CN220402006U - LED constant current driving circuit with single operational amplifier - Google Patents
LED constant current driving circuit with single operational amplifier Download PDFInfo
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- CN220402006U CN220402006U CN202322028917.XU CN202322028917U CN220402006U CN 220402006 U CN220402006 U CN 220402006U CN 202322028917 U CN202322028917 U CN 202322028917U CN 220402006 U CN220402006 U CN 220402006U
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Abstract
The utility model relates to the technical field of LED driving circuits, and discloses a single operational amplifier LED constant current driving circuit which is simpler in structure and lower in development cost, comprising a reference circuit (101) for outputting a reference signal, a current sampling circuit (103), a comparison circuit (102) and an LED switch circuit (104), wherein the current sampling circuit (103) is used for acquiring a current signal when an LED is conducted; the comparison circuit (102) is used for receiving the reference signal and the current signal and comparing the input current signal with the reference signal; when the current signal is larger than the reference signal, the output of the comparison circuit (102) is high level, the internal resistance of the LED switch circuit (104) is increased, and the current flowing through the LED is reduced; when the current signal is smaller than the reference signal, the output of the comparison circuit is at a low level, the internal resistance of the LED switch circuit is reduced, and the current flowing through the LED is increased.
Description
Technical Field
The utility model relates to the technical field of LED driving circuits, in particular to a single operational amplifier LED constant current driving circuit.
Background
LED driving power is a more common power supply device in LED light bars. At present, a linear driving chip and a switch driving chip are adopted for general DC-DC LED driving, the output power is from small to large, the application of the LED driving is relatively simple and convenient for a developer, but the development cost is high, and the LED driving is not easy to control when the LED driving is applied to a medium-low end product.
Therefore, how to reduce the development cost of the LED constant current driving power supply is a technical problem to be solved by those skilled in the art.
Disclosure of Invention
The utility model aims at solving the technical problems that the LED driving adopts a linear driving chip and a switch driving chip in the prior art, the output power is from small to large, the LED driving circuit is relatively simple and convenient for a developer to apply, but has higher development cost, and the utility model provides a single operational amplifier LED constant current driving circuit with relatively simple structure and lower development cost.
The technical scheme adopted for solving the technical problems is as follows: a single operational amplifier LED constant current drive circuit is constructed, which comprises:
a reference circuit configured within the driving circuit for outputting a reference signal;
one end of the current sampling circuit is connected with the negative electrode of the LED and used for acquiring a current signal when the LED is conducted;
an input end of the comparison circuit is connected with the output end of the reference circuit and is used for receiving the reference signal,
the other input end of the comparison circuit is connected with one end of the current sampling circuit and is used for receiving the current signal and comparing the input current signal with the reference signal;
an input end of the LED switch circuit is connected with an output end of the comparison circuit;
when the current signal is larger than the reference signal, the comparison circuit outputs a high level, the internal resistance of the LED switch circuit is increased, and the current flowing through the LED is reduced;
when the current signal is smaller than the reference signal, the comparison circuit outputs a low level, the internal resistance of the LED switch circuit decreases, and the current flowing through the LED increases.
In some embodiments, the LED switch circuit comprises at least a first MOS transistor, a fourth resistor, a first inductor and a first diode,
one end of the grid electrode of the first MOS tube and one end of the fourth resistor are connected with the output end of the comparison circuit,
the source electrode of the first MOS tube and the other end of the fourth resistor are connected with a power supply end,
the drain electrode of the first MOS tube is connected with one end of the first inductor and the cathode of the first diode,
the other end of the first inductor is connected with the anode of the LED,
the anode of the first diode is connected with the common terminal.
In some embodiments, the comparison circuit includes an operational amplifier,
the inverting terminal of the operational amplifier is connected with the output terminal of the reference circuit and is used for receiving the reference signal,
the non-inverting terminal of the operational amplifier is connected with one end of the current sampling circuit and is used for receiving the current signal and comparing the input current signal with the reference signal,
the output end of the operational amplifier is coupled to the grid electrode of the first MOS tube.
In some embodiments, the reference circuit includes a voltage reference controller,
the feedback end and the cathode of the voltage reference controller are connected with the inverting end of the operational amplifier,
and the anode of the voltage reference controller is connected with the common terminal.
In some implementations, the reference circuit also includes a second resistor and a third resistor connected in series,
one end of the second resistor is connected with the feedback end of the voltage reference controller,
the connection end of the second resistor and the third resistor is connected with the inverting end of the operational amplifier,
the other end of the third resistor is connected with the common end.
In some embodiments, the current sampling circuit includes a fifth resistor,
one end of the fifth resistor is connected with the negative electrode of the LED and the same-phase end of the operational amplifier,
the other end of the fifth resistor is connected with the common terminal.
In some embodiments, the first MOS transistor is selected as an N-channel MOS transistor.
The single operational amplifier LED constant current driving circuit comprises a reference circuit for outputting a reference signal, a current sampling circuit, a comparison circuit and an LED switch circuit, wherein the current sampling circuit is used for acquiring a current signal when an LED is conducted; the comparison circuit is used for receiving the reference signal and the current signal and comparing the input current signal with the reference signal; when the current signal is larger than the reference signal, the output of the comparison circuit is high level, the internal resistance of the LED switch circuit is increased, and the current flowing through the LED is reduced; when the current signal is smaller than the reference signal, the output of the comparison circuit is at a low level, the internal resistance of the LED switch circuit is reduced, and the current flowing through the LED is increased. Compared with the prior art, the comparison circuit is used for comparing the input current signal with the reference signal and outputting a high level or a low level according to the comparison result so as to control the internal resistance of the LED switch circuit and further adjust the current signal flowing through the LED.
The technical scheme adopts the common operational amplifier to replace the LED constant current driving chip special for market parts, so that the technical scheme can be applied to mobile lighting products such as middle-low-end flashlights and the like, and the development cost of the products is effectively reduced.
Drawings
The utility model will be further described with reference to the accompanying drawings and examples, in which:
FIG. 1 is a schematic diagram of a frame of an embodiment of a single op-amp LED constant current drive circuit according to the present utility model;
fig. 2 is a schematic diagram of an embodiment of a single op amp LED constant current driving circuit according to the present utility model.
Detailed Description
For a clearer understanding of technical features, objects and effects of the present utility model, a detailed description of embodiments of the present utility model will be made with reference to the accompanying drawings.
As shown in fig. 1-2, in the first embodiment of the single op LED constant current driving circuit of the present utility model, the single op LED constant current driving circuit 10 includes a reference circuit 101, a comparison circuit 102, a current sampling circuit 103, an LED switch circuit 104, and LEDs.
Wherein the reference circuit 101 is configured to output a reference signal;
the comparison circuit 102 is configured to receive the reference signal and a current signal flowing through the LED lamp bead when the LED lamp strip works, compare the current signal with the reference signal, and output a level signal (high level or low level) according to a comparison result;
the current sampling circuit 103 is used for checking current signals when the LED lamp beads work;
the LED switch circuit 104 is used to control/regulate the operating current of the LED light bar.
Specifically, the reference circuit 101 is configured within the driving circuit for outputting a reference signal;
one end of the current sampling circuit 103 is connected with the cathode of the LED and used for acquiring a current signal when the LED is conducted;
an input of the comparison circuit 102 is coupled to an output of the reference circuit 101, for receiving a reference signal,
the other input end of the comparison circuit 102 is connected with one end of the current sampling circuit 103, and is used for receiving a current signal and comparing the input current signal with a reference signal;
an input end of the LED switch circuit 104 is connected with an output end of the comparison circuit 102;
when the current signal is greater than the reference signal, the comparison circuit 102 outputs a high level, the internal resistance of the LED switch circuit 104 increases, and the current flowing through the LED decreases;
when the current signal is smaller than the reference signal, the comparison circuit 102 outputs a low level, the internal resistance of the LED switch circuit 104 decreases, and the current flowing through the LED increases.
With the present solution, the comparison circuit 102 compares the input current signal with the reference signal, and outputs a high level or a low level according to the comparison result, so as to control the internal resistance of the LED switch circuit 104, and further adjust the current signal flowing through the LED. The technical scheme adopts the common operational amplifier to replace the LED constant current driving chip special for market parts, so that the technical scheme can be applied to mobile lighting products such as middle-low-end flashlights and the like, and the development cost of the products can be effectively reduced.
In some embodiments, in order to ensure the reliability of the output current signal, as shown in fig. 2, a first MOS transistor VT101, a fourth resistor R4, a first inductor L101, and a first diode D101 may be disposed in the LED switch circuit 104, where the first MOS transistor VT101 is selected as an N-channel MOS transistor, which has a switching function;
the first diode D101 is selected as a freewheeling diode.
Specifically, one end of the gate of the first MOS transistor VT101 and one end of the fourth resistor R4 are connected with the output end of the comparison circuit 102,
the other ends of the source electrode of the first MOS tube VT101 and the fourth resistor R4 are connected with a power supply end (corresponding to the positive electrode of the BAT),
the drain electrode of the first MOS tube VT101 is connected with one end of the first inductor L101 and the cathode electrode of the first diode D101,
the other end of the first inductance L101 is connected with the anode of the LED,
the anode of the first diode D101 is connected to the common terminal.
In some embodiments, to ensure the reliability of the output current signal, as shown in fig. 2, an operational amplifier U102 may be included in the comparison circuit 102, which has the function of signal comparison.
Specifically, the inverting terminal (corresponding to 3 pins) of the operational amplifier U102 is connected to the output terminal of the reference circuit 101, for receiving the reference signal,
the non-inverting terminal (corresponding to 2 pins) of the operational amplifier U102 is connected to one end of the current sampling circuit 103, for receiving the current signal, and comparing the input current signal with the reference signal,
the output end (corresponding to pin 1) of the operational amplifier U102 is coupled to the gate of the first MOS transistor VT 101.
Specifically, the inverting terminal (corresponding to 3 pins) of the operational amplifier U102 is the base reference voltage signal,
the non-inverting terminal (corresponding to pin 2) of op-amp U102 is a real-time feedback load current signal,
when the current of the load (or the LED) is increased, the voltage of the non-inverting end (corresponding to the 2 pin) of the operational amplifier U102 is high, the output of the operational amplifier U102 is low, the first MOS tube VT101 is cut off, and the current signal of the load (or the LED) is promoted to be reduced;
when the current of the load (or the LED) becomes smaller, the voltage of the same-phase end (corresponding to the 2 pin) is lower than the voltage of the opposite-phase end (corresponding to the 3 pin), the output is in a high level, the first MOS tube VT101 is conducted, and the current signal of the load (or the LED) is promoted to be increased.
Therefore, the voltage change of the in-phase end (corresponding to 2 pins) is monitored in real time to control the on or off of the first MOS tube VT101, so that the purpose of final constant current of the driving circuit is achieved.
In some embodiments, in order to ensure the reliability of the output level signal, as shown in fig. 2, a voltage reference controller U101 may be provided in the reference circuit 101, where the feedback terminal and the cathode of the voltage reference controller U101 are connected to the inverting terminal (corresponding to 3 pins) of the operational amplifier U102,
the anode of the voltage reference controller U101 is connected to the common terminal.
The cathode of the voltage reference controller U101 is connected to the power supply terminal through a first resistor R101.
Further, the reference circuit 101 further includes a second resistor R102 and a third resistor R103 connected in series, which have a voltage dividing function.
Specifically, one end of the second resistor R102 is connected with the feedback end of the voltage reference controller U101,
the connection end of the second resistor R102 and the third resistor R103 is connected with the inverting end (corresponding to 3 pins) of the operational amplifier U102,
the other end of the third resistor R103 is connected to the common terminal.
Specifically, the voltage signal output by the voltage reference controller U101 is divided by the second resistor R102 and the third resistor R103, and then a stable reference voltage signal or a reference signal is obtained.
In some embodiments, as shown in fig. 2, the current sampling circuit 103 includes a fifth resistor R105 for detecting a current signal when the load is operating.
Specifically, one end of the fifth resistor R105 is connected to the negative electrode of the LED and the non-inverting terminal (corresponding to the 2 pin) of the operational amplifier U102, and the other end of the fifth resistor R105 is connected to the common terminal.
Specifically, when the voltage at two ends of the fifth resistor R105 changes, the voltage is directly fed back to the in-phase end (corresponding to the 2 pins) of the operational amplifier U102, the difference between the fed-back current signal and the reference signal at the opposite-phase end (corresponding to the 3 pins) is amplified and compared by the operational amplifier U102, and then a level signal for controlling the gate voltage of the first MOS transistor VT101 is output according to the comparison result of the two signals, so that the internal resistance of the first MOS transistor VT101 is changed, the voltage drop between the source and the drain is changed, and the voltage of the sampling resistor (corresponding to the fifth resistor R105) is kept unchanged, so that the purpose of keeping the load current constant is achieved.
When the voltage input by the non-inverting terminal (corresponding to the 2 pins) of the operational amplifier U102 is larger than the reference signal of the inverting terminal (corresponding to the 3 pins), the triode in the operational amplifier U102 is cut off, and the output terminal (corresponding to the 1 pin) outputs high level;
when the voltage input by the in-phase terminal (corresponding to the 2 pin) is smaller than the reference signal of the opposite-phase terminal (corresponding to the 3 pin), the triode in the operational amplifier U102 is conducted, and the output terminal (corresponding to the 1 pin) outputs a low level.
The working principle is as follows:
in the figure, BAT is a power supply system of a battery pack, and the input voltage range is 3-9V;
the first resistor R1, the voltage reference controller U101, the second resistor R102, the third resistor R103 and the third capacitor C103 form a reference circuit 101,
the voltage reference controller U101 provides a stable reference voltage for the reference circuit 101, so that the reference circuit is not interfered by fluctuation of input voltage, and the resistance value of the second resistor R102 can be adjusted to change the current of the LED;
wherein the first diode D101 is a freewheeling diode,
the first inductor L101 uses the inductance with large inductance as much as possible under the space permission, the constant current is more stable, the current is born as the LED current 3A, the first inductor L101 is proper only by selecting 5A, and the second capacitor C102 can enable the voltage of the LED to be smoother, so that the LED flicker is avoided;
the voltage reference controller U101 divides the voltage through the second resistor R102 and the third resistor R103 to provide a stable reference voltage for the inverting terminal (corresponding to 3 pins) of the operational amplifier U102,
when the load works, the voltage at two ends of the fifth resistor R105 changes, at this time, if the voltage signal (or current signal) input by the in-phase end (corresponding to the 2 pin) is greater than the reference signal of the opposite-phase end (corresponding to the 3 pin), the triode inside the operational amplifier U102 is cut off, the output end (corresponding to the 1 pin) outputs high level, the grid voltage of the first MOS tube VT101 changes, the internal resistance increases, and the current flowing through the load becomes small;
if the voltage signal (or current signal) input by the in-phase terminal (corresponding to the 2 pins) is smaller than the reference signal of the opposite-phase terminal (corresponding to the 3 pins), the triode inside the operational amplifier U102 is conducted, the output terminal (corresponding to the 1 pin) outputs a low level, the grid voltage of the first MOS tube VT101 is changed, the internal resistance is reduced, and the current flowing through the load is increased.
The grid voltage of the first MOS tube VT101 is controlled through output, the internal resistance of the first MOS tube VT101 is changed, so that the voltage drop between a source electrode and a drain electrode is changed, the voltage of the fifth resistor R105 is kept unchanged, and finally constant stable current is achieved.
The scheme adopts the common operational amplifier to replace the LED constant current driving chip special for market parts, can be applied to mobile lighting products such as middle-low-end flashlights and the like, and has lower cost.
The embodiments of the present utility model have been described above with reference to the accompanying drawings, but the present utility model is not limited to the above-described embodiments, which are merely illustrative and not restrictive, and many forms may be made by those having ordinary skill in the art without departing from the spirit of the present utility model and the scope of the claims, which are to be protected by the present utility model.
Claims (7)
1. A single operational amplifier LED constant current drive circuit is characterized by comprising:
a reference circuit configured within the driving circuit for outputting a reference signal;
one end of the current sampling circuit is connected with the negative electrode of the LED and used for acquiring a current signal when the LED is conducted;
an input end of the comparison circuit is connected with the output end of the reference circuit and is used for receiving the reference signal,
the other input end of the comparison circuit is connected with one end of the current sampling circuit and is used for receiving the current signal and comparing the input current signal with the reference signal;
an input end of the LED switch circuit is connected with an output end of the comparison circuit;
when the current signal is larger than the reference signal, the comparison circuit outputs a high level, the internal resistance of the LED switch circuit is increased, and the current flowing through the LED is reduced;
when the current signal is smaller than the reference signal, the comparison circuit outputs a low level, the internal resistance of the LED switch circuit decreases, and the current flowing through the LED increases.
2. The single op-amp LED constant current drive circuit of claim 1, wherein,
the LED switch circuit at least comprises a first MOS tube, a fourth resistor, a first inductor and a first diode,
one end of the grid electrode of the first MOS tube and one end of the fourth resistor are connected with the output end of the comparison circuit,
the source electrode of the first MOS tube and the other end of the fourth resistor are connected with a power supply end,
the drain electrode of the first MOS tube is connected with one end of the first inductor and the cathode of the first diode,
the other end of the first inductor is connected with the anode of the LED,
the anode of the first diode is connected with the common terminal.
3. The single op-amp LED constant current drive circuit of claim 2, wherein,
the comparison circuit comprises an operational amplifier which,
the inverting terminal of the operational amplifier is connected with the output terminal of the reference circuit and is used for receiving the reference signal,
the non-inverting terminal of the operational amplifier is connected with one end of the current sampling circuit and is used for receiving the current signal and comparing the input current signal with the reference signal,
the output end of the operational amplifier is coupled to the grid electrode of the first MOS tube.
4. The single op-amp LED constant current drive circuit according to claim 3, wherein,
the reference circuit comprises a voltage reference controller,
the feedback end and the cathode of the voltage reference controller are connected with the inverting end of the operational amplifier,
and the anode of the voltage reference controller is connected with the common terminal.
5. The single op-amp LED constant current drive circuit of claim 4, wherein,
the reference circuit further comprises a second resistor and a third resistor connected in series,
one end of the second resistor is connected with the feedback end of the voltage reference controller,
the connection end of the second resistor and the third resistor is connected with the inverting end of the operational amplifier,
the other end of the third resistor is connected with the common end.
6. The single op-amp LED constant current drive circuit according to claim 3, wherein,
the current sampling circuit includes a fifth resistor,
one end of the fifth resistor is connected with the negative electrode of the LED and the same-phase end of the operational amplifier,
the other end of the fifth resistor is connected with the common terminal.
7. The single op-amp LED constant current drive circuit of claim 2, wherein,
the first MOS tube is selected as an N-channel MOS tube.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322028917.XU CN220402006U (en) | 2023-07-31 | 2023-07-31 | LED constant current driving circuit with single operational amplifier |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202322028917.XU CN220402006U (en) | 2023-07-31 | 2023-07-31 | LED constant current driving circuit with single operational amplifier |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN220402006U true CN220402006U (en) | 2024-01-26 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN202322028917.XU Active CN220402006U (en) | 2023-07-31 | 2023-07-31 | LED constant current driving circuit with single operational amplifier |
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2023
- 2023-07-31 CN CN202322028917.XU patent/CN220402006U/en active Active
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