CN104362712A - Automatic power-off charger for mobile phone - Google Patents

Abstract

The invention provides an automatic power-off charger for a mobile phone, which belongs to the technical field of electronics. It includes a DC voltage stabilizing circuit, a charging control circuit, an AC and DC power supply state indicating circuit and a filter circuit. The DC voltage stabilizing circuit converts it into a 5V DC voltage output by connecting to a 220V AC power supply, and the charging control circuit controls the charging and disconnection of the mobile phone by controlling a pair of contacts of the electromagnetic relay to be turned on and off, It realizes that the battery of the mobile phone can be automatically disconnected after it is fully charged, the AC and DC power supply state indication circuit can give the AC and DC working status prompt, and the filter circuit filters out the AC component in the output voltage of the rectifier circuit, thereby obtaining a relatively smooth The beneficial effect of the direct current voltage invention of the invention is that the charging circuit can be automatically disconnected after the battery of the mobile phone is fully charged, which saves the waste of electric energy and can make a circuit reminder after the battery is fully charged.

Description

A mobile phone automatic power-off charger

technical field

The invention belongs to the field of electronic technology, in particular to a mobile phone automatic power-off charger.

Background technique

At present, with the continuous development of society and the improvement of living standards, mobile communication has become an indispensable and important tool for all human beings. After charging the mobile phone, most mobile phone users do not pull out the power plug in order to save trouble, so as to charge it next time. This causes the charger to be in an unloaded state for a long time. In addition, when the mobile phone battery is fully charged, the mobile phone is not removed in time and the charger is in a floating charge state. In the prior art, mobile phone chargers all contain a high-frequency transformer, and the primary side of the high-frequency transformer can form a loop with the AC power supply. Therefore, in the above-mentioned no-load state or floating charge state, the high-frequency transformer has ferromagnetic loss, which consumes Electricity is wasted, and there are potential safety hazards.

Contents of the invention

The object of the present invention is to avoid the problems existing in the prior art, and to provide a mobile phone that can automatically disconnect the charging circuit after the battery is fully charged, which saves the waste of electric energy and can make a circuit reminder after the battery is fully charged. charger.

The technical solution of the present invention is: an automatic power-off charger for a mobile phone, including a DC voltage stabilizing circuit, a charging control circuit, an AC/DC power supply state indicating circuit and a filter circuit, the DC stabilizing circuit includes a power interface, a transformer B and A rectifier circuit, the power interface is used to connect to a 220V AC power supply, the high voltage side of the transformer B is connected to the power interface, the low voltage side of the transformer B is connected to a rectifier circuit, and the output terminal of the rectifier circuit outputs a 5V DC voltage;

The charging control circuit includes an electromagnetic relay, a resistor R2, a light-emitting diode D3 and a charging interface. One end of a pair of contacts of the electromagnetic relay is connected to the output end of the rectifier circuit, and the other end of the electromagnetic relay is connected through the connecting resistor R2 and The light-emitting diode D3 is connected to the positive pole of the charging interface, and the negative pole of the charging interface is grounded to GND; the charging and disconnection of the mobile phone is controlled by controlling the pair of contacts of the electromagnetic relay to be turned on and off;

The filter circuit includes an electrolytic capacitor C1 and a capacitor C2. One end of the electrolytic capacitor C1 and capacitor C2 are respectively connected to the output end of the rectification circuit, and the other ends are respectively grounded to GND for filtering out the AC component in the output voltage of the rectification circuit, thereby obtaining Relatively smooth DC voltage;

The AC and DC power supply status indication circuit includes a light emitting diode D1 and a resistor R1, the anode of the light emitting diode D1 is connected to the output terminal of the rectifier circuit, and the negative pole of the light emitting diode D1 is grounded to GND through the resistor R1.

Further, it also includes a full indication circuit, which includes a three-terminal micro-power consumption voltage detector IC, a resistor R3, a resistor R4, a resistor R5 and a light-emitting diode D2, one end of the resistor R3 and one end of the resistor R4 are connected to the three-terminal micro The second pin of the power consumption voltage detector IC, the other end of the resistor R3 is connected to the positive pole of the charging interface, the other end of the resistor R4 and the third pin of the three-terminal micro-power consumption voltage detector IC are grounded to GND, and the three-terminal micro-power consumption voltage detection The first pin of the device IC is connected to the anode of the light-emitting diode D2 through the resistor R5, and the cathode of the light-emitting diode D2 is grounded to GND.

Further, the positive pole of the output terminal of the rectification circuit is connected to the positive pole VCC of the circuit, and the negative pole of the output terminal of the rectification circuit is grounded to GND.

Further, the positive pole of the electrolytic capacitor C1 is connected to the output terminal of the rectifier circuit, and the negative pole of the electrolytic capacitor C1 is grounded to GND.

Further, a fuse FU is connected between the high voltage side of the transformer B and the power interface.

Further, the rectification circuit is composed of four diodes D1-D4.

The advantages and positive effects of the present invention are: due to the adoption of the above technical scheme, by controlling the pair of contacts of the electromagnetic relay to be turned on and off so as to control the charging and disconnection of the mobile phone, it is realized that after the battery of the mobile phone is fully charged It can be disconnected automatically, which saves the waste of electric energy and can make a circuit reminder when the battery of the mobile phone is fully charged. A fuse FU is also connected between the high-voltage side of the transformer B and the power interface to avoid damage to the charging circuit due to unstable input voltage. Etc.

Description of drawings

Fig. 1 is a schematic circuit diagram of the present invention;

Detailed ways

The present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in the circuit principle diagram of the present invention in Fig. 1, an automatic power-off charger for a mobile phone of the present invention includes a DC voltage stabilizing circuit, a charging control circuit, an AC/DC power supply state indicating circuit and a filter circuit, and the DC stabilizing circuit It includes a power interface, a transformer B and a rectifier circuit. The power interface is used to connect to a 220V AC power supply. The high-voltage side of the transformer B is connected to the power interface. A fuse FU is also connected between the high-voltage side of the transformer B and the power interface. The transformer The low-voltage side of B is connected to a rectification circuit, the output terminal of the rectification circuit outputs a 5V DC voltage, the positive pole of the output terminal of the rectification circuit is connected to the positive pole VCC of the circuit, and the negative pole of the output terminal of the rectification circuit is grounded to GND.

The charging control circuit includes an electromagnetic relay, a resistor R2, a light-emitting diode D3 and a charging interface. One end of a pair of contacts of the electromagnetic relay is connected to the output end of the rectifier circuit, and the other end of the electromagnetic relay is connected through the connecting resistor R2 and The light-emitting diode D3 is connected to the positive pole of the charging interface, and the negative pole of the charging interface is grounded to GND; the charging and disconnection of the mobile phone is controlled by controlling a pair of contacts of the electromagnetic relay to be turned on and off.

The filter circuit includes an electrolytic capacitor C1 and a capacitor C2. One end of the electrolytic capacitor C1 and capacitor C2 are respectively connected to the output end of the rectification circuit, and the other ends are respectively grounded to GND for filtering out the AC component in the output voltage of the rectification circuit, thereby obtaining For a relatively smooth DC voltage, the positive pole of the electrolytic capacitor C1 is connected to the output terminal of the rectifier circuit, and the negative pole of the electrolytic capacitor C1 is grounded to GND.

The AC and DC power supply status indication circuit includes a light emitting diode D1 and a resistor R1, the anode of the light emitting diode D1 is connected to the output terminal of the rectifier circuit, and the negative pole of the light emitting diode D1 is grounded to GND through the resistor R1.

It also includes a full indication circuit, which includes a three-terminal micro-power consumption voltage detector IC, a resistor R3, a resistor R4, a resistor R5 and a light-emitting diode D2, one end of the resistor R3 and one end of the resistor R4 are connected to the three-terminal micro-power consumption The second pin of the voltage detector IC, the other end of the resistor R3 is connected to the positive pole of the charging interface, the other end of the resistor R4 and the third pin of the three-terminal micro-power voltage detector IC are grounded to GND, the three-terminal micro-power voltage detector IC The first leg of the LED is connected to the positive pole of the light-emitting diode D2 through the resistor R5, and the negative pole of the light-emitting diode D2 is grounded to GND.

The working process of this example: the power interface of the DC voltage stabilizing circuit is connected to the 220V AC power supply through the transformer B and the rectifier circuit, which is converted into a 5V DC voltage output, the filter circuit electrolytic capacitor C1 and capacitor C2, the electrolytic capacitor C1, its The capacity is 1000μF, and the capacity of the capacitor C2 is 3000μF; it will filter out the AC component in the output voltage of the rectifier circuit, so as to obtain a relatively smooth DC voltage output, and manually close one end of a pair of contacts of the electromagnetic relay to make it and The output terminal of the rectifier circuit is connected, and the battery of the mobile phone is charged through the current limiting resistor R2. The resistance of R2 is 250Ω. The automatic power-off charger of the mobile phone is connected with a 4.15V full indication circuit. The resistance of the resistor R3 is 220～390Ω , the resistance value of resistor R4 is 3.3KΩ, and the resistance value of resistor R5 is 270Ω. When the lithium battery terminal voltage on the charging circuit reaches 4.15V, the first pin of the three-terminal micro-power consumption voltage detector IC outputs a high level. At this time The high level lights up the light-emitting diode D6 through the resistor R5, which indicates that the cross-current charging of the lithium battery of the mobile phone is over. The three-terminal micro-power consumption voltage detector IC uses LM7806. Diode D6 can be selected from red or green. Then enter the constant voltage charging. When the constant voltage charging is nearly completed, the current in the charging control circuit is greatly reduced until the magnetic force is not enough to make the armature pull in, the relay is disconnected, and the charging is completed. Reached the purpose of saving a large amount of electric energy. The AC/DC power supply status indication circuit can give a reminder of the AC/DC working status. If the DC voltage stabilizing circuit normally performs AC-DC conversion, the light-emitting diode D5 lights up, indicating that the DC stabilizing circuit is working normally.

An embodiment of the present invention has been described in detail above, but the content described is only a preferred embodiment of the present invention, and cannot be considered as limiting the implementation scope of the present invention. All equivalent changes and improvements made according to the application scope of the present invention shall still belong to the scope covered by the patent of the present invention.

Claims (6)

1. An automatic power-off charger for a mobile phone, comprising a DC voltage stabilizing circuit, a charging control circuit, an AC/DC power supply state indicating circuit and a filter circuit, characterized in that: the DC stabilizing circuit includes a power interface, a transformer B and a rectifier circuit, the power interface is used to access a 220V AC power supply, the high-voltage side of the transformer B is connected to the power interface, the low-voltage side of the transformer B is connected to a rectifier circuit, and the output terminal of the rectifier circuit outputs a 5V DC voltage; The charging control circuit includes an electromagnetic relay, a resistor R2, a light-emitting diode D3 and a charging interface. One end of a pair of contacts of the electromagnetic relay is connected to the output end of the rectifier circuit, and the other end of the electromagnetic relay is connected through the connecting resistor R2 and The light-emitting diode D3 is connected to the positive pole of the charging interface, the negative pole of the charging interface is grounded to GND, and the charging and disconnection of the mobile phone is controlled by controlling the pair of contacts of the electromagnetic relay to be turned on and off; The filter circuit includes an electrolytic capacitor C1 and a capacitor C2. One end of the electrolytic capacitor C1 and capacitor C2 are respectively connected to the output end of the rectification circuit, and the other ends are respectively grounded to GND for filtering out the AC component in the output voltage of the rectification circuit, thereby obtaining Relatively smooth DC voltage; The AC and DC power supply status indication circuit includes a light emitting diode D1 and a resistor R1, the anode of the light emitting diode D1 is connected to the output terminal of the rectifier circuit, and the negative pole of the light emitting diode D1 is grounded to GND through the resistor R1. 2. A mobile phone automatic power-off charger according to claim 1, characterized in that: it also includes a full indication circuit, and the full indication circuit includes a three-terminal micro-power consumption voltage detector IC, a resistor R3, a resistor R4, Resistor R5 and light-emitting diode D2, one end of resistor R3 and one end of resistor R4 are connected to pin 2 of the three-terminal micro-power consumption voltage detector IC, the other end of resistor R3 is connected to the positive pole of the charging interface, the other end of resistor R4 is connected to the three-terminal micro The third pin of the power consumption voltage detector IC is grounded to GND, the first pin of the three-terminal micro power consumption voltage detector IC is connected to the positive pole of the light-emitting diode D2 through the resistor R5, and the negative pole of the light-emitting diode D2 is grounded to GND. 3. The mobile phone automatic power-off charger according to claim 1, wherein the positive pole of the output end of the rectification circuit is connected to the positive pole VCC of the circuit, and the negative pole of the output end of the rectification circuit is grounded to GND. 4. The mobile phone automatic power-off charger according to claim 1, characterized in that: the positive pole of the electrolytic capacitor C1 is connected to the output terminal of the rectifier circuit, and the negative pole of the electrolytic capacitor C1 is grounded to GND. 5. The mobile phone automatic power-off charger according to claim 1, characterized in that: a fuse FU is connected between the high-voltage side of the transformer B and the power interface. 6. The automatic power-off charger for a mobile phone according to claim 1, wherein the rectification circuit is composed of four diodes D1-D4.