CN219536357U - Loop control circuit and constant current power supply - Google Patents
Loop control circuit and constant current power supply Download PDFInfo
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- CN219536357U CN219536357U CN202320262405.7U CN202320262405U CN219536357U CN 219536357 U CN219536357 U CN 219536357U CN 202320262405 U CN202320262405 U CN 202320262405U CN 219536357 U CN219536357 U CN 219536357U
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Abstract
The utility model discloses a loop control circuit and a constant current power supply, wherein the loop control circuit comprises an operational amplifier U1A, an operational amplifier U1B, a triode Q1-2, a resistor R3-4, a resistor R6-9, a resistor R11-14, a resistor R16-18, a capacitor C3, a capacitor C5, a diode D1 and a diode D4; through the structure, in the normal operation of the loop, the lower the voltage of the output ends of the operational amplifier U1A and the operational amplifier U1B is, the larger the current flowing to the ground of the FB end is, the smaller the current output by the LED power supply to the lamp is, and the lower the voltage of the two ends of the lamp is, and vice versa; the constant-current power supply is stable and reliable, almost has no temperature drift, and forms a perfect fixed proportion relation between output current and control duty ratio through reasonable parameter setting, thereby providing a hardware foundation for accurate current output and having very good practicability.
Description
Technical Field
The utility model relates to the field of loop control circuits, in particular to a loop control circuit and a constant current power supply.
Background
In the LED lighting industry, constant-current lamps are favored by consumers in terms of high-efficiency luminous efficiency, and LED dimming power supplies serving as control and driving components are also favored in the market; with continuous upgrading of consumption, consumers put forward higher requirements on the dimming depth of a dimming constant-current power supply, but the same difficult problems are also caused on the constant-current power supply, for example, the minimum dimming brightness cannot be compared with that of a constant-voltage power supply, the current constant-current power supply for the dimming mode of analog signals can be made to be 1% at least, and serious temperature drift problems occur under the conditions of high temperature and low temperature; therefore, a loop control circuit and a constant current power supply are urgently needed to solve the above-mentioned problems.
Disclosure of Invention
The present utility model aims to solve at least one of the technical problems existing in the prior art. Therefore, the utility model provides a loop control circuit and a constant current power supply.
The technical scheme adopted by the embodiment of the utility model for solving the technical problems is as follows: a loop control circuit comprises an operational amplifier U1A, an operational amplifier U1B, a triode Q1-2, a resistor R3-4, a resistor R6-9, a resistor R11-14, a resistor R16-18, a capacitor C3, a capacitor C5, a diode D1 and a diode D4, wherein the inverting input end of the operational amplifier U1B is connected with the Vout-end through the resistor R3 and the IPWM2 end through the resistor R4 and the diode D1, the non-inverting input end of the operational amplifier U1B is respectively connected with one end of a resistor R6, one end of a resistor R7, the collector of a triode Q2 and one end of a resistor R16, one end of the resistor R16 is connected with the VREF end, the base of the triode Q2 is respectively connected with one end of a resistor R17, one end of a resistor R18 and the anode of a diode D4, the emitter of the triode Q2 is respectively connected with the other end of the resistor R18 and the SGND end, the other end of the resistor R17 is connected with a power supply, the cathode of the diode D4 is connected with the IPWM1 end, the positive input end of the operational amplifier U1A is respectively connected with the VREF end and one end of the capacitor C3, the other end of the capacitor C3 is respectively connected with the other end of the resistor R6, the other end of the resistor R7, the grounding end of the operational amplifier U1A and the SGND end, the power supply end of the operational amplifier U1A is connected with a power supply, the inverting input end of the operational amplifier U1A is respectively connected with one end of the resistor R8, one end of the resistor R9 and one end of the resistor R12, the other end of the resistor R8 is connected with the Vout+ end, the other end of the resistor R9 is respectively connected with the emitter of the triode Q1, the other end of the resistor R12, one end of the resistor R14 and the SGND end of the resistor R14 is connected with the base of the triode Q1 and the VPWM end through the resistor R13, the output of the operational amplifier U1A and the output of the operational amplifier U1B are connected to a dimming circuit.
Preferably, the loop control circuit further includes a resistor R15 and a capacitor C6, one end of the resistor R15 is connected with one end of the resistor R16 and a collector of the triode Q2, the other end of the resistor R15 is connected with a non-inverting input end of the operational amplifier U1B and one end of the capacitor C6, and the other end of the capacitor C6 is connected with an emitter of the triode Q2.
Preferably, a loop control circuit further includes a resistor R1 and a capacitor C1 connected in series between the inverting input terminal of the operational amplifier U1B and the output terminal of the operational amplifier U1B.
Preferably, a loop control circuit further comprises a resistor R10 and a capacitor C4 connected in series between the inverting input of the operational amplifier U1A and the output of the operational amplifier U1A.
Preferably, the loop control circuit further comprises an optocoupler DU1, a resistor R2, a resistor R5, a capacitor C2 and a diode D2-3, wherein one end of the light emitter of the optocoupler DU1 is connected with a power supply through the resistor R2 and is respectively connected with the anode of the diode D2, the anode of the diode D3 and the other end of the light emitter of the optocoupler DU1 through the resistor R5, the cathode of the diode D2 is connected with the output end of the operational amplifier U1B, the cathode of the diode D3 is connected with the output end of the operational amplifier U1A, one end of the light receiver of the optocoupler DU1 is respectively connected with one end of the capacitor C2 and the GND end, and the other end of the light receiver of the optocoupler DU1 is respectively connected with the other end of the capacitor C2 and the dimming circuit.
The constant-current power supply comprises an alternating-current input filtering rectification current, a power factor correction circuit, a DC-DC dimming circuit, a main control circuit and a loop control circuit, wherein the alternating-current input filtering rectification current, the power factor correction circuit and the DC-DC dimming circuit are sequentially connected, a load is connected with the DC-DC dimming circuit, a load is connected with the FB end, and the IPWM1 end, the IPWM2 end and the VPWM end are connected with the main control circuit.
The utility model has the beneficial effects that: the loop control circuit comprises an operational amplifier U1A, an operational amplifier U1B, a triode Q1-2, a resistor R3-4, a resistor R6-9, a resistor R11-14, a resistor R16-18, a capacitor C3, a capacitor C5, a diode D1 and a diode D4; through the structure, in the normal operation of the loop, the lower the voltage of the output ends of the operational amplifier U1A and the operational amplifier U1B is, the larger the current flowing to the ground of the FB end is, the smaller the current output by the LED power supply to the lamp is, and the lower the voltage of the two ends of the lamp is, and vice versa; the constant-current power supply is stable and reliable, almost has no temperature drift, and forms a perfect fixed proportion relation between output current and control duty ratio through reasonable parameter setting, thereby providing a hardware foundation for accurate current output and having very good practicability.
Drawings
The foregoing and/or additional aspects and advantages of the utility model will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:
FIG. 1 is a schematic circuit diagram of a constant current power supply;
fig. 2 is a schematic circuit diagram of a loop control circuit.
Detailed Description
Reference will now be made in detail to the present embodiments of the present utility model, examples of which are illustrated in the accompanying drawings, wherein the accompanying drawings are used to supplement the description of the written description so that one can intuitively and intuitively understand each technical feature and overall technical scheme of the present utility model, but not to limit the scope of the present utility model.
In the description of the present utility model, plural means two or more, and greater than, less than, exceeding, etc. are understood to not include the present number, and the above, below, within, etc. are understood to include the present number. The description of the first and second is for the purpose of distinguishing between technical features only and should not be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated or implicitly indicating the precedence of the technical features indicated.
In the description of the present utility model, it should be understood that references to orientation descriptions such as upper, lower, front, rear, left, right, etc. are based on the orientation or positional relationship shown in the drawings, are merely for convenience of description of the present utility model and to simplify the description, and do not indicate or imply that the apparatus or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present utility model.
In the present utility model, unless clearly defined otherwise, the terms "disposed," "mounted," "connected," and the like are to be construed broadly and may be connected directly or indirectly through an intermediary; the connecting device can be fixedly connected, detachably connected and integrally formed; may be a mechanical connection; may be a communication between two elements or an interaction between two elements. The specific meaning of the words in the utility model can be reasonably determined by a person skilled in the art in combination with the specific content of the technical solution.
Referring to FIGS. 1 to 2, a loop control circuit includes an operational amplifier U1A, an operational amplifier U1B, a triode Q1-2, a resistor R3-4, a resistor R6-9, a resistor R11-14, a resistor R16-18, a capacitor C3, a capacitor C5, a diode D1 and a diode D4, wherein an inverting input end of the operational amplifier U1B is connected with a Vout-end via the resistor R3 and with an IPWM2 end via the resistor R4 and the diode D1, a non-inverting input end of the operational amplifier U1B is connected with one end of a resistor R6, one end of a resistor R7, a collector of a triode Q2 and one end of a resistor R16 respectively, one end of the resistor R16 is connected with a VREF end, a base of the triode Q2 is connected with one end of a resistor R17, one end of the resistor R18 and an anode of the diode D4 respectively, an emitter of the triode Q2 is connected with the other end of the resistor R18 and an SGND end respectively, the other end of the resistor R17 is connected with a power supply, the cathode of the diode D4 is connected with the IPWM1 end, the positive input end of the operational amplifier U1A is respectively connected with the VREF end and one end of the capacitor C3, the other end of the capacitor C3 is respectively connected with the other end of the resistor R6, the other end of the resistor R7, the grounding end of the operational amplifier U1A and the SGND end, the power supply end of the operational amplifier U1A is connected with a power supply, the inverting input end of the operational amplifier U1A is respectively connected with one end of the resistor R8, one end of the resistor R9 and one end of the resistor R12, the other end of the resistor R8 is connected with the Vout+ end, the other end of the resistor R9 is respectively connected with the emitter of the triode Q1, the other end of the resistor R12, one end of the resistor R14 and the SGND end of the resistor R14 is connected with the base of the triode Q1 and the VPWM end through the resistor R13, the output of the operational amplifier U1A and the output of the operational amplifier U1B are connected to a dimming circuit.
In the utility model, the working principle is as follows:
1. the voltage of the output Vout-is equal to the product of the current detection resistor RS1 and the output current, and after the voltage passes through the resistor R3, the voltage of the inverting input end of the operational amplifier U1B is almost equal to the voltage of the non-inverting input end of the operational amplifier under the normal control of a loop, the voltage of the non-inverting input end of the operational amplifier is generated under the combined action of the VREF end and the IPWM1 end, and the VREF end is an internal reference provided by a main control IC in the main control circuit 40, so that the precision is extremely high and the temperature drift is extremely small, the duty ratio of the IPWM1 end is controlled to control the voltage of the non-inverting input end of the operational amplifier, and the output current is further controlled;
2. when the IPWM1 end outputs the duty ratio of the corresponding current, the triode Q2 enters an on-off state opposite to the corresponding duty ratio, so that the VREF end is chopped through a resistor R16 and then is filtered into direct current through a low-pass filter consisting of a resistor R15 and a capacitor C6, the resistor R6 and the resistor R7 function to set the output maximum current, and the charge of the non-inverting input end of the operational amplifier U1B is discharged when the switch is closed;
3. the IPWM2 end is a current control second path PWM, which has the function of avoiding that under the condition that the IPWM1 end is arranged high, the impedance of the triode Q2 is not infinitely small, so that the voltage of the non-inverting input end of the operational amplifier U1B is not truly 0V, when the detection resistance is relatively small, the current with a few milliamperes can be output to the LED lamp, the lamp is slightly bright, and after the IPWM2 end is arranged high, the output is thoroughly turned off; specifically, the process is as follows: when the IPWM2 end is high, the voltage of 3.3V passes through the diode D1, the resistor R3, the resistor R4 and the current detection resistor RS1, and the potential generated at the inverting input end of the operational amplifier is higher than the voltage at the non-inverting input end of the operational amplifier, so that the aim of closing is fulfilled;
4. the VPWM terminal is used for controlling output voltage, vout+ generates different voltages (namely VREF) equivalent to the non-inverting input terminal of the operational amplifier U1B at the inverting input terminal of the operational amplifier U1B through the resistor R8, the resistor R9, the resistor R11, the resistor R12 and the triode Q1 under different duty ratios, and since the voltage at the inverting input terminal of the operational amplifier U1B is a fixed value under a normal operating state, under different duty ratios of the VPWM terminal, the loop adjusts the primary duty ratio to divide vout+ to enable the voltage to reach the voltage of VREF at the inverting input terminal of the operational amplifier U1B;
5. in normal operation of the loop, the lower the voltages at the output ends of the operational amplifier U1A and the operational amplifier U1B, the larger the current flowing through the light emitter of the optocoupler DU1, the larger the current flowing from the optocoupler DU1 to the ground at the FB end, the smaller the current output from the LED power supply to the lamp, and the lower the voltages at the two ends of the lamp, and vice versa.
6. In the system implementation process, taking fig. 1 as an example:
after alternating current commercial power passes through alternating current input filtering rectification current 10, a steamed bread wave with frequency being frequency doubling of the commercial power is provided for a power factor correction circuit 20, and the input steamed bread wave is boosted and rectified into direct current voltage in the power factor correction circuit 20; after the DC voltage from the pfc circuit 20, the DC-DC dimmer circuit 30 steps down the DC voltage, and the duty cycle output of the loop control circuit is controlled by the main control circuit 40 to form a specific current or voltage.
The utility model has the advantages that: the constant-current power supply is stable and reliable, almost has no temperature drift, and forms a perfect fixed proportion relation between output current and control duty ratio through reasonable parameter setting, thereby providing a hardware foundation for accurate current output and having very good practicability.
The loop control circuit further comprises a resistor R15 and a capacitor C6, one end of the resistor R15 is connected with one end of a resistor R16 and the collector of the triode Q2, the other end of the resistor R15 is respectively connected with the normal phase input end of the operational amplifier U1B and one end of the capacitor C6, and the other end of the capacitor C6 is connected with the emitter of the triode Q2.
The loop control circuit also comprises a resistor R1 and a capacitor C1 which are connected in series between the inverting input end of the operational amplifier U1B and the output end of the operational amplifier U1B; and includes a resistor R10 and a capacitor C4 connected in series between the inverting input of the operational amplifier U1A and the output of the operational amplifier U1A.
The loop control circuit further comprises an optical coupler DU1, a resistor R2, a resistor R5, a capacitor C2 and a diode D2-3, wherein one end of a light emitter of the optical coupler DU1 is connected with a power supply through the resistor R2 and is respectively connected with an anode of the diode D2, an anode of the diode D3 and the other end of the light emitter of the optical coupler DU1 through the resistor R5, a cathode of the diode D2 is connected with an output end of an operational amplifier U1B, a cathode of the diode D3 is connected with an output end of the operational amplifier U1A, one end of a light receiver of the optical coupler DU1 is respectively connected with one end of the capacitor C2 and a GND end, and the other end of the light receiver of the optical coupler DU1 is respectively connected with the other end of the capacitor C2 and a dimming circuit.
The constant-current power supply comprises an alternating-current input filtering rectification current 10, a power factor correction circuit 20, a DC-DC dimming circuit 30, a main control circuit 40 and a loop control circuit, wherein the alternating-current input filtering rectification current 10, the power factor correction circuit 20 and the DC-DC dimming circuit 30 are sequentially connected, a load access port and a FB port are connected to the DC-DC dimming circuit 30, an IPWM1 end, an IPWM2 end and a VPWM end are connected to the main control circuit 40.
Of course, the present utility model is not limited to the above-described embodiments, and those skilled in the art can make equivalent modifications and substitutions without departing from the spirit of the present utility model, and these equivalent modifications and substitutions are included in the scope of the present utility model as defined in the appended claims.
Claims (6)
1. A loop control circuit, characterized by: the circuit comprises an operational amplifier U1A, an operational amplifier U1B, a triode Q1-2, a resistor R3-4, a resistor R6-9, a resistor R11-14, a resistor R16-18, a capacitor C3, a capacitor C5, a diode D1 and a diode D4, wherein the inverting input end of the operational amplifier U1B is connected with the Vout-end through the resistor R3 and the IPWM2 end through the resistor R4 and the diode D1, the non-inverting input end of the operational amplifier U1B is respectively connected with one end of the resistor R6, one end of the resistor R7, the collector of the triode Q2 and one end of the resistor R16, one end of the resistor R16 is connected with the VREF end, the base of the triode Q2 is respectively connected with one end of the resistor R17, one end of the resistor R18 and the anode of the diode D4, the emitter of the triode Q2 is respectively connected with the other end of the resistor R18 and the SGND end, the other end of the resistor R17 is connected with a power supply, the cathode of the diode D4 is connected with the IPWM1 end, the positive input end of the operational amplifier U1A is respectively connected with the VREF end and one end of the capacitor C3, the other end of the capacitor C3 is respectively connected with the other end of the resistor R6, the other end of the resistor R7, the grounding end of the operational amplifier U1A and the SGND end, the power supply end of the operational amplifier U1A is connected with a power supply, the inverting input end of the operational amplifier U1A is respectively connected with one end of the resistor R8, one end of the resistor R9 and one end of the resistor R12, the other end of the resistor R8 is connected with the Vout+ end, the other end of the resistor R9 is respectively connected with the emitter of the triode Q1, the other end of the resistor R12, one end of the resistor R14 and the SGND end of the resistor R14 is connected with the base of the triode Q1 and the VPWM end through the resistor R13, the output of the operational amplifier U1A and the output of the operational amplifier U1B are connected to a dimming circuit.
2. A loop control circuit according to claim 1, wherein: the circuit further comprises a resistor R15 and a capacitor C6, wherein one end of the resistor R15 is connected with one end of a resistor R16 and the collector electrode of the triode Q2, the other end of the resistor R15 is respectively connected with the normal phase input end of the operational amplifier U1B and one end of the capacitor C6, and the other end of the capacitor C6 is connected with the emitter electrode of the triode Q2.
3. A loop control circuit according to claim 1, wherein: the circuit also comprises a resistor R1 and a capacitor C1 which are connected in series between the inverting input end of the operational amplifier U1B and the output end of the operational amplifier U1B.
4. A loop control circuit according to claim 1, wherein: the circuit also comprises a resistor R10 and a capacitor C4 which are connected in series between the inverting input end of the operational amplifier U1A and the output end of the operational amplifier U1A.
5. A loop control circuit according to claim 1, wherein: the light source is connected with the anode of the diode D2, the anode of the diode D3 and the other end of the light emitter of the light coupler DU1 through the resistor R5, the cathode of the diode D2 is connected with the output end of the operational amplifier U1B, the cathode of the diode D3 is connected with the output end of the operational amplifier U1A, one end of a light receiver of the light coupler DU1 is connected with one end of the capacitor C2 and the GND end respectively, and the other end of the light receiver of the light coupler DU1 is connected with the other end of the capacitor C2 and the dimming circuit respectively.
6. The utility model provides a constant current power supply which characterized in that: the circuit comprises an alternating current input filtering rectification current (10), a power factor correction circuit (20), a DC-DC dimming circuit (30), a main control circuit (40) and the loop control circuit as claimed in any one of claims 1 to 5, wherein the alternating current input filtering rectification current (10), the power factor correction circuit (20) and the DC-DC dimming circuit (30) are sequentially connected, a load access port and a FB port are connected to the DC-DC dimming circuit (30), and the IPWM1 end, the IPWM2 end and the VPWM end are connected to the main control circuit (40).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320262405.7U CN219536357U (en) | 2023-02-20 | 2023-02-20 | Loop control circuit and constant current power supply |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202320262405.7U CN219536357U (en) | 2023-02-20 | 2023-02-20 | Loop control circuit and constant current power supply |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN219536357U true CN219536357U (en) | 2023-08-15 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202320262405.7U Active CN219536357U (en) | 2023-02-20 | 2023-02-20 | Loop control circuit and constant current power supply |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN219536357U (en) |
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2023
- 2023-02-20 CN CN202320262405.7U patent/CN219536357U/en active Active
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