TWM343888U - Improved LED driving circuit - Google Patents

Description

M343888 Eight, new description: [New technology field] This creation involves a kind of LED axis circuit, especially a led drive circuit that can adjust the wheel. [Prior Art] Light Emitting Diode (LED) has the advantages of small size, low power consumption, fast lighting speed, vibration resistance, long service life and mass production. Therefore, LED has been widely used in Information, communication and consumer electronics are on display and display devices' and can be expected to be more widely used in the future and are expected to replace most traditional lighting components. As is known, the light-emitting diode generally operates under a forward voltage, and its operating characteristic is that when the voltage across the LED diode exceeds the startup voltage, the current of the LED can be turned on to start the light-emitting operation, and the LED The brightness of the light is approximately proportional to the magnitude of the on-current; in general, in practical applications, a driving circuit k is used for a stable current to operate the LED to maintain a certain brightness, and the general driving circuit is designed. For the fixed current drive, this can also have the purpose of extending the service life of the LED; as shown in the fifth figure, the conventional UED drive circuit includes: the power controller 1C, the LED, and the detection resistor. Rs, input voltage source p, reference voltage Vref, detection voltage Vd, and output voltage Vout. Wherein, the reference voltage Vref is a fixed voltage value, and the detection voltage vd is a voltage drop caused by the current iLed outputted by the power supply control 1C flowing through the detecting resistor Rs; the power controller 1C is based on the two voltages The difference is used to control the magnitude of the current iLed, thereby controlling the brightness of the LED of the light-emitting element; and such an IJED driving circuit is basically operated in the voltage mode 5 M343888, which maintains the voltage of the detecting resistor RS at a certain value, thereby stabilizing the current. Change, to supply LED illumination operation with a fixed output current. In addition, the power control state ic mostly uses a pulse width modulation (PWM) controller or a pulse frequency modulation controller (PFM) to input the voltage through a PWM or PFM controller. Converted to led current, supply LED lighting operation; power controller IC has an input terminal electrically connected to input voltage source P, and another input terminal is electrically connected to reference voltage Vref, and the output controller of the power controller provides - input $ And the input end of the LED of the electroluminescent element; the private end of the detecting resistor is electrically connected to the output end of the LED, and the other end is connected to the ground; wherein the detecting resistor Rs is connected to the LED of the LED The point is the measurement point of the detection voltage Vd. In fact, the voltage Vd is equal to the voltage on the detection resistor Rs, and the measurement is transferred to the motor, and the power controller is Adjusting the output voltage value according to the difference between the reference voltage Vrem_voltage Vd and the voltage so that the final debt measurement voltage Vd is equal to the reference voltage Vref, so that the light-emitting element is stabilized and the current is suitable for current supply. . In the foregoing prior art, when the output voltage v〇ut is greater than the forward voltage drop VLed of the light-emitting element, the light-emitting element LED obtains a driving current - and the light-emitting and brightening is about the size of the electric catch! Led = (V〇 Ut_Vud) The power controller "determines the output current value based on the difference between the voltage of the reference voltage Vref and the feedback side voltage Vd" to thereby accurately control the brightness that can be generated by the light-emitting element LED. Although such a conventional LED axis circuit can align the light-receiving element (4), the power supplied by the input source is mostly - most of it is consumed on the sense resistor Rs, thus making M343888

The light-emitting element LED has significantly less power compared to the obtained power, so that the performance of the LED driving circuit is low, and the power consumed on the detecting resistor Rs is converted into high heat, thereby causing many adverse effects on the circuit; in order to reduce the heat problem At present, most of the existing methods are to reduce the internal fresh voltage and make the detection resistor 1 smaller. However, the smaller the detection resistor, the lower the cost of the Rs component and the higher the error value, which not only makes [ The manufacturing cost of the ED drive circuit is high, and the charm of the power supply control is reduced.

Point, for example, the LED driver circuit will cause errors in the accuracy of the current control due to the error of the resistance value of the sense resistor Rs, the error of the reference voltage, and the stomach consumption of the line.

10/. The above 'again because of the _ error introduced by the secret & current noise problems will lead to LED specifications are low, for example: 1A specification of the coffee in the design, due to the error of the current control quasi-born, usually only designed The specifications are used, so in actual use, if the error value of the output current is added, the noise current of the coffee operation is about - between 810mA and 990mA', so the LED's luminous efficiency will be seriously degraded. [New content] ^;, b paste main purpose is to provide - type change _led drive circuit, :::: The voltage difference across the resistor through the differential amplification to the power controller as a tuning supply LED. The current is suitable for the current, and the current is provided by a 动 动 ( (4), ... thief complement _ circuit, which is greatly reduced by the voltage difference. & The average secret of light and the maximum use of power 7 M343888 This creation is also aimed at providing an improved LED driver circuit, which can reduce the detection resistance rate of 4 volts, and also avoid detection. The disadvantages of high cost and high error values derived from resistance miniaturization. "The purpose of this creation is to provide an improved LED driver circuit, which has the advantage of being extremely simple in adjusting the output power grab value, as long as the power is adjusted by the voltage adjustment loop and the value is reduced. Need to face & electric wire, no county to change other circuit units 4 'So there is no additional design cost and difficulty in production technology. • Another objective of this creation is to provide an improved LED driver circuit. It has an adjustable resistor which can be used to adjust the magnification of the voltage differential amplification, so it can adjust the level of the output current according to the demand and adjust the brightness of the LED. According to this creation, the LED circuit, including: “Lion Control” Key, - voltage back

The road detection view, the illuminating turn and the _ voltage side circuit; the voltage input end of the power controller is connected to the power source, and has a reference voltage therein; the voltage stabilizing circuit is connected to the voltage output end of the power controller; The first end of the detecting resistor is connected to the output of the voltage stabilizing circuit, and the second light source is connected to the light emitting element, and the other end of the light emitting element is grounded. The voltage_circuit has a voltage input. The end is connected to the first end of the detecting resistor, and the second detecting voltage input end is connected to the second end of the detecting resistor, and the output end of the voltage detecting circuit is connected to the feedback end of the power controller to output one of the outputs The electric difficulty number is to the power control II; and the control (4) adjusts the output voltage value according to the difference between the reference lag signal and the debt measurement voltage signal, and the output _ is stable and the electric current is suitable for the illuminating element. . /;, L, parallel or string and wherein the light-emitting element is composed of one or several light-emitting diodes in series M343888 to form a light-emitting diode group or a light-emitting diode array. The voltage side circuit can be selected as a differential amplifier (Amplifier Amplifier) having at least a first side voltage input terminal, a second fine voltage input terminal, and an output terminal of a voltage signal, and includes a first-resistor, a first a second resistor, a third resistor and a fourth resistor, the first sense voltage input end of the differential amplifier has a third resistor and is connected to the first end of the sense resistor, and is at the first detection voltage input end and the third A fourth resistor is connected between the resistors, and the other end of the fourth resistor is connected to the ground, and the second detecting voltage input end of the differential amplifier has a first resistance and is connected to the second end of the detecting resistance, and is in the A second resistor is connected between the second voltage measuring input terminal and the first resistor, and the other end of the second resistor is connected to the output end of the differential amplifier, and the output end of the differential amplifier is connected to the voltage detecting circuit. The output terminal can adjust the output current value of the LED driving circuit by adjusting the ratio of the first to fourth resistors on the differential amplifier. In addition, the voltage detecting circuit further includes an adjustable resistor located between the fourth resistor of the differential amplifier and the ground, and the adjustable resistor ¥11 can be used to adjust the magnification of the differential amplification by controlling the Adjusting the resistance value of the resistor VR can adjust the level of the output current to achieve the purpose of controlling the brightness of the light-emitting element. This will further clarify other functions and technical features of the present work, which will be realized by those skilled in the art after reading the description in the text. [Embodiment] Please refer to the first figure for a LED driving circuit according to a preferred embodiment of the present invention; the LH3 driving circuit includes at least: a power controller i, a voltage stabilization loop 2, a voltage detection loop 3, and a detection resistor Rs. And the light-emitting element LH), the connection relationship is slightly as shown in the first figure: the voltage input terminal VIN of the power controller 1 is connected with the voltage source, the voltage output of the power controller i is 9 M343888 terminal OUT is connected to the voltage stabilization circuit 2, and the voltage is stabilized. The loop 2 is connected to the detecting resistor Rs and the light-emitting element LED ' and the feedback terminal fb of the power supply control 1 is connected to the output terminal of the voltage detecting circuit 3 and the first detecting voltage input terminal of the voltage detecting circuit 3 is connected to the detecting The first end of the resistor Rs, the second detecting voltage input of the voltage detecting circuit 3 is connected to the second end of the detecting resistor Rs. In the present embodiment, the power controller 1 is a pulse width modulation (PWM) controller. In fact, the power controller 1 is not limited to using a pulse width modulation controller, and Is a pulse frequency modulation controller (pUlse freq·m〇 (julati〇n, pFM) or a general power converter, including DC TO DC or AC TO DC architecture power supply ic and power supply for the voltage or buck architecture The IC is the same; the direct current (DC) or alternating current (AC) power supply is processed by the pre-processing, such as rectification, filtering, boosting or bucking, and the input voltage value is output to the voltage input terminal VIN of the power supply control 1 The voltage output terminal out of the power controller 1 is connected to the input end of the voltage stabilization circuit 2. The output enable terminal EN of the power controller 用以 is used to set the dimming function, and the ground terminal GND of the power controller i is grounded. The feedback terminal FB of the electric source controller 1 is connected to the wheel-out terminal of the voltage detecting circuit 3; in addition, a reference voltage is internally provided in the power controller 1, and the reference voltage is a fixed voltage value. (Vdtage Regula (4) 2 series provides - _ _ _ _ _ _ _ _ _ _ The LED comprises a filter, a wave inductor L, one end of which is connected to the input end of the voltage stabilization circuit 2, and the other end is connected to the output end of the voltage stabilization circuit 2; a filter capacitor c〇ut, one end of which is connected to The output end of the filter inductor L is connected to the output end of the voltage regulator circuit 2, and the other end is grounded; - freewheeling diode _1^ diode) D, one end of which is connected between the input end of the voltage stabilizing circuit 2 and the filter inductor L The other end of the freewheeling diode D is grounded. M343888 ', the first end of the _i resistor Rs is connected to the output end of the voltage stabilizing circuit 2, and the second end of the detecting electric (4) is connected to the LED of the light emitting element, which is the light emitting element The other end of the ground is further grounded, and the towel 'lighting tree LED can be a light-emitting diode group or a light-emitting diode array composed of - to several digital light-emitting diodes connected in series, parallel or series-parallel. The voltage thin circuit 3 includes a differential amplifier __ Am_er) 31 and an adjustable resistor (10); wherein the differential amplifier 31 includes a first resistor R, a second resistor, a -f resistor 113, and a fourth resistor R4; The first detecting voltage input terminal has a third resistor and is connected to the first end of the detecting resistor & A fourth resistor R4 is connected between the first detector voltage input terminal and the second resistor phantom, and the other end of the fourth resistor is connected to the grounded adjustable resistor VR. In addition, the second detection voltage of the differential amplifier 31 The input end has a first electric_connection and is connected to the second end of the inspection _(four), and a second resistor 连接 is connected between the second copper voltage input end and the first resistance illusion, and the other end of the second electric m ^ is reconnected At the output of the differential amplifier μ; further, the output of the differential amplifier 31 is connected to the output of the voltage side circuit 3, and the power supply terminal is connected to = control ϋ 1 (four) inverting the terminal, and the ground terminal Connected to ground. And then please refer to the figure-Fig. 4 The differential amplification voltage output from the voltage detection circuit 3 and the relationship between the above components are: VFFt^lm + R2 Ί (R4+VR), R3 + (R4 + VR) J Rl According to the above structure, the first and second detecting voltage input terminals of the differential amplifier 31 of the voltage detecting circuit 3 are respectively connected to the first and second ends of the detecting resistor Rs to obtain the detecting resistor Rs. The voltage difference between the two ends [, the voltage difference signal 11 M343888 is further differentially amplified by a loop composed of the first to fourth resistors R1, R2, R3, R4, and the voltage signal is amplified to n times (n =R2/Rl orR4/R3) to obtain a differential amplification voltage VFB, and then the differential amplification voltage signal is sent to the feedback terminal FB of the power controller 1, and the power controller 1 according to the differential amplification voltage VFB and its reference Adjusting the output voltage value by the difference between the voltages, so as to output a stable current and a suitable current for supplying the light-emitting element LED, and the aforementioned differential amplification effect can also reduce the noise of the output current to The original 1/n' can therefore provide more The output current is correct, so that the brightness of the light-emitting component LED is more uniform and the luminous efficiency is close to full load; in addition, the adjustable resistance VR in the voltage detecting circuit 3 can be used to adjust the magnification of the differential amplification effect, so The impedance value of the adjustable resistor VR can be controlled at any time according to actual needs to adjust the level of the output current without requiring an additional setting switch to control the brightness of the LED of the light-emitting element. In a practical case, for example, the resistance of the sense resistor rs is 〇1Ω (ohm), the resistance values of the first and third resistors R1 and R3 are 1ΚΩ, and the second and fourth resistors R2 and R4 The resistance value is 10 ΚΩ, the reference voltage of the power controller 1 is set to 1.23V (volts), and the resistance value of the adjustable resistor VR is 〇~ι〇κΩ; based on the aforementioned setting, when the adjustable resistor VR = ΟΚΩ When the output current iLed is 1.2A (amperes), the voltage difference between the sense resistors Rs is Δν=1·2ΑΧ0·1Ω = 0.12V, and the differential amplifier voltage VFB is: VFB = [(R1+R2) ) /(R3+R4)] X R4/R1 X (V+). R2/R1 χ (γ.) Since R2/R1 = R4/R3,

VFB = R2/R1 X AV = 10K/1K X 0.12V = 1.2V 12 M343888 Since the differential amplification voltage VFB is 1·2ν less than the reference voltage of 1 23V, the power supply controller 1 will increase the output voltage value so that Increase the output current value also ^. When the output current iLed is raised to 1.23A, the voltage difference across the sense resistor rs is 0.923V. Therefore, the adjusted differential amplifier voltage VFB is:

VFB = R2/R1X AV=10K/1KX0.123V=1.23V Therefore, the differential amplification voltage VFB is 1.23V equal to 123V of the reference voltage, and the power supply controller 1 will fix the output voltage value to output a 123A. The fixed current is supplied to the light-emitting element LED. In summary, the present invention adjusts the output current value of the power control by means of voltage differential amplification, so that the accuracy of the output current can be greatly improved, and the error range is less than 0_5%; Accurate value, so the u-spec coffee is taken as an example, that is, it can be designed to be used in the 995 mA specification. The driving current of the LED is about 90.025 to 999.975 mA, which results in an increase in the average LED illumination. The brightness H surface village allows the LED (4) to make the _ maximum conversion specification; in addition, the creation can make the county up to several ohms of detection resistance & by setting the differential amplifier 31 and the adjustable resistance w, it can be reduced to only The resistance below i ohm, so that the power of the power supply will be almost completely secreted on the LED of the light-emitting element to improve the efficiency of the material and achieve the power saving effect, and also avoid the miniaturization of the detection resistor. High cost and high error value, etc.; this creation is extremely variable in the output current value (4), as long as the ratio of the resistance values of R1 RR4 can be adjusted to reach the i'j customer. Thief seek value, no other county circuit design more materials for iv, 13 M343888 designed so no extra cost and difficulty of producing molding techniques. The present invention is not limited to the above-mentioned forms, and it is obvious that after the above description, there can be more improvements and changes in the technical uniformity, for example, the voltage detecting circuit 3 may not include the adjustable resistor VR component. The other end of the fourth resistor of the differential amplifier 31 is directly grounded (as shown in the third figure), or the LED of the light-emitting element is connected to the detecting resistor, and the detecting resistor is tilted. The second end of the private ground (such as the first __) ·........ The effect of these changes in the establishment of the job is similar to the implementation of the previous disclosure, should be combined with the pre-existing technology is the essence _. Therefore, any modification of the creation of the creation under the spirit of __ should still be

BRIEF DESCRIPTION OF THE DRAWINGS The first figure is a circuit diagram of the creation - the preferred embodiment

The fourth figure is a circuit diagram of a conventional LED_t. [Main component symbol description] Power controller 1 Voltage detection circuit 3 Detection resistance Rs

Regulator circuit 2 differential amplifier 31 light-emitting element LED

Claims (1)

M343888 IX. Patent application scope: 1. An improved LED driving circuit, comprising: a power controller, wherein the voltage input end is connected to the power source and has a reference voltage therein; a voltage stabilizing circuit connected to the power source a voltage output terminal of the controller; a detecting resistor connected to the output end of the voltage stabilizing circuit to receive an output current; the first light emitting element is composed of one or a plurality of LEDs, one end of which is connected to the Detecting a second end of the resistor and grounding the other end; and a voltage detecting circuit having a first detecting voltage input end connected to the first end of the detecting resistor, and a second detecting voltage input end connected to the detecting resistor The two ends end, and the output end of the voltage detection circuit is connected to the feedback end of the power controller to output a detection voltage signal to the power controller; the power controller according to the reference voltage signal and the detection voltage The difference between the signals is determined by the power controller according to the difference between the reference voltage signal and the detected voltage signal to adjust the output voltage value, and the rotation is stable and the current is A suitable fixed current is supplied to the light-emitting element. 2. The improved LED driving circuit according to claim 1, wherein the light emitting element is a light emitting diode group or a light emitting diode composed of one to several light emitting diodes connected in series, in parallel or in series and parallel. Body array. 3. The improved LED driving circuit according to claim 1, wherein the voltage detecting circuit is a differential amplifier (Difference Amplifier). 4. The improved LED driving circuit as described in claim 3, wherein the difference 15 M343888 is dynamically amplified to have a first-thin voltage input terminal, a second voltage measurement input terminal, and a beta test. a voltage source _^ terminal, and includes a first resistor, a second resistor, a first resistor, and a fourth resistor, wherein the first-thrush voltage input terminal of the differential amplifier has a first resistor and is connected to the first resistor And connecting a fourth resistor between the first thin voltage input end and the first resistor, the other end of the fourth resistor is grounded, and the second voltage input end of the differential amplifier has a first resistor connected to the detecting resistor The H-side two-voltage input terminal is connected to the first resistor. The other end of the first resistor is connected to the wheel-out end of the differential amplifier H, and the wheel-out end of the differential amplifier is Connected to the output of the voltage detection loop. 5. The improved LED driver circuit as described in item ith or item 4 of the claim, the voltage side loop further includes an adjustable resistor located at the differential amplifier (4) Between four electrics, . 16