Universal high-precision DCDC constant current circuit

Abstract

The utility model relates to a universal high-precision DCDC constant current circuit. The circuit comprises an input unit, a current protection unit, a filtering unit, a constant current control unit and an LED display unit which are connected in sequence. The filtering unit comprises a pi-type filtering circuit and a first filtering circuit which are connected with each other, and the pi-type filtering circuit comprises a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first inductor L1 and a first diode D1. One end of the first capacitor C1 is respectively connected with the current protection unit, one end of the second capacitor C2, one end of the first inductor L1 and the negative electrode of the first diode D1; the other end of the first capacitor C1 is connected with the other end of the second capacitor C2 and then is grounded; the positive electrode of the first diode D1 is connected with the other end of the first inductor L1, one end of the third capacitor C3, one end of the fourth capacitor C4 and the first filter circuit.

Description

TECHNICAL FIELD

[0001] The utility model relates to a car light circuit, especially disclose a general high accuracy DCDC constant current circuit. BACKGROUND

[0002] With the rapid development of the automobile industry, the automobile lamp market prospect can be expected. As one of the most common LED circuits, people increasingly hope that the circuit of each function can have universality, modularity and high precision. The present application aims to invent a multi-purpose, high-precision linear circuit that can easily cope with various interference experiments such as EMC.

[0003] The current separate constant current circuit either concentrates heat on some components, resulting in uneven heat distribution of the entire lamp panel; or has no price advantage, and the use precision is not obvious enough, which has a greater impact on the LED light of the vehicle. There are many components that meet the precision requirements; or uses IC control, which has no cost advantage and is subject to greater EMC interference. SUMMARY

[0004] The utility model discloses a kind of general high accuracy DCDC constant current circuits, which can achieve constant current with as few components as possible, have simple structure and good universality, can greatly reduce cost and save space, and adapt to the miniaturization trend of car light.

[0005] The utility model is implemented as follows: a general high accuracy DCDC constant current circuit, comprising input unit, current protection unit, filter unit, constant current control unit and LED display unit connected in sequence; the filter unit comprises a π-type filter circuit and a first filter circuit connected to each other, the π-type filter circuit comprises a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first inductor L1 and a first diode D1, one end of the first capacitor C1 is connected to the current protection unit, one end of the second capacitor C2, one end of the first inductor L1 and the negative electrode of the first diode D1 respectively; the other end of the first capacitor C1 is connected to the other end of the second capacitor C2 and then grounded; the positive electrode of the first diode D1 is connected to the other end of the first inductor L1, one end of the third capacitor C3, one end of the fourth capacitor C4 and the first filter circuit respectively; the other end of the third capacitor C3 is connected to the other end of the fourth capacitor C4 and then grounded.

[0006] The first filter circuit comprises a fifth capacitor C5, a sixth capacitor C6 and a seventh capacitor C7 connected in parallel; one end of the fifth capacitor C5, the sixth capacitor C6 and the seventh capacitor C7 connected in parallel is grounded, and the other end is connected to the π-type filter circuit and the constant current control unit respectively.

[0007] The constant current control unit includes a control chip U1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, an eighth capacitor C8, a ninth capacitor C9, a tenth capacitor C10, an eleventh capacitor C11, a twelfth capacitor C12, a thirteenth capacitor C13, a fourteenth capacitor C14, a fifteenth capacitor C15, a Schottky diode D2, a second inductor L2, a first magnetic bead B1, a second magnetic bead B2, and a first interface P1; the control chip U1 includes a VIN pin, an EN pin, a TON pin, a VCC pin, a SW pin, a BOOT pin, a CS pin, an EP pin, and a GND pin;

[0008] One end of the first resistor R1 is connected with the filtering unit, the VIN pin, and the EN pin of the control chip U1, and the other end of the first resistor R1 is connected with the TON pin; the VCC pin is grounded through the fourteenth capacitor C14.

[0009] The BOOT pin is connected with one end of the fifteenth capacitor C15, and the other end of the fifteenth capacitor C15 is connected with the SW pin, one end of the second inductor L2, the negative electrode of the Schottky diode D2, and one end of the eighth capacitor C8; the other end of the eighth capacitor C8 is connected with one end of the second resistor R2, and the other end of the second resistor R2 is connected with the positive electrode of the Schottky diode D2 and then grounded; the other end of the second inductor L2 is connected with one end of the ninth capacitor C9, one end of the tenth capacitor C10, and one end of the first magnetic bead B1, and the other end of the first magnetic bead B1 is connected with the first interface P1; the other end of the ninth capacitor C9 is connected with one end of the third resistor R3, one end of the fourth resistor R4, one end of the fifth resistor R5, the other end of the tenth capacitor C10, and one end of the second magnetic bead B2; the other end of the second magnetic bead B2 is connected with the first interface P1; the other end of the fourth resistor R4 is connected with the other end of the fifth resistor R5 and then grounded; the other end of the third resistor R3 is connected with one end of the sixth resistor R6, one end of the twelfth capacitor C12, and the CS pin, and the other end of the twelfth capacitor C12 is grounded; the other end of the sixth resistor R6 is connected with one end of the thirteenth capacitor C13 and the first interface P1, and the other end of the thirteenth capacitor C13 is grounded; the constant current control unit is connected with the LED display unit through the first interface P1.

[0010] The current protection unit includes a reverse protection unit and a surge protection unit, one end of the reverse protection unit is connected with the input unit, and the other end of the reverse protection unit is connected with the surge protection unit and the π-type filtering unit.

[0011] The reverse protection unit comprises a third diode D3, the surge protection unit comprises a seventh resistor R7 and a bidirectional transient voltage suppression diode D4, the positive electrode of the third diode D3 is connected with the input unit, the negative electrode of the third diode D3 is connected with one end of the seventh resistor R7 and the filter unit respectively, the other end of the seventh resistor R7 is connected with one end of the bidirectional transient voltage suppression diode D4, and the other end of the bidirectional transient voltage suppression diode D4 is grounded.

[0012] The input unit comprises a sixteenth capacitor C16 and a seventeenth capacitor C17, one end of the sixteenth capacitor C16 is an input end and is connected with the current protection unit, and the other end of the sixteenth capacitor C16 is grounded through the seventeenth capacitor C17.

[0013] The LED display unit comprises a second interface P2, an eighteenth capacitor C18, a nineteenth capacitor C19, a twentieth capacitor C20, an eighth resistor R8, a first light emitting diode LD1 and a second light emitting diode LD2, one end of the eighteenth capacitor C18 is connected with the second interface P2 and the positive electrode of the first light emitting diode LD1 respectively, the other end of the eighteenth capacitor C18 is connected with one end of the nineteenth capacitor C19, the negative electrode of the first light emitting diode LD1 and the positive electrode of the second light emitting diode LD2 respectively, the other end of the nineteenth capacitor C19 is connected with the negative electrode of the second light emitting diode LD2 and then connected into the second interface P2, and one end of the twentieth capacitor C20 is connected with one end of the eighth resistor R8 and the second interface P2 respectively, and the other end of the twentieth capacitor C20 is connected with the second interface P2 and the other end of the eighth resistor R8 and then grounded.

[0014] The beneficial effects of the utility model are: through the filter unit π type circuit plus reverse protection and pulse protection, various experimental requirements such as EMC and pulse are easily coped with, through the constant current control unit, constant current output is provided to drive the LED, through the DCDC step-down conversion of control chip U1, the resistance for adjusting LED current is placed on the LED display unit, the current flowing through the LED can be adjusted at any time according to the model of LED to realize the constant of LED current.

[0015] The utility model can reach constant current, simple structure and good universality with as few components as possible, can greatly reduce cost and save space, conforms to the trend of miniaturization of vehicle lamp and is applied to multifunctional module. ACCORDING TO THE DRAWINGS

[0016] Figure 1 It is the circuit structure schematic view of the input unit, current protection unit, filter unit and constant current control unit of the utility model.

[0017] Figure 2It is the circuit structure schematic view of the LED display unit of the utility model.

[0018] Among them: 1, input unit, 2, current protection unit, 3, filter unit, 4, constant current control unit, 5, LED display unit, 6, π type filter circuit, 7, first filter circuit, 8, reverse protection unit, 9, surge protection unit. PREFERRED EMBODIMENT

[0019] According to Figure 1 、 Figure 2 The utility model discloses a general high-precision DCDC constant current circuit, which comprises input unit 1, current protection unit 2, filter unit 3, constant current control unit 4 and LED display unit 5 which are sequentially connected, the filter unit 3 comprises π type filter circuit 6 and first filter circuit 7 which are connected with each other, the π type filter circuit 6 comprises first capacitor C1, second capacitor C2, third capacitor C3, fourth capacitor C4, first inductor L1 and first diode D1, one end of the first capacitor C1 is connected with the current protection unit 2, one end of the second capacitor C2, one end of the first inductor L1 and the negative pole of the first diode D1 respectively, the other end of the first capacitor C1 is connected with the other end of the second capacitor C2 and then grounded, the positive pole of the first diode D1 is connected with the other end of the first inductor L1, one end of the third capacitor C3, one end of the fourth capacitor C4 and the first filter circuit respectively, the other end of the third capacitor C3 is connected with the other end of the fourth capacitor C4 and then grounded.

[0020] The first filter circuit comprises fifth capacitor C5, sixth capacitor C6 and seventh capacitor C7 which are connected in parallel, one end of the fifth capacitor C5, the sixth capacitor C6 and the seventh capacitor C7 connected in parallel is grounded, and the other end is connected with the π type filter circuit 6 and the constant current control unit 4 respectively.

[0021] The first round of filtering interference signal is filtered through the first capacitor C1 and the second capacitor C2 to remove a part of interference components. After the second round of filtering, the signal is added to the first inductor L1, the third capacitor C3 and the fourth capacitor C4, which can be regarded as LC filtering. Due to the complexity of the working environment, the current on the first inductor L1 changes rapidly in a short time, for example, the power supply end is powered on, U=L*di / dt, which causes a voltage difference between the two ends of the first inductor L1. At this time, the current is collected to the node connected with the third capacitor C3 at the rear end of the first inductor L1, and the current is released after the impact on the control main chip U1 behind the circuit. At this time, the first diode D1 exists and releases the current at the rear end of the first inductor L1 to the node connected with the second capacitor C2.

[0022] The constant current control 4 unit includes a control chip U1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, an eighth capacitor C8, a ninth capacitor C9, a tenth capacitor C10, an eleventh capacitor C11, a twelfth capacitor C12, a thirteenth capacitor C13, a fourteenth capacitor C14, a fifteenth capacitor C15, a Schottky diode D2, a second inductor L2, a first magnetic bead B1, a second magnetic bead B2, and a first interface P1; the control chip U1 includes a VIN pin, an EN pin, a TON pin, a VCC pin, a SW pin, a BOOT pin, a CS pin, an EP pin, and a GND pin;

[0023] One end of the first resistor R1 is connected with the filter unit, the VIN pin, and the EN pin of the control chip U1, and the other end of the first resistor R1 is connected with the TON pin; the VCC pin is grounded through the fourteenth capacitor C14;

[0024] The BOOT pin is connected with one end of the fifteenth capacitor C15, and the other end of the fifteenth capacitor C15 is connected with the SW pin, one end of the second inductor L2, the negative electrode of the Schottky diode D2, and one end of the eighth capacitor C8; the other end of the eighth capacitor C8 is connected with one end of the second resistor R2, and the other end of the second resistor R2 is connected with the positive electrode of the Schottky diode D2 and then grounded; the other end of the second inductor L2 is connected with one end of the ninth capacitor C9, one end of the tenth capacitor C10, and one end of the first magnetic bead B1, and the other end of the first magnetic bead B1 is connected with the first interface P1; the other end of the ninth capacitor C9 is connected with one end of the third resistor R3, one end of the fourth resistor R4, one end of the fifth resistor R5, the other end of the tenth capacitor C10, and one end of the second magnetic bead B2; the other end of the second magnetic bead B2 is connected with the first interface P1; the other end of the fourth resistor R4 is connected with the other end of the fifth resistor R5 and then grounded; the other end of the third resistor R3 is connected with one end of the sixth resistor R6, one end of the twelfth capacitor C12, and the CS pin, and the other end of the twelfth capacitor C12 is grounded; the other end of the sixth resistor R6 is connected with one end of the thirteenth capacitor C13 and the first interface P1, and the other end of the thirteenth capacitor C13 is grounded; the constant current control unit is connected with the LED display unit through the first interface P1.

[0025] The control chip U1 is an A6217 chip produced by American Eglo (EGLO) Company. allegro)

[0026] ​When the circuit is working normally, the positive input port is powered on, and when the voltage is 13.5V, the third diode D3 is turned on, and a large current flows through the first inductor L1 into the control chip U1. When the upper FET in the control chip U1 is turned on, the current flows through the FET, T, through the second inductor L2, the first magnetic bead B1, and into the load, i.e. the first light-emitting diode LD1 and the second light-emitting diode LD2. When the upper FET in the control chip U1 is turned off, the freewheeling current flows from the Schottky diode D2, the second inductor L2, back to the load, i.e. the first light-emitting diode LD1 and the second light-emitting diode LD2. The twelfth capacitor C12, the third resistor R3, the fourth resistor R4, the fifth resistor R5, and the sixth resistor R6, and the eighth resistor R8 of the LED display unit part form a current regulating unit for regulating the current flowing through the first light-emitting diode LD1 and the second light-emitting diode LD2. The twelfth capacitor C12 is configured to control the current, the detection resistor, and the capacitor near the control IC, and through the signal line and the GND, the noise influence is suppressed. The resistance value of the eighth resistor R8 is adjusted according to the actual specification parameters of the first light-emitting diode LD1 and the second light-emitting diode LD2, and is produced together with the first light-emitting diode LD1 and the second light-emitting diode LD2, and the other parts are fixed values. The first resistor R1 is used to set the switching frequency of the chip. The first magnetic bead B1 and the second magnetic bead B2 are mainly used to suppress high-frequency parts, mainly for RI and BCI.

[0027] The current protection unit 2 includes a reverse protection unit 8 and a surge protection unit 9, one end of the reverse protection unit 8 is connected with the input unit 1, and the other end of the reverse protection unit 8 is connected with the surge protection unit 9 and the π-type filter unit 6 respectively.

[0028] The reverse protection unit 8 includes a third diode D3, and the surge protection unit 9 includes a seventh resistor R7 and a bidirectional transient suppression diode D4; the positive electrode of the third diode D3 is connected with the input unit, and the negative electrode of the third diode D3 is connected with one end of the seventh resistor R7 and the filter unit respectively; the other end of the seventh resistor R7 is connected with one end of the bidirectional transient suppression diode D4, and the other end of the bidirectional transient suppression diode D4 is grounded. The reverse protection unit 8 protects the rear-end circuit from polarity reverse connection and negative surge impact; the surge protection unit 9 further protects the rear-end circuit from the surge impact defined in ISO 7637-2 and the electrostatic discharge impact of ISO, and provides long-term reliability stability.

[0029] The input unit 1 comprises a sixteenth capacitor C16 and a seventeenth capacitor C17, one end of the sixteenth capacitor C16 is an input end and is connected with the current protection unit 2; the other end of the sixteenth capacitor C16 is grounded through the seventeenth capacitor C17. The sixteenth capacitor C16 and the seventeenth capacitor C17 filter and remove the noise on the connector or the inductive noise, static electricity of the noise injection type.

[0030] The LED display unit 5 comprises a second interface P2, an eighteenth capacitor C18, a nineteenth capacitor C19, a twentieth capacitor C20, an eighth resistor R8, a first light emitting diode LD1 and a second light emitting diode LD2; one end of the eighteenth capacitor C18 is connected with the second interface P2 and the positive electrode of the first light emitting diode LD1 respectively, the other end of the eighteenth capacitor C18 is connected with one end of the nineteenth capacitor C19, the negative electrode of the first light emitting diode LD1 and the positive electrode of the second light emitting diode LD2 respectively; the other end of the nineteenth capacitor C19 is connected with the negative electrode of the second light emitting diode LD2 and then connected into the second interface P2; one end of the twentieth capacitor C20 is connected with one end of the eighth resistor R8 and the second interface P2 respectively, the other end of the twentieth capacitor C20 is connected with the second interface P2 and the other end of the eighth resistor R8 respectively and then grounded.

Claims

1. A general-purpose high-precision DC-DC constant current circuit, characterized in that: The LED display device comprises an input unit, a current protection unit, a filter unit, a constant current control unit and an LED display unit connected in sequence; the filter unit comprises a π-type filter circuit and a first filter circuit connected with each other; the π-type filter circuit comprises a first capacitor C1, a second capacitor C2, a third capacitor C3, a fourth capacitor C4, a first inductor L1 and a first diode D1; one end of the first capacitor C1 is connected with the current protection unit, one end of the second capacitor C2, one end of the first inductor L1 and the negative electrode of the first diode D1 respectively; the other end of the first capacitor C1 is connected with the other end of the second capacitor C2 and then grounded; the positive electrode of the first diode D1 is connected with the other end of the first inductor L1, one end of the third capacitor C3, one end of the fourth capacitor C4 and the first filter circuit respectively; the other end of the third capacitor C3 is connected with the other end of the fourth capacitor C4 and then grounded. The first filter circuit comprises a fifth capacitor C5, a sixth capacitor C6 and a seventh capacitor C7 connected in parallel with each other; one end of the fifth capacitor C5, the sixth capacitor C6 and the seventh capacitor C7 connected in parallel is grounded, and the other end is connected with the π-type filter circuit and the constant current control unit respectively.

2. The universal high-precision DC-DC constant current circuit according to claim 1, characterized in that: The constant current control unit comprises a control chip U1, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, an eighth capacitor C8, a ninth capacitor C9, a tenth capacitor C10, an eleventh capacitor C11, a twelfth capacitor C12, a thirteenth capacitor C13, a fourteenth capacitor C14, a fifteenth capacitor C15, a Schottky diode D2, a second inductor L2, a first magnetic bead B1, a second magnetic bead B2 and a first interface P1; the control chip U1 comprises a VIN pin, an EN pin, a TON pin, a VCC pin, a SW pin, a BOOT pin, a CS pin, an EP pin and a GND pin; one end of the first resistor R1 is connected with the filter unit, the VIN pin and the EN pin of the control chip U1 respectively, and the other end of the first resistor R1 is connected with the TON pin; the VCC pin is grounded through the fourteenth capacitor C14. The BOOT pin is connected with one end of the fifteenth capacitor C15, the other end of the fifteenth capacitor C15 is connected with the SW pin, one end of the second inductor L2, the negative electrode of the Schottky diode D2 and one end of the eighth capacitor C8 respectively; the other end of the eighth capacitor C8 is connected with one end of the second resistor R2, the other end of the second resistor R2 is connected with the positive electrode of the Schottky diode D2 and then grounded; the other end of the second inductor L2 is connected with one end of the ninth capacitor C9, one end of the tenth capacitor C10 and one end of the first magnetic bead B1 respectively, the other end of the first magnetic bead B1 is connected with the first interface P1; the other end of the ninth capacitor C9 is connected with one end of the third resistor R3, one end of the fourth resistor R4, one end of the fifth resistor R5, the other end of the tenth capacitor C10 and one end of the second magnetic bead B2 respectively; the other end of the second magnetic bead B2 is connected with the first interface P1; the other end of the fourth resistor R4 is connected with the other end of the fifth resistor R5 and then grounded; the other end of the third resistor R3 is connected with one end of the sixth resistor R6, one end of the twelfth capacitor C12 and the CS pin respectively, the other end of the twelfth capacitor C12 is grounded; the other end of the sixth resistor R6 is connected with one end of the thirteenth capacitor C13 and the first interface P1 respectively, the other end of the thirteenth capacitor C13 is grounded; the constant current control unit is connected with the LED display unit through the first interface P1.

3. The universal high-precision DC-DC constant current circuit according to claim 1, characterized in that: The current protection unit includes a reverse protection unit and a surge protection unit, one end of the reverse protection unit is connected with the input unit, and the other end of the reverse protection unit is connected with the surge protection unit and the π type filter unit respectively.

4. The universal high-precision DC-DC constant current circuit according to claim 3, characterized in that: The reverse protection unit includes a third diode D3, and the surge protection unit includes a seventh resistor R7 and a bidirectional transient suppression diode D4; the positive electrode of the third diode D3 is connected with the input unit, and the negative electrode of the third diode D3 is connected with one end of the seventh resistor R7 and the filter unit respectively; the other end of the seventh resistor R7 is connected with one end of the bidirectional transient suppression diode D4, and the other end of the bidirectional transient suppression diode D4 is grounded.

5. The universal high-precision DC-DC constant current circuit according to claim 1, characterized in that: The input unit includes a sixteenth capacitor C16 and a seventeenth capacitor C17, one end of the sixteenth capacitor C16 is an input end and is connected with the current protection unit; the other end of the sixteenth capacitor C16 is grounded through the seventeenth capacitor C17.

6. The universal high-precision DC-DC constant current circuit according to claim 1, characterized in that: The LED display unit comprises a second interface P2, an eighteenth capacitor C18, a nineteenth capacitor C19, a twentieth capacitor C20, an eighth resistor R8, a first light emitting diode LD1 and a second light emitting diode LD2; one end of the eighteenth capacitor C18 is connected with the second interface P2 and the positive electrode of the first light emitting diode LD1 respectively, the other end of the eighteenth capacitor C18 is connected with one end of the nineteenth capacitor C19, the negative electrode of the first light emitting diode LD1 and the positive electrode of the second light emitting diode LD2 respectively; the other end of the nineteenth capacitor C19 is connected with the negative electrode of the second light emitting diode LD2 and then connected into the second interface P2; one end of the twentieth capacitor C20 is connected with one end of the eighth resistor R8 and the second interface P2 respectively, and the other end of the twentieth capacitor C20 is connected with the second interface P2 and the other end of the eighth resistor R8 and then grounded.

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