A fast discharge circuit based on MTK protocol

Abstract

The application discloses a kind of quick discharge circuit based on MTK agreement, it belongs to circuit design technical field, its scheme includes synchronous rectification check module, threshold voltage configuration module, voltage comparison module, program control module and discharge module.Synchronous rectification check module is used to rectify power supply operating frequency value;Threshold voltage configuration module is used to output preset threshold voltage;Voltage comparison module is used to compare power supply output end voltage and preset threshold voltage, and output voltage comparison result;Program control module is used to receive voltage comparison result and rectified square wave signal, determine whether to trigger discharge module discharge;Discharge module is used to control power supply output end quick discharge.The quick discharge circuit of the application is used to speed up the discharge speed of power supply output end, avoid the problem that the charging equipment using MTK charging agreement is suddenly connected when charging, secondary circuit discharge speed is slow, and the newly connected charging equipment is damaged due to high voltage of power supply output end.

Description

Technical Field

[0001] This application relates to the technical field of circuit design, and in particular to a fast discharge circuit based on the MTK protocol. Background Technology

[0002] In pursuit of a better battery life experience, in addition to increasing battery capacity, charging speed is also an important factor affecting user experience. Fast charging is becoming increasingly widespread. Currently, the mainstream fast charging protocols are as follows: one is MediaTek's MTK charging protocol, another is Qualcomm's QC charging protocol, and the third is the USB-PD fast charging protocol developed by the USB-IF organization.

[0003] In charging devices using the MTK charging protocol (such as mobile phones, computers, and tablets), if the connection is suddenly lost during charging, for example, if the charging device is suddenly unplugged, the primary circuit of the charger can react quickly and discharge to reduce the voltage to a safe voltage, such as 5V. However, the voltage of the secondary circuit of the charger remains high. If it relies solely on its own capacitor to discharge, the discharge speed is slow, and the discharge time may reach more than 10 seconds. On the one hand, this does not meet the MTK protocol's requirement that the charger's discharge time should be at most 500ms. On the other hand, if another charging device is connected before the secondary circuit has discharged to a safe voltage, the high voltage at the power output terminal may damage the newly connected charging device. Therefore, some manufacturers choose to build a series of complex circuits around the secondary chip to speed up the discharge speed. However, building circuits around the chip makes the structure more complicated and increases the size and production cost of the charger. Summary of the Invention

[0004] To address the issue that when charging devices using the MTK fast charging protocol suddenly disconnect during charging, the secondary circuit discharges slowly, resulting in high voltage at the power output terminal that damages newly connected charging devices, this application provides a fast discharge circuit based on the MTK fast charging protocol.

[0005] This application provides a fast discharge circuit based on the MTK fast charging protocol, which adopts the following technical solution:

[0006] A fast discharge circuit based on the MTK protocol, wherein the fast discharge circuit is externally powered, and the fast discharge circuit includes: a synchronous rectification check module, a threshold voltage configuration module, a voltage comparison module, a program control module, and a discharge module;

[0007] The synchronous rectification check module is used to detect the voltage at the power supply output terminal and rectify the power supply operating frequency value to output a square wave signal.

[0008] The threshold voltage configuration module is used to output a preset threshold voltage V.REF ;

[0009] The voltage comparison module is used to compare the power supply output voltage V. OUT and the preset threshold voltage V REF The magnitude of the voltage and the output voltage comparison result V. result ;

[0010] The program control module is used to receive the voltage comparison result V output by the voltage comparison module. result The square wave signal output by the synchronous rectification and testing module, and based on the voltage comparison result V... result The square wave signal is used to determine whether the discharge module is conducting.

[0011] The discharge module is used to control the power output terminal based on the judgment result of the program control module.

[0012] By adopting the above technical solution, the program control module can accurately and quickly determine whether the charging device is in a disconnected or charging state based on the voltage comparison result output by the voltage comparison module and the square wave signal output by the synchronous rectification check module. In turn, it controls whether the discharge module performs a rapid discharge operation to prevent high voltage in the secondary circuit from damaging the newly connected charging device.

[0013] In one specific implementation, the voltage comparison module is used to compare the power supply output voltage V. OUT and the preset threshold voltage V REF Comparison, when the power supply output voltage V OUT The voltage is greater than the preset threshold voltage V REF When the voltage comparison module outputs a first voltage comparison result, the first voltage comparison result is the output signal of the voltage comparison module; when the power supply output voltage V OUT Less than the preset threshold voltage V REF When the voltage comparison module outputs a second voltage comparison result, the second voltage comparison result is the output signal of the voltage comparison module after the flip.

[0014] By adopting the above technical solution, the comparator determines the voltage V at the power supply output terminal. OUT Does it exceed the threshold voltage V? REF It also outputs the voltage comparison results.

[0015] In one specific implementation, the program control module is used to acquire the voltage comparison result V. result ; Calculate the low-level time T of the square wave signal within the first preset time period. low ; Calculate the number N of rising or falling edges of the square wave signal within the second preset time period. status Through N statusDetermine the frequency f of the square wave signal within a second preset time period. square According to the voltage comparison result V result The low-level time T of the square wave signal within the first preset time period low The frequency f of the square wave signal within the second preset time period square Determine whether the discharge module is discharging.

[0016] By adopting the above technical solution, the program control module acquires the square wave signal output by the synchronous rectification check module and calculates the low-level time T of the square wave signal within a first preset time. low The frequency f within the second preset time period square Combined with the voltage comparison result V output by the voltage comparison module result Determine whether to trigger the discharge operation of the discharge module.

[0017] In one specific implementation scheme, the processing procedure of the program control module includes: converting the power output voltage V... OUT and the preset threshold voltage V REF Comparison, when the power supply output voltage V OUT Less than the preset threshold voltage V REF When the charging device is in a charging state, the program control module controls the discharge module to not conduct, so that the discharge module does not discharge.

[0018] By adopting the above technical solution, the power supply output voltage V OUT Less than the threshold voltage V REF At that time, the program control module controls the discharge module to not conduct and not discharge.

[0019] In one specific implementation, the processing of the program control module further includes: the processing of the program control module further includes: converting the power output voltage V... OUT and the preset threshold voltage V REF Comparison, when the power supply output voltage V OUT The voltage is greater than the preset threshold voltage V REF At that time, the frequency f of the square wave signal is continuously acquired a preset number of times. square And the frequency f of the square wave signal is preset to a certain number of times. square and the preset threshold frequency f th The comparison is performed, and if the frequency f of the square wave signal is at the preset number of times... square All are less than the preset threshold frequency f th If the charging device is disconnected, the program control module will control the discharge module to turn on, causing the discharge module to discharge; if the frequency f of the preset number of square wave signals... square Not all frequencies are less than the preset threshold frequency fth If the charging device is in a charging state, the program control module will control the discharge module to not conduct, so that the discharge module does not discharge.

[0020] By adopting the above technical solution, the power supply output voltage V OUT Greater than the threshold voltage V REF At that time, the program control module determines the frequency f of the square wave signal according to the preset number of times. square and threshold frequency f th The comparison results determine whether the discharge module is turned on and discharged.

[0021] In one specific implementation scheme, the processing of the program control module further includes: when the power supply output voltage V OUT The voltage is greater than the preset threshold voltage V REF And the low-level time T of the square wave signal within the first preset time period low Exceeding the preset time threshold t th When the charging device is disconnected, the program control module controls the discharge module to turn on, causing the discharge module to discharge; when the power output voltage V... OUT The voltage is greater than the preset threshold voltage V REF And the low-level time T of the square wave signal low Not exceeding the preset time threshold t th When the charging device is in a charging state, the program control module controls the discharge module to not conduct, so that the discharge module does not discharge.

[0022] By adopting the above technical solution, the power supply output voltage V OUT Greater than the threshold voltage V REF At that time, the program control module determines the low-level duration T of the square wave signal. low and the preset time threshold t th The comparison results determine whether the discharge module is turned on and discharged.

[0023] In one specific implementation, the discharge module includes a MOSFET, a diode, and a resistor. The drain of the MOSFET is connected to the cathode of the diode, and the source of the MOSFET is connected to the anode of the diode. The MOSFET and the diode are connected in parallel, with one end connected in series with the resistor and the other end grounded.

[0024] By adopting the above technical solution, diodes and resistors are used to protect the drain and source of the MOSFET, preventing the MOSFET from being broken down when a large instantaneous reverse current is generated in the circuit.

[0025] In one specific implementation, the MOS transistor is a device with switching control function.

[0026] By adopting the above technical solution, the MOSFET has the function of switching control: when the MOSFET is turned on, the power output terminal is grounded through the resistor and the MOSFET to perform rapid discharge; when the MOSFET is not turned on, the power output terminal does not discharge.

[0027] In one specific implementation, the frequency f of continuously acquiring the square wave signal a preset number of times... square Specifically, the frequency f of the square wave signal is continuously acquired a preset number of times within the first duration. square The first duration is greater than or equal to 240ms.

[0028] By adopting the above technical solution, the frequency f of the square wave signal is continuously acquired a preset number of times. square The time should not be too short to avoid errors in judging the power supply's operating frequency value.

[0029] In summary, this application includes at least one of the following beneficial technical effects:

[0030] 1. By adding a fast discharge circuit to the secondary circuit of the charger, the problem of slow discharge speed of the secondary circuit when the charging device using the MTK charging protocol is suddenly disconnected during the charging process is solved. This avoids the situation where another charging device is connected when the secondary circuit is at a high potential and has not been discharged to a safe voltage, which would cause damage to the newly connected charging device.

[0031] 2. By designing the discharge circuit inside the secondary chip, instead of building the circuit structure on the periphery of the secondary chip in the traditional way, the integration level of the chip is improved, and the size and production cost of the charger are reduced. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of a fast discharge circuit in an embodiment of this application;

[0033] Figure 2 This is a detailed structural schematic diagram of a fast discharge circuit according to an embodiment of this application;

[0034] Figure 3 This is a schematic diagram of the processing logic of the program control module in the embodiments of this application.

[0035] Figure label:

[0036] 1. Synchronous rectification check module; 2. Threshold voltage configuration module; 3. Voltage comparison module; 31. Comparator; 4. Program control module; 5. Discharge module; 51. MOSFET; 52. Diode; 53. Resistor. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the embodiments of this application will be further described in detail below with reference to the accompanying drawings.

[0038] This application discloses a fast discharge circuit based on the MTK protocol. The fast discharge circuit is externally powered. (Refer to...) Figure 1 The fast discharge circuit includes a synchronous rectification check module 1, a threshold voltage configuration module 2, a voltage comparison module 3, a program control module 4, and a discharge module 5.

[0039] Synchronous rectification test module 1 is used to detect the voltage V at the power supply output terminal. OUT It also rectifies the power supply operating frequency value and outputs a square wave signal;

[0040] Threshold voltage configuration module 2 is used to output a preset threshold voltage V REF ;

[0041] Voltage comparator module 3 is used to compare the voltage V at the power supply output terminal. OUT and the preset threshold voltage V REF The magnitude of the voltage and the output voltage comparison result V. result ;

[0042] The program control module 4 is used to receive the voltage comparison result output by the voltage comparison module 3 and the square wave signal output by the synchronous rectification check module 1, and to determine whether the discharge module 5 is conducting based on the voltage comparison result and the square wave signal.

[0043] The discharge module 5 is used to control the power output terminal based on the judgment result of the program control module 4.

[0044] Reference Figure 2 The input terminal of the synchronous rectification check module 1 is connected to the secondary winding of the transformer T. The synchronous rectification check module 1 is used to rectify the power supply operating frequency value and output a square wave signal, and transmit the square wave signal to the program control module 4.

[0045] Reference Figure 2 The voltage comparison module 3 includes a comparator 31. The non-inverting input of comparator 31 is connected to the power output, the inverting input is connected to the output of the threshold voltage configuration module 2, and the output is connected to the input of the program control module 4. The discharge module 5 includes a MOSFET 51, a diode 52, and a resistor 53. MOSFET 51 and diode 52 are connected in parallel and then in series with resistor 53. The gate of MOSFET 51 is connected to the program control module 4, the drain of MOSFET 51 is connected to the power output through resistor 53, and the source of MOSFET 51 is grounded. The output of the synchronous rectification check module 1 is connected to the gate of MOSFET Q1 and the program control module 4.

[0046] Reference Figure 2 Ports 1 and 2 of transformer T are connected to the power input terminal, ports 3 and 4 of transformer T are connected to the primary circuit, port 5 of transformer T is connected to the power output terminal, and port 6 of transformer T is connected to the secondary circuit. The drain of MOSFET Q1 is connected to the input terminal of synchronous rectification check module 1, and the source of MOSFET Q1 is grounded. Capacitor CE1 is connected in parallel with resistor R1. The positive terminal of capacitor CE1 is connected to port 5 of transformer T and resistor R1, and the negative terminal of capacitor CE1 is grounded.

[0047] Comparator 31 is used to compare the voltage V at the power supply output terminal. OUT and the preset threshold voltage V REF And compare the voltage results V result The signal is transmitted to program control module 4. When the power output voltage V... OUT The voltage is greater than the preset threshold voltage V REF Voltage comparison result V result The voltage at the power supply output terminal is high level "1"; when the voltage at the power supply output terminal V is high level "1". OUT Less than the preset threshold voltage V REF Voltage comparison result V result The level is "0" (low level).

[0048] Specifically, when the power supply output voltage V OUT Equal to the preset threshold voltage V REF Voltage comparison result V result Maintain the original state: If the original voltage comparison result V result If the voltage is high ("1"), comparator 31 will continue to output a high level ("1"); if the original voltage comparison result V... result If the output is low level "0", then comparator 31 will continue to output low level "0".

[0049] The program control module 4 is used to acquire the square wave signal output by the synchronous rectification check module 1 and the voltage comparison result V output by the comparator 31. result Calculate the low-level time T of the square wave signal within the first preset time period. low ; Calculate the number N of rising or falling edges of the square wave signal within the second preset time period. status Through N status Determine the frequency f of the square wave signal within a second preset time period. square According to the voltage comparison result V result The low-level time T of the square wave signal within the first preset time period low The frequency f of the square wave signal within the second preset time period square Determine whether the discharge module 5 is discharging.

[0050] The first preset time and the second preset time can be set to be the same or different.

[0051] Diode 52 and resistor 53 are used to protect the drain and source of MOSFET 51 to prevent MOSFET 51 from being broken down when a large instantaneous reverse current is generated in the circuit.

[0052] In one embodiment, the processing procedure of the program control module 4 includes the following steps:

[0053] The voltage V at the power supply output terminal OUT and the preset threshold voltage V REF Compare;

[0054] When the voltage at the power supply output terminal V OUT Less than the preset threshold voltage V REF When the charging device is in a charging state, the program control module 4 controls the discharge module 5 to not conduct, so that the discharge module 5 does not discharge.

[0055] When the voltage at the power supply output terminal V OUT The voltage is greater than the preset threshold voltage V REF At that time, the frequency f of the square wave signal is continuously acquired a preset number of times. square And set the frequency f of the square wave signal to the preset number of times. square and the preset threshold frequency f th Comparison:

[0056] If the frequency f of the preset number of square wave signals is... square All are less than the preset threshold frequency f th If the charging device is disconnected, the program control module 4 will control the discharge module 5 to conduct, so that the discharge module 5 discharges.

[0057] If the frequency f of the preset number of square wave signals is... square Not all frequencies are less than the preset threshold frequency f th If the charging device is in a charging state, the program control module 4 will control the discharge module 5 to not conduct, so that the discharge module 5 will not discharge.

[0058] Specifically, the frequency f of the square wave signal is continuously acquired a preset number of times. square Specifically, the frequency f of the square wave signal is continuously acquired a preset number of times within the first duration. square The first duration is greater than or equal to 240ms.

[0059] In another embodiment, the processing procedure of the program control module 4 includes the following steps:

[0060] The voltage V at the power supply output terminal OUT and the preset threshold voltage V REF Comparison:

[0061] When the voltage at the power supply output terminal VOUT The voltage is greater than the preset threshold voltage V REF And the low-level time T of the square wave signal within the first preset time period low Exceeding the preset time threshold t th If the charging device is disconnected, the program control module 4 will control the discharge module 5 to conduct, so that the discharge module 5 discharges.

[0062] When the voltage at the power supply output terminal V OUT The voltage is greater than the preset threshold voltage V REF And the low-level time T of the square wave signal within the first preset time period low Not exceeding the preset time threshold t th If the charging device is in a charging state, the program control module 4 will control the discharge module 5 to not conduct, so that the discharge module 5 will not discharge.

[0063] Preferably, the preset threshold voltage V REF The voltage is 5V. The preset time is 40ms, and the threshold frequency is f. th The frequency is 5kHz, the preset number of times is 6, and the time threshold is t. th The time is 25ms. The following examples illustrate the processing flow of the program control module under different conditions:

[0064] Scenario 1: If the power supply output voltage is 4V, the processing procedure of the program control module is as follows:

[0065] The power supply output voltage is 4V, which is less than the preset threshold voltage of 5V, i.e., the power supply output voltage V OUT Less than the preset threshold voltage V REF Voltage comparison result V result If the signal level is low "0", it is determined that the charging device is in a charging state. The program control module 4 controls the discharge module 5 to not conduct, and the discharge module 5 does not discharge.

[0066] Scenario 2: The power supply output voltage is 6V. The number of rising edges of a square wave signal within a preset time of 40ms is collected, and this is repeated 6 times, meaning the frequency of the square wave signal is continuously acquired a preset number of times within a time of 240ms. The number of rising edges collected in the first instance is 180, the second is 189, the third is 191, the fourth is 160, the fifth is 172, and the sixth is 168. It can be seen that the number of rising edges of the square wave signal within the preset time of 40ms is less than 200 in all 6 consecutive instances. Therefore, the processing procedure of the program control module is as follows:

[0067] ① Power supply output voltage V OUT The voltage is greater than the preset threshold voltage V REFVoltage comparison result V result The value is a high level "1";

[0068] ② Further processing of the preset number of square wave signal frequencies: If the number of rising edges of the square wave signal within 40ms is less than 200, the frequency of the square wave signal is less than 5kHz, and the frequency of the square wave signal is less than 5kHz for 6 consecutive times. That is, within 240ms, the frequency f of the preset number of square wave signals is... square All are less than the preset threshold frequency f th If the charging device is disconnected, the program control module 4 will control the discharge module 5 to conduct, and the discharge module 5 will discharge.

[0069] Optionally, the program control module can also calculate the frequency of the square wave signal and the preset threshold frequency f by collecting the number of falling edges of the square wave signal within a preset time of 40ms. th The magnitude of the square wave signal is measured continuously six times, and the frequency of these six square wave signals is compared with the preset threshold frequency f. th The comparison results determine whether the charging device is in a charging state or a disconnected state, and then control whether the discharge module is turned on and whether it discharges.

[0070] Scenario 3: The power output voltage is 6V. The number of rising edges of a square wave signal within a preset time of 40ms is collected, and this is repeated 6 times, meaning the frequency of the square wave signal is continuously acquired a preset number of times within a time of 240ms. The number of rising edges acquired in the first acquisition is 172, the second is 189, the third is 188, the fourth is 160, the fifth is 172, and the sixth is 213. It can be seen that the number of rising edges of the square wave signal within the preset time is less than 200 for the first 5 consecutive acquisitions, while the number of rising edges of the square wave signal within the preset time of 40ms is greater than 200 for the 6th acquisition. Therefore, the processing procedure of the program control module is as follows:

[0071] ① Power supply output voltage V OUT The voltage is greater than the preset threshold voltage V REF Voltage comparison result V result The value is a high level "1";

[0072] ② Further processing of the preset frequency of the square wave signal: If the number of rising edges of the square wave signal within 40ms is less than 200, the frequency of the square wave signal is less than 5kHz. The frequency of the square wave signal is less than 5kHz for five consecutive iterations, and greater than 5kHz for the sixth iteration. That is, within 240ms, the frequency f of the preset frequency square wave signal... square Not all frequencies are less than the preset threshold frequency f thIf the charging device is in a charging state, the program control module 4 will control the discharge module 5 to not conduct, and the discharge module 5 will not discharge.

[0073] Scenario 4: If the power supply output voltage is 6V and the low-level time of the square wave signal is 20ms, the processing procedure of the program control module is as follows:

[0074] ① Power supply output voltage V OUT The voltage is greater than the preset threshold voltage V REF Voltage comparison result V result The value is a high level "1";

[0075] ② Further processing of the low-level time of the square wave signal: The low-level time of the square wave signal is 20ms, which does not exceed the preset time threshold of 25ms, that is, the low-level time T of the square wave signal within the first preset time. low Not exceeding the preset time threshold t th If the charging device is in a charging state, the program control module 4 will control the discharge module 5 to not conduct, and the discharge module 5 will not discharge.

[0076] Scenario 5: The power supply output voltage is 6V, and the low-level time of the square wave signal is 28ms. The processing procedure of the program control module is as follows:

[0077] ① Power supply output voltage V OUT The voltage is greater than the preset threshold voltage V REF Voltage comparison result V result The value is a high level "1";

[0078] ② Further processing of the low-level time of the square wave signal: The low-level time of the square wave signal is 28ms, which exceeds the preset time threshold of 25ms, that is, the low-level time T of the square wave signal within the first preset time. low Exceeding the preset time threshold t th If the charging device is disconnected, the program control module 4 will control the discharge module 5 to conduct, and the discharge module 5 will discharge.

[0079] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A fast discharge circuit based on MTK protocol, the fast discharge circuit being externally connected with a power supply, characterized in that, Include: Synchronous rectification check module (1), threshold voltage configuration module (2), voltage comparison module (3), program control module (4), discharge module (5); The synchronous rectification check module (1) is used for detecting the voltage of the power supply output end, rectifying the power supply working frequency value, and outputting a square wave signal; The threshold voltage configuration module (2) is configured to output a preset threshold voltage V REF ; The voltage comparison module (3) is used for comparing the size of the power output end voltage V OUT and the preset threshold voltage V REF , and outputting the voltage comparison result V result ; The program control module (4) is used for receiving the voltage comparison result V output by the voltage comparison module (3) result and the square wave signal output by the synchronous rectification checking module (1), and judging whether the discharge module (5) is turned on according to the voltage comparison result V result and the square wave signal. The discharge module (5) is used for controlling the power supply output end according to the judgment result of the program control module (4); The program control module (4) is used to obtain the voltage comparison result V. result ; Calculate the low-level time T of the square wave signal within the first preset time period. low ; Calculate the number N of rising or falling edges of the square wave signal within the second preset time period. status Through N status Determine the frequency f of the square wave signal within a second preset time period. square According to the voltage comparison result V result The low-level time T of the square wave signal within the first preset time period low The frequency f of the square wave signal within the second preset time period square Determining whether the discharge module (5) is discharging includes: The power output voltage V OUT is compared with a preset threshold voltage V REF When the power output voltage V OUT is greater than the preset threshold voltage V REF , the frequency f square of the preset number of square wave signals is continuously obtained, and the frequency f square of the preset number of square wave signals is compared with a preset threshold frequency f th If the frequency f square of the preset number of square wave signals is less than the preset threshold frequency f th , it is determined that the charging device is disconnected, and the discharge module (5) is turned on by the program control module (4) to make the discharge module (5) discharge; if the frequency f square of the preset number of square wave signals is not less than the preset threshold frequency f th , it is determined that the charging device is in a charging state, and the discharge module (5) is not turned on by the program control module (4) to make the discharge module (5) not discharge. When the output voltage V OUT of the power supply is greater than the preset threshold voltage V REF , and the low level time T low of the square wave signal exceeds the preset time threshold t th in the first preset time, it is determined that the charging device is disconnected, and the discharge module (5) is turned on by the program control module (4) to make the discharge module (5) discharge; when the output voltage V OUT of the power supply is greater than the preset threshold voltage V REF , and the low level time T low of the square wave signal does not exceed the preset time threshold t th , it is determined that the charging device is in the charging state, and the discharge module (5) is not turned on by the program control module (4) to make the discharge module (5) not discharge.

2. The fast discharge circuit based on MTK protocol according to claim 1, characterized in that: The voltage comparison module (3) is used for comparing the power output end voltage V OUT with the preset threshold voltage V REF When the power output end voltage V OUT is greater than the preset threshold voltage V REF , the voltage comparison module (3) outputs a first voltage comparison result, and the first voltage comparison result is the output signal of the voltage comparison module (3); when the power output end voltage V OUT is less than the preset threshold voltage V REF , the voltage comparison module (3) outputs a second voltage comparison result, and the second voltage comparison result is the output signal of the voltage comparison module (3) after being inverted.

3. The fast discharge circuit based on MTK protocol according to claim 1, characterized in that: The processing procedure of the program control module (4) includes: comparing the power output terminal voltage V OUT with the preset threshold voltage V REF When the power output terminal voltage V OUT is less than the preset threshold voltage V REF , it is determined that the charging device is in the charging state, and the discharge module (5) is controlled by the program control module (4) to be non-conducting, so that the discharge module (5) does not discharge.

4. The fast discharge circuit based on MTK protocol according to claim 1, characterized in that: The discharge module (5) includes a MOS tube (51), a diode (52) and a resistor (53), the drain of the MOS tube (51) is connected with the negative electrode of the diode (52), the source of the MOS tube (51) is connected with the positive electrode of the diode (52), the MOS tube (51) and the diode (52) are connected in parallel, one end of which is connected with the resistor (53) in series, and the other end is grounded.

5. The fast discharge circuit based on MTK protocol according to claim 4, characterized in that: The MOS tube (51) is a device with switch control function.

6. The fast discharge circuit based on MTK protocol according to claim 1, characterized in that: The frequency f of the square wave signal is continuously acquired for a preset number of times square Specifically, the frequency f of the square wave signal is continuously acquired for a preset number of times in a first duration square , and the first duration is greater than or equal to 240 ms.

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