CN112235896A - Circuit for automatically adjusting output current by low-voltage input and driving power supply - Google Patents
Circuit for automatically adjusting output current by low-voltage input and driving power supply Download PDFInfo
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- CN112235896A CN112235896A CN202010949576.8A CN202010949576A CN112235896A CN 112235896 A CN112235896 A CN 112235896A CN 202010949576 A CN202010949576 A CN 202010949576A CN 112235896 A CN112235896 A CN 112235896A
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- 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
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- 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]
- H05B45/50—Circuit arrangements for operating light-emitting diodes [LED] responsive to malfunctions or undesirable behaviour of LEDs; responsive to LED life; Protective circuits
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
- Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
Abstract
The invention relates to a circuit and a driving power supply for automatically adjusting output current by low-voltage input, comprising: the device comprises a voltage sampling comparison circuit, a primary monitoring circuit, a primary conversion circuit, a secondary monitoring circuit, a current reference control circuit and a current comparison circuit; the input end of the voltage sampling comparison circuit is connected with the input line voltage, the output end of the voltage sampling comparison circuit is connected with the input end of the primary monitoring circuit, the output end of the primary monitoring circuit is connected with the input end of the primary conversion circuit, the output end of the primary conversion circuit is connected with the input end of the secondary monitoring circuit, the output end of the secondary monitoring circuit is connected with the current reference control circuit, the input end of the current signal comparison circuit is connected with the current reference control circuit, and the output end of the current reference control circuit is connected with the secondary feedback circuit. The invention can automatically reduce the output current when the input voltage is low, avoids the failure of a power supply device caused by the full output state of low-voltage work, and improves the applicable voltage range and the practical value of the driving power supply.
Description
Technical Field
The invention relates to the technical field of driving power supplies, in particular to a circuit for automatically adjusting output current by low-voltage input and a driving power supply.
Background
With the large number of applications of LED driving power sources, the operating conditions and requirements thereof are continuously increasing. Wide input voltage range, high reliability, low cost, high power density, etc. are required. At present, most LED power supplies are required to be capable of simultaneously applying the working voltages of alternating current 110V and 220V, which requires that the working voltage of the LED power supply must be designed to be alternating current 100 and 277V, but in some application environments with higher requirements and severe occasions, the LED power supply can work even if the working voltage is lower than 100V, which requires that a circuit or a method capable of meeting the requirements is designed. There are many LED driving power devices on the market, and these LED driving power devices can not work with a stable and reliable rated input voltage, and the input voltage has a range in which the driving device can work normally at full current and full power, or can be protected by active derating below the range. If the LED power supply apparatus still outputs full power below this voltage range, it may cause unstable operation and even damage to the power supply.
The common input low-voltage protection circuit detects input voltage, directly judges the output of a power supply when the detected voltage is lower than a set voltage, theoretically, the protection only plays a role in closing the output when the voltage is low, and cannot meet the requirement that the power supply can continuously work in certain severe environments with wide input voltage range. Another low voltage input protection is passive protection, which is not practical for the end user to passively reduce the LED load when the input voltage is low.
In addition, a low-voltage protection device is not added in the existing LED driving power supply, under the condition, when the input voltage is lower, the input line current of the power supply is inevitably increased under the same output power, and at the moment, if the output power is not limited, the problem that the current stress exceeds the standard easily occurs in devices such as an MOS (metal oxide semiconductor) tube, a freewheeling diode and the like of the power supply, so that serious heating is caused, and the power supply is finally burnt.
Disclosure of Invention
The present invention provides a circuit and a driving power supply with low voltage input for automatically adjusting output current, which address the above-mentioned drawbacks of the prior art.
The technical scheme adopted by the invention for solving the technical problems is as follows: a circuit for automatically adjusting output current by low-voltage input is constructed, and the circuit comprises: the device comprises a voltage sampling comparison circuit, a primary monitoring circuit, a primary conversion circuit, a secondary monitoring circuit, a current reference control circuit and a current comparison circuit;
the input end of the voltage sampling comparison circuit is connected with an input line voltage, the output end of the voltage sampling comparison circuit is connected with the input end of the primary monitoring circuit, the output end of the primary monitoring circuit is connected with the input end of the primary conversion circuit, the output end of the primary conversion circuit is connected with the input end of the secondary monitoring circuit, the output end of the secondary monitoring circuit is connected with the current reference control circuit, the input end of the current signal comparison circuit is connected with the current reference control circuit, and the output end of the current reference control circuit is connected with the secondary feedback circuit.
Preferably, the primary monitoring circuit comprises: a primary first monitoring circuit and a primary second monitoring circuit;
the input end of the primary first monitoring circuit is connected with the output end of the voltage sampling comparison circuit, the output end of the primary first monitoring circuit is connected with the input end of the primary second monitoring circuit, the output end of the primary second monitoring circuit is connected with the input end of the primary conversion circuit, and the primary first monitoring circuit is also connected to the primary power supply circuit;
the input end of the primary first monitoring circuit is the input end of the primary monitoring circuit, and the output end of the primary second monitoring circuit is the output end of the primary monitoring circuit.
Preferably, the primary conversion circuit is a photoelectric conversion circuit.
Preferably, the voltage sampling comparison circuit includes: the primary first resistor, the primary second resistor, the primary third resistor, the primary fourth resistor, the primary first capacitor and the primary comparator;
a first terminal of the primary first resistor is connected to the input line voltage, a second terminal of the primary first resistor is connected to a first terminal of the primary second resistor, and a second terminal of the primary second resistor is connected to a first terminal of the primary third resistor and a first terminal of the primary comparator;
the second end of the primary third resistor is connected with the first end of the primary fourth resistor and the third end of the primary comparator, the second end of the primary fourth resistor, the second end of the primary first capacitor and the second end of the primary comparator are grounded, and the first end of the primary first capacitor is connected with the third end of the primary comparator;
the first end of the primary first resistor is the input end of the voltage sampling comparison circuit, and the first end of the primary comparator is the output end of the voltage sampling comparison circuit.
Preferably, the primary first monitoring circuit comprises: the first MOS transistor comprises a primary fifth resistor, a primary first voltage regulator tube and a primary first MOS tube; the primary second monitoring circuit includes: a primary sixth resistor and a primary second MOS tube;
the first end of the primary fifth resistor is connected with the output end of the voltage sampling comparison circuit, and the second end of the primary fifth resistor is connected with the cathode of the primary first voltage-regulator tube and the grid of the primary first MOS tube; the anode of the primary first voltage regulator tube and the source electrode of the primary first MOS tube are grounded; the drain electrode of the primary first MOS tube is connected with the second end of the primary sixth resistor and the grid electrode of the primary second MOS tube;
the first end of the primary sixth resistor is connected with a primary power supply circuit, the source electrode of the primary second MOS tube is grounded, and the drain electrode of the primary second MOS tube is connected with the input end of the primary conversion circuit;
the first end of the primary fifth resistor is the input end of the primary first monitoring circuit, and the drain electrode of the primary first MOS transistor is the output end of the primary first monitoring circuit; the grid electrode of the primary second MOS tube is the input end of the primary second monitoring circuit, and the drain electrode of the primary second MOS tube is the output end of the primary second monitoring circuit.
Preferably, the primary conversion circuit includes: the primary seventh resistor, the primary eighth resistor and the primary photoelectric coupler;
the first end of the primary seventh resistor and the first end of the primary photoelectric coupler are connected and connected to a primary power supply circuit, and the second end of the primary seventh resistor is connected with the first end of the primary eighth resistor and the second end of the primary photoelectric coupler; the second end of the primary eighth resistor is connected with the output end of the primary monitoring circuit;
the fourth end of the primary photoelectric coupler is connected with the input end of the secondary monitoring circuit, and the third end of the primary photoelectric coupler is grounded;
the connection end of the second end of the primary eighth resistor is the input end of the conversion circuit, and the fourth end of the photoelectric coupler is the output end of the conversion circuit.
Preferably, the secondary monitoring circuit comprises: a secondary first diode, a secondary first resistor and a secondary second resistor;
the anode of the secondary first diode is connected with a secondary power supply circuit, the cathode of the secondary first diode is connected with a first end of the secondary first resistor, a second end of the secondary first resistor is connected with the output end of the conversion circuit and a first end of the secondary second resistor, and a second end of the secondary second resistor is grounded; the connection end of the second end of the secondary first resistor and the first end of the secondary second resistor is also connected to the input end of the current reference control circuit;
the second end of the secondary first resistor is an input end of the secondary monitoring circuit, and a connection end of the second end of the secondary first resistor and the first end of the secondary second resistor is an output end of the secondary monitoring circuit.
Preferably, the current reference control circuit includes: the second-stage first triode, the second-stage third resistor and the second-stage fourth resistor;
the base electrode of the secondary first triode is connected with the output end of the secondary monitoring circuit, the emitter electrode of the secondary first triode is grounded, the collector electrode of the secondary first triode is connected with the second end of the secondary third resistor, the first end of the secondary third resistor is connected with the input end of the current comparison circuit, the first end of the secondary fourth resistor is connected with the input end of the current comparison circuit, and the second end of the secondary fourth resistor is grounded;
the base electrode of the first triode of the secondary stage is the input end of the current reference control circuit, and the first end of the third resistor of the secondary stage and the first end of the fourth resistor of the secondary stage are the output end of the current reference control circuit.
Preferably, the current comparison circuit includes: the secondary fifth resistor, the secondary sixth resistor, the secondary seventh resistor, the secondary second capacitor, the secondary eighth resistor, the secondary ninth resistor, the secondary second diode and the secondary first operational amplifier;
a second end of the secondary fifth resistor is connected with a reference current, a second end of the secondary fifth resistor is connected with an output end of the current reference control circuit and a second end of the secondary sixth resistor, and a first end of the secondary sixth resistor is connected with a same-direction input end of the secondary first operational amplifier;
the reverse input end of the secondary first operational amplifier is connected with the output circuit through the secondary seventh resistor, the output end of the secondary first operational amplifier is connected with the cathode of the secondary second diode through the secondary ninth resistor, and the anode of the secondary second diode is connected with the secondary feedback circuit; a first end of the secondary eighth resistor is connected with the output end of the secondary first operational amplifier, and a second end of the secondary eighth resistor is connected with the inverting input end of the secondary first operational amplifier through the secondary second capacitor;
the connection end of the first end of the secondary fifth resistor and the second end of the secondary sixth resistor is the input end of the current comparison circuit, and the anode of the secondary second diode is the output end of the current comparison circuit.
The invention also provides a driving power supply which comprises the circuit for automatically adjusting the output current by the low-voltage input.
The circuit for automatically adjusting the output current by low-voltage input and the driving power supply have the following beneficial effects: the method comprises the following steps: the device comprises a voltage sampling comparison circuit, a primary monitoring circuit, a primary conversion circuit, a secondary monitoring circuit, a current reference control circuit and a current comparison circuit; the input end of the voltage sampling comparison circuit is connected with the input line voltage, the output end of the voltage sampling comparison circuit is connected with the input end of the primary monitoring circuit, the output end of the primary monitoring circuit is connected with the input end of the primary conversion circuit, the output end of the primary conversion circuit is connected with the input end of the secondary monitoring circuit, the output end of the secondary monitoring circuit is connected with the current reference control circuit, the input end of the current signal comparison circuit is connected with the current reference control circuit, and the output end of the current reference control circuit is connected with the secondary feedback circuit. The invention can automatically reduce the output current when the input voltage is low, avoids the failure of a power supply device caused by the full output state of low-voltage work, and improves the applicable voltage range and the practical value of the driving power supply.
Drawings
The invention will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a schematic block diagram of a low voltage input auto-regulation output current circuit according to an embodiment of the present invention;
fig. 2 is a schematic circuit diagram of a circuit for automatically adjusting an output current with a low voltage input according to an embodiment of the present invention.
Detailed Description
For a more clear understanding of the technical features, objects and effects of the present invention, embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
The invention provides a low-voltage input automatic output current adjusting circuit, which can meet the requirement that a driving power supply can work in the occasion with higher application requirement and wide input voltage, has no practical value because a terminal client passively adjusts and changes a load according to the magnitude of alternating current input voltage, and can cause power supply damage because of no low-voltage protection device.
Referring to fig. 1, fig. 1 is a schematic block diagram of an alternative embodiment of various embodiments provided by the present invention.
As shown in fig. 1, the circuit for automatically adjusting the output current of the low voltage input includes: a voltage sampling comparison circuit 10, a primary monitoring circuit 20, a primary conversion circuit 30, a secondary monitoring circuit 40, a current reference control circuit 50, and a current comparison circuit 60.
The input end of the voltage sampling comparison circuit 10 is connected to the input line voltage, the output end of the voltage sampling comparison circuit 10 is connected to the input end of the primary monitoring circuit 20, the output end of the primary monitoring circuit 20 is connected to the input end of the primary conversion circuit 30, the output end of the primary conversion circuit 30 is connected to the input end of the secondary monitoring circuit 40, the output end of the secondary monitoring circuit 40 is connected to the current reference control circuit 50, the input end of the current signal comparison circuit is connected to the current reference control circuit 50, and the output end of the current reference control circuit 50 is connected to the secondary feedback circuit.
Further, as shown in fig. 1, in some embodiments, the primary monitoring circuit 20 includes: a primary first monitoring circuit and a primary second monitoring circuit.
The input end of the primary first monitoring circuit is connected with the output end of the voltage sampling comparison circuit 10, the output end of the primary first monitoring circuit is connected with the input end of the primary second monitoring circuit, the output end of the primary second monitoring circuit is connected with the input end of the primary conversion circuit 30, and the primary first monitoring circuit is further connected to the primary power supply circuit. Wherein, the input terminal of the primary first monitoring circuit is the input terminal of the primary monitoring circuit 20, and the output terminal of the primary second monitoring circuit is the output terminal of the primary monitoring circuit 20.
In some embodiments, the voltage sampling comparison circuit 10 is configured to sample the input line voltage and compare the sampled sampling signal with its internal reference voltage to obtain a sampling comparison signal, and the sampling comparison signal is configured to control the primary first monitoring circuit to be turned on or off.
In some embodiments, the primary first monitoring circuit is turned on or off according to the sampling comparison signal output by the voltage sampling comparison circuit 10, so as to achieve the purpose of controlling the turn-on or turn-off of the primary second monitoring circuit.
In some embodiments, the primary second monitoring circuit is turned on or off according to the control of the primary first monitoring circuit, thereby controlling the operating state of the switching circuit.
Further, in some embodiments, the primary conversion circuit 30 is a photoelectric conversion circuit. The on or off working state of the photoelectric conversion circuit can be controlled by the primary second monitoring circuit. When the primary second monitoring circuit is conducted, the photoelectric conversion circuit is conducted; when the primary second monitoring circuit is turned off, the photoelectric conversion circuit is turned off.
In some embodiments, the current reference control circuit 50 is configured to change the magnitude of the current loop current reference, wherein the turning on and off of the current loop current reference is controlled by the photoelectric conversion circuit. Specifically, when the photoelectric conversion circuit is turned on, the current reference control circuit 50 is turned off; the current reference control circuit 50 is turned on when the photoelectric conversion circuit is turned off, and changes the magnitude of the current loop current reference after being turned on.
In some embodiments, the current comparison circuit 60 varies the magnitude of the output current at the output of the drive power supply by comparison of the current loop input signal and the current loop reference signal.
Specifically, when the input line voltage is decreased, when the current reference control circuit 50 is turned on, the current loop reference current of the current comparison circuit 60 is decreased due to the turn-on of the current reference control circuit 50, and the decreased signal is fed back to the feedback end of the primary main control chip through the secondary feedback circuit, so that the primary main control chip adjusts the output current of the driving power supply according to the feedback of the secondary feedback circuit, and finally the purpose of decreasing the output current of the driving power supply is achieved.
Referring to fig. 2, fig. 2 is a schematic circuit diagram of an alternative embodiment of the embodiments of the present invention.
As shown in fig. 2, the input line voltage is Uin, the primary supply circuit is VCC, and the secondary supply circuit is VDD.
In this embodiment, the voltage sampling comparison circuit 10 includes: the circuit comprises a primary first resistor R101, a primary second resistor R102, a primary third resistor R103, a primary fourth resistor R104, a primary first capacitor C101 and a primary comparator U101.
A first terminal of the primary first resistor R101 is connected to the input line voltage, a second terminal of the primary first resistor R101 is connected to a first terminal of the primary second resistor R102, and a second terminal of the primary second resistor R102 is connected to a first terminal of the primary third resistor R103 and a first terminal of the primary comparator U101; the second end of the primary third resistor R103 is connected to the first end of the primary fourth resistor R104 and the third end of the primary comparator U101, the second end of the primary fourth resistor R104, the second end of the primary first capacitor C101 and the second end of the primary comparator U101 are grounded, and the first end of the primary first capacitor C101 is connected to the third end of the primary comparator U101.
A first end of the primary first resistor R101 is an input end of the voltage sampling comparison circuit 10, and a first end of the primary comparator U101 is an output end of the voltage sampling comparison circuit 10.
In addition, the connection end of the first end of the primary comparator U101 and the second end of the primary second resistor R102 is also connected to the first end of the primary fifth resistor R105.
Further, as shown in fig. 2, in this embodiment, the primary comparator U101 is a TL413 reference comparator. Of course, it is understood that in other embodiments, the primary comparator U101 may also be an op-amp with a comparison function.
Further, as shown in fig. 2, the primary first monitoring circuit includes: a primary fifth resistor R105, a primary first voltage regulator ZD1 and a primary first MOS transistor Q101; the primary second monitoring circuit includes: a primary sixth resistor R106 and a primary second MOS transistor Q102.
A first end of the primary fifth resistor R105 is connected to the output end of the voltage sampling comparison circuit 10, and a second end of the primary fifth resistor R105 is connected to the cathode of the primary first voltage regulator ZD1 and the gate of the primary first MOS transistor Q101; the anode of the primary first voltage regulator tube ZD1 and the source of the primary first MOS tube Q101 are grounded; the drain of the primary first MOS transistor Q101 is connected to the second end of the primary sixth resistor R106 and the gate of the primary second MOS transistor Q102; a first end of the primary sixth resistor R106 is connected to the primary power supply circuit, a source of the primary second MOS transistor Q102 is grounded, and a drain of the primary second MOS transistor Q102 is connected to an input end of the primary conversion circuit 30 (i.e., a second end of the primary eighth resistor R108 in fig. 2).
A first end of the primary fifth resistor R105 is an input end of the primary first monitoring circuit, and a drain of the primary first MOS transistor Q101 is an output end of the primary first monitoring circuit; the gate of the primary second MOS transistor Q102 is the input terminal of the primary second monitoring circuit, and the drain of the primary second MOS transistor Q102 is the output terminal of the primary second monitoring circuit.
As shown in fig. 2, the primary conversion circuit 30 includes: a primary seventh resistor R107, a primary eighth resistor R108 and a primary optocoupler U102.
A first end of the primary seventh resistor R107 is connected with a first end of the primary photocoupler U102 and connected to a primary power supply circuit, and a second end of the primary seventh resistor R107 is connected with a first end of the primary eighth resistor R108 and connected to a second end of the primary photocoupler U102; a second end of the primary eighth resistor R108 is connected to the output end of the primary monitoring circuit 20; the fourth terminal of the primary optocoupler U102 is connected to the input terminal of the secondary monitoring circuit 40 (i.e., the second terminal of the secondary first resistor R201 in fig. 2), and the third terminal of the primary optocoupler U102 is grounded.
The connection end of the second end of the primary eighth resistor R108 is the input end of the conversion circuit, and the fourth end of the photoelectric coupler is the output end of the conversion circuit.
In this embodiment, the secondary monitoring circuit 40 includes: a secondary first diode D201, a secondary first resistor R201, and a secondary second resistor R202.
The anode of the secondary first diode D201 is connected with a secondary power supply circuit, the cathode of the secondary first diode D201 is connected with a first end of the secondary first resistor R201, a second end of the secondary first resistor R201 is connected with the output end of the conversion circuit and a first end of the secondary second resistor R202, and a second end of the secondary second resistor R202 is grounded; the connection between the second terminal of the secondary first resistor R201 and the first terminal of the secondary second resistor R202 is further connected to the input terminal of the current reference control circuit 50 (i.e., the base of the secondary first transistor Q201 in fig. 2).
A second end of the secondary first resistor R201 is an input end of the secondary monitoring circuit 40, and a connection end between the second end of the secondary first resistor R201 and the first end of the secondary second resistor R202 is an output end of the secondary monitoring circuit 40.
In this embodiment, the current reference control circuit 50 includes: a secondary first triode Q201, a secondary third resistor R203 and a secondary fourth resistor R204.
The base of the secondary first triode Q201 is connected to the output end of the secondary monitoring circuit 40, the emitter of the secondary first triode Q201 is grounded, the collector of the secondary first triode Q201 is connected to the second end of the secondary third resistor R203, the first end of the secondary third resistor R203 is connected to the input end of the current comparison circuit 60, the first end of the secondary fourth resistor R204 is connected to the input end of the current comparison circuit 60, and the second end of the secondary fourth resistor R204 is grounded.
The base of the secondary first triode Q201 is the input terminal of the current reference control circuit 50, and the first terminal of the secondary third resistor R203 and the first terminal of the secondary fourth resistor R204 are the output terminals of the current reference control circuit 50.
As shown in fig. 2, the current comparison circuit 60 includes: a secondary fifth resistor R205, a secondary sixth resistor R206, a secondary seventh resistor R207, a secondary second capacitor C202, a secondary eighth resistor R208, a secondary ninth resistor R209, a secondary second diode D202, and a secondary first operational amplifier U201A.
A second terminal of the secondary fifth resistor R205 is connected to the reference current, a second terminal of the secondary fifth resistor R206 is connected to the output terminal of the current reference control circuit 50 and a second terminal of the secondary sixth resistor R206, and a first terminal of the secondary sixth resistor R206 is connected to the non-inverting input terminal of the secondary first operational amplifier U201A.
The inverting input terminal of the secondary first operational amplifier U201A is connected to the output circuit through the secondary seventh resistor R207, the output terminal of the secondary first operational amplifier U201A is connected to the cathode of the secondary second diode D202 through the secondary ninth resistor R209, and the anode of the secondary second diode D202 is connected to the secondary feedback circuit; a first terminal of the secondary eighth resistor R208 is connected to the output terminal of the secondary first operational amplifier U201A, and a second terminal of the secondary eighth resistor R208 is connected to the inverting input terminal of the secondary first operational amplifier U201A through the secondary second capacitor C202.
A connection end between the first end of the secondary fifth resistor R205 and the second end of the secondary sixth resistor R206 is an input end of the current comparison circuit 60, and an anode of the secondary second diode D202 is an output end of the current comparison circuit 60.
Specifically, as shown in fig. 2, when the driving power supply is applied to a wide range of input voltages, if the ac input voltage is too low, that is, the input line voltage Uin decreases, the R-base of the primary comparator U101 is at a low level, at this time, the primary comparator U101 is not turned on, and since the primary comparator U101 is not turned on, the gate of the primary first MOS transistor Q101 is at a high level, the primary first MOS transistor Q101 is turned on, and after the primary first MOS transistor Q101 is turned on, the gate of the primary second MOS transistor Q102 is at a low level, the primary second MOS transistor Q102 is not turned on, so that the drain of the primary second MOS transistor Q102 is at a high level, and therefore, the primary photocoupler U102 is also not turned on. Since the primary photocoupler U102 is not turned on, the base of the secondary first triode Q201 is at a high level, the secondary first triode Q201 is turned on, at this time, the secondary third resistor R203 and the secondary fourth resistor R204 are connected in parallel, and since the secondary third resistor R203 and the secondary fourth resistor R204 are connected in parallel, the total resistance is reduced, so that after the voltage of the current loop reference signal (Iref) is divided by the secondary fifth resistor R205, the secondary third resistor R203 and the secondary fourth resistor R204, the divided voltage is reduced due to the reduction of the total resistance of the secondary third resistor R203 and the secondary fourth resistor R204, the voltage signal input to the same-direction input end of the secondary first operational amplifier U201A is reduced, and then the secondary first operational amplifier U201A compares the voltage signal input to the voltage signal (Io) input to the reverse input end thereof, the output end thereof outputs a low level signal, and the secondary second diode D202 is turned on, and further, a secondary photoelectric coupler U103 of the secondary feedback circuit is conducted, and a first end of the secondary photoelectric coupler U103 is connected to a feedback end of the primary main control chip, so that a conducting signal of the secondary photoelectric coupler U103 is fed back to the feedback end of the primary main control chip, the primary main control chip carries out feedback regulation according to the conducting signal of the secondary photoelectric coupler U103 received by the feedback end of the primary main control chip, the output current of the driving power supply is finally reduced, and the function that the output end can adaptively reduce the output current when the input voltage is low is achieved.
On the contrary, when the situation that the alternating current input voltage of the driving power supply is too low is removed, that is, the input line voltage Uin is increased, the R base of the primary comparator U101 is at a high level, at this time, the primary comparator U101 is turned on, so that the gate of the primary first MOS transistor Q101 is at a low level, the primary first MOS transistor Q101 is turned off, the gate of the primary second MOS transistor Q102 is at a high level, and the primary second MOS transistor Q102 is turned on; however, after the primary second MOS transistor Q102 is turned on, the drain thereof is at a low level, so that the primary photoelectric coupler U102 is turned on, and after the primary photoelectric coupler U102 is turned on, the base of the secondary first triode Q201 is at a low level, and the secondary first triode Q201 is not turned on; further, the secondary third resistor R203 and the secondary fourth resistor R204 are not connected in parallel, and the total resistance value is relatively increased, so that after the voltage of the current loop reference signal is divided by the secondary fifth resistor R205, the secondary third resistor R203 and the secondary fourth resistor R204, the total resistance value is relatively increased and the divided voltage is increased because the secondary third resistor R203 and the secondary fourth resistor R204 are not connected in parallel, so that the voltage signal input to the same-direction input end of the secondary first operational amplifier U201A is increased, and after being compared with the input signal at the reverse input end thereof, a high-level signal is output, the secondary second diode D202 is not conducted, so that the secondary photocoupler U103 is not conducted, and because the first end of the secondary photocoupler U103 is connected to the feedback end of the primary main control chip, the primary main control chip increases and recovers the output current of the driving power supply according to the signal fed back to the feedback end of the secondary feedback circuit, the function that the driving power supply automatically recovers the full-current and full-power operation after the condition that the input voltage is too low is eliminated is achieved.
The invention also provides a driving power supply which can comprise the circuit for automatically adjusting the output current by the low-voltage input, disclosed by the embodiment of the invention. Alternatively, the driving power supply may be an LED driving power supply.
The above embodiments are merely illustrative of the technical ideas and features of the present invention, and are intended to enable those skilled in the art to understand the contents of the present invention and implement the present invention, and not to limit the scope of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be covered by the claims of the present invention.
Claims (10)
1. A circuit for automatically adjusting output current for a low voltage input, comprising: the device comprises a voltage sampling comparison circuit, a primary monitoring circuit, a primary conversion circuit, a secondary monitoring circuit, a current reference control circuit and a current comparison circuit;
the input end of the voltage sampling comparison circuit is connected with an input line voltage, the output end of the voltage sampling comparison circuit is connected with the input end of the primary monitoring circuit, the output end of the primary monitoring circuit is connected with the input end of the primary conversion circuit, the output end of the primary conversion circuit is connected with the input end of the secondary monitoring circuit, the output end of the secondary monitoring circuit is connected with the current reference control circuit, the input end of the current signal comparison circuit is connected with the current reference control circuit, and the output end of the current reference control circuit is connected with the secondary feedback circuit.
2. The low voltage input automatic output current regulation circuit of claim 1 wherein the primary monitoring circuit comprises: a primary first monitoring circuit and a primary second monitoring circuit;
the input end of the primary first monitoring circuit is connected with the output end of the voltage sampling comparison circuit, the output end of the primary first monitoring circuit is connected with the input end of the primary second monitoring circuit, the output end of the primary second monitoring circuit is connected with the input end of the primary conversion circuit, and the primary first monitoring circuit is also connected to the primary power supply circuit;
the input end of the primary first monitoring circuit is the input end of the primary monitoring circuit, and the output end of the primary second monitoring circuit is the output end of the primary monitoring circuit.
3. The low voltage input automatic output current regulation circuit of claim 1 wherein the primary conversion circuit is a photoelectric conversion circuit.
4. The low voltage input automatic output current regulation circuit of claim 1 wherein the voltage sample comparison circuit comprises: the primary first resistor, the primary second resistor, the primary third resistor, the primary fourth resistor, the primary first capacitor and the primary comparator;
a first terminal of the primary first resistor is connected to the input line voltage, a second terminal of the primary first resistor is connected to a first terminal of the primary second resistor, and a second terminal of the primary second resistor is connected to a first terminal of the primary third resistor and a first terminal of the primary comparator;
the second end of the primary third resistor is connected with the first end of the primary fourth resistor and the third end of the primary comparator, the second end of the primary fourth resistor, the second end of the primary first capacitor and the second end of the primary comparator are grounded, and the first end of the primary first capacitor is connected with the third end of the primary comparator;
the first end of the primary first resistor is the input end of the voltage sampling comparison circuit, and the first end of the primary comparator is the output end of the voltage sampling comparison circuit.
5. The low voltage input automatic regulated output current circuit of claim 2, wherein said primary first monitoring circuit comprises: the first MOS transistor comprises a primary fifth resistor, a primary first voltage regulator tube and a primary first MOS tube; the primary second monitoring circuit includes: a primary sixth resistor and a primary second MOS tube;
the first end of the primary fifth resistor is connected with the output end of the voltage sampling comparison circuit, and the second end of the primary fifth resistor is connected with the cathode of the primary first voltage-regulator tube and the grid of the primary first MOS tube; the anode of the primary first voltage regulator tube and the source electrode of the primary first MOS tube are grounded; the drain electrode of the primary first MOS tube is connected with the second end of the primary sixth resistor and the grid electrode of the primary second MOS tube;
the first end of the primary sixth resistor is connected with a primary power supply circuit, the source electrode of the primary second MOS tube is grounded, and the drain electrode of the primary second MOS tube is connected with the input end of the primary conversion circuit;
the first end of the primary fifth resistor is the input end of the primary first monitoring circuit, and the drain electrode of the primary first MOS transistor is the output end of the primary first monitoring circuit; the grid electrode of the primary second MOS tube is the input end of the primary second monitoring circuit, and the drain electrode of the primary second MOS tube is the output end of the primary second monitoring circuit.
6. The low voltage input automatic output current regulation circuit of claim 1 wherein the primary conversion circuit comprises: the primary seventh resistor, the primary eighth resistor and the primary photoelectric coupler;
the first end of the primary seventh resistor and the first end of the primary photoelectric coupler are connected and connected to a primary power supply circuit, and the second end of the primary seventh resistor is connected with the first end of the primary eighth resistor and the second end of the primary photoelectric coupler; the second end of the primary eighth resistor is connected with the output end of the primary monitoring circuit;
the fourth end of the primary photoelectric coupler is connected with the input end of the secondary monitoring circuit, and the third end of the primary photoelectric coupler is grounded;
the connection end of the second end of the primary eighth resistor is the input end of the conversion circuit, and the fourth end of the photoelectric coupler is the output end of the conversion circuit.
7. The low voltage input auto-regulating output current circuit of claim 1, wherein said secondary monitoring circuit comprises: a secondary first diode, a secondary first resistor and a secondary second resistor;
the anode of the secondary first diode is connected with a secondary power supply circuit, the cathode of the secondary first diode is connected with a first end of the secondary first resistor, a second end of the secondary first resistor is connected with the output end of the conversion circuit and a first end of the secondary second resistor, and a second end of the secondary second resistor is grounded; the connection end of the second end of the secondary first resistor and the first end of the secondary second resistor is also connected to the input end of the current reference control circuit;
the second end of the secondary first resistor is an input end of the secondary monitoring circuit, and a connection end of the second end of the secondary first resistor and the first end of the secondary second resistor is an output end of the secondary monitoring circuit.
8. The low voltage input automatic regulated output current circuit of claim 1, wherein said current reference control circuit comprises: the second-stage first triode, the second-stage third resistor and the second-stage fourth resistor;
the base electrode of the secondary first triode is connected with the output end of the secondary monitoring circuit, the emitter electrode of the secondary first triode is grounded, the collector electrode of the secondary first triode is connected with the second end of the secondary third resistor, the first end of the secondary third resistor is connected with the input end of the current comparison circuit, the first end of the secondary fourth resistor is connected with the input end of the current comparison circuit, and the second end of the secondary fourth resistor is grounded;
the base electrode of the first triode of the secondary stage is the input end of the current reference control circuit, and the first end of the third resistor of the secondary stage and the first end of the fourth resistor of the secondary stage are the output end of the current reference control circuit.
9. The low voltage input automatic output current regulation circuit of claim 1 wherein the current comparison circuit comprises: the secondary fifth resistor, the secondary sixth resistor, the secondary seventh resistor, the secondary second capacitor, the secondary eighth resistor, the secondary ninth resistor, the secondary second diode and the secondary first operational amplifier;
a second end of the secondary fifth resistor is connected with a reference current, a second end of the secondary fifth resistor is connected with an output end of the current reference control circuit and a second end of the secondary sixth resistor, and a first end of the secondary sixth resistor is connected with a same-direction input end of the secondary first operational amplifier;
the reverse input end of the secondary first operational amplifier is connected with the output circuit through the secondary seventh resistor, the output end of the secondary first operational amplifier is connected with the cathode of the secondary second diode through the secondary ninth resistor, and the anode of the secondary second diode is connected with the secondary feedback circuit; a first end of the secondary eighth resistor is connected with the output end of the secondary first operational amplifier, and a second end of the secondary eighth resistor is connected with the inverting input end of the secondary first operational amplifier through the secondary second capacitor;
the connection end of the first end of the secondary fifth resistor and the second end of the secondary sixth resistor is the input end of the current comparison circuit, and the anode of the secondary second diode is the output end of the current comparison circuit.
10. A driving power supply comprising a low voltage input auto-regulating output current circuit as claimed in any one of claims 1 to 9.
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Cited By (1)
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| CN113225875A (en) * | 2021-04-20 | 2021-08-06 | 深圳市崧盛电子股份有限公司 | Drive power supply and output short-circuit protection circuit thereof |
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| CN112235896B (en) | 2023-04-18 |
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