of the mobile terminal further comprises an external charging chip connected with the load.

In order to reduce the impedance of the charge and discharge protection circuit of the mobile terminal and reduce the loss on the circuit, the resistor R1 is 10 kilo-ohms, the resistor R2 is 10 kilo-ohms, the resistor R3 is 4.7 kilo-ohms, the resistor R4 is 4.7 kilo-ohms, and the capacitor C1 is 1 microfarad.

In order to enable the NMOS transistor Q1, the PMOS transistor Q2 and the NMOS transistor Q3 to better control the charge-discharge protection circuit of the mobile terminal, the threshold voltage Vth of the NMOS transistor Q3 and the NMOS transistor Q1 is 0.7V, and the threshold voltage Vth of the PMOS transistor Q2 is-0.7V.

The utility model discloses the charge-discharge protection circuit of mobile terminal who obtains utilizes the very little characteristic of the voltage drop that switches on of MOS pipe, and the voltage loss of each charging path after switching on is minimum, has promoted the availability factor of power, realizes under the charging condition, if the power connects then can stop charging to the load to and the effectual MOS pipe of having protected in the circuit, the circuit is simple, and the function is reliable, and is with low costs.

Drawings

Fig. 1 is a schematic circuit diagram of a charge and discharge protection circuit of a mobile terminal in embodiment 1;

fig. 2 is a graph of the voltage across the capacitor C1 in example 1.

Detailed Description

The present invention will be further explained with reference to the drawings and examples.

Example 1:

the charge and discharge protection circuit of the mobile terminal described in this embodiment, as shown in fig. 1, includes a power interface and a switch circuit, where the switch circuit is connected between the power interface and a load, the power interface includes a positive power interface and a negative power interface, the switch circuit is provided with a plurality of nodes, the nodes include a first node, a second node, a third node, a fourth node, and a fifth node, the switch circuit includes a capacitor C1, a resistor R1, a resistor R2, a resistor R3, a resistor R4, an NMOS Q1, a PMOS Q2, and an NMOS Q3, and the positive power interface, the first end of the resistor R1, the first end of the capacitor C1, and a gate of the PMOS Q2 are all connected to the first node; the second end of the resistor R1, the first end of the resistor R2, the second end of the capacitor C1, the drain of the NMOS transistor Q1 and the gate of the NMOS transistor Q3 are all connected to a second node; the second end of the resistor R2, the first end of the resistor R4, the source of the NMOS transistor Q1, the source of the NMOS transistor Q3 and the ground are all connected to a third node; the first end of the resistor R3, the second end of the resistor R4 and the gate of the NMOS transistor Q1 are connected to a fourth node; the drain of the PMOS transistor Q2 is connected with the second end of the resistor R3, and the drain of the NMOS transistor Q3, the source of the PMOS transistor Q2 and the power supply cathode interface are all connected to the fifth node.

In order to reduce the impedance of a charge-discharge protection circuit of the mobile terminal and reduce the loss on the circuit, the resistor R1 is 10 kilo-ohms, the resistor R2 is 10 kilo-ohms, the resistor R3 is 4.7 kilo-ohms, the resistor R4 is 4.7 kilo-ohms, the capacitor C1 is 1 microfarad, and the capacitor C1 is an aluminum capacitor with a low Q value.

In this embodiment, U1 is an external charging chip, U2 is a power supply, and U3 is a load.

The first terminal of the capacitor C1 is denoted as point C, and the second terminal of the capacitor C1 is denoted as point D.

And under the condition that the positive electrode and the negative electrode are connected with the power interface correctly, namely, the positive electrode of the power supply is connected with the positive electrode interface of the power supply, and the negative electrode of the power supply is connected with the negative electrode interface of the power supply. If the power supply is 4V, the voltage of the NMOS transistor Q3 is 2V under the condition of the partial voltage of the resistor R1 and the resistor R2, Vgs of the NMOS transistor Q3 is greater than the threshold voltage of the NMOS transistor Q3, the NMOS transistor Q3 is turned on, the PMOS transistor Q2 is turned off, the gate voltage of the NMOS transistor Q1 is pulled down by the R4, and the gate voltage of the NMOS transistor Q1 is turned off. The power supply U2 may normally supply power to the load U3.

Under the condition that the positive electrode and the negative electrode of the power supply are correctly connected with the power supply interface, if +5V input of an external power supply charger exists, the +5V input can also charge the power supply normally through an external charging chip U1.

And under the condition of wrong connection of the anode and the cathode of the power supply, namely, the anode of the power supply is connected with the cathode interface of the power supply, and the cathode of the power supply is connected with the anode interface of the power supply.

When the power supply is 4V, Vgs of the NMOS transistor Q3 is negative, and the NMOS transistor Q3 is cut off. Vgs of the PMOS transistor Q2 is-4 v, and the PMOS transistor Q2 is turned on. Under the action of the PMOS transistors Q2 and R3, the NMOS transistor Q1 is turned on by the NMOS transistor Q1. Further pulling the gate of the NMOS transistor Q3 low to GND. Thereby completely closing the NMOS transistor Q3 and cutting off the entire circuit path. At this time, the external power supply charger is inserted again, and normal charging cannot be performed. The load U3 and the switch circuit are effectively protected.

When +5V of an external power supply charger is input into the external charging chip U1, and the charging voltage of the external charging chip U1 is stably established, if the power supply does not exist, the NMOS transistor Q3 is conducted, the NMOS transistor Q1 and the PMOS transistor Q2 are cut off, and the whole circuit is in a closed circuit state; if the power supply is powered on at the moment, and the connection of the positive electrode and the negative electrode of the power supply is wrong, because the voltage at the two ends of the capacitor cannot suddenly change, as shown in fig. 2, at 30ms, the voltage at the C end of the capacitor C1 is pulled down at the moment of power supply application, the voltage at the D end of the capacitor C1 is also pulled down correspondingly, R2 has the function of dividing the output voltage of the charger, so that a certain voltage difference exists at the two ends of the capacitor C1, the phenomenon that when the voltage at the C end of the capacitor C1 is reduced, the voltage at the D end of the capacitor C1 is lowered, Vgs of the NMOS tube Q3 is smaller than the threshold voltage of the NMOS tube Q3 in a short time, the NMOS tube Q3 is closed, the circuit is disconnected to protect the NMOS tube Q3, and the whole circuit is in a disconnected state.

The charging and discharging protection circuit of the mobile terminal provided by the embodiment utilizes the characteristic that the conduction voltage drop of the MOS tube is very small, the voltage loss of each charging path after conduction is very small, the service efficiency of a power supply is improved, the charging of a load can be stopped if the power supply is reversely connected under the charging condition, the MOS tube in the circuit is effectively protected, and the charging and discharging protection circuit is simple in circuit, reliable in function and low in cost.

Claims

1. A charging and discharging protection circuit of a mobile terminal comprises a power interface and a switch circuit, wherein the switch circuit is connected between the power interface and a load, the power interface comprises a power anode interface and a power cathode interface, the switch circuit is provided with a plurality of nodes, the nodes comprise a first node, a second node, a third node, a fourth node and a fifth node, and the charging and discharging protection circuit is characterized in that the switch circuit comprises a capacitor C1, a resistor R1, a resistor R2, a resistor R3, a resistor R4, an NMOS transistor Q1, a PMOS transistor Q2 and an NMOS transistor Q3, and the power anode interface, the first end of the resistor R1, the first end of the capacitor C1 and the grid of the PMOS transistor Q2 are all connected to the first node; the second end of the resistor R1, the first end of the resistor R2, the second end of the capacitor C1, the drain of the NMOS transistor Q1 and the gate of the NMOS transistor Q3 are all connected to a second node; the second end of the resistor R2, the first end of the resistor R4, the source of the NMOS transistor Q1, the source of the NMOS transistor Q3 and the ground are all connected to a third node; the first end of the resistor R3, the second end of the resistor R4 and the gate of the NMOS transistor Q1 are connected to a fourth node; the drain of the PMOS transistor Q2 is connected with the second end of the resistor R3, and the drain of the NMOS transistor Q3, the source of the PMOS transistor Q2 and the power supply cathode interface are all connected to the fifth node.

2. The charging and discharging protection circuit of the mobile terminal according to claim 1, further comprising an external charging chip connected to a load.

3. The charging/discharging protection circuit of claim 1 or 2, wherein the resistor R1 is 10 kilo-ohms, the resistor R2 is 10 kilo-ohms, the resistor R3 is 4.7 kilo-ohms, the resistor R4 is 4.7 kilo-ohms, and the capacitor C1 is 1 microfarad.

4. The charging/discharging protection circuit of claim 1 or 2, wherein the threshold voltage Vth of the NMOS transistor Q3 and the NMOS transistor Q1 is 0.7V, and the threshold voltage Vth of the PMOS transistor Q2 is-0.7V.