USB charging current detection circuit

Abstract

A USB charging current detection circuit comprises a voltage stabilizer U1, a resistor R1, a power supply VCC and a triode Q1, the power supply VCC is grounded through a capacitor C1, the power supply VCC is connected with one end of the resistor R1, the other end of the resistor R1 is connected with a voltage terminal of a USB, the other end of the resistor R1 is grounded through a capacitor C2, the voltage terminal of the USB is grounded after sequentially passing through a resistor R4 and a resistor R5, and the triode Q1 is connected with the voltage stabilizer U1. A voltage terminal of the USB is grounded after sequentially passing through a resistor R6 and a resistor R7, two input ends of the voltage stabilizer U1 are connected to two ends of the resistor R1, an output end of the voltage stabilizer U1 is connected with a base electrode of the triode Q1, an emitting electrode of the triode Q1 is grounded, and a collector electrode of the triode Q1 is connected with the MCU. The voltage stabilizer design circuit is low in cost, few in periphery, simple in circuit, easy to debug and small in error.

Description

Technical Field

[0001] The utility model relates to the technical field of audio, in particular to a USB charging current detection circuit. Background Art

[0002] At present, many audio products with USB external charging function need to shut down when the audio products are not working after charging in order to meet the ERP energy consumption requirements of CE certification. Therefore, it is often necessary to add a USB external charging current detection circuit. Most of the existing machines use comparator circuits to achieve this, but the circuit has many peripherals and debugging is troublesome. Summary of the invention

[0003] The technical problem to be solved by the utility model is to provide a USB charging current detection circuit, which completes the USB external charging current detection function, has low cost, simple circuit and simple debugging.

[0004] In order to solve the above technical problems, the technical solution of the utility model is: a USB charging current detection circuit, including a voltage regulator U1, a resistor R1, a power supply VCC and a transistor Q1, the power supply VCC is grounded through a capacitor C1, the power supply VCC is connected to one end of the resistor R1, the other end of the resistor R1 is connected to a USB voltage terminal, the other end of the resistor R1 is grounded through a capacitor C2, the USB voltage terminal is grounded after passing through resistors R4 and R5 in sequence, the USB voltage terminal is grounded after passing through resistors R6 and R7 in sequence, the two input ends of the voltage regulator U1 are connected to the two ends of the resistor R1, the output end of the voltage regulator U1 is connected to the base of the transistor Q1, the emitter of the transistor Q1 is grounded, and the collector of the transistor Q1 is connected to the MCU. The principle of the utility model is as follows: VCC is charged externally through the resistor R1, a voltage difference is generated at both ends of the resistor R1, the voltage is detected through the 2nd and 3rd pins of the voltage regulator U1, and then the control voltage is output at the 1st pin to the MCU; when the external device is fully charged and there is no output voltage, if the whole machine is not working, the MUC turns off the power of the whole machine to achieve shutdown, meeting the energy consumption requirements of the certified ERP.

[0005] As an improvement, the model of the voltage regulator U1 is ZXCT1009, and the power supply VCC is +5V.

[0006] Compared with the prior art, the utility model has the following beneficial effects:

[0007] The circuit is designed with a voltage regulator, which has low cost, few peripherals, simple circuit, easy debugging and small error. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is the circuit diagram of the utility model. DETAILED DESCRIPTION

[0009] The utility model will be further described below in conjunction with the accompanying drawings.

[0010] like Figure 1 As shown, a USB charging current detection circuit includes a voltage regulator U1, a resistor R1, a power supply VCC and a transistor Q1. The voltage regulator U1 is of model ZXCT1009, and the power supply VCC is +5V. The first pin of the USB is a voltage terminal V+, the second pin is a data terminal D-, the third pin is a data terminal D+, and the fourth, fifth and sixth pins are ground terminals G. The power supply VCC is grounded through a capacitor C1, the power supply VCC is connected to one end of the resistor R1, the other end of the resistor R1 is connected to a voltage terminal V+ of a USB, the other end of the resistor R1 is grounded through a capacitor C2, the voltage terminal V+ of the USB is grounded after passing through resistors R4 and R5 in sequence, the voltage terminal V+ of the USB is grounded after passing through resistors R6 and R7 in sequence, the 4th pin of the USB is grounded, the 5th pin and the 6th pin are combined and then grounded through a capacitor C3, the two input ends of the voltage regulator U1 are connected to the two ends of the resistor R1, the output end of the voltage regulator U1 is connected to the base of the transistor Q1 through a resistor R2, the emitter of the transistor Q1 is grounded, and the collector of the transistor Q1 is connected to the MCU.

[0011] The principle of the utility model is as follows: VCC is charged externally through the resistor R1, a voltage difference is generated at both ends of the resistor R1, the voltage is detected through the 2nd and 3rd pins of the voltage regulator U1, and then the control voltage is output at the 1st pin to the MCU; when the external device is fully charged and there is no output voltage, if the whole machine is not working, the MUC turns off the power of the whole machine to achieve shutdown, meeting the energy consumption requirements of the certified ERP.

Claims

1. A USB charging current detection circuit, characterized in that: The invention comprises a voltage stabilizer U1, a resistor R1, a power supply VCC and a transistor Q1, wherein the power supply VCC is grounded through a capacitor C1, the power supply VCC is connected to one end of the resistor R1, the other end of the resistor R1 is connected to a voltage terminal of a USB, the other end of the resistor R1 is grounded through a capacitor C2, the voltage terminal of the USB is grounded after passing through resistors R4 and R5 in sequence, the voltage terminal of the USB is grounded after passing through resistors R6 and R7 in sequence, two input ends of the voltage stabilizer U1 are connected to two ends of the resistor R1, the output end of the voltage stabilizer U1 is connected to the base of the transistor Q1, the emitter of the transistor Q1 is grounded, and the collector of the transistor Q1 is connected to an MCU.

2. A USB charging current detection circuit according to claim 1, characterized in that: The model of the voltage regulator U1 is ZXCT1009, and the power supply VCC is +5V.

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