CN216600150U - Linear LED drive circuit - Google Patents
Linear LED drive circuit Download PDFInfo
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- CN216600150U CN216600150U CN202123233920.2U CN202123233920U CN216600150U CN 216600150 U CN216600150 U CN 216600150U CN 202123233920 U CN202123233920 U CN 202123233920U CN 216600150 U CN216600150 U CN 216600150U
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Abstract
The application provides a linear LED drive circuit, includes: the LED lamp bank comprises an input rectifying circuit, an input energy storage filter capacitor, a charging current control circuit, a line voltage sampling circuit, an LED current control circuit and an LED lamp bank; one end of the line voltage sampling circuit is connected with the first end of the output end of the input rectification circuit, the other end of the line voltage sampling circuit is connected with the LED current control circuit, the line voltage sampling circuit is provided with a compensation current generating circuit, and compensation current is generated according to the level of a pulsating direct current voltage signal output by the input rectification circuit and is sent to the LED current control circuit. The linear LED driving circuit has the advantages of high power factor, no stroboflash, constant power output, wide power grid input voltage range and the like.
Description
Technical Field
The application relates to the technical field of circuit design, in particular to a linear LED driving circuit.
Background
In the technical field of LED lighting driving, a linear driving circuit is widely used in a photoelectric integrated LED lighting product because a magnetic component with high cost and large volume is not required. The linear driving technology widely used at present mainly focuses on the application occasions of low power factor, low flash output, narrow voltage range input and non-constant power. However, from the development trend of increasing the performance of the LED lighting product, the requirements on the driving performance of the LED will become higher and higher in the future, and especially, the requirements on the performance such as high power factor, no stroboscopic output, high power density, and wider input voltage range of the power grid are met. It is therefore desirable to provide a LED driver circuit solution that addresses some or all of the above performance requirements.
SUMMERY OF THE UTILITY MODEL
The application aims to provide a linear LED driving circuit with a high power factor.
To achieve the above object, the present application provides a linear LED driving circuit, comprising: the LED lamp bank comprises an input rectifying circuit, an input energy storage filter capacitor, a charging current control circuit, a line voltage sampling circuit, an LED current control circuit and an LED lamp bank;
the input rectifying circuit has an input end connected with external alternating current and an output end connected with the input energy storage filter capacitor and the charging current control circuit, receives external alternating current input, converts the external alternating current input into a pulsating direct current voltage signal and outputs the pulsating direct current voltage signal;
the input energy storage filter capacitor and the charging current control circuit are connected in series, the free end of the input energy storage filter capacitor is connected with the first end of the output end of the input rectifying circuit, and the free end of the charging current control circuit is connected with the second end of the output end of the input rectifying circuit;
the LED lamp bank and the LED current control circuit are connected in series, the free end of the LED lamp bank is connected with the first end of the output end of the input rectifying circuit, and the free end of the LED current control circuit is connected with the charging current control circuit;
one end of the line voltage sampling circuit is connected with the first end of the output end of the input rectifying circuit, the other end of the line voltage sampling circuit is connected with the LED current control circuit, the line voltage sampling circuit is provided with a compensation current generating circuit, and compensation current is generated according to the level of the pulsating direct current voltage signal output by the input rectifying circuit and is sent to the LED current control circuit.
Further, the input rectification circuit comprises a first diode, a second diode, a third diode and a fourth diode; the anode of the first diode is the first end of the input rectifying circuit, and the cathode of the first diode is the first end of the output end of the input rectifying circuit; the anode of the third diode is the second end of the input alternating current circuit, and the cathode of the third diode is the second end of the output end of the input rectifying circuit; the cathode of the second diode is connected with the anode of the first diode, and the anode of the second diode is connected with the anode of the third diode; and the cathode of the fourth diode is connected with the cathode of the first diode, and the anode of the fourth diode is connected with the cathode of the third diode.
Further, the input energy storage filter capacitor is a first electrolytic capacitor, the anode of the first electrolytic capacitor is connected with the first end of the input rectifying circuit, and the cathode of the first electrolytic capacitor is connected with the charging current control circuit.
Further, the charging current control circuit comprises a first MOS (metal oxide semiconductor) tube, a first operational amplifier and a first sampling resistor, wherein the drain electrode of the first MOS tube is connected with the negative electrode of the first electrolytic capacitor, the source electrode of the first MOS tube is connected with one end of the first sampling resistor, the other end of the first sampling resistor is connected with the second end of the output end of the input rectifying circuit, the grid electrode of the first MOS tube is connected with the output end of the first operational amplifier, the forward input end of the first operational amplifier is connected with a first reference voltage, and the reverse input end of the first operational amplifier is connected with the source electrode of the first MOS tube.
Further, LED current control circuit includes that second MOS pipe, second fortune are put and second sampling resistor, the drain electrode of second MOS pipe with LED banks links to each other, the source electrode of second MOS pipe with the one end of second sampling resistor links to each other, the other end of second sampling resistor with charging current control circuit links to each other, the grid of second MOS pipe with the output that second fortune was put links to each other, the forward input that second fortune was put links to each other with second reference voltage, the reverse input that second fortune was put with the source electrode of second MOS pipe links to each other.
Furthermore, the line voltage sampling circuit also comprises a first resistor, a second resistor, a third resistor, a fourth resistor and a first capacitor; the first resistor and the second resistor are connected in series and are connected in parallel to two ends of the input energy storage filter capacitor; the third resistor and the first capacitor are connected in series and are connected in parallel to two ends of the second resistor; the connection point of the third resistor and the first capacitor is connected with the input end of the compensation current generating circuit, the output end of the compensation current generating circuit is connected with the reverse input end of the second operational amplifier, and the reverse input end of the second operational amplifier is connected with the source electrode of the second MOS tube through the fourth resistor.
Further, the LED lamp group comprises a first LED lamp group and a second LED lamp group which are connected in series, and the LED current control circuit further comprises a third MOS tube and a third operational amplifier; the drain electrode of the third MOS tube is connected with the connection point of the first LED lamp group and the second LED lamp group, the source electrode of the third MOS tube is connected with one end of the second sampling resistor, the grid electrode of the third MOS tube is connected with the output end of the third operational amplifier, the forward input end of the third operational amplifier is connected with a third reference voltage, and the reverse input end of the third operational amplifier is connected with the source electrode of the third MOS tube through the fourth resistor.
Further, the LED lamp group further comprises a third LED lamp group which is sequentially connected with the first LED lamp group and the second LED lamp group in series, and the LED current control circuit further comprises a fourth MOS (metal oxide semiconductor) tube and a fourth operational amplifier; the drain electrode of the fourth MOS tube is connected with the connection point of the second LED lamp group and the third LED lamp group, the source electrode of the fourth MOS tube is connected with one end of the second sampling resistor, the grid electrode of the fourth MOS tube is connected with the output end of the fourth operational amplifier, the forward input end of the fourth operational amplifier is connected with a fourth reference voltage, and the reverse input end of the fourth operational amplifier is connected with the source electrode of the fourth MOS tube through the fourth resistor.
Furthermore, the LED lamp group also comprises X LED lamp groups which are sequentially connected with the first LED lamp group, the second LED lamp group and the third LED lamp group in series, and the LED current control circuit also comprises X MOS (metal oxide semiconductor) tubes and X operational amplifiers; the connection relation of the X LED lamp groups, the X MOS tubes and the X operational amplifiers refers to the connection relation of the third LED lamp group, the fourth MOS tube and the fourth operational amplifier, and so on, wherein X is a positive integer.
The linear LED drive circuit controls the charging current and the charging working time of input energy storage filtering electrolysis through the charging current control circuit, so that the aim of actively adjusting the phase difference between the input current waveform and the input voltage waveform to be as close as possible is achieved, and the power factor of a drive circuit system is improved. The LED current control circuit samples the LED current in real time and feeds the LED current back to an internal reference circuit of the LED current control circuit for comparison, so that the purposes of constant current and no stroboscopic work are achieved. The line voltage sampling circuit adjusts the compensation quantity of a reference signal in the LED current control circuit through real-time detection of the power grid voltage to control the system output of constant power in different input voltage ranges.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a schematic block diagram of a linear LED driver circuit provided herein;
fig. 2 is a schematic structural diagram of an embodiment of a linear LED driving circuit provided in the present application;
fig. 3 is a schematic structural diagram of another embodiment of a linear LED driving circuit provided in the present application.
Detailed Description
The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application. Furthermore, it should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the invention, are given by way of illustration and explanation only, and are not intended to limit the scope of the invention. In the present application, unless otherwise specified, the use of directional terms such as "upper", "lower", "left" and "right" generally refer to upper, lower, left and right in the actual use or operation of the device, and specifically to the orientation of the drawing figures.
The present application provides a linear LED driving circuit, which will be described in detail below. It should be noted that the following description of the embodiments is not intended to limit the preferred order of the embodiments of the present application. In the following embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to related descriptions of other embodiments for parts that are not described in detail in a certain embodiment.
Referring to fig. 1, the present application provides a linear LED driving circuit, including: the LED lamp bank comprises an input rectifying circuit, an input energy storage filter capacitor, a charging current control circuit, a line voltage sampling circuit, an LED current control circuit and an LED lamp bank;
the input rectifying circuit has an input end connected with external alternating current and an output end connected with the input energy storage filter capacitor and the charging current control circuit, receives external alternating current input, converts the external alternating current input into a pulsating direct current voltage signal and outputs the pulsating direct current voltage signal;
the input energy storage filter capacitor and the charging current control circuit are connected in series, the free end of the input energy storage filter capacitor is connected with the first end of the output end of the input rectifying circuit, and the free end of the charging current control circuit is connected with the second end of the output end of the input rectifying circuit;
the LED lamp bank and the LED current control circuit are connected in series, the free end of the LED lamp bank is connected with the first end of the output end of the input rectifying circuit, and the free end of the LED current control circuit is connected with the charging current control circuit;
one end of the line voltage sampling circuit is connected with the first end of the output end of the input rectifying circuit, the other end of the line voltage sampling circuit is connected with the LED current control circuit, the line voltage sampling circuit is provided with a compensation current generating circuit, and compensation current is generated according to the level of the pulsating direct current voltage signal output by the input rectifying circuit and is sent to the LED current control circuit.
The input rectifying circuit comprises a first diode D1, a second diode D2, a third diode D3 and a fourth diode D4; the anode of the first diode D1 is the first end of the input rectification circuit, and the cathode of the first diode D1 is the first end of the output end of the input rectification circuit; the anode of the third diode D3 is the second end of the input alternating current circuit, and the cathode is the second end of the output end of the input rectifying circuit; the cathode of the second diode D2 is connected with the anode of the first diode D1, and the anode is connected with the anode of the third diode D3; the cathode of the fourth diode D4 is connected to the cathode of the first diode D1, and the anode is connected to the cathode of the third diode D3. Two ends of the input end of the input rectification circuit are connected with Alternating Current (AC) provided by an external power grid, a first end of the output end of the input rectification circuit outputs a pulsating direct current voltage signal Vin, and a second end of the output end of the input rectification circuit is connected with Ground (GND) (see fig. 2).
The input energy storage filter capacitor is a first electrolytic capacitor EC1, the positive electrode of the first electrolytic capacitor EC1 is connected with the first end of the input rectifying circuit, the first end of the output end of the input rectifying circuit outputs a pulsating direct current voltage signal Vin, and the negative electrode of the input energy storage filter capacitor is connected with the charging current control circuit.
Referring to fig. 2, the charging current control circuit includes a first MOS transistor Q1, a first operational amplifier U1, and a first sampling resistor Rcs1, a drain of the first MOS transistor Q1 is connected to a negative electrode of the first electrolytic capacitor EC1, a source of the first MOS transistor Q1 is connected to one end of the first sampling resistor Rcs1, another end of the first sampling resistor Rcs1 is connected to a second end of an output end of the input rectification circuit, that is, to ground GND, a gate of the first MOS transistor Q1 is connected to an output end of the first operational amplifier U1, a forward input end of the first operational amplifier U1 is connected to a first reference voltage Vref1, and a reverse input end of the first operational amplifier U1 is connected to a source of the first MOS transistor Q1. Wherein the first reference voltage Vref1 is additionally set in advance.
The LED current control circuit includes a second MOS transistor Q2, a second operational amplifier U2, and a second sampling resistor Rcs2, a drain of the second MOS transistor Q2 is connected to the LED lamp group LEDs 1-LEDn, a source of the second MOS transistor Q2 is connected to one end of the second sampling resistor Rcs2, another end of the second sampling resistor Rcs2 is connected to the charging current control circuit, specifically, the drain of the first MOS transistor Q1 is connected to the drain of the second MOS transistor Q2, a gate of the second MOS transistor Q2 is connected to an output end of the second operational amplifier U2, a forward input end of the second operational amplifier U2 is connected to a second reference voltage Vref2, and a reverse input end of the second operational amplifier U2 is connected to a source of the second MOS transistor Q2. Wherein the second reference voltage Vref2 is additionally set in advance.
The line voltage sampling circuit further comprises a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4 and a first capacitor C1; the first resistor R1 and the second resistor R2 are connected in series and are connected in parallel with two ends of the input energy storage filter capacitor, namely two ends of the first electrolytic capacitor EC 1; the third resistor R2 and the first capacitor C1 are connected in series and are connected in parallel with two ends of the second resistor R2; the connection point of the third resistor R2 and the first capacitor C1 is connected with the input end of the compensation current generation circuit, the output end of the compensation current generation circuit is connected with the reverse input end of the second operational amplifier U2, and the reverse input end of the second operational amplifier U2 is connected with the source electrode of the second MOS transistor Q2 through the fourth resistor R4. The compensation current generating circuit is a conversion circuit and converts a voltage signal into a current signal, specifically, the pulsating direct current voltage signal output by the input rectifying circuit and collected by the line voltage sampling circuit is converted into a current signal in an equal proportion relation with the voltage signal, and when the voltage signal is higher, the compensation current generated by the compensation current generating circuit is larger.
When the linear LED driving circuit is powered on, a charging current control circuit formed by a linear constant current driving circuit consisting of the first MOS tube Q1 (power tube), the first sampling resistor Rcs1, the first operational amplifier U1 and the first reference voltage Vref1 is connected in series with the first electrolytic capacitor EC1 of the input energy storage filter capacitor for charging, and the charging current and time of the first electrolytic capacitor EC1 are controlled by the charging current control circuit.
Generally, the charging time tc of the first electrolytic capacitor EC1 and the magnitude of the charging current Ic have the following mathematical relationship:
wherein C is the capacitance value of the first electrolytic capacitor EC1, and Δ V is the variation from the voltage corresponding to the initial charging of the capacitor to the voltage corresponding to the end of the charging.
When the power factor of the linear LED driving circuit is low, the working current of the charging current control circuit can be reduced by increasing the resistance value of the first sampling resistor Rcs1, so that the charging time of the first electrolytic capacitor EC1 is prolonged, the purpose of increasing the input current conduction angle is achieved, and the power factor of the circuit is improved.
The charging current control circuit can keep constant current output in the voltage range of the whole pulsating direct current voltage signal Vin, and the mathematical relational expression of the charging current control circuit is as follows:
therefore, no matter the pulsating direct current voltage signal Vin is high or low, the first electrolytic capacitor EC1 can obtain a proper charging current by adjusting the resistance of the first sampling resistor Rcs1 to achieve a non-stroboscopic output in the whole voltage range of the pulsating direct current voltage signal Vin (wherein, the larger the charging current Ic is, the higher the charging voltage of the first electrolytic capacitor EC1 is, the easier the non-stroboscopic output is).
In the charging process of the first electrolytic capacitor EC1, when the pulsating direct current voltage signal Vin output by the input rectifying circuit is greater than the working voltage Vled of the LED lamp groups LED1-LEDn, the LED current control circuit starts to enter a working state, and the LED lamp groups LED1-LEDn are gradually lighted for working. When the difference value between the pulsating direct current voltage signal Vin and the working voltage Vled of the LED lamp groups LED1-LEDn reaches the minimum working voltage value corresponding to the preset working current in the LED current control circuit, the LED lamp groups LED1-LEDn are fully lighted to work and stably work with the preset working current Iled, and the current magnitudes have the following relations:
here, IA1 is a compensation current in the compensation current generation circuit.
It can be seen from the above mathematical relational expression that, when the pulsating dc voltage signal Vin is continuously increased, the magnitude of the voltage signal sampled by the line voltage sampling circuit is continuously increased, and at this time, the magnitude of the compensation current IA1 in the compensation current generating circuit is also continuously increased, so that the magnitude of the current preset in the LED current control circuit is continuously decreased, and then the power is decreased, thereby realizing the constant power. Generally speaking, the linear driving circuit has larger loss in the circuit along with the increase of the input voltage, and if the input voltage is allowed to continuously rise without controlling the magnitude of the operating current in the circuit, the input power of the circuit system will become larger and larger, which will result in very large power loss, and finally result in the reliability of the circuit system being reduced, and even the failure of overheating and burning out components. The linear LED driving circuit realizes constant power control through the cooperation of the line voltage sampling circuit and the compensation current generating circuit.
During the stable operation of the linear LED driving circuit, when the charging current control circuit operates, the operating current Iin of the charging current control circuit has the following relationship:
iin ═ Ic + Iled (formula iv).
In the voltage range of the pulsating direct current voltage signal Vin, it can be seen that if the pulsating direct current voltage signal Vin increases continuously, the preset operating current in the LED current control circuit decreases continuously due to the negative feedback of the line voltage sampling circuit, and the current Iin in the charging current control circuit is constant and constant in the voltage range of the pulsating direct current voltage signal Vin, therefore, it can be seen that the charging current Ic input to the first electrolytic capacitor EC1 of the energy storage filter capacitor increases continuously with the increase of the pulsating direct current voltage signal Vin, the increase of the charging current Ic of the first electrolytic capacitor EC1 will result in a faster charging speed of the first electrolytic capacitor EC1, the voltage at two ends of the first electrolytic capacitor EC1 will be charged higher, so that the voltage difference between the pulsating direct current voltage signal output by the input rectification circuit and the operating voltage LED of the LED lamp groups LED1-LEDn will be larger (the LED lamp groups LED1-LEDn will not operate under voltage, it needs enough driving voltage to maintain its stable working state), the LED1-LEDn will always maintain stable working under the preset working current, achieving the effect of wide voltage input without stroboscopic output. When the charging current control circuit is turned off, the first electrolytic capacitor EC1 serves as an input voltage source to provide power for the LED lamp groups LED1-LEDn and the LED current control circuit, and at this time, the LED lamp groups LED1-LEDn do not output stroboflash at a constant working current, and the stroboflash-free effect depends on that the peak value and the bottom value of the charging voltage of the first electrolytic capacitor EC1 must satisfy that the voltage difference between the pulsating direct-current voltage signal Vin and the working voltage Vled of the LED lamp groups LED1-LEDn is greater than the corresponding minimum input voltage value when the LED current control circuit can work at a preset current, in a linear circuit, this is generally called a constant current knee voltage value, and also during this period (i.e., during the discharging period of the first electrolytic capacitor EC1, i.e., during the turning-off period of the charging current control circuit), the magnitude of the currents Iled of the LED lamp groups LED1-LEDn is still controlled by the relational expression formula three.
Further, referring to fig. 3, in another embodiment, the LED lamp set is two-stage, and includes a first LED lamp set LED1-LEDn and a second LED lamp set LEDn +1-LEDm connected in series, and the LED current control circuit further includes a third MOS transistor Q3 and a third operational amplifier U3; the drain of the third MOS transistor Q3 is connected to a connection point between the first LED lamp group LED1-LEDn and the second LED lamp group LEDn +1-LEDm, the source of the third MOS transistor Q3 is connected to one end of the second sampling resistor Rcs2, the gate of the third MOS transistor Q3 is connected to the output end of the third operational amplifier U3, the positive input end of the third operational amplifier U3 is connected to a third reference voltage Vref3, and the reverse input end of the third operational amplifier U3 is connected to the source of the third MOS transistor Q3 through the fourth resistor R4. Wherein the third reference voltage Vref3 is additionally set in advance.
The first lamp group LEDs 1-LEDn and the second lamp group LEDn +1-LEDm work in series when the pulsating direct current voltage signal Vin is high, higher system efficiency and system output power are achieved, when the pulsating direct current voltage signal Vin is low, the second lamp group LEDn +1-LEDm is closed, the first lamp group LEDs 1-LEDn maintain a normal working state and do not output stroboflash (the voltage difference between the pulsating direct current voltage signal Vin and the working voltage Vled1 of the first lamp group LEDs 1-LEDn is still large enough, the first lamp group LEDs 1-LEDn can be driven to work normally, and the second lamp group LEDn +1-LEDm cannot be driven to work normally). Because the circuit has the function of a line voltage compensation mechanism (the voltage variation of the pulsating direct current voltage signal Vin is sampled by the line voltage sampling circuit to adjust the magnitude of the output current, as described above), the preset working current of the LED current control circuit is higher when the pulsating direct current voltage signal Vin is lower (see formula three, when the pulsating direct current voltage signal Vin is lower, the compensation current IA1 is not compensated, and can be considered as zero), so as to make up for the problem that the system output power is lower (the output current is increased) when only the first lamp group LEDs 1-LEDn work. The basic structure of the circuit for controlling the second lamp group LEDn +1-LEDm is the same as the basic structure of the circuit for controlling the first lamp group LEDs 1-LEDn, and the third MOS tube Q3 for controlling the working current of the first lamp group LEDs 1-LEDn can be naturally turned off only when the pulsating direct current voltage signal Vin works at a higher voltage. In order to realize the natural turning off of the third MOS transistor Q3, the third reference voltage Vref3 may be designed to be smaller than the second reference voltage Vref2, so that when the product of the current flowing through the second sampling resistor Rcs2 and the second sampling resistor Rcs2 is larger than the third reference voltage Vref3, the third operational amplifier U3 outputs a low level signal, and the third MOS transistor Q3 is naturally turned off, and at this time, the working currents of the first lamp group LED1-LEDn and the second lamp group LED +1-LEDm are equal and are both controlled by the second MOS transistor Q2, and the current magnitude is still as shown in formula three.
Thus, and so on, the LED lamp set may comprise more segmented LED lamp sets. For example, the LED lamp set further includes a third LED lamp set sequentially connected in series with the first LED lamp set and the second LED lamp set, and the LED current control circuit further includes a fourth MOS transistor and a fourth operational amplifier; the drain electrode of the fourth MOS tube is connected with the connection point of the second LED lamp group and the third LED lamp group, the source electrode of the fourth MOS tube is connected with one end of the second sampling resistor, the grid electrode of the fourth MOS tube is connected with the output end of the fourth operational amplifier, the forward input end of the fourth operational amplifier is connected with a fourth reference voltage, and the reverse input end of the fourth operational amplifier is connected with the source electrode of the fourth MOS tube through the fourth resistor.
Even, the LED lamp group further comprises X LED lamp groups which are sequentially connected with the first LED lamp group, the second LED lamp group and the third LED lamp group in series, and the LED current control circuit further comprises X MOS (metal oxide semiconductor) tubes and X operational amplifiers; the connection relation of the X LED lamp groups, the X MOS tubes and the X operational amplifiers refers to the connection relation of the third LED lamp group, the fourth MOS tube and the fourth operational amplifier, and so on, wherein X is a positive integer.
However, the circuit structure of the two-segment or three-segment LED lamp set is preferable in consideration of the cost of the integrated circuit architecture and the performance of the actual solution.
The linear LED drive circuit controls the charging current and the charging working time of input energy storage filtering electrolysis through the charging current control circuit, so that the aim of actively adjusting the phase difference between the input current waveform and the input voltage waveform to be as close as possible is achieved, and the power factor of a drive circuit system is improved. The LED current control circuit samples the LED current in real time and feeds the LED current back to an internal reference circuit of the LED current control circuit for comparison, so that the purposes of constant current and no stroboscopic work are achieved. The line voltage sampling circuit adjusts the compensation quantity of a reference signal in the LED current control circuit through real-time detection of the power grid voltage to control the system output of constant power in different input voltage ranges.
The foregoing detailed description has provided a linear LED driving circuit, and the principles and embodiments of the present application are described herein using specific examples, which are merely used to help understand the method and the core concept of the present application; meanwhile, for a person skilled in the art, according to the idea of the present application, there may be variations in the specific embodiments and the application scope, and in summary, the content of the present specification should not be construed as a limitation to the present application.
Claims (9)
1. A linear LED driving circuit, comprising: the LED lamp bank comprises an input rectifying circuit, an input energy storage filter capacitor, a charging current control circuit, a line voltage sampling circuit, an LED current control circuit and an LED lamp bank;
the input end of the input rectifying circuit is connected with external alternating current, and the output end of the input rectifying circuit is connected with the input energy storage filter capacitor and the charging current control circuit, receives external alternating current input, converts the external alternating current input into a pulsating direct current voltage signal and outputs the pulsating direct current voltage signal;
the input energy storage filter capacitor and the charging current control circuit are connected in series, the free end of the input energy storage filter capacitor is connected with the first end of the output end of the input rectifying circuit, and the free end of the charging current control circuit is connected with the second end of the output end of the input rectifying circuit;
the LED lamp bank and the LED current control circuit are connected in series, the free end of the LED lamp bank is connected with the first end of the output end of the input rectification circuit, and the free end of the LED current control circuit is connected with the charging current control circuit;
one end of the line voltage sampling circuit is connected with the first end of the output end of the input rectifying circuit, the other end of the line voltage sampling circuit is connected with the LED current control circuit, the line voltage sampling circuit is provided with a compensation current generating circuit, and compensation current is generated according to the level of the pulsating direct current voltage signal output by the input rectifying circuit and is sent to the LED current control circuit.
2. The linear LED driving circuit of claim 1, wherein the input rectification circuit comprises a first diode, a second diode, a third diode, and a fourth diode; the anode of the first diode is the first end of the input rectifying circuit, and the cathode of the first diode is the first end of the output end of the input rectifying circuit; the anode of the third diode is the second end of the input rectifying circuit, and the cathode of the third diode is the second end of the output end of the input rectifying circuit; the cathode of the second diode is connected with the anode of the first diode, and the anode of the second diode is connected with the anode of the third diode; and the cathode of the fourth diode is connected with the cathode of the first diode, and the anode of the fourth diode is connected with the cathode of the third diode.
3. The linear LED driving circuit according to claim 1, wherein the input energy storage filter capacitor is a first electrolytic capacitor, an anode of the first electrolytic capacitor is connected to the first end of the input rectifying circuit, and a cathode of the first electrolytic capacitor is connected to the charging current control circuit.
4. The linear LED driving circuit according to claim 3, wherein the charging current control circuit comprises a first MOS transistor, a first operational amplifier and a first sampling resistor, a drain of the first MOS transistor is connected to a negative electrode of the first electrolytic capacitor, a source of the first MOS transistor is connected to one end of the first sampling resistor, another end of the first sampling resistor is connected to a second end of the output end of the input rectifying circuit, a gate of the first MOS transistor is connected to the output end of the first operational amplifier, a forward input end of the first operational amplifier is connected to a first reference voltage, and a reverse input end of the first operational amplifier is connected to the source of the first MOS transistor.
5. The linear LED driving circuit according to claim 4, wherein the LED current control circuit comprises a second MOS transistor, a second operational amplifier and a second sampling resistor, a drain of the second MOS transistor is connected to the LED lamp set, a source of the second MOS transistor is connected to one end of the second sampling resistor, the other end of the second sampling resistor is connected to the charging current control circuit, a gate of the second MOS transistor is connected to an output terminal of the second operational amplifier, a forward input terminal of the second operational amplifier is connected to a second reference voltage, and a reverse input terminal of the second operational amplifier is connected to a source of the second MOS transistor.
6. The linear LED drive circuit of claim 5, wherein the line voltage sampling circuit further comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a first capacitor; the first resistor and the second resistor are connected in series and are connected in parallel to two ends of the input energy storage filter capacitor; the third resistor and the first capacitor are connected in series and are connected in parallel to two ends of the second resistor; the connection point of the third resistor and the first capacitor is connected with the input end of the compensation current generating circuit, the output end of the compensation current generating circuit is connected with the reverse input end of the second operational amplifier, and the reverse input end of the second operational amplifier is connected with the source electrode of the second MOS tube through the fourth resistor.
7. The linear LED driving circuit according to claim 6, wherein the LED lamp set comprises a first LED lamp set and a second LED lamp set connected in series, and the LED current control circuit further comprises a third MOS transistor and a third operational amplifier; the drain electrode of the third MOS tube is connected with the connection point of the first LED lamp group and the second LED lamp group, the source electrode of the third MOS tube is connected with one end of the second sampling resistor, the grid electrode of the third MOS tube is connected with the output end of the third operational amplifier, the forward input end of the third operational amplifier is connected with a third reference voltage, and the reverse input end of the third operational amplifier is connected with the source electrode of the third MOS tube through the fourth resistor.
8. The linear LED driving circuit according to claim 7, wherein the LED lamp set further comprises a third LED lamp set connected in series with the first LED lamp set and the second LED lamp set in sequence, and the LED current control circuit further comprises a fourth MOS transistor and a fourth operational amplifier; the drain electrode of the fourth MOS tube is connected with the connection point of the second LED lamp group and the third LED lamp group, the source electrode of the fourth MOS tube is connected with one end of the second sampling resistor, the grid electrode of the fourth MOS tube is connected with the output end of the fourth operational amplifier, the forward input end of the fourth operational amplifier is connected with a fourth reference voltage, and the reverse input end of the fourth operational amplifier is connected with the source electrode of the fourth MOS tube through the fourth resistor.
9. The linear LED driving circuit according to claim 8, wherein the LED lamp set further comprises X LED lamp sets connected in series with the first LED lamp set, the second LED lamp set, and the third LED lamp set in sequence, and the LED current control circuit further comprises X MOS transistors and X operational amplifiers; the connection relation of the X LED lamp groups, the X MOS tubes and the X operational amplifiers refers to the connection relation of the third LED lamp group, the fourth MOS tube and the fourth operational amplifier, and so on, wherein X is a positive integer.
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| CN114205963A (en) * | 2021-12-21 | 2022-03-18 | 欧普照明股份有限公司 | Linear LED driving circuit and driving method |
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