CN109413791B - Feedback circuit - Google Patents
Feedback circuit Download PDFInfo
- Publication number
- CN109413791B CN109413791B CN201710710987.XA CN201710710987A CN109413791B CN 109413791 B CN109413791 B CN 109413791B CN 201710710987 A CN201710710987 A CN 201710710987A CN 109413791 B CN109413791 B CN 109413791B
- Authority
- CN
- China
- Prior art keywords
- unit
- signal
- coupled
- voltage
- output
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B45/00—Circuit arrangements for operating light-emitting diodes [LED]
- H05B45/30—Driver circuits
- H05B45/37—Converter circuits
Landscapes
- Led Devices (AREA)
- Circuit Arrangement For Electric Light Sources In General (AREA)
- Dc-Dc Converters (AREA)
Abstract
The invention provides a feedback circuit which is helpful for maintaining constant current, constant voltage and constant power output of an LED power supply, mainly comprising the following components: the sampling unit, the feedback unit, the signal conversion unit and the signal adjustment unit. In the operation of the feedback circuit, the current error amplifier in the feedback unit outputs a current error signal according to the current sampling signal and the dimming signal output by the signal conversion unit, and further informs the PWM control unit to maintain the constant current output of the LED power supply. Meanwhile, according to the voltage sampling signal and the adjusting signal output by the reference signal adjusting unit, the voltage error amplifier in the feedback unit is matched with the PWM control unit, so that the output constant voltage of the LED power supply is adaptively adjusted along with the output constant current, and the constant power output of the LED power supply is maintained through the method.
Description
Technical Field
The present invention relates to the field of electronic circuits, and more particularly, to a feedback circuit applied to a power converter and a power supply.
Background
With the development and progress of electronic technology, various electronic devices and products are widely used in daily life, and a linear power supply (linear power supply) is conventionally used to provide stable voltage/current to the electronic devices. However, the conventional linear Power Supply has the disadvantages of large volume and low Power conversion efficiency, so the Switching Mode Power Supply (SMPS) was proposed in 1970 by neth r.m. rao.
The technology of the switching power supply is also applied to the LED power supply (or LED driver). Referring to fig. 1, a block diagram of a conventional LED power supply is shown. As shown in fig. 1, the conventional LED power supply 1' includes: coupled to a voltage source VSThe electromagnetic interference filter unit 10 ', the rectifier unit 11', the PFC unit 12 '(power factor correction unit), the power switch unit 13', the transformer unit 14 ', the output filter rectifier unit 15', and the feedback unit16 ', and a PWM control unit 17'; the feedback unit 16 ' is generally composed of an error amplifier unit 161 ' and an optocoupler feedback unit 162 '. Also, as is well known to those skilled in the art of power electronic circuitry, the error amplifier unit 161 ' typically includes a voltage error amplifier 1611 ' and a current error amplifier 1612 '.
It should be noted that, according to the dimming and feedback control technique of the LED driving circuit disclosed in chinese patent No. CN102668712A, the voltage error amplifier 1611 'and the current error amplifier 1612' respectively pass through the voltage sampling unit VSU 'and the current sampling unit CSU' from the output terminal Vout 'obtains the voltage sampling signal and the current sampling signal, and further outputs an error signal to the PWM control unit 17' through the optocoupler feedback 162 ', so that the PWM control unit 17' can correspondingly output a pulse width modulation signal to control the switching of the power switch unit 13 ', thereby achieving the effect of stabilizing the output signal of the LED power supply 1'.
In addition, the LED power supply 1 ' shown in fig. 1 also has a dimming unit 19 ' for outputting a dimming control signal to the error amplifier unit 161 '. As shown in fig. 1, the current error amplifier 1612 'outputs a current error signal to the PWM control unit 17' according to the dimming control signal and the current sampling signal; similarly, the voltage error amplifier 1612 'also outputs a voltage error signal to the PWM control unit 17' according to the voltage sampling signal. It should be noted that in the design of the LED power supply 1 'shown in fig. 1, only the error signal for informing the PWM control unit 17' to adjust the output voltage/current of the switching power supply 1 'is outputted through the OR logic gate 1613'.
Obviously, the prior art mainly utilizes the error amplifier unit 161 ' composed of the voltage error amplifier 1611 ', the current error amplifier 1612 ' and the OR logic gate 1613 ' to notify the PWM control unit 17 ' to reduce the output voltage/current of the switching power supply 1 ' according to the dimming control signal outputted by the dimming unit 19 '. However, initially, the regulation of the output voltage/current by the feedback unit 16 'and the PWM control unit 17' is a droop control, and the droop control can only singly drop the output voltage or current. Even though the conventional LED power supply 1 ' can drive the LED lamp 2 ' with constant current or constant voltage, the feedback control mechanism for singly adjusting the output voltage or current will cause the LED power supply 1 ' to be unable to maintain constant power output.
Since the feedback unit 16 'used in the prior art can only maintain the constant voltage output or the constant current output of the LED power supply 1', the inventor of the present invention has developed a feedback circuit.
Disclosure of Invention
Since the feedback unit used in the prior art can only singly maintain the constant voltage output or the constant current output of the LED power supply, the main objective of the present invention is to provide a feedback circuit, which is particularly helpful for maintaining the constant current, the constant voltage and the constant power output of the LED power supply, and mainly comprises: a sampling unit, a feedback unit, a signal conversion unit, and a signal adjustment unit. In the operation of the feedback circuit, the current error amplifier in the feedback unit outputs a current error signal according to the current sampling signal and the dimming signal output by the signal conversion unit, so as to inform the PWM control unit to maintain the constant current output of the LED power supply. Meanwhile, according to the voltage sampling signal and the adjusting signal output by the reference signal adjusting unit, the voltage error amplifier in the feedback unit is matched with the PWM control unit, so that the output constant voltage of the LED power supply is adaptively adjusted along with the output constant current, and the constant power output of the LED power supply is maintained through the method.
In order to solve the technical problems, the invention adopts the following technical scheme:
the embodiment of the present invention provides a feedback circuit, which is disposed in an LED power supply, wherein the LED power supply at least includes: the power supply comprises a rectifying unit, a power switch unit, a transformer unit, an output filtering rectifying unit and a PWM control unit; further, the feedback circuit includes:
the sampling unit is coupled to a power output end of the LED power supply and is used for obtaining a voltage sampling signal and a current sampling signal from the power output end;
a feedback unit coupled to the sampling unit and including a current error amplifier and a voltage error amplifier;
a signal conversion unit, coupled to an external dimming circuit and the current error amplifier, for converting a dimming control signal output by the dimming circuit into a dimming signal and outputting the dimming signal to the current error amplifier;
a signal adjusting unit, coupled to the signal converting unit and the voltage error amplifier, for performing signal adjustment processing according to a reference signal of the dimming signal pair output by the signal converting unit and outputting an adjusting signal to the voltage error amplifier;
according to the current sampling signal and the dimming signal, the current error amplifier outputs a current error signal to the PWM control unit, so that the PWM control unit correspondingly outputs a first pulse width modulation signal to control the switch of the power switch unit, and the output constant current of the LED power supply is enabled to be transmitted to an external LED lamp in such a way;
according to the voltage sampling signal and the adjusting signal, the voltage error amplifier outputs a voltage error signal to the PWM control unit, so that the PWM control unit correspondingly outputs a second pulse width modulation signal to control the switch of the power switch unit, and the output constant voltage of the LED power supply is adaptively adjusted along with the output constant current in such a way, so as to maintain the constant power output of the LED power supply.
Moreover, in order to solve the above technical problem, the inventor of the present invention provides a second embodiment of the feedback circuit, wherein the feedback circuit is disposed in an LED power supply, and the LED power supply at least includes: the power supply comprises a rectifying unit, a power switch unit, a transformer unit, an output filtering rectifying unit and a PWM control unit; further, the feedback circuit includes:
the sampling unit is coupled to a power output end of the LED power supply and is used for obtaining a voltage sampling signal and a current sampling signal from the power output end;
a feedback unit coupled to the sampling unit and including a current error amplifier and a voltage error amplifier;
a signal conversion unit, coupled to an external dimming circuit and the current error amplifier, for converting a dimming control signal output by the dimming circuit into a dimming signal and outputting the dimming signal to the current error amplifier;
according to the current sampling signal and the dimming signal, the current error amplifier outputs a current error signal to the PWM control unit, so that the PWM control unit correspondingly outputs a first pulse width modulation signal to control the switch of the power switch unit, and the output constant current of the LED power supply is enabled to be transmitted to an external LED lamp in such a way;
the voltage error amplifier outputs a voltage error signal to the PWM control unit according to the voltage sampling signal, the reference signal, and the adjustment signal, so that the PWM control unit correspondingly outputs a second PWM signal to control the switch of the power switch unit, and thus, the output constant voltage of the LED power supply is adaptively adjusted along with the output constant current, so as to maintain the constant power output of the LED power supply.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:
fig. 1 is a block diagram of a conventional LED power supply;
FIG. 2 is a block diagram of an LED power supply including a feedback circuit according to a first embodiment of the present invention;
FIG. 3 is a circuit diagram of a feedback circuit according to a first embodiment of the present invention;
FIG. 4 is a data graph of output current versus output voltage of the feedback circuit according to the present invention;
FIG. 5 is a circuit diagram of a feedback circuit according to a second embodiment of the present invention;
FIG. 6 is a block diagram of an LED power supply including a second embodiment of the feedback circuit of the present invention.
In the drawings, the components represented by the respective reference numerals are listed below:
1 ', switching power supply, 2', LED lamp, VSVoltage source, 10 ', emi filter unit, 11', rectifier unit, 12 ', PFC unit, 13', power switch unit, 14 ', transformer unit, 15', output filter rectifier unit, 16 ', feedback unit, 17', PWM control unit, 161 ', error amplifier unit, 162', optocoupler feedback, 1611 ', voltage error amplifier, 1612', current error amplifier, VoutAn output terminal, a VSU ', a voltage sampling unit, a CSU ' current sampling unit, a DVC ', a voltage dividing circuit, 19 ', a dimming unit, 1613 ', an OR logic gate;
2. an LED power supply, 20, an electromagnetic interference filter unit, 21, a rectifier unit, 22, a power factor correction unit, 23, a power switch unit, 24, a transformer unit, 25, an output filter rectifier unit, 27, a PWM control unit, 1, a feedback circuit, 10, a sampling unit, 11, a feedback unit, 12, a signal conversion unit, 13, a signal adjustment unit, 101, an output current sampling unit, 102, an output voltage sampling unit, Rsen, a current detection resistor, Rsam, a signal sampling resistor, GND, a ground, Rv1, a first voltage dividing resistor, Rv2, a second voltage dividing resistor, 111, a current error amplifier, 112, a voltage error amplifier, 113, an optical coupler, 4, a dimming circuit, Rx1, a first signal conversion resistor, Rx2, a second signal conversion resistor, 17, a nonlinear dimming unit, 15, a signal isolation unit, 1112, a first input buffer unit, 1113. a first error amplifier 151, a first voltage follower 131, a differential amplifier unit 132, a voltage comparator unit 133, and a voltage regulator unitElement 152, second voltage follower, VREF1A first reference voltage, OP, an operational amplifier, R514, a first resistor, R515, a second resistor, Di, a diode, R511, a third resistor, VREF2A second reference voltage 1121, a second input buffer unit 1122, a second error amplifier, a curve, B, a curve, C, a curve, D, a curve, 130, an error detector, OP', an operational amplifier, Rv3, a third voltage dividing resistor, Rv4, a fourth voltage dividing resistor, D1, a first diode, D2, a second diode, Eop, an error amplifier, V2, a second error amplifierREFA reference signal.
Detailed Description
The present invention will be described in further detail with reference to the following examples, which are not intended to limit the invention thereto.
First embodiment
Referring to fig. 2, a block diagram of an LED power supply including the feedback circuit according to the first embodiment of the present invention is shown. As shown in fig. 2, a conventional LED power supply (LED power supply) 2 generally includes: an electromagnetic interference filtering unit 20, a rectifying unit 21, a power factor correcting unit 22, a power switching unit 23, a transformer unit 24, an output filtering rectifying unit 25, and a PWM control unit 27.
The feedback circuit 1 provided by the present invention is disposed in the LED power supply 2, and is used for achieving feedback control by cooperating with the PWM control unit 27 to stabilize the output voltage, current and power of the LED power supply 2. In brief, the feedback circuit 1 of the present invention is used to make the LED power supply 2 output a constant current and/or a constant voltage to the external LED lamp 3 in a constant power state. As shown in fig. 2, the feedback circuit 1 of the present invention further includes: a sampling unit 10, a feedback unit 11, a signal conversion unit 12, and a signal adjustment unit 13. Fig. 3 is a circuit architecture diagram of a feedback circuit according to a first embodiment of the present invention. As shown in fig. 2 and fig. 3, the sampling unit 10 includes an output current sampling unit 101 and an output voltage sampling unit 102. The output current sampling unit 101 is composed of a current detection resistor Rsen and a signal sampling resistor Rsam; one end of the current detection resistor Rsen is coupled to the power output end, and two ends of the signal sampling resistor Rsam are respectively coupled to the other end of the current detection resistor Rsen and the ground GND. On the other hand, the output voltage sampling unit 102 is composed of a first voltage-dividing resistor Rv1 and a second voltage-dividing resistor Rv 2; one end of the first voltage-dividing resistor Rv1 is coupled to the power output end, and two ends of the second voltage-dividing resistor Rv2 are coupled to the other end of the first voltage-dividing resistor Rv1 and the ground GND, respectively.
Similar to the conventional feedback circuit, the present invention couples the feedback unit 11, which is composed of the current error amplifier 111, the voltage error amplifier 112 and the optical coupler 113, to the sampling unit 10. However, unlike the conventional feedback circuit, the signal conversion unit 12 of the present invention is coupled to an external dimming circuit 4 for converting the dimming control signal output by the dimming circuit 4 into the dimming signal and outputting the dimming signal to the current error amplifier 111 and the signal adjustment unit 13. In brief, in the design of the present invention, the current error amplifier 111 is not directly coupled to the external dimming circuit 4. By such design, according to the current sampling signal and the reference signal, the current error amplifier 111 outputs a current error signal to the PWM control unit 27 through the optical coupler 113, so that the PWM control unit 27 correspondingly outputs a first pulse width modulation signal to control the switching of the power switch unit 23, thereby maintaining the constant current output of the LED power supply 2. It should be noted that the reference signal is referred to as the dimming signal.
As shown in fig. 2 and fig. 3, a signal adjusting unit 13 is also arranged and coupled to the signal converting unit 12 and the voltage error amplifier 112. By such a circuit configuration, the signal adjusting unit 13 further performs signal adjustment processing on the reference signal that should be directly input to the voltage error amplifier 112 according to the dimming signal output by the signal converting unit 12, and outputs an adjustment signal to the voltage error amplifier 112. Finally, according to the voltage sampling signal and the adjustment signal, the voltage error amplifier 112 outputs a voltage error signal to the PWM control unit 27 through the optical coupler 113, so that the PWM control unit 27 correspondingly outputs a second PWM signal to control the switching of the power switch unit 23; in this way, the output constant voltage of the LED power supply 2 can be adaptively adjusted along with the output constant current, so as to maintain the constant power output of the LED power supply 2. It should be noted that, the signal conversion unit 12 is utilized to convert the dimming control signal outputted by the dimming circuit 4 into the dimming signal, so that the signal adjustment unit 13 and the current error amplifier 111 can be ensured to receive the same dimming signal, thereby avoiding signal distortion or signal transmission error between circuit modules.
As can be seen from fig. 3, the signal conversion unit 12 is composed of a first signal conversion resistor Rx1 and a second signal conversion resistor Rx 2. One end of the first signal conversion resistor Rx1 is coupled to an external dimming circuit 4, and two ends of the second signal conversion resistor Rx2 are coupled to the other end of the first signal conversion resistor Rx1 and a ground GND, respectively. It should be noted that in the design of the present invention, the non-linear dimming unit 17 can be selectively coupled to two ends of the first signal conversion resistor Rx1, for example: a dip switch or a variable resistor. Due to the addition of the nonlinear dimming unit 17, a user can utilize the nonlinear dimming unit to finish nonlinear dimming on the LED lamp 3. It should be added that the external dimming circuit 4 may be a variable resistance dimmer, a direct current dimmer (1-10VDC), a pulse width modulation signal dimmer, a digital dimmer (DALI DIM) including a demodulation interface, or a TOUCH dimmer (TOUCH DIM); however, these dimmers accomplish linear dimming of the LED lamp 3 by outputting a dimming control signal to the signal conversion unit.
It should be noted that, in order to avoid the dimming signal directly input to the current error amplifier 111 and the signal adjusting unit 13, the present invention further couples a signal isolating unit 15 between the signal converting unit 12 and the current error amplifier 111 and the signal adjusting unit 13. Also, as shown in fig. 3, the current error amplifier 111 is composed of a first input buffer unit 1112 coupled to the first voltage follower 151 in the signal isolation unit 15 and a first error amplifier 1113. The negative input terminal of the first error amplifier 1113 is coupled to the other terminal of the signal sampling resistor Rsam, and the positive input terminal and the output terminal thereof are coupled to the first input buffer unit 1112 and the optical coupler 113, respectively.
See fig. 3. The reference signal adjusting unit 13 is composed of a differential amplifier unit 131, a voltage comparator unit 132 and a voltage stabilizing unit 133; wherein the negative input terminal of the differential amplifier unit 131 is coupled to the second voltage follower 152 of the signal isolation unit 15 for receiving the dimming signal, and the positive input terminal thereof is coupled to the first reference voltage VREF1. On the other hand, the voltage comparator unit 132 is composed of an operational amplifier OP, a first resistor R514, a second resistor R515, a diode Di, and a third resistor R511. As shown in fig. 3, the positive input terminal of the operational amplifier OP is coupled to a second reference voltage VREF2And the negative input terminal thereof is coupled to the signal isolation unit 15 through a voltage dividing resistance unit formed by the first resistor R514 and the second resistor R515. Further, an output terminal of the operational amplifier OP is coupled to a positive input terminal of the differential amplifier unit 131 through the first diode Di and the third resistor R511 which are connected in series with each other.
The voltage stabilization unit 133 is coupled to the output terminal of the differential amplifier unit 131. The voltage error amplifier 112 is composed of a second input buffer unit 1121 and a second error amplifier 1122. The second input buffer unit 1121 is coupled to the signal adjusting unit 13 for receiving the adjusting signal. The positive input terminal of the second error amplifier 1122 is coupled to the output terminal of the differential amplifier unit 131 through the voltage stabilizing unit 133, and the negative input terminal and the output terminal are coupled to the output voltage sampling unit 102 and the optocoupler 113, respectively. It should be noted that the voltage comparator 132 and the voltage stabilizer 133 are provided to stabilize the output of the adjustment signal and prevent the signal from drifting.
Thus, the above description has been provided for a complete and clear description of the details of the feedback circuit of the present invention. Continuing, the feasibility of the feedback circuit of the present invention will be demonstrated hereinafter by the presentation of simulation data. Referring to fig. 4, a data plot of output current versus output voltage is shown. The information about the curves a to D in fig. 4 is summarized in the following table (1).
Watch (1)
It should be noted that curve C is the actual simulation result of maintaining the constant power output of the LED power supply 2 by using the feedback circuit 1 of the present invention; in contrast, the curve B is an ideal result of maintaining the constant power output of the LED power supply 2 by using the feedback circuit 1 of the present invention. Thus, the circuit simulation data of fig. 4 confirms that the feedback circuit 1 of the present invention is indeed helpful to maintain constant current, constant voltage and constant power output of the LED power supply 2.
Second embodiment
Fig. 5 is a circuit architecture diagram of a feedback circuit according to a second embodiment of the present invention. Meanwhile, referring to fig. 6, a circuit block diagram of an LED power supply including a second embodiment of the feedback circuit of the present invention is shown. As can be seen from comparing fig. 5 and fig. 3, compared to the first embodiment described above, the second embodiment of the feedback circuit 1 also includes: a sampling unit 10, a feedback unit 11, a signal conversion unit 12, and a signal adjustment unit 13. It is noted that, as shown in fig. 3, the signal adjusting unit 13 of the first embodiment is composed of a differential amplifier unit 131, a voltage comparator unit 132 and a voltage stabilizing unit 133; however, in the second embodiment shown in fig. 5, an error detector 130 is mainly used as the signal adjusting unit 13.
In the second embodiment, the signal adjusting unit 13 is composed of an operational amplifier OP', a third voltage dividing resistor Rv3, a fourth voltage dividing resistor Rv4, a first diode D1, and a second diode D2; the positive input end of the operational amplifier OP' is coupled to the signal conversion unit 12 for receiving the dimming signal. Also, one end of the third voltage dividing resistor Rv3 is coupled to the negative input terminal of the operational amplifier OP', and one end of the fourth voltage dividing resistor Rv4 is coupled to the other end of the third voltage dividing resistor Rv 3. On the other hand, the first diode D1 has its positive input terminal coupled to the output terminal of the operational amplifier OP' and its negative input terminal coupled to the other terminal of the fourth voltage-dividing resistor Rv 4. In addition, the second diode D2 has its positive input terminal coupled to the output terminal of the operational amplifier OP' and its negative input terminal coupled to the voltage error amplifier 112.
As is well known to engineers familiar with electronic circuit design, the operational amplifier OP', the third voltage dividing resistor Rv3 and the fourth voltage dividing resistor Rv4 constitute the main structure of the error detector 130. In addition, in the second embodiment, the first diode D1 and the second diode D2 are further added to the main structure of the error detector 130, so as to enable the stable signal adjusting unit 13 to stably output the adjusting signal and avoid the signal drift phenomenon of the adjusting signal. On the other hand, in the second embodiment of the feedback circuit 1, the main structure of the voltage error amplifier 112 is a set of error amplifiers Eop; the positive input terminal of the error amplifier Eop is coupled to the reference signal VREFIts negative input terminal is coupled to the signal adjusting unit 13, and its output terminal is coupled to the optical coupler 113.
Thus, the circuit architectures of all embodiments of the feedback circuit of the present invention have been fully and clearly described above, and thus, the present invention has the following advantages:
(1) since the feedback unit 16 '(as shown in fig. 1) used in the prior art can only maintain the constant voltage output or the constant current output of the LED power supply 1' singly, the present invention provides a new feedback circuit 1 for maintaining the constant current, the constant voltage and the constant power output of the LED power supply 2, which mainly comprises: a sampling unit 10, a feedback unit 11, a signal conversion unit 12, and a signal adjustment unit 13. In the operation of the feedback circuit 1, the current error amplifier 111 in the feedback unit 11 outputs a current error signal according to the current sampling signal and the dimming signal outputted from the signal conversion unit 12, so as to inform the PWM control unit 27 to maintain the constant current output of the LED power supply 2. Meanwhile, according to the voltage sampling signal and the reference signal outputted by the signal adjusting unit 13, the voltage error amplifier 112 in the feedback unit 11 is matched with the PWM control unit 27, so that the output constant voltage of the LED power supply 2 is adaptively adjusted along with the output constant current, thereby maintaining the constant power output of the LED power supply 2.
(2) In addition, it should be noted that the circuit simulation data provided by the inventor of the present invention shows that the feedback circuit 1 of the present invention is indeed helpful to maintain the constant current, the constant voltage and the constant power output of the LED power supply 2 in the actual circuit operation.
It must be emphasized that the above embodiments are only exemplary embodiments of the invention, which is not to be considered as limiting the invention, the scope of protection of which is defined by the claims. Various modifications and equivalents may be made by those skilled in the art within the spirit and scope of the present invention, and such modifications and equivalents should also be considered as falling within the scope of the present invention.
Claims (18)
1. A feedback circuit is disposed in an LED power supply, wherein the LED power supply at least comprises: the power supply comprises a rectifying unit, a power switch unit, a transformer unit, an output filtering rectifying unit and a PWM control unit; further, the feedback circuit includes:
the sampling unit is coupled to a power output end of the LED power supply and is used for obtaining a voltage sampling signal and a current sampling signal from the power output end;
a feedback unit coupled to the sampling unit and including a current error amplifier and a voltage error amplifier;
a signal conversion unit, coupled to an external dimming circuit and the current error amplifier, for converting a dimming control signal output by the dimming circuit into a dimming signal and outputting the dimming signal to the current error amplifier;
a signal adjusting unit, coupled to the signal converting unit and the voltage error amplifier, for performing signal adjustment processing on a reference signal according to the dimming signal output by the signal converting unit and outputting an adjusting signal to the voltage error amplifier;
according to the current sampling signal and the dimming signal, the current error amplifier outputs a current error signal to the PWM control unit, so that the PWM control unit correspondingly outputs a first pulse width modulation signal to control the switch of the power switch unit, and the output constant current of the LED power supply is enabled to be transmitted to an external LED lamp in such a way;
according to the voltage sampling signal and the adjusting signal, the voltage error amplifier outputs a voltage error signal to the PWM control unit, so that the PWM control unit correspondingly outputs a second pulse width modulation signal to control the switch of the power switch unit, and the output constant voltage of the LED power supply is adaptively adjusted along with the output constant current in such a way, so as to maintain the constant power output of the LED power supply.
2. The feedback circuit of claim 1, wherein the sampling unit comprises:
an output current sampling unit comprising:
a current detection resistor, one end of which is coupled to the power output end; and
a signal sampling resistor, one end of which is coupled to the other end of the current detection resistor, and the other end of which is coupled to the ground; and
an output voltage sampling unit comprising:
a first voltage-dividing resistor, one end of the first voltage-dividing resistor being coupled to the power output terminal; and
a second voltage dividing resistor, one end of which is coupled to the other end of the first voltage dividing resistor, and the other end of which is coupled to the ground.
3. The feedback circuit of claim 2, wherein the feedback unit further comprises:
the optical coupler is coupled with the current error amplifier, the voltage error amplifier and the PWM control unit and is used for transmitting the current error signal output by the current error amplifier and the voltage error signal output by the voltage error amplifier to the PWM control unit; and
and a signal isolation unit coupled between the signal conversion unit and the current error amplifier and the signal adjustment unit for preventing the dimming signal from being directly input into the current error amplifier and the signal adjustment unit.
4. The feedback circuit of claim 1, wherein the signal conversion unit comprises:
a first signal conversion resistor, one end of which is coupled to the dimming circuit;
and one end of the second signal conversion resistor is coupled to the other end of the first signal conversion resistor, and the other end of the second signal conversion resistor is coupled to the ground.
5. The feedback circuit of claim 3, wherein the current error amplifier comprises:
a first input buffer unit coupled to the signal isolation unit; and
a first error amplifier, a negative input terminal of which is coupled to the other terminal of the signal sampling resistor, a positive input terminal of which is coupled to the first input buffer unit, and an output terminal of which is coupled to the optical coupler.
6. The feedback circuit of claim 4, wherein a non-linear dimming unit is coupled to both ends of the first signal converting resistor, and the non-linear dimming unit is any one of: a dip switch or a variable resistor.
7. The feedback circuit of claim 5, wherein the signal conditioning unit comprises:
a negative input terminal of the differential amplifier unit is coupled to the signal isolation unit to receive the dimming signal, and a positive input terminal of the differential amplifier unit is coupled to a first reference voltage;
a voltage stabilizing unit coupled to an output terminal of the differential amplifier unit; and
a positive input end of the voltage comparator unit is coupled to a second reference voltage, and a negative input end of the voltage comparator unit is coupled to the signal isolation unit through a voltage dividing resistor unit; and an output terminal of the voltage comparator unit is coupled to the positive input terminal of the differential amplifier unit.
8. The feedback circuit of claim 6, wherein the dimming circuit completes linear dimming of the LED lamp by outputting the dimming control signal to the signal conversion unit; and the nonlinear dimming unit is utilized to finish the nonlinear dimming of the LED lamp.
9. The feedback circuit of claim 7, wherein the voltage error amplifier comprises:
a second input buffer unit coupled to the signal adjusting unit to receive the adjusting signal; and
a second error amplifier, a positive input terminal of which is coupled to the output terminal of the differential amplifier unit through the voltage stabilizing unit, a negative input terminal of which is coupled to the output voltage sampling unit, and an output terminal of which is coupled to the optical coupler.
10. A feedback circuit is disposed in an LED power supply, wherein the LED power supply at least comprises: the power supply comprises a rectifying unit, a power switch unit, a transformer unit, an output filtering rectifying unit and a PWM control unit; further, the feedback circuit includes:
the sampling unit is coupled to a power output end of the LED power supply and is used for obtaining a voltage sampling signal and a current sampling signal from the power output end;
a feedback unit coupled to the sampling unit and including a current error amplifier and a voltage error amplifier;
a signal conversion unit, coupled to an external dimming circuit and the current error amplifier, for converting a dimming control signal output by the dimming circuit into a dimming signal and outputting the dimming signal to the current error amplifier;
a signal adjusting unit, coupled to the signal converting unit and the voltage error amplifier, for performing signal adjustment processing on the dimming signal output by the signal converting unit and outputting an adjusting signal to the voltage error amplifier;
according to the current sampling signal and the dimming signal, the current error amplifier outputs a current error signal to the PWM control unit, so that the PWM control unit correspondingly outputs a first pulse width modulation signal to control the switch of the power switch unit, and the output constant current of the LED power supply is enabled to be transmitted to an external LED lamp in such a way;
the voltage error amplifier outputs a voltage error signal to the PWM control unit according to the voltage sampling signal, the reference signal, and the adjustment signal, so that the PWM control unit correspondingly outputs a second PWM signal to control the switch of the power switch unit, and the output constant voltage of the LED power supply is adaptively adjusted along with the output constant current in this way, thereby maintaining the constant power output of the LED power supply.
11. The feedback circuit of claim 10, wherein the sampling unit comprises:
an output current sampling unit comprising:
a current detection resistor, one end of which is coupled to the power output end; and
a signal sampling resistor, one end of which is coupled to the other end of the current detection resistor, and the other end of which is coupled to the ground; and
an output voltage sampling unit comprising:
a first voltage-dividing resistor, one end of the first voltage-dividing resistor being coupled to the power output terminal; and
a second voltage dividing resistor, one end of which is coupled to the other end of the first voltage dividing resistor, and the other end of which is coupled to the ground.
12. The feedback circuit of claim 11, wherein the feedback unit further comprises:
the optical coupler is coupled with the current error amplifier, the voltage error amplifier and the PWM control unit and is used for transmitting the current error signal output by the current error amplifier and the voltage error signal output by the voltage error amplifier to the PWM control unit; and
and a signal isolation unit coupled between the signal conversion unit and the current error amplifier and the signal adjustment unit for preventing the dimming signal from being directly input into the current error amplifier and the signal adjustment unit.
13. The feedback circuit of claim 10, wherein the signal conversion unit comprises:
a first signal conversion resistor, one end of which is coupled to the dimming circuit;
and one end of the second signal conversion resistor is coupled to the other end of the first signal conversion resistor, and the other end of the second signal conversion resistor is coupled to the ground.
14. The feedback circuit of claim 12, wherein the current error amplifier comprises:
a first input buffer unit coupled to the signal isolation unit; and
a negative input terminal of the first error amplifier is coupled to the other terminal of the signal sampling resistor, a positive input terminal of the first error amplifier is coupled to the first input buffer unit, and an output terminal of the first error amplifier is coupled to the optical coupler.
15. The feedback circuit of claim 13, wherein a non-linear dimming unit is coupled to both ends of the first signal converting resistor, and the non-linear dimming unit is any one of: a dip switch or a variable resistor.
16. The feedback circuit of claim 11, wherein the signal conditioning unit comprises:
a positive input end of the operational amplifier is coupled to the signal conversion unit to receive the dimming signal;
a third voltage dividing resistor, one end of the third voltage dividing resistor being coupled to the negative input terminal of the operational amplifier;
a fourth voltage dividing resistor, one end of which is coupled to the other end of the third voltage dividing resistor;
a first diode, coupling the positive input end of the first diode to the output end of the operational amplifier, and coupling the negative input end of the first diode to the other end of the fourth voltage-dividing resistor; and
a second diode coupling a positive input of the second diode to the output of the operational amplifier and coupling a negative input of the second diode to the voltage error amplifier.
17. The feedback circuit of claim 12, wherein the voltage error amplifier comprises:
an error amplifier having a positive input coupled to the reference signal, a negative input coupled to the signal adjusting unit, and an output coupled to the optical coupler.
18. The feedback circuit of claim 15, wherein the dimming circuit performs linear dimming of the LED lamp by outputting the dimming control signal to the signal conversion unit; and the nonlinear dimming unit is utilized to finish the nonlinear dimming of the LED lamp.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710710987.XA CN109413791B (en) | 2017-08-18 | 2017-08-18 | Feedback circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201710710987.XA CN109413791B (en) | 2017-08-18 | 2017-08-18 | Feedback circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109413791A CN109413791A (en) | 2019-03-01 |
| CN109413791B true CN109413791B (en) | 2020-11-24 |
Family
ID=65455262
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710710987.XA Active CN109413791B (en) | 2017-08-18 | 2017-08-18 | Feedback circuit |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109413791B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109757012B (en) * | 2019-03-28 | 2021-04-27 | 长春光华学院 | LED lamp self-adaptive constant power adjustment control method |
| WO2020252605A1 (en) * | 2019-06-17 | 2020-12-24 | Redisem Ltd. | Controller for limiting power |
| CN113068287B (en) * | 2019-12-13 | 2022-04-12 | 明纬(广州)电子有限公司 | Dimming circuit with stable output voltage |
| TWI740663B (en) * | 2020-09-24 | 2021-09-21 | 宏碁股份有限公司 | Power supply capable of stabilizing compensation current |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1193250A (en) * | 1997-03-07 | 1998-09-16 | 电灯专利信托有限公司 | Switch-over control for working circuit |
| CN102026443A (en) * | 2009-09-18 | 2011-04-20 | 立锜科技股份有限公司 | Average current regulator and driver circuit thereof and method for regulating average current |
| CN203327322U (en) * | 2013-07-02 | 2013-12-04 | 中节能晶和照明有限公司 | Power self-compensation device of LED light fixture |
| CN203872056U (en) * | 2014-05-06 | 2014-10-08 | 中国电子科技集团公司第四十一研究所 | Direct-current power supply controlled by constant power |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2005006444A (en) * | 2003-06-13 | 2005-01-06 | Japan Aviation Electronics Industry Ltd | Power supply device for illumination lamp |
| TWI334259B (en) * | 2007-06-07 | 2010-12-01 | Young Green Energy Co | Power supply for relieving spikes |
| CN102238773A (en) * | 2010-04-30 | 2011-11-09 | 奥斯兰姆有限公司 | LED (light-emitting diode) drive method and system |
-
2017
- 2017-08-18 CN CN201710710987.XA patent/CN109413791B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1193250A (en) * | 1997-03-07 | 1998-09-16 | 电灯专利信托有限公司 | Switch-over control for working circuit |
| CN102026443A (en) * | 2009-09-18 | 2011-04-20 | 立锜科技股份有限公司 | Average current regulator and driver circuit thereof and method for regulating average current |
| CN203327322U (en) * | 2013-07-02 | 2013-12-04 | 中节能晶和照明有限公司 | Power self-compensation device of LED light fixture |
| CN203872056U (en) * | 2014-05-06 | 2014-10-08 | 中国电子科技集团公司第四十一研究所 | Direct-current power supply controlled by constant power |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109413791A (en) | 2019-03-01 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US10039171B1 (en) | Feedback circuit | |
| CN109413791B (en) | Feedback circuit | |
| TWI642326B (en) | Feedback circuit | |
| US9113519B2 (en) | LED driving apparatus and LED lighting apparatus | |
| US9564815B2 (en) | Flyback power converter, secondary side control circuit, and control method thereof | |
| CN101754541B (en) | DC bus voltage following control circuit suitable for multi-path parallel LEDs | |
| CN102201202B (en) | Driving power supply control circuit and driving power supply control method of light emitting diode | |
| CN102332827B (en) | Power supply converter with electricity-saving mechanism and power supply conversion method | |
| US20140327366A1 (en) | Illumination device and led dimming circuit thereof | |
| US9532421B2 (en) | LED driving device and control method for LED driving device | |
| TWI590574B (en) | Power supply apparatus | |
| US20140340295A1 (en) | Led backlight driving circuit, lcd device, and method for driving the led backlight driving circuit | |
| CN104902653A (en) | LED constant-voltage dimming power supply and LED lamp dimming system | |
| CN210536999U (en) | Adjustable resistor, chip, circuit system, current ripple eliminating circuit and line voltage compensating circuit | |
| US20140306613A1 (en) | Light-emitting diode driving apparatus | |
| US10893591B2 (en) | Controllers, systems, and methods for driving a light source | |
| EP2802100B1 (en) | Improved choke circuit, and bus power supply incorporating same | |
| KR100790709B1 (en) | Converter having wave sahping of input current | |
| CN110062500B (en) | Power supply circuit control method, control circuit and power supply circuit | |
| US20150006932A1 (en) | Power supply apparatus | |
| US10104738B1 (en) | Feedback circuit capable of regulating response according to variation of dimming signal | |
| US10070493B2 (en) | Lighting device, luminaire, and signboard | |
| CN111526626A (en) | Voltage-regulating phase-cut dimming power supply | |
| CN111404390A (en) | Magnetic isolation feedback device and method of switching power supply and switching power supply | |
| CN101841952B (en) | Drive circuit realizing constant current of two paths of LEDs by utilizing capacitors |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |