Battery constant-voltage LED drive circuit

Abstract

The utility model belongs to the circuit field, and especially relates to a battery constant voltage LED drive circuit comprising a boost module, a step-down module and an anti-backflow circuit, a common terminal of the boost module and the step-down module is provided with an access terminal used for connecting an LED lamp, and the anti-backflow circuit is arranged between the access terminal and the step-down module. According to the utility model, through the arrangement of the boost module and the step-down module, the step-down module can be used for step-down in a high-voltage state and also can be used for step-up in a low-voltage state, the anti-backflow circuit can prevent the current after step-up from flowing back to the power supply through the step-down module, and the modules are high in conversion efficiency, small in dissipation power and high in reliability. The low-voltage state electric energy of the battery can be effectively utilized, and obvious practical value and economic benefit are achieved.

Description

Technical Field

[0001] The utility model belongs to the field of circuits, and particularly relates to a battery constant voltage LED driving circuit. Background Art

[0002] In LED drive circuits, the existing technology generally adopts the following solutions:

[0003] Method 1: As follows Figure 1 , using LDO voltage regulator and step-down chip, outputting stable DC MOS tube to drive LED. This method has high power consumption. When the battery voltage is higher, the power consumption on the LDO chip is greater, and the LDO heats up seriously. LD0 itself has a voltage regulation range. When the battery is in a low voltage state, the LDO voltage reduction cannot work, the LED cannot be lit, and the low voltage part of the battery cannot be fully utilized.

[0004] Method 2: As follows Figure 2 , using resistor current limiting, directly driving the LED through the MOS tube. This method has high power consumption, and the current of lighting the LED will consume part of the energy in the form of heat on the current limiting resistor. The LED itself has a minimum voltage for lighting. When the battery is in a low voltage state, the LED cannot be lit, and the low voltage part of the battery energy cannot be fully utilized.

[0005] Therefore, there is an urgent need for a solution that has low power consumption, effectively utilizes the low-voltage state of the battery, and has obvious practical value and economic benefits. Utility Model Content

[0006] In order to solve the above problems, the purpose of the utility model is to provide a battery constant voltage LED driving circuit, which has low power consumption, effectively utilizes the low voltage state electric energy of the battery, and has obvious practical value and economic benefits.

[0007] In order to achieve the above-mentioned purpose, the technical solution of the utility model is as follows.

[0008] A battery constant voltage LED driving circuit, characterized in that it includes a boost module, a buck module and an anti-backflow circuit, wherein the common end of the boost module and the buck module is provided with an access end for connecting an LED lamp, and the anti-backflow circuit is provided between the access end and the buck module.

[0009] In the utility model, by setting up the boost module and the buck module, the voltage can be stepped down through the buck module when the voltage is high, and the voltage can be stepped up through the boost module when the voltage is low. The anti-backflow circuit can prevent the current after boosting from backflowing to the power supply through the buck module. The above-mentioned setting module has high conversion efficiency and low power dissipation, and can effectively utilize the electric energy of the battery in the low-voltage state, which has obvious practical value and economic benefits.

[0010] Furthermore, the model of the step-down module is QX34062.

[0011] Furthermore, the model of the boost module is QX2319L.

[0012] Furthermore, the buck module includes an output pin SW, the boost module includes an output pin VOUT, the access end is located at a common end of the output pin SW and the output pin VOUT, and the backflow prevention circuit is located between the output pin SW and the access end.

[0013] Furthermore, the anti-backflow circuit includes a first MOS tube Q2 and a second MOS tube Q4, the source of the first MOS tube Q2 is connected to the source of the second MOS tube Q4, the drain of the first MOS tube Q2 is connected to the output pin SW, and the drain of the second MOS tube Q4 is connected to the access end.

[0014] Furthermore, the circuit also includes a third MOS transistor Q3, a source of the third MOS transistor Q3 is connected to the output pin VOUT, and a drain of the third MOS transistor Q3 is connected to the access terminal.

[0015] Furthermore, the gate of the third MOS transistor Q3 is connected to the common end of the output pin VOUT and the source of the third MOS transistor Q3 through the first resistor R9, and the gate of the third MOS transistor Q3 is connected to the signal end SUW_EN through the second resistor R10.

[0016] Furthermore, the gate of the first MOS transistor Q2 is connected to the common end of the output pin SW and the drain of the first MOS transistor Q2 through the third resistor R8, and the gate of the first MOS transistor Q2 is connected to the signal end SDW_EN through the fourth resistor R11.

[0017] Furthermore, the gate of the second MOS transistor Q4 is connected to the common end of the source of the first MOS transistor Q2 and the source of the second MOS transistor Q4 through the fifth resistor R4, and the gate of the second MOS transistor Q4 is connected to the signal end SDW_EN through the sixth resistor R13.

[0018] In the utility model, compared with the prior art, through the setting of the boost module and the buck module, the voltage can be stepped down through the buck module when the voltage is high, and the voltage can be stepped up through the boost module when the voltage is low. The anti-backflow circuit can prevent the current after boosting from backflowing to the power supply through the buck module. The above-mentioned setting module has high conversion efficiency and low power dissipation, and can effectively utilize the electric energy of the battery in the low-voltage state, which has obvious practical value and economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of an LDO voltage-stabilizing and voltage-stepping LED driving circuit in the prior art.

[0020] Figure 2 It is a schematic diagram of a resistor current limiting LED driving circuit in the prior art.

[0021] Figure 3 It is a circuit schematic diagram of the utility model. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the utility model and are not used to limit the utility model.

[0023] See also Figure 3 A battery constant voltage LED driving circuit includes a boost module U3, a buck module U5 and an anti-backflow circuit. The common end of the boost module U3 and the buck module U5 is provided with an access end for connecting an LED lamp, and the anti-backflow circuit is arranged between the access end and the buck module U5.

[0024] In the utility model, by setting the boost module U3 and the buck module U5, the voltage can be stepped down through the buck module U5 when the voltage is high, and the voltage can be stepped up through the boost module U3 when the voltage is low. The anti-backflow circuit can prevent the boosted current from backflowing to the power supply through the buck module U5. The above-mentioned setting module has high conversion efficiency and low power dissipation, and can effectively utilize the low-voltage electric energy of the battery, which has obvious practical value and economic benefits.

[0025] In this embodiment, the model of the step-down module U5 is QX34062.

[0026] In this embodiment, the model of the boost module U3 is QX2319L.

[0027] In this embodiment, the buck module U5 includes an output pin SW, the boost module U3 includes an output pin VOUT, the access terminal is located at the common terminal of the output pin SW and the output pin VOUT, and the backflow prevention circuit is located between the output pin SW and the access terminal.

[0028] In this embodiment, the backflow prevention circuit includes a first MOS transistor Q2 and a second MOS transistor Q4, the source of the first MOS transistor Q2 is connected to the source of the second MOS transistor Q4, the drain of the first MOS transistor Q2 is connected to the output pin SW, and the drain of the second MOS transistor Q4 is connected to the access terminal.

[0029] In this embodiment, the circuit further includes a third MOS transistor Q3, a source of the third MOS transistor Q3 is connected to the output pin VOUT, and a drain of the third MOS transistor Q3 is connected to the access terminal.

[0030] In this embodiment, the gate of the third MOS transistor Q3 is connected to the common end of the output pin VOUT and the source of the third MOS transistor Q3 through the first resistor R9, and the gate of the third MOS transistor Q3 is connected to the signal end SUW_EN through the second resistor R10.

[0031] In this embodiment, the gate of the first MOS transistor Q2 is connected to the common end of the output pin SW and the drain of the first MOS transistor Q2 through the third resistor R8, and the gate of the first MOS transistor Q2 is connected to the signal end SDW_EN through the fourth resistor R11.

[0032] In this embodiment, the gate of the second MOS transistor Q4 is connected to the common end of the source of the first MOS transistor Q2 and the source of the second MOS transistor Q4 through the fifth resistor R4, and the gate of the second MOS transistor Q4 is connected to the signal end SDW_EN through the sixth resistor R13.

[0033] During specific operation, the buck module U5 (QX34062): BAT is powered by an external battery and inputs 1.8V~5V DC. SD_EN is the buck enable pin, which is enabled at a high level when the buck module needs to be enabled. FB is the feedback pin, which is connected to the external R6 feedback resistor to determine the output voltage. SW is the output pin that outputs the stepped-down DC power, and C2 is the output filter capacitor. Q2 and Q4 form an anti-backflow circuit, which is used to prevent the power supply from backflowing to BAT through the buck circuit after boosting. R8 is used to provide pull-up for the G stage of Q2, R4 is used to provide pull-up for the G stage of Q4, and R11 and R13 are current limiting resistors for the control signal.

[0034] There is a boost module U3 (QX2319L): BAT is powered by an external battery, inputting 1.8V~5V DC. SU_EN is to enable boost, and high level is enabled when it is needed. VOUT is the output pin, outputting boosted DC, and C10 is the output filter capacitor. Q3 is an electronic switch for driving LEDs, used for LED dimming, R9 provides pull-up for the G level of Q3, and R10 is a control signal current limiting resistor. LED+ is connected to the positive pole of the external LED, and LED- is connected to the negative pole of the external LED.

[0035] Anti-backflow circuit: Q2 and Q4 form an anti-backflow circuit, which is used to prevent the power supply from backflowing to BAT through the step-down circuit after boosting.

[0036] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A battery constant voltage LED driving circuit, characterized in that: It includes a boost module, a buck module and an anti-backflow circuit. The common end of the boost module and the buck module is provided with an access end for connecting an LED lamp, and the anti-backflow circuit is arranged between the access end and the buck module.

2. A battery constant voltage LED driving circuit as claimed in claim 1, characterized in that: The model of the step-down module is QX34062.

3. A battery constant voltage LED driving circuit as claimed in claim 1, characterized in that: The model of the boost module is QX2319L.

4. A battery constant voltage LED driving circuit as claimed in claim 1, characterized in that: The buck module includes an output pin SW, the boost module includes an output pin VOUT, the access end is located at a common end of the output pin SW and the output pin VOUT, and the backflow prevention circuit is located between the output pin SW and the access end.

5. A battery constant voltage LED driving circuit as claimed in claim 4, characterized in that: The backflow prevention circuit includes a first MOS tube Q2 and a second MOS tube Q4, the source of the first MOS tube Q2 is connected to the source of the second MOS tube Q4, the drain of the first MOS tube Q2 is connected to the output pin SW, and the drain of the second MOS tube Q4 is connected to the access terminal.

6. A battery constant voltage LED driving circuit as claimed in claim 5, characterized in that: The circuit also includes a third MOS transistor Q3, a source of the third MOS transistor Q3 is connected to the output pin VOUT, and a drain of the third MOS transistor Q3 is connected to the access terminal.

7. A battery constant voltage LED driving circuit as claimed in claim 6, characterized in that: The gate of the third MOS transistor Q3 is connected to the common end of the output pin VOUT and the source of the third MOS transistor Q3 through the first resistor R9, and the gate of the third MOS transistor Q3 is connected to the signal end SUW_EN through the second resistor R10.

8. A battery constant voltage LED driving circuit as claimed in claim 5, characterized in that: The gate of the first MOS transistor Q2 is connected to the common end of the output pin SW and the drain of the first MOS transistor Q2 through the third resistor R8, and the gate of the first MOS transistor Q2 is connected to the signal end SDW_EN through the fourth resistor R11.

9. A battery constant voltage LED driving circuit as claimed in claim 5, characterized in that: The gate of the second MOS transistor Q4 is connected to the common end of the source of the first MOS transistor Q2 and the source of the second MOS transistor Q4 through the fifth resistor R4, and the gate of the second MOS transistor Q4 is connected to the signal end SDW_EN through the sixth resistor R13.

Images