Electric bicycle lamp control circuit

Abstract

The utility model provides an electric bicycle lamp control circuit which comprises a DC-DC power supply chip, a single-chip microcomputer and a resistance voltage-dividing network composed of at least two resistors, the voltage output end of the DC-DC power supply chip and a feedback pin are connected with the resistance voltage-dividing network, and a DAC function pin of the single-chip microcomputer is connected with the feedback pin of the DC-DC power supply chip after passing through a voltage-dividing resistor. According to the invention, the single-chip microcomputer outputs the DAC voltage to the FB pin of the DC-DC chip, so that the chip adjusts the output frequency according to the VFB voltage; therefore, the effect that the output voltage is adjustable in software is achieved. Compared with a traditional scheme of changing the output voltage by adjusting hardware feedback resistance, maintenance work of hardware BOM and materials is reduced, and research and development management cost is reduced.

Description

Technical Field

[0001] This application relates to the field of electric bicycle light control, and more specifically, to an electric bicycle light control circuit. Background Technology

[0002] As a convenient mode of transportation, the performance and reliability of electric bicycle lights are crucial. Existing electric bicycle light control circuits suffer from inconsistent power supply voltages, including 6V, 12V, and battery voltage. Traditional solutions involve adjusting the output feedback resistor using a DC-DC power supply chip to obtain the target voltage. However, this increases the number of feedback resistor models and the quantity of components in the production BOM (Bill of Materials), leading to potential errors and higher maintenance and management costs. Therefore, a low-cost electric bicycle light control circuit with adjustable output voltage is needed to address these issues. Utility Model Content

[0003] The purpose of this application is to provide an electric bicycle light control circuit that solves the problem of high maintenance, development and management costs in the prior art.

[0004] An electric bicycle light control circuit is provided, including a DC-DC power chip. The input terminal of the DC-DC power chip is connected to a power source, and the voltage output terminal of the DC-DC power chip provides the voltage required for the operation of the electric bicycle light. It also includes a control module with analog signal output function and a resistor divider network composed of at least two resistors. The voltage output terminal and feedback pin of the DC-DC power chip are connected to the resistor divider network, and the analog signal output pin of the control module is connected to the feedback pin of the DC-DC power chip through the voltage divider resistors.

[0005] In one optional embodiment, the resistor divider network includes a first resistor and a second resistor. The first resistor is connected to the voltage output terminal and the feedback pin of the DC-DC power chip, respectively. The first terminal of the second resistor is connected to the feedback pin, and the second terminal is grounded.

[0006] In one optional implementation, the control module is a microcontroller, and the DAC function pin of the microcontroller is connected to the feedback pin of the DC-DC power supply chip through a voltage divider resistor.

[0007] In one optional embodiment, a MOS transistor control circuit is further included. The MOS transistor control circuit includes a MOS transistor, the source and drain of which are respectively connected to the voltage output terminal of the DC-DC power supply chip and the electric bicycle light, and the gate is connected to the control signal.

[0008] In one alternative implementation, the source and gate of the MOS transistor are interconnected.

[0009] In one optional implementation, the MOS transistor control circuit further includes a transistor, wherein the emitter of the transistor is grounded, the collector is connected to the gate of the MOS transistor through a resistor, and the base is connected to the control signal.

[0010] In one optional implementation, the BST pin of the DC-DC power supply chip is connected to the SW pin through a resistor and a capacitor, and the SW pin is connected to the MOSFET control circuit through an inductor.

[0011] In one alternative implementation, a diode is further included, with the negative terminal of the diode connected to the SW pin and the positive terminal grounded.

[0012] In one optional embodiment, a capacitor is further provided between the feedback pin and the voltage output terminal of the DC-DC power supply chip.

[0013] In one optional implementation, the maximum power dissipation of the MOSFET is greater than the power loss.

[0014] This application outputs a DAC voltage from a microcontroller to the FB pin of a DC-DC chip, allowing the chip to adjust its output frequency based on the VFB voltage; thus achieving software-adjustable output voltage. Compared to traditional methods that adjust the output voltage by changing the hardware feedback resistor, this reduces hardware BOM and material maintenance work, lowering R&D management costs.

[0015] Furthermore, a MOSFET control circuit has been added to the output end, which can not only provide isolation to prevent the power chip from outputting high voltage at the moment of power-on and damaging the low voltage lamp, but also meet the customer's need for multi-channel vehicle light control by adding a multi-channel MOSFET control circuit. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments of this application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of a DC-DC power supply circuit for an electric bicycle light control circuit provided in an embodiment of this application.

[0018] Figure 2 This is a schematic diagram of a DAC output circuit for an electric bicycle headlight control circuit provided in an embodiment of this application.

[0019] Figure 3 This is a schematic diagram of a MOS transistor control circuit for an electric bicycle headlight control circuit provided in an embodiment of this application. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. Unless otherwise defined, the technical or scientific terms used in this application should have the ordinary meaning understood by those skilled in the art. The words "first," "second," and similar terms used in this application do not indicate any order, quantity, or importance, but are only used to distinguish different components. The words "comprising" or "including," etc., mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, but do not exclude other elements or objects. The words "connected," "coupled," or "connected," etc., are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. "Up," "down," "left," "right," etc., are only used to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0021] The preferred embodiments of this application are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit this application. Furthermore, the embodiments and features in the embodiments of this application can be combined with each other without conflict.

[0022] The electric bicycle light control circuit provided in this application includes three parts: the first part is a DC-DC power supply circuit, the second part is a MOSFET control circuit, and the third part is a DAC output circuit. The three parts are described in detail below.

[0023] DC-DC power supply circuits such as Figure 1 As shown, the device includes a DC-DC power supply chip. The VIN pin of the DC-DC power supply chip is connected to a 36V power supply, and the EN pin is connected to a 5V control voltage. The output voltage of the DC-DC power supply chip provides the necessary voltage for the electric bicycle's lights. A resistor divider network consisting of at least two resistors is configured. The output voltage of the DC-DC power supply chip and the feedback pin (FB pin) are connected to the resistor divider network. The resistor divider network includes a first resistor R056 and a second resistor R066. The two ends of the first resistor R056 are connected to the output voltage of the DC-DC power supply chip and the feedback pin, respectively. The first end of the second resistor is connected to the feedback pin, and the second end is grounded.

[0024] The BST pin of the DC-DC power supply chip is connected to the SW pin via resistor R049 and capacitor C005. The SW pin is then connected to the MOSFET control circuit via inductor L001. Additionally, a diode D001 is included, with its cathode connected to the SW pin and its anode grounded. A capacitor C006 is also placed between the feedback pin and the voltage output terminal of the DC-DC power supply chip.

[0025] The SW pin is the connection point between the internal power switch of the power chip and the external inductor. The SW pin participates in the energy storage and release process and is crucial for voltage conversion. When the internal switch is on, current flows through the SW pin to the external inductor and then to the output. When the switch is off, current continues to flow in the inductor, but due to the collapse of the magnetic field, the current returns to the input or ground through the freewheeling diode or synchronous rectifier MOSFET.

[0026] The BST pin is the connection point for the bootstrap capacitor used to drive the high-side MOSFET. When the high-side MOSFET needs to be turned on, the bootstrap capacitor provides the necessary voltage to drive its gate. Choosing a suitable bootstrap capacitor is crucial; it needs to be able to charge and discharge quickly and have sufficient capacitance to ensure the high-side MOSFET can be reliably turned on. The bootstrap capacitor should be placed as close as possible to the BST and SW pins to reduce parasitic inductance and noise interference.

[0027] DAC output circuit such as Figure 2 As shown, it includes a microcontroller with DAC function. The DAC function pin is connected to the feedback pin of the DC-DC power supply chip through a voltage divider resistor R096.

[0028] The microcontroller outputs a voltage to the FB pin of the DC-DC power supply chip via its DAC function pin. When the voltage VFB applied to the FB pin of the DC-DC power supply chip is greater than 0.8V, the chip's internal comparator is triggered, automatically reducing the output frequency. Conversely, when VFB is less than 0.8V, the chip automatically increases the output frequency to maintain VFB at 0.8V. It should be noted that the VFB value may differ between different power supply chip models, and 0.8V may represent other values. This example only uses a power supply chip with a VFB of 0.8V.

[0029] Combination Figure 1 and Figure 2 It can be seen that the current through resistor R066 is the sum of the currents through resistors R056 and R096. Further, it can be deduced that:

[0030] (VOUT-0.8V) / R056+(Vdac-0.8V) / R096=0.8V / R066;

[0031] Where VOUT represents the output voltage of the DC-DC power supply circuit, and Vdac represents the adjustable voltage provided by the microcontroller. The output voltage of the power supply circuit can be adjusted simply by changing the Vdac value provided by the microcontroller, without needing to replace the resistors in the resistor divider network. Utilizing the programmable nature of the microcontroller, the value of Vdac can be directly adjusted through the program, reducing errors and lowering subsequent maintenance and management costs.

[0032] MOSFET control circuit, such as Figure 3 As shown, the device includes a MOSFET Q7. The source and drain of MOSFET Q7 are connected to the voltage output terminal of the DC-DC power supply chip and the electric bicycle light, respectively, while the gate is connected to a control signal. The source and gate of the MOSFET are interconnected, and a resistor R69 can be placed on the interconnection branch.

[0033] The MOSFET control circuit also includes a transistor Q8. The emitter of the transistor is grounded, the collector is connected to the gate of the MOSFET through a resistor R71, and the base is connected to the control signal. The control signal comes from the main control chip of the electric bicycle motor controller.

[0034] When the enable pin of this power chip is not controlled by the microcontroller, the chip will output a high voltage of about 41V when the DAC pin of the microcontroller does not output voltage at the moment of power-on, due to the feedback resistor. When the DAC voltage is applied to the FB pin of the chip, the output voltage will be adjusted to the target voltage. Therefore, a MOSFET control circuit is added at the output end, which can not only play an isolation role to prevent the high voltage at the moment of power-on from damaging the low voltage lamp, but also solve the control needs of multiple vehicle lights.

[0035] Considering the situations of output overcurrent and short circuit to ground, in order to ensure that the MOSFET is not burned out, it is necessary to calculate the conduction loss of the MOSFET itself when the subsequent stage is short-circuited.

[0036] When the headlights are on, the Q7 MOSFET is turned on, and the headlights operate normally. When the positive terminal of the headlight is short-circuited to ground, the current increases instantaneously, triggering the short-circuit protection function of the DC-DC power supply. The DC-DC chip has peak current limits and special valley current limits. During the HS-FET's conduction period, it monitors the inductor current. If the sensed inductor current reaches the peak current limit after the blanking time, the HS-FET will turn off. Because the peak current limit has a blanking time, for asynchronous buck circuits, the inductor current may run away when the output is short-circuited to ground. Its special valley current limit prevents this from happening. When the HS-FET is off and the inductor current is greater than the valley current limit, the HS-FET will remain off until the output current drops below the valley current limit threshold. When the output is short-circuited to ground, the DC-DC chip automatically reduces the switching frequency to prevent current runaway and improve system reliability.

[0037] The conduction loss power P of the MOSFET is calculated by dividing the VDS voltage drop of the MOSFET by its internal resistance. Then, a MOSFET with a maximum dissipation power PD that is much greater than this power loss is selected.

[0038] Obviously, those skilled in the art can make various modifications and variations to the embodiments of this application without departing from the spirit and scope of the embodiments of this application. Therefore, if these modifications and variations to the embodiments of this application fall within the scope of the claims in this application and their equivalents, then this application also intends to include these modifications and variations.

[0039] Although preferred embodiments of this application have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this application.

Claims

1. An electric bicycle light control circuit, comprising a DC-DC power supply chip, wherein the input terminal of the DC-DC power supply chip is connected to a power source, and the voltage output terminal of the DC-DC power supply chip provides the voltage required for the operation of the electric bicycle light, characterized in that: It also includes a control module with analog signal output function and a resistor divider network consisting of at least two resistors. The voltage output terminal and feedback pin of the DC-DC power chip are connected to the resistor divider network, and the analog signal output pin of the control module is connected to the feedback pin of the DC-DC power chip through the voltage divider resistor.

2. The electric bicycle light control circuit as described in claim 1, characterized in that: The resistor divider network includes a first resistor and a second resistor. The first resistor is connected to the voltage output terminal and the feedback pin of the DC-DC power chip, respectively. The first terminal of the second resistor is connected to the feedback pin, and the second terminal is grounded.

3. The electric bicycle light control circuit as described in claim 1, characterized in that: The control module is a microcontroller, and the DAC function pin of the microcontroller is connected to the feedback pin of the DC-DC power supply chip through a voltage divider resistor.

4. The electric bicycle light control circuit as described in claim 3, characterized in that: It also includes a MOS transistor control circuit, which further includes a MOS transistor. The source and drain of the MOS transistor are respectively connected to the voltage output terminal of the DC-DC power supply chip and the electric bicycle light, and the gate is connected to the control signal.

5. The electric bicycle light control circuit as described in claim 4, characterized in that: The source and gate of the MOS transistor are interconnected.

6. The electric bicycle light control circuit as described in claim 4 or 5, characterized in that: The MOS transistor control circuit also includes a transistor, the emitter of which is grounded, the collector is connected to the gate of the MOS transistor through a resistor, and the base is connected to the control signal.

7. The electric bicycle light control circuit as described in claim 6, characterized in that: The BST pin of the DC-DC power chip is connected to the SW pin through a resistor and a capacitor, and the SW pin is connected to the MOSFET control circuit through an inductor.

8. The electric bicycle light control circuit as described in claim 7, characterized in that: It also includes a diode, the negative terminal of which is connected to the SW pin and the positive terminal is grounded.

9. The electric bicycle light control circuit as described in claim 8, characterized in that: A capacitor is also provided between the feedback pin and the voltage output terminal of the DC-DC power supply chip.

10. The electric bicycle light control circuit as described in claim 9, characterized in that: The maximum power dissipation of the MOSFET is greater than the power loss.

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