TW201422051A - LED control circuit - Google Patents

Abstract

The present invention is an LED control circuit, which includes: a protection unit, a rectifying filtering unit, a control unit and an LED driving unit; the LED driving unit is provided with at least a first LED, at least a second LED and a transistor; a detection current feedback unit is disposed between the LED driving unit and the control unit; and at least one relay, the relay is corresponding connected to ac power supply of the protection unit, the first LED, the second LED and the detection current feedback unit. When alternating current power source changes, change the first LED and the second LED from parallel to serial by activating the relay, in order to apply different input voltage, and achieve the purpose of reduced cost, non-electromagnetic interference and voltage compensating protection effects.

Description

LED control circuit

The invention relates to an LED control circuit, in particular to an application of different input voltages, which can fully utilize the light-emitting diodes in the circuit, so as to achieve cost saving, no electromagnetic interference and high and low voltage compensation protection. The effect.

First, referring to Fig. 1, the conventional LED control circuit is a DC power supply that provides a constant current and power in a manner of a flyback circuit 82 and a pulse width modulation (PWM) 81. The missing is that there is a pulse. The cost of the wave width modulator and the required parts of the EMI filter.

Furthermore, the LED control circuit is not used, and the protection circuit with high voltage feedback compensation is not used. If it adopts the linear power supply mode, although there is no electromagnetic interference, the higher the voltage of the input AC power supply, the electricity on the opposite circuit. The higher the cross-voltage of the crystal, the higher the AC power supply voltage input, resulting in a rapid rise in power (W) (as shown in Figure 2), so the LED cannot be protected and the LED is easily overheated.

Moreover, the conventional LED control circuit, if a linear power supply is used to drive the light-emitting diode, there is a problem that the operation is limited to a single voltage, and the light-emitting diode cannot be fully utilized, so that when the input voltage of the AC power source is 220V, The light-emitting diode will be fully lit; when the input voltage of the AC power source is changed to 110V, the light-emitting diode will become semi-bright or non-bright, and in order to achieve the best working current and power of the light-emitting diode, When the input voltage of the AC power source is different, different LED control circuits must be used correspondingly, and they cannot be used at different inputs. The use of voltage, so it is easy to waste a lot of cost.

In view of this, the inventors have devoted themselves to research and design, and can provide an LED control circuit that can be applied to different input voltages to achieve cost saving, and has no electromagnetic interference and high and low voltage compensation protection effects. That is, the author of the creation of the invention.

The main purpose of the present invention is to provide an LED control circuit corresponding to the AC power supply of the protection unit, the first LED, the second LED, and the detection current feedback unit. When the input voltage of the alternating current power source is changed, the first light emitting diode and the second light emitting diode are converted into a series connection by starting the relay, so that the input voltage can be applied to the different input voltages. Use the LEDs in the circuit to achieve cost savings.

A second object of the present invention is to provide an LED control circuit that uses a transistor to operate in a linear region without switching frequency without using a filter for electromagnetic interference, which makes the circuit structure simple and low in cost.

Another object of the present invention is to provide an LED control circuit having a detection current feedback unit to form a protection circuit, which can avoid a situation in which the voltage input of the AC power source is too high and the power is increased.

To achieve the above objective, the present invention is an LED control circuit comprising: a protection unit connected to an AC power supply; a rectification and filtering unit electrically connected to the protection unit; and a control unit electrically connected to the rectification at one end Filter unit; an LED drive unit, Having at least one first light emitting diode, at least one second light emitting diode, and a transistor, the first light emitting diode has a positive electrode and a negative electrode, and the second light emitting diode also has a positive electrode and a negative electrode; the positive electrode of the first light emitting diode is electrically connected to the rectifying filter unit and the control unit, and the negative electrode of the second light emitting diode is connected to the transistor; The locating unit is disposed between the LED driving unit and the control unit, and the detecting current feedback unit is provided with: a first resistor, a second resistor, a third resistor and a fourth resistor, the first One end of the resistor is electrically connected to one end of the second resistor and the control unit, and the other end of the first resistor is electrically connected to the negative electrode of the second LED, and the other end of the second resistor is electrically connected to the transistor. And a relay of the protection unit, an anode of the first LED And the detection current feedback And the relay is activated by sensing the change of the alternating current power of the protection unit by the relay; thereby, when the input voltage of the alternating current power source is changed from 110V to 220V, the first relay is provided to provide the first The light-emitting diode and the second light-emitting diode are converted into a series connection in parallel, which can be applied to different input voltages, and can fully utilize the light-emitting diodes in the circuit to achieve cost saving and no electromagnetic interference. And has the effect of high and low voltage compensation protection.

For a fuller understanding of the features, features and aspects of the present invention, reference should be made to the accompanying drawings.

Please refer to the third to fifth embodiments, the present invention is an LED control circuit, comprising: a protection unit 10, is connected to an AC power supply 70; a rectification and filtering unit 20, is electrically connected to the protection unit 10; A control unit 30 is electrically connected to the rectifying and filtering unit 20 at one end. An LED driving unit 40 is provided with at least one first LED 201, at least one second LED 42 and a transistor 43. The first light-emitting diode 41 has a positive electrode 411 and a negative electrode 412, and the second light-emitting diode 42 also has a positive electrode 421 and a negative electrode 422. The first light-emitting diode 41 is positive. The electrode 411 is electrically connected to the rectifying and filtering unit 20 and the control unit 30. The negative electrode of the second illuminating diode is connected to the transistor 43. A detecting current feedback unit 50 is disposed on the LED driving unit 40 and Between the control unit 30, the detection current feedback unit 50 is provided with a first resistor 51, a second resistor 52, a third resistor 53, and a fourth resistor 54. Electrically connecting one end of the second resistor 52 and the control unit 30, the first resistor 51 The second end of the second resistor 52 is electrically connected to the transistor 43, the end of the third resistor 53 and the end of the fourth resistor 54; and at least one relay 60. The relay 60 is corresponding to the AC power source 70 connected to the protection unit 10, the negative electrode 412 of the first LED 201, the positive electrode 421 of the second LED 42 and the detection current feedback unit. 50. The relay 60 is activated by the relay 60 corresponding to sensing the change of the AC power source 70 of the protection unit 10; when the input voltage of the AC power source 70 is changed, the relay 60 is activated to provide the first illumination. The diode 41 and the second LED 42 are converted into a series connection in parallel, which can be applied to different input voltages, and can be fully utilized in the circuit. Light-emitting diodes for cost savings.

The at least one relay 60 includes: a first pin 601, a second pin 602, a third pin 603, a fourth pin 604, a fifth pin 605, and a sixth pin 606. a seventh pin 607, an eighth pin 608, a ninth pin 609, a tenth pin 610 and an eleventh pin 611; the first pin 601 is connected to the third resistor 53 The second pin 602 is connected to the other end of the fourth resistor 54. The third pin 604 is connected to the ground. The fourth pin 604 is connected to the positive electrode 421 of the second LED 42 and the fifth pin. 605 is connected to the eighth pin 608. The sixth pin 606 is connected to the first LEDs 41 and the positive electrodes 411 and 421 of the second LED 42. The seventh pin 607 is connected to the second LED. The negative electrode 422 of the electrode body 42 and the transistor 43 and the ninth pin 610 are connected to the negative electrode 412 of the first light-emitting diode 41. The tenth pin 610 and the eleventh pin 611 are connected to the AC power source. 70.

When the input voltage of the AC power source 70 is 110V, the at least one relay 60 is not activated, and the third pin 603 is electrically connected to the first pin 601, and the sixth pin 606 is electrically connected to the fourth pin 604. The ninth pin 609 is electrically connected to the seventh pin 607, so that the first LED body 41 and the second LED body 42 are connected in parallel.

When the input voltage of the AC power source 70 is 220V, the at least one relay 60 is activated, the third pin 603 is electrically connected to the second pin 602, and the sixth pin 606 is electrically connected to the fifth pin 605. The ninth pin 609 is electrically connected to the eighth pin 608, thereby forming the first light emitting diode 41 and the second light emitting diode 42 into a string. Union.

Therefore, the LED control circuit of the present invention connects at least one first light-emitting diode 41 and at least one second light-emitting diode 42 with at least one relay 60 to solve the problem that the linear power source operates at a single voltage, and allows the light-emitting two The pole body is fully utilized, and the at least one first light-emitting diode 41 and the at least one second light-emitting diode 42 are determined to be in series or parallel according to the input voltage of the AC power source 70, thereby achieving an optimal operating current and power. When the input voltage of the alternating current power source is changed, by applying the relay 60 to provide the first light emitting diode 41 and the second light emitting diode 42 to be connected in parallel to be connected in series, the input voltage can be applied. At the same time, the LEDs in the circuit are fully utilized to achieve cost saving, and the LEDs achieve optimal operating current and power.

The input voltage may be changed from 110V to 220V, 220V to 110V or between 110V and 220V, and the relay 60 is activated by a change in the input voltage.

The control unit 30 includes a voltage regulator 301, a voltage reference unit 303, an operational amplifier 304, and a temperature protection unit 302. The control unit 30 has a high voltage terminal (HV) 311 and a low voltage terminal. (VDD) 312, a detecting terminal (CS) 315, a grounding terminal (GND) 313, and a gate terminal (GATE) 314; the voltage regulator 301 is connected at one end to the high voltage terminal (HV) 311, the voltage regulator The other end of the 301 is connected to the low voltage terminal (VDD) 312. The operational amplifier 304 has a positive phase input terminal 305, an inverting input terminal 306 and an output terminal 307. The positive phase input terminal 305 is connected to the voltage reference unit 303. The inverting input terminal 306 is connected to the detecting terminal (CS) 315, and the output terminal 307 is connected to the temperature protection unit 302 and the gate terminal (GATE) 314. Also, the gate terminal (GATE) of the control unit 30 The 314 is electrically connected to the transistor 43 of the LED driving unit 40. The high voltage terminal (HV) 311 is electrically connected to the rectifying and filtering unit 20 via a fifth resistor 33. The low voltage terminal (VDD) 312 and the ground terminal 313 A first capacitor 32 is connected between the first resistor 51 and one end of the second resistor 52. The fifth resistor 33 is used to control the high voltage start current limit, and the first capacitor 32 is provided to filter noise.

Furthermore, the transistor 43 of the LED driving unit has a 汲 terminal 431, a gate terminal 432 and a source terminal 433. The gate terminal 432 of the transistor 43 is connected to the gate terminal (GATE) 314 of the control unit 30. The terminal 433 is connected to the negative electrode 422 of the second LED 42 and the relay 60. The source terminal 433 is connected to the other end of the second resistor 52 and one end of the third resistor 53 and the fourth resistor 54. The transistor 43 is a metal oxide semiconductor field effect transistor (MOSFET). The control unit 30 and the detection current feedback unit 50 operate the transistor 43 in a linear region, and the electricity is The heat source of the crystal is combined with an LED light panel (not shown) to provide heat dissipation.

The protection unit 10 includes a fuse 11, a thermistor (NTC) 12 and a varistor (TVR) 13. The AC power source 70 has a live end (L) 71 and a ground end (N). 72, one end of the fuse 11 is connected to the live end 71 of the AC power source 70, and the other end of the fuse 11 is connected to the thermistor (NTC) 12 and one end of the varistor (TVR) 13, and the varistor (TVR) The other end of the 13 is connected to the ground terminal (N) 72 of the AC power source 70 and the rectifying and filtering unit 20. Thereby, the fuse 11 is used to provide short circuit protection, and the thermistor (NTC) 12 provides protection against surge current, the varistor The resistance (TVR) 13 provides a protection surge voltage.

The rectifying and filtering unit 20 includes a bridge rectifier 21 and a filter capacitor 22. The bridge rectifier 21 has a first pin 211, a second pin 212, a third pin 213, and a fourth. The first pin 211 is connected to the other end of the thermistor (NTC) 12 of the protection unit 10 by a sixth resistor 14. The second pin 212 is grounded, and the third pin 213 is connected to the AC. The ground terminal (N) 72 of the power supply and the other end of the varistor (TVR) 13 are electrically connected to the at least one filter capacitor 22, the control unit 30, and the LED driving unit 40. Thereby, the bridge rectifier 21 is rectified corresponding to the AC power source 70, and the filter capacitor 22 is used to filter out high frequency noise, and the sixth resistor 14 can provide an adjustment power factor.

In addition, the detection current feedback unit 50 of the LED control circuit of the present invention can provide detection current feedback and high and low voltage compensation protection. When the input voltage of the AC power source 70 is lower, the voltage across the transistor 43 is lower, and the utilization is lower. The first resistor 51 and the second resistor 52 detect the voltage across the transistor 43. The lower the relative feedback voltage ΔV is, the lower the voltage detected by the third resistor 53 in parallel with the fourth resistor 54 is. The output currents of the first light-emitting diode 41 and the second light-emitting diode 42 are lowered to form a protection circuit.

When the input voltage of the AC power source 70 is higher, the relative voltage of the opposing transistor 43 is higher. The first resistor 51 and the second resistor 52 are used to detect the voltage across the transistor 43, and the relative feedback voltage ΔV is also The higher the voltage of the third resistor 53 in parallel with the fourth resistor 54 is, the lower the output current of the first LED 201 and the second LED 42 is, thereby forming a protection circuit. The AC power supply voltage input is too high and the power (W) rises.

Features of the invention:

The LED control circuit of the present invention connects at least one first light emitting diode and at least one second light emitting diode with at least one relay, and when the input voltage of the alternating current power source changes, the first relay is activated to provide the first The light-emitting diode and the second light-emitting diode are converted into a series connection in parallel, and can be applied to different input voltages, and at the same time fully utilize the light-emitting diodes in the circuit to achieve cost saving.

2. The LED control circuit of the present invention selectively switches the at least one first light emitting diode and the at least one second light emitting diode in series or in parallel according to an input voltage of the alternating current power source to optimize the light emitting diode. Working current and power.

3. The LED control circuit of the present invention uses a linear power supply, and is not a pulse width modulation (PWM) method, and has no electromagnetic interference (EMI) problem.

4. The LED control circuit of the present invention has no electromagnetic interference (EMI), which can reduce the cost of safety parts.

5. The detection current feedback unit of the LED control circuit of the invention can provide detection current feedback and low voltage compensation protection. When the input AC power supply voltage is lower, the relative voltage across the transistor is lower, and the first resistor and the first resistor are used. The second resistor detects the voltage across the transistor, and the lower the relative feedback voltage ΔV is, and the lower the voltage detected by the third resistor in parallel with the fourth resistor, the first LED and The output current of the second LED is lowered to form a protection circuit.

6. The detection current feedback unit of the LED control circuit of the invention can provide detection current feedback and high voltage compensation protection. When the input voltage of the AC power source is higher, the relative voltage across the transistor is higher, and the first resistor is used. And the second resistor detects the voltage across the transistor, and the relative feedback voltage ΔV is also higher, and the third resistor is connected in parallel with the voltage divider on the fourth resistor. The output current of one of the light-emitting diodes and the second light-emitting diode is lowered to form a protection circuit, which prevents the power supply (W) from rising due to excessive input of the AC power supply voltage.

The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The equivalent structural changes of the present invention and the contents of the drawings are all included in the scope of the present invention. , combined with Chen Ming.

10‧‧‧Protection unit

11‧‧‧Fuse

12‧‧‧Thermistor (NTC)

13‧‧‧ varistor (TVR)

14‧‧‧6th resistor

20‧‧‧Rectifier Filter Unit

21‧‧‧Bridge rectifier

211‧‧‧First pin

212‧‧‧second pin

213‧‧‧ third pin

214‧‧‧fourth pin

22‧‧‧Filter capacitor

30‧‧‧Control unit

301‧‧‧Voltage regulator

302‧‧‧Temperature protection unit

303‧‧‧Voltage reference unit

304‧‧‧Operational Amplifier

305‧‧‧Positive input

306‧‧‧Inverting input

307‧‧‧output

311‧‧‧High voltage terminal (HV)

312‧‧‧Low voltage terminal (VDD)

313‧‧‧ Ground (GND)

314‧‧‧Gate Extreme (GATE)

315‧‧‧Detection (CS)

32‧‧‧first capacitor

33‧‧‧ fifth resistor

40‧‧‧LED drive unit

41‧‧‧First Light Emitting Diode

411‧‧‧ positive electrode

412‧‧‧negative electrode

42‧‧‧Second light-emitting diode

421‧‧‧ positive electrode

422‧‧‧negative electrode

43‧‧‧Optoelectronics

431‧‧‧汲 Extreme

432‧‧ ‧ gate extreme

433‧‧‧ source extreme

50‧‧‧Detection current feedback unit

51‧‧‧First resistance

52‧‧‧second resistance

53‧‧‧ Third resistor

54‧‧‧fourth resistor

60‧‧‧ relay

601‧‧‧first pin

602‧‧‧second pin

603‧‧‧ third pin

604‧‧‧fourth pin

605‧‧‧ fifth pin

606‧‧‧ sixth pin

607‧‧‧ seventh pin

608‧‧‧8th pin

609‧‧‧ninth pin

610‧‧‧10th pin

611‧‧‧11st pin

70‧‧‧AC power supply

71‧‧‧Firewire end (L)

72‧‧‧ Ground end (N)

81‧‧‧ Pulse width modulation (PWM)

82‧‧‧Return-type circuit

Figure 1 is a schematic diagram of a circuit of a conventional LED control circuit.

Figure 2 is a schematic diagram of the input voltage corresponding to the output power (W) of the conventional LED control circuit.

Figure 3 is a block diagram of the LED control circuit of the present invention.

Figure 4 is a schematic diagram of the LED control circuit of the present invention.

Figure 5 is a block diagram of the internal unit of the control unit of the present invention.

10‧‧‧Protection unit

20‧‧‧Rectifier Filter Unit

30‧‧‧Control unit

40‧‧‧LED drive unit

50‧‧‧Detection current feedback unit

60‧‧‧ relay

70‧‧‧AC power supply

Claims (9)

An LED control circuit comprising: a protection unit connected to an AC power supply; a rectification and filtering unit electrically connected to the protection unit; and a control unit electrically connected to the rectification and filtering unit at one end; an LED drive unit, The first light emitting diode has at least one first light emitting diode, at least one second light emitting diode, and a transistor. The first light emitting diode has a positive electrode and a negative electrode, and the second light emitting diode is also The positive electrode of the first light-emitting diode is electrically connected to the rectifying and filtering unit and the control unit, and the negative electrode of the second light-emitting diode is connected to the transistor; The feedback unit is disposed between the LED driving unit and the control unit, and the detecting current feedback unit is provided with: a first resistor, a second resistor, a third resistor and a fourth resistor, One end of the first resistor is electrically connected to one end of the second resistor and the control unit, and the other end of the first resistor is electrically connected to the negative electrode of the second LED, and the other end of the second resistor is electrically connected to the transistor. The third Blocking one end and one end of the fourth resistor; and at least one relay corresponding to an alternating current power source connected to the protection unit, a negative electrode of the first light emitting diode, a positive electrode of the second light emitting diode, and the detecting Measuring a current feedback unit, and sensing the change of the alternating current power of the protection unit corresponding to the relay to activate the relay; when the relay is activated, thereby providing the first light emitting diode and the second light emitting diode Parallel transition to series. The LED control circuit of claim 1, wherein the control unit comprises: a voltage regulator, a voltage reference unit, an operational amplifier and a temperature protection unit, the control unit having a high voltage terminal, a low voltage terminal, a detection terminal, a ground terminal and a gate terminal; the voltage adjustment One end of the voltage is connected to the high voltage end, and the other end of the voltage regulator is connected to the low voltage end. The operational amplifier has a positive phase input terminal, an inverting input terminal and an output terminal. The positive phase input terminal is connected to the voltage reference unit. The inverting input is connected to the detecting end, and the output is connected to the temperature protection unit and the gate terminal. The LED control circuit of claim 2, wherein the gate of the control unit is electrically connected to the transistor of the LED driving unit, and the high voltage terminal is electrically connected to the rectifying and filtering unit via a fifth resistor. A first capacitor is connected between the low voltage end of the control unit and the ground end, and the detecting end is electrically connected to the first resistor and one end of the second resistor. The LED control circuit of claim 3, wherein the transistor of the LED driving unit has a 汲 terminal, a gate terminal and a source terminal, and the gate terminal of the transistor is connected to the gate terminal of the control unit. The anode is connected to the negative electrode of the second LED and the relay, and the source terminal is connected to the other end of the second resistor and one end of the third resistor and the fourth resistor. The LED control circuit of claim 1, wherein the protection unit comprises: a fuse, a thermistor and a varistor, wherein the AC power source has a live terminal and a ground terminal, the fuse One end is connected to the live end of the AC power source, and the other end of the fuse is connected to the thermistor and one end of the varistor, and the other end of the varistor is connected to the ground of the AC power source and the rectifying and filtering unit. The LED control circuit of claim 5, wherein the rectifying and filtering unit comprises: a bridge rectifier and at least one filter capacitor, and the bridge rectifier has a first a pin, a second pin, a third pin and a fourth pin; the first pin is connected to the other end of the thermistor of the protection unit by a sixth resistor, the second pin is grounded, The third pin is connected to the ground terminal of the AC power source and the other end of the varistor. The fourth pin is electrically connected to the at least one filter capacitor, the control unit and the LED driving unit. The LED control circuit of claim 1, wherein the at least one relay comprises: a first pin, a second pin, a third pin, a fourth pin, and a fifth a pin, a sixth pin, a seventh pin, an eighth pin, a ninth pin, a tenth pin and an eleventh pin; the first pin is connected to the third resistor The other end is connected to the other end of the fourth resistor, the third pin is grounded, the fourth pin is connected to the positive electrode of the second LED, and the fifth pin is connected to the eighth connection. a sixth pin connected to the first LED and a positive electrode of the second LED, a seventh pin connecting the negative electrode of the second LED and the transistor, and a ninth pin The negative electrode of the first light emitting diode is connected, and the tenth pin and the eleventh pin are connected to the alternating current power source. The LED control circuit of claim 7, wherein when the at least one relay is not activated, the third pin is electrically connected to the first pin, and the sixth pin is electrically connected to the fourth pin, The ninth pin is electrically connected to the seventh pin, thereby forming the first light emitting diode and the second light emitting diode in parallel. The LED control circuit of claim 7, wherein when the at least one relay is activated, the third pin is electrically connected to the second pin, and the sixth pin is electrically connected to the fifth pin, The ninth pin is electrically connected to the eighth pin, thereby forming the first light emitting diode and the second light emitting diode in series.