CN217642782U

CN217642782U - Automatic identification switching circuit of OTG voltage and charging voltage

Info

Publication number: CN217642782U
Application number: CN202221183720.2U
Authority: CN
Inventors: 张小平; 吴术波; 蔡晓平
Original assignee: SHENZHEN ALONG ELECTRONICS CO LTD
Current assignee: SHENZHEN ALONG ELECTRONICS CO LTD
Priority date: 2022-05-17
Filing date: 2022-05-17
Publication date: 2022-10-21
Anticipated expiration: 2032-05-17

Abstract

The utility model relates to a charging circuit field, in particular to OTG voltage and charging voltage's automatic identification switching circuit. The direct current power supply comprises a main control module, a charging circuit, an OTG boosted circuit, a battery, a forward end input circuit, a reverse end input circuit, a current-limiting switch circuit, a comparator and a diode D1, wherein the main control module is respectively connected with and controls the charging circuit and the OTG boosted circuit, the battery is respectively connected with the main control module, the charging circuit and the OTG boosted circuit, the anode of the diode D1 is respectively connected with the OTG boosted circuit and an internal voltage OTG-5V, the cathode of the diode D1 is respectively connected with the current-limiting switch and an external voltage Vbus, one end of the forward end input circuit is connected with the external voltage Vbus, the other end of the forward end input circuit is connected with the forward end of the comparator, one end of the reverse end input circuit is connected with a power supply VCC-3.3V, the other end of the reverse end of the diode is connected with the reverse end of the comparator, the output end of the comparator is connected with the current-limiting switch, and the current-limiting switch is connected with the charging circuit. The circuit is simple, low in cost, free of intervention of too much software and high in universality.

Description

Automatic identification switching circuit of OTG voltage and charging voltage

Technical Field

The utility model relates to a charging circuit field, in particular to OTG voltage and charging voltage's automatic identification switching circuit.

Background

The USB OTG function (abbreviated as USB On-The-Go) is intended to implement data transfer between devices without Host, and allows a device to operate as a Host or a peripheral, such as a smart phone or a tablet computer, many of which support The function, and its principle is as follows:

as shown in fig. 1, there are 5 lines in the USB OTG interface: 2 pieces of data (D +, D-); 1 power line (VBUS); 1 ground wire (GND); 1 ID line.

The ID line is used to identify different cable endpoints, as shown in the following figures, the ID pin in the mini-a plug (i.e., a peripheral a) is grounded, and the ID pin in the mini-B plug (i.e., a peripheral B) is floating. When the OTG equipment detects the grounded ID pin, the default is the A equipment (host), and at the moment, vbus is externally supplied with power by the A equipment, otherwise, when the A equipment cannot detect the grounded ID pin, the equipment is the slave equipment, and can get power from the Vbus and charge the battery of the equipment.

From the above, it can be known that the working mode of the OTG device needs to be the slave mode, when the OTG device is in the master mode, the internal circuit of the OTG device boosts the voltage to generate an OTG-5V voltage of about 5V to supply power to the external device, although the internal charging circuit can detect the voltage, the software can turn off the charging function to prevent the boosted power from charging itself, if the charging is turned on, the charging is equivalent to invalid charging, and energy loss occurs in each link during the conversion process, which may cause the operation to be actually unnecessary power consumption, how can the OTG device work in each mode to automatically identify the charger and automatically select whether to charge? This becomes a problem to be solved. While the VBUS signal processing schematic diagram of the existing OTG device is shown in fig. 2, the circuit lacks a function of self-recognizing and switching charging.

SUMMERY OF THE UTILITY MODEL

The utility model provides an OTG voltage and charging voltage's automatic identification switching circuit aims at solving current OTG equipment and can't discern and switching circuit by oneself, leads to the invalid condition of charging to appear.

The utility model provides an automatic identification switching circuit of OTG voltage and charging voltage, including host system, charging circuit, OTG boost circuit, battery, host system connects respectively and controls charging circuit and OTG boost circuit, host system, charging circuit, OTG boost circuit are connected respectively to the battery, still include forward end input circuit, reverse end input circuit, current-limiting switch circuit, comparator, diode D1, OTG boost circuit, internal voltage OTG-5V are connected respectively to diode D1's positive pole, current-limiting switch, external voltage Vbus are connected respectively to diode D1 negative pole, external voltage Vbus is connected to forward end input circuit one end, its other end inserts the forward end of comparator, reverse end input circuit one end is connected power VCC-3.3V, its other end inserts the reverse end of comparator, the output of comparator is connected current-limiting switch, charging circuit is connected to current-limiting switch.

As a further improvement, the forward end input circuit comprises a resistor R1 and a resistor R2, the external voltage Vbus is connected to one end of the resistor R1, the other end of the resistor R1 is respectively connected to one end of the resistor R2 and the forward end of the comparator, and the other end of the resistor R2 is grounded.

As a further improvement of the utility model, reverse input circuit includes resistance R3, electric capacity C1, power VCC-3.3V is connected to resistance R3's one end, electric capacity C1's one end, the reverse end of comparator are connected respectively to resistance R3's the other end, electric capacity C1's other end ground connection.

As a further improvement of the utility model, this automatic identification switching circuit still includes pull-up circuit, pull-up circuit includes resistance R4, resistance R4's one end is connected the power VCC-3.3V, the output of comparator is connected to resistance R4's the other end.

As a further improvement of the utility model, the current-limiting switch circuit is an MOS transistor circuit.

As a further improvement of the utility model, the current-limiting switch circuit includes MOS pipe Q1, MOS pipe Q2, resistance R5, resistance R6, resistance R7, external voltage Vbus, resistance R5's one end is connected respectively to MOS pipe Q1's source electrode, charging circuit is connected to MOS pipe Q1's drain electrode, MOS pipe Q1's grid is connecting resistance R5's the other end respectively, resistance R6's one end, MOS pipe Q2's drain electrode connecting resistance R6's the other end, MOS pipe Q2's source electrode ground connection, MOS pipe Q2's grid connecting resistance R7's one end, the output of comparator is connected to resistance R7's the other end. The current limiting switch circuit is an MOS transistor circuit.

The utility model has the advantages that: the circuit is simple, low in cost, capable of achieving automatic identification and switching of the charging circuit without intervention of too much software, strong in universality, and especially important when the USB port is expanded in the OTG mode, otherwise the system cannot be charged easily in the OTG mode.

Drawings

Fig. 1 is a schematic diagram of the OTG patch cord of the present invention;

fig. 2 is a schematic diagram of processing VBUS signals of the present OTG device of the present invention:

FIG. 3 is a block diagram of the automatic identification switching circuit of the present invention;

fig. 4 is a structural diagram of the current limiting switch circuit of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail with reference to the accompanying drawings and embodiments.

The novel circuit realizes automatic identification of whether the actual voltage at the VBUS is internal OTG-5V or externally input charging 5V through a comparator and a current-limiting switch, and automatically switches charging.

As shown in fig. 3, the utility model discloses an automatic identification switching circuit of OTG voltage and charging voltage, including host system, charging circuit, OTG boost circuit, a battery, forward end input circuit, reverse end input circuit, current-limiting switch circuit, a comparator, diode D1, host system connects and controls charging circuit and OTG boost circuit respectively, host system is connected respectively to the battery, charging circuit, OTG boost circuit is connected respectively to diode D1's positive pole, internal voltage OTG-5V, current-limiting switch is connected respectively to diode D1 negative pole, external voltage Vbus is connected to forward end input circuit one end, its other end inserts the forward end of comparator, power VCC-3.3V is connected to reverse end input circuit one end, the reverse end of its other end access comparator, the output linked switch of comparator, current-limiting switch is connected to the current-limiting switch.

The positive end input circuit comprises a resistor R1 and a resistor R2, one end of the resistor R1 is connected with an external voltage Vbus, the other end of the resistor R1 is respectively connected with one end of the resistor R2 and the positive end of the comparator, and the other end of the resistor R2 is grounded. The resistors R1 and R2 divide the input of the external voltage Vbus.

The reverse end input circuit comprises a resistor R3 and a capacitor C1, one end of the resistor R3 is connected with a power supply VCC-3.3V, the other end of the resistor R3 is respectively connected with one end of the capacitor C1 and the reverse end of the comparator, and the other end of the capacitor C1 is grounded. When a power supply VCC-3.3V is input, the resistor R3 plays a role of voltage division, and the capacitor C1 plays a role of filtering.

The automatic identification switching circuit further comprises a pull-up circuit, the pull-up circuit comprises a resistor R4, one end of the resistor R4 is connected with a power supply VCC-3.3V, and the other end of the resistor R4 is connected with the output end of the comparator. The resistor R4 is hung at the output end of the comparator for pulling up, so that the output of some comparators is prevented from being opened and leaked, and no high level output is caused.

As shown in fig. 4, the current-limiting switch circuit includes a MOS transistor Q1, a MOS transistor Q2, a resistor R5, a resistor R6, and a resistor R7, wherein a source of the MOS transistor Q1 is connected to the external voltage Vbus and one end of the resistor R5, respectively, a drain of the MOS transistor Q1 is connected to the charging circuit, a gate of the MOS transistor Q1 is connected to the other end of the resistor R5 and one end of the resistor R6, a drain of the MOS transistor Q2 is connected to the other end of the resistor R6, a source of the MOS transistor Q2 is grounded, a gate of the MOS transistor Q2 is connected to one end of the resistor R7, and the other end of the resistor R7 is connected to an output terminal of the comparator.

The working principle of the automatic identification switching circuit of the OTG voltage and the charging voltage is as follows:

when no charger is inserted, the voltage at the Vbus is provided by the internal OTG-5V through the D1 and is about 4.8V, a b point signal of the voltage after voltage division through resistors R1 and R2 is given to a forward input end of a comparator, a VCC-3.3V power supply is given to an inverting input end of the comparator through an a point signal after the resistor R3, the voltage of the forward end is lower than the voltage of the inverting end at the moment, an output end c of the comparator outputs a low level signal, the signal is simultaneously given to a current limiting switch U1 as a control signal, the low level current limiting switch U1 does not output when the low level does not work, the Vbus-CHG has no charging voltage, and a charging circuit, namely, the system does not charge when the charger is not detected to be inserted; otherwise, when an external charger is inserted, the voltage at the Vbus is raised to be more than 5V, the voltage at the forward input end of the comparator is higher than the voltage at the reverse input end, the output end c of the comparator outputs a high-level signal which controls the conduction of the current-limiting switch U1, and the voltage at the Vbus-CHG is equal to the voltage at the Vbus, so that the charging circuit acquires normal charging voltage and starts charging, the OTG-5V voltage and the charger voltage are automatically identified, the working state of the internal charging circuit is switched, and charging or charging stopping is automatically determined.

In addition, the current-limiting switch can be built by a cheaper MOS tube circuit so as to further save cost, if the OTG-5V output of some platforms does not have a series diode D1 and is added with a current-limiting switch and the like, the parameters of the voltage boosting circuit of the OTG-5V can be slightly adjusted to be about 4.8V.

The foregoing is a more detailed description of the present invention, taken in conjunction with specific preferred embodiments thereof, and it is not intended that the invention be limited to the specific embodiments thereof. To the utility model belongs to the technical field of ordinary technical personnel, do not deviate from the utility model discloses under the prerequisite of design, can also make a plurality of simple deductions or replacement, all should regard as belonging to the utility model discloses a protection scope.

Claims

1. The utility model provides an automatic identification switching circuit of OTG voltage and charging voltage, includes host system, charging circuit, OTG boost circuit, battery, host system connects respectively and controls charging circuit and OTG boost circuit, host system, charging circuit, OTG boost circuit are connected respectively to the battery, its characterized in that, including forward end input circuit, reverse end input circuit, current-limiting switch circuit, comparator, diode D1, OTG boost circuit, internal voltage OTG-5V are connected respectively to diode D1's positive pole, current-limiting switch, external voltage Vbus are connected respectively to diode D1 negative pole, external voltage Vbus is connected to forward end input circuit one end, its other end inserts the forward end of comparator, power VCC-3.3V is connected to reverse end input circuit one end, its other end inserts the reverse end of comparator, the output of comparator is connected current-limiting switch, current-limiting switch connects charging circuit.

2. The OTG voltage and charging voltage automatic identification switching circuit according to claim 1, wherein the forward input circuit comprises a resistor R1 and a resistor R2, one end of the resistor R1 is connected to the external voltage Vbus, the other end of the resistor R1 is respectively connected to one end of the resistor R2 and the forward end of the comparator, and the other end of the resistor R2 is grounded.

3. The OTG voltage and charging voltage automatic identification switching circuit according to claim 1, wherein the inverting terminal input circuit comprises a resistor R3 and a capacitor C1, one terminal of the resistor R3 is connected to VCC-3.3V, the other terminal of the resistor R3 is respectively connected to one terminal of the capacitor C1 and the inverting terminal of the comparator, and the other terminal of the capacitor C1 is grounded.

4. The OTG voltage and charging voltage automatic identification switching circuit according to claim 1, further comprising a pull-up circuit, wherein the pull-up circuit comprises a resistor R4, one end of the resistor R4 is connected to a power source VCC-3.3V, and the other end of the resistor R4 is connected to the output terminal of the comparator.

5. The OTG voltage and charging voltage auto-discrimination switching circuit of claim 1, wherein the current limit switch circuit is a MOS transistor circuit.

6. The OTG voltage and charging voltage automatic identification switching circuit according to claim 1, wherein the current limiting switch circuit comprises a MOS transistor Q1, a MOS transistor Q2, a resistor R5, a resistor R6, and a resistor R7, the source of the MOS transistor Q1 is connected to the external voltage Vbus and one end of the resistor R5, respectively, the drain of the MOS transistor Q1 is connected to the charging circuit, the gate of the MOS transistor Q1 is connected to the other end of the resistor R5 and one end of the resistor R6, the drain of the MOS transistor Q2 is connected to the other end of the resistor R6, the source of the MOS transistor Q2 is grounded, the gate of the MOS transistor Q2 is connected to one end of the resistor R7, and the other end of the resistor R7 is connected to the output end of the comparator.