Control circuit for converting DC-DC into USB

Abstract

The utility model relates to the technical field of electronics, and discloses a DC-DC (Direct Current-Direct Current) conversion USB (Universal Serial Bus) control circuit capable of automatically secondary charging, which comprises a main charging circuit (800) for charging a battery pack to be charged, a first current detection circuit (30A), a second current detection circuit (30B) and a main control circuit (100), the first current detection circuit (30A) is used for acquiring a first group of electric signals flowing through the first charging branch; the second current detection circuit (30B) is used for acquiring a second group of electric signals flowing through the second charging branch; a signal input end of the main control circuit (100) is connected with an output end of the first current detection circuit (30A), and is used for receiving the first group of electric signals and outputting a first pulse signal and a second pulse signal according to the first group of electric signals and the second group of electric signals so as to control the first charging branch and the second charging branch to charge the battery pack or automatically supplement the battery pack for the second time.

Description

Technical Field

[0001] The utility model relates to the field of electronic technology, and more specifically to a control circuit for converting a DC-DC to a USB. Background Art

[0002] At present, mobile power devices are equipped with rechargeable batteries, which can be used to charge the internal batteries to store energy and to charge other devices (such as mobile phones, etc.) through the batteries. However, the static current of the existing control circuit is high, and when charging the device, the output will be turned off after it is fully charged; when the charging is turned off, although the device is connected, the use of the mobile terminal device will consume power, and since the USB charging device powered by the back front end has turned off the output, it cannot automatically replenish the power for the second time, resulting in the problem of the device being not fully charged after a long standby period or power consumption.

[0003] Therefore, how to ensure that the device terminal can automatically replenish power after power outage to maintain a fully charged state has become a technical problem that technicians in this field continue to solve. Utility Model Content

[0004] The technical problem to be solved by the utility model is that, in view of the defect in the prior art that the USB charging device powered by the rear front end has turned off the output and cannot automatically replenish the power for a second time, resulting in the device being fully charged after a long period of standby or power consumption, a control circuit for a DC-DC conversion USB that can automatically charge for a second time is provided.

[0005] The technical solution adopted by the utility model to solve the technical problem is to construct a control circuit for converting a DC-DC USB, which has:

[0006] A main charging circuit, which is configured in the control circuit and is used to charge the battery pack to be charged, wherein the main charging circuit includes a first charging branch and a second charging branch;

[0007] a first current detection circuit, a group of input terminals of which are connected to a group of signal feedback terminals of the first charging branch, for acquiring a first group of electrical signals flowing through the first charging branch;

[0008] a second current detection circuit, a group of input terminals of which are connected to a group of signal feedback terminals of the second charging branch, for acquiring a second group of electrical signals flowing through the second charging branch;

[0009] a main control circuit, a signal input end of which is connected to the output end of the first current detection circuit, for receiving the first group of electrical signals and outputting a first pulse signal according to the first group of electrical signals to control the first charging branch to charge or automatically replenish the battery pack for a second time;

[0010] Another signal input terminal of the main control circuit is connected to the output terminal of the second current detection circuit for receiving the second group of electrical signals and outputting a second pulse signal according to the second group of electrical signals to control the second charging branch to charge or automatically replenish the battery pack for a second time.

[0011] In some embodiments, the first current detection circuit includes at least a first comparator,

[0012] The non-inverting terminal of the first comparator is connected to the first signal feedback terminal of the first charging branch, and is used to obtain the first electrical signal flowing through the first charging branch.

[0013] The inverting terminal of the first comparator is connected to the second signal feedback terminal of the first charging branch, and is used to obtain the second electrical signal flowing through the first charging branch.

[0014] The first comparator compares the first electrical signal with the second electrical signal and outputs a level signal according to the comparison result.

[0015] The output end of the first comparator is connected to a signal input end of the main control circuit for receiving the level signal and adjusting the level state of the first pulse signal according to the level state of the level signal to control the first charging branch to charge / secondary automatic replenishment or shut down the battery pack.

[0016] In some embodiments, the second current detection circuit includes at least a second comparator,

[0017] The non-inverting terminal of the second comparator is connected to the first signal feedback terminal of the second charging branch, and is used to obtain the first electrical signal flowing through the second charging branch.

[0018] The inverting terminal of the second comparator is connected to the second signal feedback terminal of the second charging branch, and is used to obtain the second electrical signal flowing through the second charging branch.

[0019] The second comparator compares the first electrical signal with the second electrical signal and outputs a level signal according to the comparison result.

[0020] The output end of the second comparator is connected to another signal input end of the main control circuit for receiving the level signal and adjusting the level state of the second pulse signal according to the level state of the level signal to control the second charging branch to charge / secondary automatic replenishment or shut down the battery pack.

[0021] In some embodiments, the main control circuit includes a main controller,

[0022] A signal input terminal of the main controller is connected to the output terminal of the first comparator,

[0023] Another signal input terminal of the main controller is connected to the output terminal of the second comparator,

[0024] A signal output terminal of the main controller is connected to a signal input terminal of the first charging branch.

[0025] Another signal output terminal of the main controller is connected to the signal input terminal of the second charging branch.

[0026] In some embodiments, the first charging branch includes a first anti-reverse connection protection circuit.

[0027] The signal input end of the first anti-reverse connection protection circuit is connected to a signal output end of the main controller, and is used to receive the first pulse signal output by the main controller.

[0028] In some embodiments, the second charging branch includes a second anti-reverse connection protection circuit.

[0029] The signal input end of the second anti-reverse connection protection circuit is connected to another signal output end of the main controller, and is used to receive the second pulse signal output by the main controller.

[0030] In some embodiments, an over-temperature protection circuit is further included, one end of which is connected to one end of the battery pack to obtain a temperature signal of the battery pack.

[0031] The other end of the over-temperature protection circuit is connected to the temperature feedback end of the main control circuit, and is used to receive the temperature signal and control the on / off state of the main charging circuit according to the temperature signal.

[0032] In some embodiments, an ID detection protection circuit is further included, one end of which is connected to one end of the battery pack to obtain an ID information signal of the battery pack.

[0033] The other end of the ID detection protection circuit is connected to the ID signal feedback end of the main control circuit, and is used to receive the ID information signal and control the on / off state of the main charging circuit according to the ID information signal.

[0034] In the control circuit of the DC-DC conversion USB described in the utility model, it includes a main charging circuit for charging a rechargeable battery pack, a first current detection circuit, a second current detection circuit and a main control circuit, wherein the first current detection circuit is used to obtain a first group of electrical signals flowing through the first charging branch; the second current detection circuit is used to obtain a second group of electrical signals flowing through the second charging branch; a signal input end of the main control circuit is connected to the output end of the first current detection circuit, and is used to receive the first group of electrical signals, and output a first pulse signal and a second pulse signal according to the first group of electrical signals and the second group of electrical signals, so as to control the first charging branch and the second charging branch to charge the battery pack or automatically replenish the battery pack for a second time. Compared with the prior art, the electrical signal output by the charging branch is detected by the current detection circuit, and then fed back to the main control circuit, and after comparison / judgment by the main control circuit, the charging branch is adjusted to charge the battery pack or automatically replenish the battery pack for a second time, and the battery pack is continuously charged, so as to avoid the problem that the battery pack is not fully charged after a long period of standby or power consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which:

[0036] Figure 1 This is a circuit schematic diagram of an embodiment of a main control circuit and a main control power supply circuit provided by the utility model;

[0037] Figure 2 This is a circuit schematic diagram of an embodiment of a current detection circuit provided by the utility model;

[0038] Figure 3 This is a circuit schematic diagram of an embodiment of a wake-up circuit, a voltage detection circuit and a 5V external power supply circuit provided by the utility model;

[0039] Figure 4 This is a circuit schematic diagram of an embodiment of an over-temperature protection circuit, an ID detection protection circuit and an output protocol circuit provided by the utility model;

[0040] Figure 5 The utility model provides a circuit principle diagram of an embodiment of a main charging circuit. DETAILED DESCRIPTION

[0041] In order to have a clearer understanding of the technical features, purposes and effects of the present utility model, the specific implementation methods of the present utility model are now described in detail with reference to the accompanying drawings.

[0042] like Figure 1-Figure 5As shown, in the first embodiment of the control circuit of the DC-DC conversion USB of the utility model, the control circuit of the DC-DC conversion USB includes a main control circuit 100, a main control power circuit 200, a current detection circuit (30A, 30B), a wake-up circuit (40A, 40B), a 5V external power circuit 40C, a voltage detection circuit 40D, an over-temperature protection circuit 500, an ID detection protection circuit 600, an output protocol circuit 700 and a main charging circuit 800.

[0043] The main control circuit 100 is the core of the control circuit, and is provided with a plurality of preset values ​​(such as temperature, current and voltage). It is used to receive the detection signal fed back by the detection circuit (voltage, current and temperature), and analyze and compare it with the preset values ​​(such as temperature, current and voltage), and then output a pulse signal / control signal according to the result of the analysis and comparison; or change the duty cycle of the pulse signal to control the main charging circuit 800 to charge or continuously charge the battery pack;

[0044] The main control power supply circuit 200 provides working power to the main control circuit 100;

[0045] The current detection circuit (30A, 30B) detects the current signal of the main charging circuit 800 charging or continuously charging the battery pack, compares and processes the current signal, and then feeds it back to the main control circuit 100;

[0046] The wake-up circuit (40A, 40B) is used to wake up the device in a sleep or low-power state;

[0047] The 5V external power supply circuit 40C is used to provide a 5V voltage signal;

[0048] The voltage detection circuit 40D is used to obtain the voltage signal of the battery pack and feed the voltage signal back to the main control circuit 100;

[0049] The over-temperature protection circuit 500 is used to detect the temperature signal of the battery pack (too high / too low) and output the temperature signal to the main control circuit 100. When the input temperature signal exceeds the preset value, the main control circuit 100 will turn off the output;

[0050] The ID detection protection circuit 600 is used to obtain the information of the battery pack. If the connected battery pack does not meet the set parameters of the converter, the converter will not allow the device to discharge;

[0051] The output protocol circuit 700 is used to improve charging efficiency to shorten the charging time of the device;

[0052] The main charging circuit 800 is used to charge the battery pack or discharge the battery pack to the USB port.

[0053] Specifically, the main charging circuit 800 is configured in the control circuit and is used to charge the battery pack (B+) to be charged.

[0054] The main charging circuit 800 includes a first charging branch 810 and a second charging branch 820.

[0055] The first charging branch 810 is configured as a charging or discharging circuit to charge the battery pack (B+) connected to the branch and discharge the battery through the USB-C interface.

[0056] The function of the second charging branch 820 is the same as that of the first charging branch 810;

[0057] Further, a group of input terminals of the first current detection circuit 30A is connected to a group of signal feedback terminals of the first charging branch 810, so as to obtain a first group of electrical signals flowing through the first charging branch 810, perform comparison processing on the first group of electrical signals, and then output a group of level signals (high level or low level) according to the comparison results;

[0058] The second current detection circuit 30B has a set of input terminals connected to a set of signal feedback terminals of the second charging branch 820, and is used to obtain a second set of electrical signals flowing through the second charging branch 820, and compare and process the second set of electrical signals, and then output another set of level signals (high level or low level) according to the comparison results;

[0059] A signal input terminal of the main control circuit 100 is connected to the output terminal of the first current detection circuit 30A, and is used to receive a first set of electrical signals (or a set of level signals), and output a first pulse signal according to the first set of electrical signals (or a set of level signals), so as to control the first charging branch 810 to charge the battery pack or automatically replenish it for a second time, so as to maintain the energy of the battery pack;

[0060] Another signal input terminal of the main control circuit 100 is connected to the output terminal of the second current detection circuit 30B, and is used to receive a second group of electrical signals (or another group of level signals), and output a second pulse signal according to the second group of electrical signals (or another group of level signals) to control the second charging branch 820 to charge the battery pack or automatically replenish it for a second time to maintain the energy of the battery pack.

[0061] By using the technical solution, the electrical signal output by the charging branch (810, 820) is detected by the current detection circuit (30A, 30B), and then fed back to the main control circuit 100. After comparison / judgment by the main control circuit 100, the charging branch (810, 820) is adjusted to charge the battery pack or automatically replenish it for a second time, and the battery pack is continuously charged to avoid the problem of insufficient power of the device after the battery pack is in standby for a long time or power consumption.

[0062] In some embodiments, Figure 2 As shown, in order to obtain the accuracy of the electrical signal, a first comparator U8 may be provided in the first current detection circuit 30A, which has the function of comparing the signal and outputting a level signal according to the comparison result;

[0063] Specifically, the in-phase terminal (corresponding to pin 4) of the first comparator U8 is connected to the first signal feedback terminal (corresponding to terminal CSP1) of the first charging branch 810 through the fifty-seventh resistor R57, so as to obtain the first electrical signal flowing through the first charging branch 810.

[0064] The inverting terminal (corresponding to the 5th pin) of the first comparator U8 is connected to the second signal feedback terminal (corresponding to the CSN1 terminal) of the first charging branch 810 through the sixty-eighth resistor R68, so as to obtain the second electrical signal flowing through the first charging branch 810.

[0065] The first comparator U8 compares the first electrical signal with the second electrical signal.

[0066] When the first electrical signal is greater than the second electrical signal, the first comparator U8 outputs a high level signal.

[0067] When the second electrical signal is greater than the first electrical signal, the first comparator U8 outputs a low level signal.

[0068] The output end of the first comparator U8 (corresponding to pin 6) is connected to a signal input end of the main control circuit 100 through the sixty-second resistor R62, and is used to receive a level signal and adjust the level state of the first pulse signal according to the level state of the level signal to control the first charging branch 810 to charge / secondary automatic replenishment or shut down the battery pack.

[0069] In some embodiments, Figure 2 As shown, in order to obtain the accuracy of the electrical signal, a second comparator U3 can be set in the second current detection circuit 30B, which has the function of comparing the signal and outputting a level signal according to the comparison result;

[0070] Specifically, the in-phase terminal (corresponding to pin 4) of the second comparator U3 is connected to the first signal feedback terminal (corresponding to terminal CSP2) of the second charging branch 820 through the fifty-eighth resistor R58, so as to obtain the first electrical signal flowing through the second charging branch 820.

[0071] The inverting terminal (corresponding to the 5th pin) of the second comparator U3 is connected to the second signal feedback terminal (corresponding to the CSN2 terminal) of the second charging branch 820 through the sixty-ninth resistor R69, so as to obtain the second electrical signal flowing through the second charging branch 820.

[0072] The second comparator U3 compares the first electrical signal with the second electrical signal.

[0073] When the first electrical signal is greater than the second electrical signal, the second comparator U3 outputs a high level signal.

[0074] When the second electrical signal is greater than the first electrical signal, the second comparator U3 outputs a low-level signal, and the output end of the second comparator U3 (corresponding to pin 6) is connected to another signal input end of the main control circuit 100 through the sixty-third resistor R63, for receiving the level signal, and adjusting the level state of the second pulse signal according to the level state of the level signal, so as to control the second charging branch 820 to charge the battery pack / automatically replenish it for the second time or shut it down.

[0075] In some embodiments, Figure 1 As shown, in order to improve the reliability of the electrical signal output, the main control circuit 100 may include a main controller U4, which serves as the core of the control circuit and is used to receive corresponding temperature, current, ID or voltage signals, process the input signals, and then output pulse signals or control signals accordingly;

[0076] Specifically, a signal input terminal (corresponding to pin 14) of the main controller U4 is connected to the output terminal of the first comparator U8, and is used to receive the level signal input by the first comparator U8.

[0077] Another signal input terminal (corresponding to pin 15) of the main controller U4 is connected to the output terminal of the second comparator U3, and is used to receive the level signal input by the second comparator U3.

[0078] A signal output terminal (corresponding to pin 11) of the main controller U4 is connected to the signal input terminal of the first charging branch 810, and is used to output a first pulse signal to the first charging branch 810. When the input pulse signal is at a high level, the first charging branch 810 is controlled to be turned on;

[0079] Another signal output terminal (corresponding to pin 20) of the main controller U4 is connected to the signal input terminal of the second charging branch 820, and is used to output a second pulse signal to the second charging branch 820. When the input pulse signal is at a high level, the second charging branch 820 is controlled to be turned on.

[0080] In some embodiments, Figure 5 As shown, in order to improve the reliability of charging and discharging, a first anti-reverse connection protection circuit can be provided in the first charging branch 810, that is, when the output end is misconnected or reversely connected to other power supply equipment, the first anti-reverse connection protection circuit will close the switch tube on the output main circuit due to receiving abnormal voltage and current, thereby disconnecting the converter from the terminal equipment;

[0081] Specifically, the signal input terminal of the first anti-reverse connection protection circuit is connected to a signal output terminal (corresponding to pin 11) of the main controller U4 to receive the first pulse signal output by the main controller U4.

[0082] The first anti-reverse connection protection circuit at least includes a fifth MOS transistor Q5, which has a switch function and is selected as an N-channel MOS transistor.

[0083] The gate of the fifth MOS tube Q5 is connected to a signal output terminal (corresponding to pin 11) of the main controller U4 through the eighteenth resistor R18, the drain of the fifth MOS tube Q5 is connected to the gate of the first MOS tube Q1, the source of the fifth MOS tube Q5 is connected to the common terminal, and the source of the first MOS tube Q1 is connected to one end of the battery pack. When the output terminal is connected to other power devices by mistake or reversely, the main controller U4 outputs a low-level signal according to the feedback signal, so that the fifth MOS tube Q5 is disconnected. In some embodiments, such as Figure 5 As shown, in order to improve the reliability of charging and discharging, a second anti-reverse connection protection circuit can be provided in the second charging branch 820.

[0084] The signal input end of the second anti-reverse connection protection circuit is connected to another signal output end (corresponding to pin 20) of the main controller U4 to receive the second pulse signal output by the main controller U4.

[0085] The second anti-reverse connection protection circuit at least includes a twenty-third MOS transistor Q23, which has a switch function and is selected as an N-channel MOS transistor.

[0086] The gate of the twenty-third MOS tube Q23 is connected to another signal output terminal (corresponding to pin 20) of the main controller U4 through the one hundred and fourteenth resistor R114, the drain of the twenty-third MOS tube Q23 is connected to the gate of the twenty-second MOS tube Q22, the source of the twenty-third MOS tube Q23 is connected to the common terminal, and the source of the first MOS tube Q1 is connected to one end of the battery pack. When the output terminal is mistakenly connected or reversely connected to other power supply equipment, the main controller U4 outputs a low-level signal according to the feedback signal, so that the twenty-third MOS tube Q23 is disconnected.

[0087] In some embodiments, Figure 4 As shown, in order to improve the reliability of the battery pack operation, an over-temperature protection circuit 500 may be provided in the control circuit, which is used to detect the temperature signal of the battery pack during operation;

[0088] One end of the over-temperature protection circuit 500 (corresponding to NTC) is connected to one end of the battery pack to obtain the temperature signal of the battery pack.

[0089] The other end of the over-temperature protection circuit 500 (corresponding to MCU-NTC) is connected to the temperature feedback end (corresponding to pin 2) of the main controller U4 (belonging to the main control circuit 100) to receive the temperature signal and compare the feedback temperature signal with the temperature preset value. When the temperature signal is higher or lower than the temperature preset value, the main control circuit 100 controls the on / off state of the main charging circuit 800 according to the comparison result.

[0090] In some embodiments, Figure 4 As shown, in order to improve the reliability of the battery pack operation, an ID detection protection circuit 600 can be set in the control circuit, which is used to detect the ID information signal (or parameter information) connected to the battery pack.

[0091] Among them, one end of the ID detection protection circuit 600 (corresponding to the ID) is connected to one end of the battery pack to obtain the ID information signal of the battery pack.

[0092] The other end of the ID detection protection circuit 600 (corresponding to MCU-ID) is connected to the ID signal feedback end (corresponding to pin 1) of the main controller U4 (belonging to the main control circuit 100) to receive the ID information signal and control the on / off state of the main charging circuit 800 according to the ID information signal.

[0093] In some embodiments, Figure 3 As shown, the control circuit further includes a first wake-up circuit 40A and a second wake-up circuit 40B.

[0094] Among them, an input end of the first wake-up circuit 40A is connected to the +5V power supply end, an output end of the first wake-up circuit 40A is connected to a wake-up end (corresponding to pin 13) of the main controller U4, and another output end of the first wake-up circuit 40A is connected to an input end (corresponding to the 5V-C end) of the output protocol circuit 700;

[0095] An input end of the second wake-up circuit 40B is connected to the +5V power supply end, an output end of the second wake-up circuit 40B is connected to a wake-up end (corresponding to pin 16) of the main controller U4, and another output end of the second wake-up circuit 40B is connected to another input end (corresponding to the 5V-A end) of the output protocol circuit 700.

[0096] In some embodiments, Figure 3 As shown, the control circuit further includes a voltage detection circuit 40D, which is used to obtain a voltage signal of the battery pack;

[0097] Specifically, the input terminal of the voltage detection circuit 40D (corresponding to the BV terminal) is connected to one end of the battery pack to obtain the voltage signal of the battery pack.

[0098] The output end (Battey-V) of the voltage detection circuit 40D is connected to the voltage feedback end (corresponding to pin 4) of the main controller U4, and the acquired voltage signal is input into the main controller U4, compared with its preset voltage value, and then a control signal for controlling the first charging branch 810 and / or the second charging branch 820 to be turned on or off is output according to the comparison result.

[0099] This technical solution has the following advantages:

[0100] Plug and play, no need to set up, can automatically identify the working status and working mode; and

[0101] Automatically replenishes power until it is fully charged when power is low; and

[0102] It also has the functions of automatic wake-up, misconnection protection and reverse connection protection.

[0103] The embodiments of the utility model are described above in conjunction with the accompanying drawings, but the utility model is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the enlightenment of the utility model, ordinary technicians in this field can also make many forms without departing from the scope of protection of the utility model and the claims, which all fall within the protection of the utility model.

Claims

1. A control circuit for converting a DC-DC USB, characterized in that: have: A main charging circuit, which is configured in the control circuit and is used to charge the battery pack to be charged, wherein the main charging circuit includes a first charging branch and a second charging branch; a first current detection circuit, a group of input terminals of which are connected to a group of signal feedback terminals of the first charging branch, for acquiring a first group of electrical signals flowing through the first charging branch; a second current detection circuit, a group of input terminals of which are connected to a group of signal feedback terminals of the second charging branch, for acquiring a second group of electrical signals flowing through the second charging branch; a main control circuit, a signal input end of which is connected to the output end of the first current detection circuit, for receiving the first group of electrical signals and outputting a first pulse signal according to the first group of electrical signals to control the first charging branch to charge or automatically replenish the battery pack for a second time; Another signal input terminal of the main control circuit is connected to the output terminal of the second current detection circuit for receiving the second group of electrical signals and outputting a second pulse signal according to the second group of electrical signals to control the second charging branch to charge or automatically replenish the battery pack for a second time.

2. The control circuit of the DC-DC conversion USB according to claim 1, characterized in that: The first current detection circuit at least includes a first comparator, The non-inverting terminal of the first comparator is connected to the first signal feedback terminal of the first charging branch, and is used to obtain the first electrical signal flowing through the first charging branch. The inverting terminal of the first comparator is connected to the second signal feedback terminal of the first charging branch, and is used to obtain the second electrical signal flowing through the first charging branch. The first comparator compares the first electrical signal with the second electrical signal and outputs a level signal according to the comparison result. The output end of the first comparator is connected to a signal input end of the main control circuit for receiving the level signal and adjusting the level state of the first pulse signal according to the level state of the level signal to control the first charging branch to charge / secondary automatic replenishment or shut down the battery pack.

3. The control circuit of the DC-DC conversion USB according to claim 2, characterized in that: The second current detection circuit comprises at least a second comparator, The non-inverting terminal of the second comparator is connected to the first signal feedback terminal of the second charging branch, and is used to obtain the first electrical signal flowing through the second charging branch. The inverting terminal of the second comparator is connected to the second signal feedback terminal of the second charging branch, and is used to obtain the second electrical signal flowing through the second charging branch. The second comparator compares the first electrical signal with the second electrical signal and outputs a level signal according to the comparison result. The output end of the second comparator is connected to another signal input end of the main control circuit for receiving the level signal and adjusting the level state of the second pulse signal according to the level state of the level signal to control the second charging branch to charge / secondary automatic replenishment or shut down the battery pack.

4. The control circuit of the DC-DC conversion USB according to claim 3, characterized in that: The main control circuit comprises a main controller, A signal input terminal of the main controller is connected to the output terminal of the first comparator, Another signal input terminal of the main controller is connected to the output terminal of the second comparator, A signal output terminal of the main controller is connected to a signal input terminal of the first charging branch. Another signal output terminal of the main controller is connected to the signal input terminal of the second charging branch.

5. The control circuit of the DC-DC conversion USB according to claim 4, characterized in that: The first charging branch includes a first anti-reverse connection protection circuit, The signal input end of the first anti-reverse connection protection circuit is connected to a signal output end of the main controller, and is used to receive the first pulse signal output by the main controller.

6. The control circuit of the DC-DC conversion USB according to claim 4, characterized in that: The second charging branch includes a second anti-reverse connection protection circuit, The signal input end of the second anti-reverse connection protection circuit is connected to another signal output end of the main controller, and is used to receive the second pulse signal output by the main controller.

7. The control circuit of the DC-DC conversion USB according to claim 1, characterized in that: It also includes an over-temperature protection circuit, one end of which is connected to one end of the battery pack and is used to obtain a temperature signal of the battery pack. The other end of the over-temperature protection circuit is connected to the temperature feedback end of the main control circuit, and is used to receive the temperature signal and control the on / off state of the main charging circuit according to the temperature signal.

8. The control circuit of the DC-DC conversion USB according to claim 1, characterized in that: It also includes an ID detection protection circuit, one end of which is connected to one end of the battery pack to obtain an ID information signal of the battery pack. The other end of the ID detection protection circuit is connected to the ID signal feedback end of the main control circuit, and is used to receive the ID information signal and control the on / off state of the main charging circuit according to the ID information signal.

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