CN102141583A - LED current detection circuit - Google Patents
LED current detection circuit Download PDFInfo
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- CN102141583A CN102141583A CN2010106131588A CN201010613158A CN102141583A CN 102141583 A CN102141583 A CN 102141583A CN 2010106131588 A CN2010106131588 A CN 2010106131588A CN 201010613158 A CN201010613158 A CN 201010613158A CN 102141583 A CN102141583 A CN 102141583A
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Abstract
The embodiment of the invention provides an LED current detection circuit which comprises a transformer, a current transformer, a resistance and a detection module, wherein the primary side of the transformer is connected with an input current, the secondary side of the transformer is connected in series with the primary side of the current transformer, the primary side of the current transformer outputs the current and drives an LED, the secondary side of the current transformer is connected in series with the resistance, the detection module is used for acquiring a circuit parameter value of the resistance, and the circuit parameter value of the resistance expresses the current size of the resistance. With the adoption of the LED current detection circuit, the size of the input current of the LED can be accurately acquired, and a circuit structure is simple.
Description
Technical field
The present invention relates to the led driver technical field, particularly the LED current detection circuit in led driver.
Background technology
Light emitting diode (LED) is used as the light source of LCD (LCD) equipment, also as the light source of digital micro-mirror device (DMD) display device, handles the light source of (DLP) projection TV, projector etc. such as the digital light that adopts digital micro-mirror device (DMD).
Several schemes of utilizing isolated led driver that electric current is provided for LED have been proposed at present, the detection of isolated led driver output current (being the input current of LED) and control circuit roughly can be divided into two big classes: a class is the mode by light lotus root feedback, and the problem of existence is the circuit complexity; Another kind of for detecting the electric current on the former limit of transformer in the led driver, adopt the indirect mode of calculating to extrapolate the electric current that led driver flows to LED, the problem of existence is that current detection accuracy is not high.
Summary of the invention
The invention provides a kind of LED current detection circuit, can obtain the input current size of LED accurately, and circuit structure is simple.
In view of this, the embodiment of the invention provides:
A kind of LED current detection circuit comprises: transformer, current transformer, resistance and detection module, wherein,
The connect former limit of described current transformer of former edge joint one input current of described transformer, the secondary of described transformer; The former limit output current of described current transformer is used for driving LED; The secondary of described current transformer is connected with resistance;
Described detection module is used to obtain the circuit parameter value of described resistance, the size of current of the described resistance of circuit parameter value representation of described resistance.
The LED current detection circuit that the embodiment of the invention provides is by being used to LED that the transformer secondary series current mutual inductor of input current is provided, secondary resistance in series at current transformer, and obtain this resistance the circuit parameter value (such as, the electric current of this resistance or voltage), can extrapolate the input current size of LED in this way accurately, and circuit structure is simple.
Description of drawings
In order to be illustrated more clearly in the technical scheme of the embodiment of the invention, to do to introduce simply to the accompanying drawing of required use among the embodiment below, apparently, accompanying drawing in describing below only is some embodiments of the present invention, for those of ordinary skills, under the prerequisite of not paying creative work, can also obtain other accompanying drawing according to these accompanying drawings.
Fig. 1 is the circuit diagram of a kind of LED current detection circuit of providing of the embodiment of the invention;
Fig. 2 is the circuit diagram of the another kind of LED current detection circuit that provides of the embodiment of the invention.
Embodiment
Consult Fig. 1, the embodiment of the invention provides a kind of LED current detection circuit, and it comprises: transformer T, current transformer CT, resistance R and detection module 10, wherein,
Former edge joint one input current of transformer T, the former limit of the secondary series current mutual inductor CT of transformer T; The former limit output current of current transformer CT is used for driving LED; The secondary of current transformer CT is connected with resistance;
Wherein, among Fig. 1 the output 1 of the secondary of transformer T and export 2 between meet LED.
Concrete, the secondary of current transformer CT can be connected and is used for the alternating current of current transformer secondary output is converted to the commutation diode D and the resistance R of pulse direct current electric current, wherein, the circuit parameter value of the resistance R that detection module 10 obtains is the voltage of resistance R, and the voltage of this resistance R is the product of the resistance of described pulse direct current electric current and described resistance R.Wherein, the secondary series connection commutation diode D of current transformer CT and the concrete mode of resistance R can be as shown in Figure 1, the end of the secondary one terminating resistor R of current transformer CT, the other end ground connection of resistance R, the positive pole of another termination commutation diode of the secondary of current transformer CT D, the minus earth of commutation diode D.Perhaps, the secondary series connection commutation diode D of current transformer CT and the concrete mode of resistance R are as shown in Figure 2, one end of the secondary of current transformer CT connect in proper order commutation diode D and resistance R, concrete, the positive pole of one termination commutation diode D of the secondary of current transformer CT, the negative pole connecting resistance R of commutation diode D, the negative pole of a termination commutation diode D of resistance R, the other end ground connection of resistance R.
Wherein, current transformer CT can be no air gap current transformer, if the coefficient of mutual inductance of this no air gap current transformer is 1: 100, the output current of supposing the transformer secondary is I, the input current that is LED is I, and this moment, mutual inductor secondary output current was I/100, and then the voltage of resistance R is
The embodiment of the invention just can obtain the input current of LED according to the coefficient of mutual inductance of current transformer after obtaining the electric current of resistance R, therefore, can obtain the input current size of LED accurately.
So far, realized accurate detection to the LED input current, further, in order to realize control to the LED input current, this detection module 10 also is used for according to the absolute value of voltage of resistance R and the comparative result of threshold value, the variation of the input current on the former limit of control input transformer T.Concrete, after this detection module 10 obtains the voltage of resistance R, the voltage of more described resistance R and threshold value, according to comparative result, the variation of the input current on the former limit of the control described transformer T of input.If the voltage of resistance R is greater than threshold value, the input current that then can control the former limit of this transformer T diminishes, and becomes big if the voltage of resistance R, then can be controlled the input current on the former limit of this transformer T less than threshold value.
Optionally, this LED current detection circuit also comprises: filter capacitor C, this filter capacitor C is in parallel with resistance R, the termination detection module 10 of this filter capacitor C, the other end ground connection of filter capacitor C, the voltage on this filter capacitor C equates with the voltage on the resistance R, this moment, detection module 10 specifically was used for the voltage on the detection filter capacitor C, voltage and threshold value on the more described filter capacitor C, according to comparative result, the variation of the input current on the former limit of control input transformer T.
Wherein, the LED current detection circuit that provides of the embodiment of the invention is arranged in isolated led driver.
The embodiment of the invention can accurately detect the input current of LED, and can be according to the voltage of resistance R and the comparative result of threshold value, the size of the input current on the former limit of control transformer, linear current conversion through transformer, thereby the size of control transformer secondary output current, and then controlled the input current size of LED, make the input voltage and the output voltage of this LED current detection circuit when wide fluctuations, also can make transformer secondary output current remain on the state of high stable, and then guarantee that the input current of LED remains on the state of high stable.
More than the LED current detection circuit that the embodiment of the invention provided is described in detail, used specific case herein principle of the present invention and embodiment are set forth, the explanation of above embodiment just is used for helping to understand method of the present invention and core concept thereof; Simultaneously, for one of ordinary skill in the art, according to thought of the present invention, the part that all can change in specific embodiments and applications, in sum, this description should not be construed as limitation of the present invention.
Claims (6)
1. a LED current detection circuit is characterized in that, comprising: transformer, current transformer, resistance and detection module, wherein,
The connect former limit of described current transformer of former edge joint one input current of described transformer, the secondary of described transformer; The former limit output current of described current transformer is used for driving LED; The secondary of described current transformer is connected with resistance;
Described detection module is used to obtain the circuit parameter value of described resistance, the size of current of the described resistance of circuit parameter value representation of described resistance.
2. circuit according to claim 1 is characterized in that,
The circuit parameter value of described resistance is the voltage of described resistance;
Described detection module also is used for according to the absolute value of voltage of described resistance and the comparative result of threshold value, the variation of the input current on the former limit of the control described transformer of input.
3. circuit according to claim 2 is characterized in that,
The secondary series connection of described current transformer is used for the alternating current of current transformer secondary output is converted to the commutation diode and the described resistance of pulse direct current electric current;
Wherein, the voltage of described resistance is the product of the resistance of described pulse direct current electric current and described resistance;
Described detection module is used to obtain the voltage of described resistance, the voltage of more described resistance and threshold value, and according to comparative result, the size of the input current on the former limit of the control described transformer of input.
4. circuit according to claim 3 is characterized in that, described circuit also comprises: the filter capacitor in parallel with described resistance;
The described detection module of one termination of described filter capacitor, the other end ground connection of described filter capacitor;
Described detection module is used for the voltage on the detection filter electric capacity, voltage on the more described filter capacitor and threshold value, according to comparative result, the size of the input current on the former limit of the control described transformer of input, wherein, the voltage on the described filter capacitor equates with described ohmically voltage.
5. circuit according to claim 1 is characterized in that,
Described current transformer is no air gap linear current mutual inductor.
6. circuit according to claim 1 is characterized in that,
Described LED current detection circuit is used for isolated led driver.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010106131588A CN102141583A (en) | 2010-12-29 | 2010-12-29 | LED current detection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010106131588A CN102141583A (en) | 2010-12-29 | 2010-12-29 | LED current detection circuit |
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| CN102141583A true CN102141583A (en) | 2011-08-03 |
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| CN2010106131588A Pending CN102141583A (en) | 2010-12-29 | 2010-12-29 | LED current detection circuit |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102426288A (en) * | 2011-10-25 | 2012-04-25 | 深圳麦格米特电气股份有限公司 | Inverter tube current sampling circuit |
| CN102735987A (en) * | 2012-07-13 | 2012-10-17 | 北京经纬恒润科技有限公司 | LED (light emitting diode) detection circuit |
| CN103941434A (en) * | 2013-11-15 | 2014-07-23 | 上海中航光电子有限公司 | Backlight source module and static electricity damage detecting method thereof |
| CN106872067A (en) * | 2017-02-21 | 2017-06-20 | 焦海军 | A kind of temperature isolation Acquisition Circuit |
| CN108008200A (en) * | 2016-11-28 | 2018-05-08 | 芜湖美的厨卫电器制造有限公司 | Water resistance detection device and watering equipment |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102426288A (en) * | 2011-10-25 | 2012-04-25 | 深圳麦格米特电气股份有限公司 | Inverter tube current sampling circuit |
| CN102735987A (en) * | 2012-07-13 | 2012-10-17 | 北京经纬恒润科技有限公司 | LED (light emitting diode) detection circuit |
| CN103941434A (en) * | 2013-11-15 | 2014-07-23 | 上海中航光电子有限公司 | Backlight source module and static electricity damage detecting method thereof |
| CN108008200A (en) * | 2016-11-28 | 2018-05-08 | 芜湖美的厨卫电器制造有限公司 | Water resistance detection device and watering equipment |
| CN106872067A (en) * | 2017-02-21 | 2017-06-20 | 焦海军 | A kind of temperature isolation Acquisition Circuit |
| CN106872067B (en) * | 2017-02-21 | 2023-10-17 | 焦海军 | Temperature isolation acquisition circuit |
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Application publication date: 20110803 |