CN218213171U - LED current detection circuit - Google Patents
LED current detection circuit Download PDFInfo
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- CN218213171U CN218213171U CN202222327928.3U CN202222327928U CN218213171U CN 218213171 U CN218213171 U CN 218213171U CN 202222327928 U CN202222327928 U CN 202222327928U CN 218213171 U CN218213171 U CN 218213171U
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Abstract
The utility model provides a LED current detection circuit, it includes voltage drop drive module, the LED interface, wide range measuring unit and small-scale range measuring unit, drive module is used for providing normal work opening voltage for the LED lamp, the input of LED interface links in voltage drop drive module, the output is used for inserting the LED lamp, wide range measuring unit and small-scale range measuring unit all link in the input of LED interface, be used for acquireing LED's sampling current respectively and export the great detected signal and the less detected signal of LED lamp, small-scale range measuring unit can stop outputting based on CPU switches the instruction signal. This application has realized can adopting great magnification to measure to less electric current to improve the measurement accuracy who detects the electric current, and adopt less magnification to great electric current, in order to prevent to improve measurement accuracy, measuring circuit receives CPU low operating voltage's influence compelled to reduce the range to can't satisfying the needs of measurement work.
Description
Technical Field
The application relates to the field of detection circuits, in particular to an LED current detection circuit.
Background
At present, in order to meet the requirement on the brightness of an LED light source, a constructor needs to drive an LED lamp in a constant current mode based on the volt-ampere characteristic of an LED, and the current of the LED lamp needs to be detected in real time in order to master the constant current driving condition of the LED lamp.
However, a common way of sampling the loop current of the LED lamp in a closed loop is to sample a single resistor in series, obtain a current signal on the single resistor connected in series to the input end of the LED, amplify the current signal in a certain proportion, and then collect the amplified current signal, thereby adjusting the driving current in real time based on the collection result.
However, if the above-mentioned serial single-resistor sampling method is adopted, the sampling precision is easily limited due to the low operating voltage of the CPU, and therefore, in order to improve the sampling precision, the amplification factor of the current signal needs to be increased, and after the amplified current signal is input to the CPU, the voltage caused by the amplified current signal easily exceeds the maximum operating voltage of the CPU, and if the sampling current is reduced in order to increase the amplification factor, the sampling range is too small, and thus the sampling requirement cannot be satisfied fundamentally.
In view of the above situation, the present application provides an LED current detection circuit for improving the accuracy of LED current sampling.
SUMMERY OF THE UTILITY MODEL
In order to improve the precision of LED current sampling, this application provides an LED current detection circuit.
The application provides a LED current detection circuit adopts following technical scheme:
an LED current detection circuit comprising:
the voltage drop driving module acquires a current adjusting signal from the CPU and provides a low-voltage constant-current driving signal for the LED lamp based on the current adjusting signal;
the input end of the LED interface is connected with the voltage drop driving module, and the output end of the LED interface is used for connecting an LED lamp;
the wide-range measuring unit is connected to the input end of the LED interface and is used for acquiring the sampling current of the LED and outputting a larger detection signal of the LED lamp based on the sampling current of the LED;
and the small-range measuring unit is connected with the input end of the LED interface and used for acquiring the sampling current of the LED and outputting a small detection signal of the LED lamp based on the sampling current of the LED, and the small-range measuring unit stops outputting based on the CPU switching instruction signal.
By adopting the technical scheme, because the LED lamp needs to be driven by lower voltage, and in order to meet the requirement on the brightness of the LED light source, based on the volt-ampere characteristic of the LED, constructors need to drive the LED lamp by adopting a constant current mode, therefore, the voltage drop driving unit can acquire a current regulation signal from the CPU and provide lower voltage and constant current for the LED lamp based on the current regulation signal, and for measuring the constant current working condition of an LED loop, the input end of the LED interface is provided with two sampling units to respectively sample larger current and smaller current of the LED lamp, therefore, the smaller LED current can be measured by adopting larger amplification factor, so as to improve the measurement precision of the detection current, and the measurement circuit can not be forced to reduce the measurement range under the influence of the low working voltage of the CPU while improving the measurement precision, so that the measurement range does not meet the requirement of the measurement work. In the actual use process, when the LED current is smaller current, the current can be amplified by a larger multiple, a user can detect the current through the small-range measuring unit, when the CPU detects that the LED current is larger, namely, when the detection current signal output to the CPU is about to cause the CPU voltage to exceed the working voltage range of the CPU, the small-range measuring unit can receive the switching instruction signal of the CPU and simultaneously stops outputting the detection current signal to the CPU to protect the CPU, and then the large-range measuring unit still works and outputs the detection current signal to the CPU.
Optionally, the wide-range measuring unit includes:
the first measuring resistor R1 is connected to the input end of the LED interface and used for acquiring the sampling current of the LED lamp;
and the first amplifying element is connected to two ends of the first measuring resistor R1 and is used for amplifying the voltage signal of the LED lamp acquired by the first measuring resistor R1 to a first amplification factor and outputting the voltage signal to the CPU for measurement.
By adopting the technical scheme, the first measuring resistor R1 is connected with the LED lamp connected with the LED interface in series, so that the current on the LED lamp is equal to the current of the first measuring resistor R1, the first amplifying element is connected to the two ends of the first measuring resistor R1, the voltage at the two ends of the first amplifying element is equal to the voltage at the two ends of the first measuring resistor R1, the voltage at the two ends of the first sampling resistor is amplified by the first amplifying element and then is output to the CPU for measurement, and a user can control the measurement precision and the magnitude of an output voltage signal by controlling the amplification factor of the first amplifying element.
Optionally, the first amplifying element is a first operational amplifier OA1, a non-inverting input terminal and an inverting input terminal of the first operational amplifier OA1 are respectively connected to two ends of the first measuring resistor R1, and an output terminal of the first operational amplifier OA1 outputs an amplified voltage signal to the outside.
Optionally, the small-scale measurement unit includes:
the second measuring resistor R2 is connected to the input end of the LED interface and used for acquiring the sampling current of the LED lamp;
the second amplifying element is connected to two ends of the second measuring resistor R2 and used for amplifying the voltage signal of the LED lamp acquired by the second measuring resistor R2 to a second amplification factor and outputting the amplified voltage signal to the CPU for measurement;
and the change-over switch S1 is connected to two ends of the second measuring resistor R2 and is switched on and off based on the CPU switching instruction signal.
By adopting the above technical scheme, the second measuring resistor R2 is connected in series with the LED lamp connected to the LED interface, so that the current on the LED lamp is equal to the current of the second measuring resistor R2, the second amplifying element is connected to both ends of the second measuring resistor R2, the voltage across the second amplifying element is equal to the voltage across the second measuring resistor R2, and then the voltage across the second sampling resistor is amplified by the second amplifying element, and the voltage output to the CPU is measured, so that the user can control the measurement accuracy and the magnitude of the output voltage signal by controlling the amplification factor of the second amplifying element, when the CPU detects that the LED current is large, that is, the voltage output to the CPU is about to exceed the operating voltage range of the CPU, the switch S1 can be closed based on the received switching instruction signal of the high level of the CPU, because the switch S1 is connected to both ends of the second detecting resistor, the second detecting resistor is short-circuited, thereby stopping the output of the detection current signal to the CPU to protect the CPU.
Optionally, the second amplifying element is a second operational amplifier OA2, a non-inverting input terminal and an inverting input terminal of the second operational amplifier OA2 are respectively connected to two ends of the second measuring resistor R2, and an output terminal of the second operational amplifier OA2 outputs the amplified voltage signal to the outside.
Optionally, the switch S1 is an NMOS switch tube QS, a gate of the NMOS switch tube QS is used to obtain a CPU switching instruction signal, a source of the NMOS switch tube QS is connected to a ground, and a drain of the NMOS switch tube QS is connected to one end of the second measurement resistor R2 close to the LED interface input end.
By adopting the technical scheme, the grid electrode of the NMOS switch tube QS is used for receiving the CPU switching instruction signal, so that the CPU switching instruction signal can play a role in controlling the grid electrode-source electrode voltage of the NMOS switch tube QS, the on-off of the switch tube is controlled, when the grid electrode of the NMOS switch tube QS receives the CPU switching instruction signal with high level, the second measuring resistor R2 is switched on, the second measuring resistor R2 is short-circuited by the NMOS switch tube QS, the small-range measuring unit stops outputting the voltage to the CPU, and when the grid electrode of the NMOS switch tube QS receives the CPU switching instruction signal with low level, the second measuring resistor R2 is switched off, and the small-range measuring unit can restart to output the voltage to the CPU.
Optionally, the voltage drop driving module includes:
the voltage drop driving unit is connected between the power supply and the ground wire and used for outputting a voltage signal which changes periodically;
the anode of the first diode Z1 is connected with the output end of the voltage drop driving unit;
the energy storage inductor L1 is connected between the output end of the first diode Z1 and the input end of the LED interface;
and the energy storage capacitor C1 is connected between the input end of the LED interface and the ground wire.
By adopting the technical scheme, the high-low level condition of the voltage signal output by the voltage drop driving unit changes periodically, when the voltage signal output by the voltage drop driving unit is high level, the loop formed by the first diode Z1, the energy storage inductor L1 and the energy storage capacitor C1 is charged and the driving voltage subjected to voltage drop processing is output to the LED, when the voltage signal output by the voltage drop driving unit is low level, the loop formed by the first diode Z1, the energy storage inductor L1 and the energy storage capacitor C1 is discharged and the driving voltage subjected to voltage drop processing is output to the LED, the stability of the driving voltage output by the voltage drop driving module to the LED lamp can be ensured by the energy storage inductor L1 and the energy storage capacitor C1, meanwhile, the current direction can be kept unchanged all the time by the first diode Z1, and the driving provided by the voltage drop driving module to the LED is low-voltage constant-current driving, so as to meet the normal working requirement of the LED.
Optionally, the voltage drop driving unit includes:
the high-voltage gate driver LM5106 is connected between a power supply and a ground wire, the input end of the high-voltage gate driver is used for inputting a PWM signal, and the output end of the high-voltage gate driver is used as the output end of the voltage drop driving unit;
a first NMOS tube Q1, the grid is connected with the HO pin of the high-voltage grid driver LM5106, the source electrode is connected with the output end of the high-voltage grid driver, and is connected with the anode of the first diode Z1, and the drain electrode is connected with a power supply;
and a second NMOS tube Q2, the gate of which is connected to the LO pin of the high-voltage gate driver LM5106, the drain of which is connected to the output end of the high-voltage gate driver, and is connected to the anode of the first diode Z1, and the source of which is connected with the ground wire.
By adopting the above technical solution, LM5106 is a high voltage gate driver for driving high side and low side N channel MOSFETs in a synchronous buck or half-bridge configuration. The floating high side driver can operate at rail voltages up to 100V. A single control input is compatible with TTL signal levels and a single external resistor programs the switching transition dead time through a closely matched on-delay circuit. Robust level shifting techniques consume low power while operating at high speeds and provide clean output transitions. Through the connection mode, the second NMOS tube Q2 is periodically switched on and off, so that the voltage drop driving unit can output periodically changed voltage signals, and the CPU adjusts the PWM pulse width after sampling, thereby controlling the current provided by the voltage drop driving unit to the LED lamp.
To sum up, the application comprises the following beneficial technical effects:
the input end of the LED interface is provided with two sampling units for sampling the larger current and the smaller current of the LED lamp respectively, therefore, the larger amplification factor can be adopted for measuring the smaller LED current, so as to improve the measurement accuracy of the detection current, and the smaller amplification factor can be adopted for the larger current, so as to prevent that the measurement circuit is forced to reduce the range under the influence of the low working voltage of the CPU when the measurement accuracy is improved, and the range is not required for meeting the measurement work.
Drawings
Fig. 1 is a circuit diagram of an LED current detection circuit in an embodiment of the present application.
Description of the reference numerals:
1. a voltage drop driving module; 11. a voltage drop driving unit; 2. an LED interface; 3. a wide-range measuring unit; 4. a small-range measuring unit.
Detailed Description
The present application is described in further detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the inventive concepts. As part of this description, some of the drawings of the present disclosure represent structures and devices in block diagram form in order to avoid complicating the disclosed principles. In the interest of clarity, not all features of an actual implementation are described in this specification. Reference in the present disclosure to "one implementation" or "an implementation" means that a particular feature, structure, or characteristic described in connection with the implementation is included in at least one implementation, and references to "one implementation" or "an implementation" are not to be understood as necessarily all referring to the same implementation.
Unless explicitly defined otherwise, the terms "a," "an," and "the" are not intended to refer to a singular entity, but include the general class of which a particular example may be used for illustration. Thus, use of the terms "a" or "an" can mean any number of at least one, including "a," one or more, "" at least one, "and" one or more than one. The term "or" means any of the alternatives and any combination of alternatives, including all alternatives, unless alternatives are explicitly indicated as mutually exclusive. The phrase "at least one of," when combined with a list of items, refers to a single item in the list or any combination of items in the list. The phrase does not require all of the listed items unless explicitly so limited.
The embodiment of the application discloses a light-emitting diode (LED) current detection circuit. Referring to fig. 1, an LED current detection circuit includes a voltage drop driving module 1, an LED interface 2, a large range measuring unit 3 and a small range measuring unit 4, wherein the voltage drop driving module 1 can obtain a current adjustment signal from a CPU and provide a low-voltage constant current driving signal for an LED lamp based on the current adjustment signal, an input terminal of the LED interface 2 is connected to the voltage drop driving module 1, an output terminal thereof is connected to the LED lamp, the large range measuring unit 3 is connected to an input terminal of the LED interface 2 and outputs a large detection signal of the LED lamp based on a sampling current of the LED, the small range measuring unit 4 is connected to an input terminal of the LED interface 2 and outputs a small detection signal of the LED lamp based on the sampling current of the LED, and the small range measuring unit stops outputting based on a CPU switching instruction signal.
Because the LED lamp needs to be driven by lower voltage, the requirement on the brightness of an LED light source is met, and based on the volt-ampere characteristic of the LED, constructors need to drive the LED lamp in a constant current mode, therefore, a voltage drop driving unit 11 is adopted to obtain a current regulation signal from a CPU and provide lower voltage and constant current for the LED lamp based on the current regulation signal, and for measuring the constant current working condition of an LED loop, two sampling units are arranged at the input end of an LED interface 2 to respectively sample larger current and smaller current of the LED lamp, therefore, the smaller LED current can be measured by using larger amplification factor to improve the measurement precision of the detection current, and the smaller amplification factor can be used for the larger current to prevent the measurement circuit from being forced to reduce the measuring range under the influence of the low working voltage of the CPU while improving the measurement precision, so that the measuring range does not meet the requirement of the measurement work.
In the actual use process, when the LED current is a small current, the current can be amplified by a large multiple, a user can detect the current through the small-range measuring unit 4, when the CPU detects that the LED current is large, namely, the detection current signal output to the CPU is about to cause the CPU voltage to exceed the working voltage range of the CPU, the small-range unit can receive the switching instruction signal of the CPU and simultaneously stops outputting the detection current signal to the CPU to protect the CPU, and when the CPU detects that the LED current is large, the large-range measuring unit 3 still works and outputs the detection current signal to the CPU, and because the amplification multiple of the large-range measuring unit 3 is small, the detection current signal output by the large-range measuring unit 3 cannot cause the voltage of the CPU to exceed the working voltage.
In different embodiments, the wide-range measuring unit 3 may be composed of different elements, but it is sufficient to ensure that the output detection current signal does not cause the CPU voltage to exceed the operating voltage range of the CPU when the LED current is large on the premise of meeting the sampling requirement, and the present application specifically, but not by way of limitation, proposes a solution, where the wide-range measuring unit 3 includes a first measuring resistor R1 and a first amplifying element, the first measuring resistor R1 is connected to the input end of the LED interface 2 and is used for obtaining the sampling current of the LED lamp, and the first amplifying element is connected to both ends of the first measuring resistor R1 and is used for amplifying the voltage signal of the LED lamp obtained by the first measuring resistor R1 to a first amplification factor and outputting the amplified voltage signal to the CPU for measurement.
Because the first measuring resistor R1 is connected with the LED lamp connected with the LED interface 2 in series, the current on the LED lamp is equal to the current of the first measuring resistor R1, the first amplifying element is connected to the two ends of the first measuring resistor R1, the voltage of the two ends of the first amplifying element is equal to the voltage of the two ends of the first measuring resistor R1, the voltage of the two ends of the first sampling resistor is amplified by the first amplifying element and then is output to the CPU for measurement, and a user can control the measurement precision and the magnitude of an output voltage signal by controlling the amplification factor of the first amplifying element.
In view of the above, in different embodiments, the first amplifying element may be composed of different elements, but any element that can amplify the sampling signal obtained by the first measuring resistor R1 to a desired multiple may be used, and the present application specifically but not by way of limitation proposes an element as an example, where the first amplifying element is a first operational amplifier OA1, a non-inverting input terminal and an inverting input terminal of the first operational amplifier OA1 are respectively connected to two ends of the first measuring resistor R1, and an output terminal of the first operational amplifier OA1 outputs an amplified voltage signal to the outside.
Correspondingly, in different embodiments, the wide-range measuring unit 3 may be composed of different elements, but it is sufficient to ensure that the output detection current signal does not cause the CPU voltage to exceed the operating voltage range of the CPU when the LED current is large on the premise of meeting the sampling requirement, and the present application specifically but not limitingly proposes a solution, where the narrow-range measuring unit 4 includes a second measuring resistor R2, a second amplifying element and a switch S1, the second measuring resistor R2 is connected to the input end of the LED interface 2 for obtaining the sampling current of the LED lamp, the second amplifying element is connected to both ends of the second measuring resistor R2 for amplifying the voltage signal of the LED lamp obtained by the second measuring resistor R2 to the second amplification factor and outputting the amplified voltage signal to the CPU for measurement, and the switch S1 is connected to both ends of the second measuring resistor R2 and is switched on and off based on the CPU switching instruction signal.
Since the second measuring resistor R2 is connected in series with the LED lamp connected to the LED interface 2, the current of the LED lamp is equal to the current of the second measuring resistor R2, and the second amplifying element is connected to both ends of the second measuring resistor R2, the voltage across the second amplifying element is equal to the voltage across the second measuring resistor R2, and the voltage across the second sampling resistor R is amplified by the second amplifying element and then outputted to the CPU for measurement, so that the user can control the measurement accuracy and the magnitude of the output voltage signal by controlling the amplification factor of the second amplifying element, and when the CPU detects that the LED current is large, that is, the voltage outputted to the CPU is about to exceed the operating voltage range of the CPU, the switch S1 can be closed based on the received high-level switching command signal of the CPU, and since the switch S1 is connected to both ends of the second detecting resistor, when the switch S1 is closed, the second detecting resistor is short-circuited, and thereby the output of the detection current signal to the CPU can be stopped to protect the CPU.
In view of the above, in different embodiments, the second amplifying element may be composed of different elements, but any element that can amplify the sampling signal obtained by the second measuring resistor R2 to a desired multiple may be used, and the present application specifically but not by way of limitation proposes an element as an example, the second amplifying element is a second operational amplifier OA2, a non-inverting input terminal and an inverting input terminal of the second operational amplifier OA2 are respectively connected to two ends of the second measuring resistor R2, and an output terminal of the second operational amplifier OA2 outputs an amplified voltage signal to the outside.
In view of the above, in different embodiments, the switch S1 may be composed of different elements, but it is only necessary to block the output of the small-scale measurement unit 4 based on the CPU switching command signal, and the present application provides an example specifically but not by way of limitation, where the switch S1 is an NMOS switch tube QS, a gate of the NMOS switch tube QS is used for obtaining the CPU switching command signal, a source of the NMOS switch tube QS is connected to the ground, and a drain of the NMOS switch tube QS is connected to one end of the second measurement resistor R2 close to the input end of the LED interface 2.
The gate of the NMOS switch tube QS is used for receiving the CPU switch instruction signal, so that the CPU switch instruction signal can play a role in controlling the gate-source voltage of the NMOS switch tube QS, thereby controlling the on/off of the switch tube, when the gate of the NMOS switch tube QS receives the CPU switch instruction signal with a high level, the second measurement resistor R2 is short-circuited by the NMOS switch tube QS, the small-range measurement unit 4 stops outputting the voltage to the CPU, and when the gate of the NMOS switch tube QS receives the CPU switch instruction signal with a low level, the small-range measurement unit 4 is turned off, and the small-range measurement unit 4 can restart outputting the voltage to the CPU.
Specifically, in different embodiments, the voltage drop driving module 1 may have different components, but any driving module can provide low-voltage constant current for the LED, and the present application provides a scheme specifically but not limited thereto,
the voltage drop driving module 1 comprises a voltage drop driving unit 11, a first diode Z1, an energy storage inductor L1 and an energy storage capacitor C1, wherein the voltage drop driving unit 11 is connected between a power supply and a ground wire and is used for outputting a voltage signal which changes periodically, the anode of the first diode Z1 is connected to the output end of the voltage drop driving unit 11, the energy storage inductor L1 is connected between the output end of the first diode Z1 and the input end of the LED interface 2, and the energy storage capacitor C1 is connected between the input end of the LED interface 2 and the ground wire.
The high-low level condition of the voltage signal output by the voltage drop driving unit 11 changes periodically, when the voltage signal output by the voltage drop driving unit 11 is high level, a loop formed by the first diode Z1, the energy storage inductor L1 and the energy storage capacitor C1 charges and outputs the driving voltage subjected to voltage drop processing to the LED, when the voltage signal output by the voltage drop driving unit 11 is low level, the loop formed by the first diode Z1, the energy storage inductor L1 and the energy storage capacitor C1 discharges and outputs the driving voltage subjected to voltage drop processing to the LED, the energy storage inductor L1 and the energy storage capacitor C1 can ensure the stability of the driving voltage output by the voltage drop driving module 1 to the LED lamp, and meanwhile, the first diode Z1 can keep the current direction unchanged all the time, so that the driving provided by the voltage drop driving module 1 to the LED is low-voltage constant-current driving, and the normal working requirement of the LED can be met.
With respect to the above solution, in different embodiments, the voltage drop driving unit 11 may be composed of different elements, but any voltage signal capable of generating a periodic variation may be used, and the present application specifically but not limited to provide a solution, where the voltage drop driving unit 11 includes a high voltage gate driver LM5106, a first NMOS transistor Q1, and a second NMOS transistor Q2.
The high voltage gate driver LM5106 is connected between a power supply and a ground, the input terminal is used for inputting a PWM signal, the output terminal is used as the output terminal of the voltage drop driving unit 11, the gate of the first NMOS transistor Q1 is connected to the HO pin of the high voltage gate driver LM5106, the source is connected to the output terminal of the high voltage gate driver and is connected to the anode of the first diode Z1, the drain is connected to the power supply, the gate of the second NMOS transistor Q2 is connected to the LO pin of the high voltage gate driver LM5106, the drain is connected to the output terminal of the high voltage gate driver and is connected to the anode of the first diode Z1, and the source is connected to the ground.
LM5106 is a high voltage gate driver for driving high side and low side N-channel MOSFETs in a synchronous buck or half-bridge configuration. The floating high side driver can operate at rail voltages up to 100V. A single control input is compatible with TTL signal levels and a single external resistor programs the switching transition dead time through a closely matched on-delay circuit. Robust level shifting techniques consume low power while operating at high speeds and provide clean output transitions. Through the above connection manner, the second NMOS transistor Q2 is periodically turned on and off, so that the voltage drop driving unit 11 can output a periodically varying voltage signal. Specifically, pins VDD, EN, and HB of the LM5106 are all connected to a power supply, a pin IN is used for inputting a PWM signal, a pin VSS is connected to a ground, a pin HO is connected to a first NMOS transistor, and a CPU adjusts a PWM pulse width after sampling, thereby controlling a current supplied to the LED lamp by the voltage drop driving unit.
The above embodiments are preferred embodiments of the present application, and the protection scope of the present application is not limited by the above embodiments, so: all equivalent changes made according to the structure, shape and principle of the present application shall be covered by the protection scope of the present application.
Claims (8)
1. An LED current sensing circuit, comprising:
the voltage drop driving module (1) acquires a current regulation signal from the CPU and provides a low-voltage constant-current driving signal for the LED lamp based on the current regulation signal;
the input end of the LED interface (2) is connected to the voltage drop driving module (1), and the output end of the LED interface is used for connecting an LED lamp;
the wide-range measuring unit (3) is connected to the input end of the LED interface (2) and is used for acquiring the sampling current of the LED and outputting a larger detection signal of the LED lamp based on the sampling current of the LED;
and the small-range measuring unit (4) is connected with the input end of the LED interface (2) and is used for acquiring the sampling current of the LED and outputting a small detection signal of the LED lamp based on the sampling current of the LED, and the small-range measuring unit (4) stops outputting based on the CPU switching instruction signal.
2. LED current detection circuit according to claim 1, characterized in that the wide-range measurement unit (3) comprises:
the first measuring resistor R1 is connected to the input end of the LED interface (2) and is used for acquiring the sampling current of the LED lamp;
and the first amplifying element is connected to two ends of the first measuring resistor R1 and is used for amplifying the voltage signal of the LED lamp acquired by the first measuring resistor R1 to a first amplification factor and outputting the amplified voltage signal to a CPU (Central processing Unit) for measurement.
3. The LED current detection circuit according to claim 2, wherein the first amplifying element is a first operational amplifier OA1, a non-inverting input terminal and an inverting input terminal of the first operational amplifier OA1 are respectively connected to two terminals of the first measuring resistor R1, and an output terminal of the first operational amplifier OA1 outputs the amplified voltage signal to the outside.
4. The LED current detection circuit according to claim 1, wherein the small-scale measurement unit (4) comprises:
the second measuring resistor R2 is connected to the input end of the LED interface (2) and is used for acquiring the sampling current of the LED lamp;
the second amplifying element is connected to two ends of the second measuring resistor R2 and used for amplifying the voltage signal of the LED lamp acquired by the second measuring resistor R2 to a second amplification factor and outputting the amplified voltage signal to the CPU for measurement;
and the change-over switch S1 is connected to two ends of the second measuring resistor R2 and is switched on and off based on the CPU switching instruction signal.
5. The LED current detection circuit according to claim 4, wherein the second amplifying element is a second operational amplifier OA2, a non-inverting input terminal and an inverting input terminal of the second operational amplifier OA2 are respectively connected to two terminals of the second measuring resistor R2, and an output terminal of the second operational amplifier OA2 outputs the amplified voltage signal to the outside.
6. The LED current detection circuit according to claim 4, wherein the switch S1 is an NMOS switch tube QS, a gate of the NMOS switch tube QS is used for obtaining a CPU switching instruction signal, a source of the NMOS switch tube QS is connected to a ground, and a drain of the NMOS switch tube QS is connected to one end of the second measurement resistor R2 close to the input end of the LED interface (2).
7. LED current detection circuit according to claim 1, characterized in that said drop driver module (1) comprises:
the voltage drop driving unit (11) is connected between a power supply and a ground wire and is used for outputting a voltage signal which changes periodically;
a first diode Z1, the anode of which is connected with the output end of the voltage drop driving unit (11);
the energy storage inductor L1 is connected between the output end of the first diode Z1 and the input end of the LED interface (2);
and the energy storage capacitor C1 is connected between the input end of the LED interface (2) and the ground wire.
8. The LED current detection circuit according to claim 7, wherein the voltage drop driving unit (11) comprises:
the high-voltage gate driver LM5106 is connected between a power supply and a ground wire, the input end of the high-voltage gate driver is used for inputting a PWM signal, and the output end of the high-voltage gate driver is used as the output end of the voltage drop driving unit (11);
a first NMOS transistor Q1, the grid electrode of which is connected with the HO pin of the high-voltage grid driver LM5106, the source electrode of which is connected with the output end of the high-voltage grid driver and is connected with the anode of the first diode Z1, and the drain electrode of which is connected with a power supply;
and a second NMOS transistor Q2, the gate of which is connected to the LO pin of the high-voltage gate driver LM5106, the drain of which is connected to the output end of the high-voltage gate driver, and is connected to the positive electrode of the first diode Z1, and the source of which is connected to the ground wire.
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| CN202222327928.3U CN218213171U (en) | 2022-08-31 | 2022-08-31 | LED current detection circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202222327928.3U CN218213171U (en) | 2022-08-31 | 2022-08-31 | LED current detection circuit |
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