External high-precision direct current dimming circuit

Abstract

The utility model provides an external high-precision direct-current dimming circuit, which comprises a signal generator, a switching circuit and an IC (integrated circuit), the signal generator provides a direct current dimming signal, and the direct current dimming signal is transmitted to the switching circuit; reference voltage is provided in the IC and is transmitted to the switching circuit; when the direct-current dimming signal is at a high level, the reference voltage outputs a high level to the IC after passing through the switching circuit; and when the direct current dimming signal is at a low level, the reference voltage outputs a low level to the IC after passing through the switching circuit. According to the technical scheme, the stable reference voltage is introduced into the circuit, and the direct current dimming signal can be used as a trigger condition of the switching circuit, so that the signal input to the IC realizes synchronization of the switching frequency and the dimming frequency of the direct current dimming signal, the influence of line loss and ground line voltage floating is avoided, the direct current dimming precision is improved, and the dimming effect is improved. And the requirement of + / -5% dimming current change can be met.

Description

TECHNICAL FIELD

[0001] The utility model relates to circuit technical field especially relates to a kind of external high-precision direct current dimming circuit. BACKGROUND

[0002] In prior art, when using direct current dimming signal, dimming current is not linear, dimming current deviation is very large, cannot satisfy + / -10% specification requirement, the reason is as follows:

[0003] Reference Figure 1 It is the circuit diagram of ordinary direct current dimming circuit in prior art, wherein, direct current dimming signal provided by signal generator is sent by ADIM-3 pin, is transmitted to IC dimming foot ADIM-4 after circuit voltage division filtering;Due to the loss of signal line and ground voltage float high, IC dimming foot ADIM-4 dimming signal voltage value is easily caused to rise, causes the nonlinearity of direct current dimming current, dimming current deviation is very large, exceeds + / -10% specification requirement. UTILITY MODEL CONTENTS

[0004] Therefore, the utility model provides a kind of external high-precision direct current dimming circuit.

[0005] The utility model provides a kind of external high-precision direct current dimming circuit, comprising:

[0006] Signal generator, switching circuit and IC;

[0007] The signal generator provides direct current dimming signal, and the direct current dimming signal is transmitted to the switching circuit;

[0008] The IC internally provides reference voltage, and the reference voltage is transmitted to the switching circuit;

[0009] When the direct current dimming signal is high level, the reference voltage is output high level to the IC after the switching circuit;

[0010] When the direct current dimming signal is low level, the reference voltage is output low level to the IC after the switching circuit.

[0011] As a preferred embodiment of the utility model, the switching circuit includes first voltage division circuit, first triode Q306, second voltage division circuit and second triode Q307;

[0012] The direct current dimming signal is transmitted to the first voltage division circuit after the ADIM-1 pin of the signal generator;

[0013] The reference voltage is transmitted to the second voltage division circuit after the VREF pin of the IC;

[0014] When the direct current dimming signal is high, the direct current dimming signal is divided by the first voltage dividing circuit, so that the first triode Q306 is turned on and the second triode Q307 is turned off, and the reference voltage is divided by the second voltage dividing circuit and then outputs a high level to the ADIM-2 pin of the IC.

[0015] When the direct current dimming signal is low, the direct current dimming signal is divided by the first voltage dividing circuit, so that the first triode Q306 is turned off and the second triode Q307 is turned on, and the reference voltage is divided by the second voltage dividing circuit and then directly grounded through the second triode Q307, and outputs a low level to the ADIM-2 pin of the IC.

[0016] As a preferred embodiment of the utility model, the direct current dimming signal is a PWM square wave signal with a dimming frequency of 20KHZ and a voltage range of 0V-3.3V.

[0017] As a preferred embodiment of the utility model, the first voltage dividing circuit comprises a jumper JP19, a resistor R348 and a resistor R383 connected in series.

[0018] The direct current dimming signal is input at the end of the jumper JP19.

[0019] As a preferred embodiment of the utility model, one end of the resistor R383 is connected to the resistor R348 and the B electrode of the first triode Q306.

[0020] The other end of the resistor R383 is connected to the E electrode of the first triode Q306 and grounded.

[0021] As a preferred embodiment of the utility model, the second voltage dividing circuit comprises a jumper J3, a resistor R387, a resistor R384, a resistor R385, a resistor R386 and a resistor R341.

[0022] One end of the jumper J3 is connected to the VREF pin, and the other end of the jumper J3 is connected to one end of the resistor R387, one end of the resistor R384 and one end of the resistor R385.

[0023] The other end of the resistor R387 is connected to the B electrode of the first triode Q306.

[0024] The other end of the resistor R384 is connected to the C electrode of the first triode Q306 and the B electrode of the second triode Q307.

[0025] The other end of the resistor R385 is connected to one end of the resistor R386 and the C electrode of the second triode Q307.

[0026] Another end of the resistor R386 is connected to one end of the resistor R341.

[0027] Another end of the resistor R341 is grounded.

[0028] As a preferred embodiment of the utility model, the E pole of the second triode Q307 is grounded.

[0029] As a preferred embodiment of the utility model, the filter circuit is further included.

[0030] The filter circuit is used for filtering the square wave signal transmitted to the ADIM-2 pin.

[0031] As a preferred embodiment of the utility model, the filter circuit includes a capacitor C329.

[0032] One end of the capacitor C329 is connected to the ADIM-2 pin, and the other end of the capacitor C329 is grounded.

[0033] As a preferred embodiment of the utility model, the filter circuit includes a capacitor C315.

[0034] One end of the capacitor C315 is connected to the ADIM-2 pin, and the other end of the capacitor C315 is grounded.

[0035] Compared with the prior art, the utility model has the beneficial effects as follows:

[0036] The utility model discloses the setting of the above-mentioned technical scheme, introduces the stable reference voltage in the circuit, can adopt 6V reference voltage in the utility model, and the direct current dimming signal is the square wave signal of fluctuation, for example, the PWM square wave signal of the dimming frequency being 20KHZ, voltage range being 0V-3.3V. When the direct current dimming signal is high level (3.3V), the reference voltage is outputted high level to the IC after the switch circuit, and when the direct current dimming signal is low level (0V), the reference voltage is outputted low level to the IC after the switch circuit.

[0037] Specifically, in the embodiment of the utility model, when the direct current dimming signal is high level (3.3V), the direct current dimming signal passes through the first voltage dividing circuit voltage division and makes the first triode Q306 conduct, the second triode Q307 cut off, the reference voltage passes through the second voltage dividing circuit voltage division and outputs high level (3.3V) to the ADIM-2 pin of IC;When the direct current dimming signal is low level (0V), the direct current dimming signal passes through the first voltage dividing circuit voltage division and makes the first triode Q306 cut off, the second triode Q307 conduct, the reference voltage passes through the second voltage dividing circuit voltage division and directly ground through the second triode, and outputs low level (0V) to the ADIM-2 pin of IC.

[0038] In summary, the signal input to the ADIM-2 pin of IC in the embodiment of the utility model also realizes 0-3.3V switching, the switching frequency is the same as the dimming frequency of ADIM-1 pin, and the influence of line loss and ground voltage floating is avoided, thereby improving the precision of direct current dimming and meeting the + / -5% dimming current change requirement. BRIEF DESCRIPTION OF DRAWINGS

[0039] In order to more clearly illustrate the technical scheme in the embodiments of the utility model or the prior art, the drawings needed to be used in the embodiment or the prior art description will be briefly introduced below, and obviously, the drawings in the following description are only some embodiments of the utility model, and other drawings can be obtained according to the structure shown in the drawings without creative labor for those skilled in the art.

[0040] Figure 1 It is the circuit diagram of the direct current dimming circuit in the prior art;

[0041] Figure 2 It is the circuit module schematic diagram of the external high-precision direct current dimming circuit of the embodiment of the utility model;

[0042] Figure 3 It is the circuit diagram of the external high-precision direct current dimming circuit of the embodiment of the utility model. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical scheme and advantages of the embodiment of the utility model more clear, the technical scheme in the embodiment of the utility model will be clearly and completely described below in combination with the drawings in the embodiment of the utility model, obviously, the described embodiment is a part of the embodiment of the utility model, rather than all the embodiments, and all other embodiments obtained by those skilled in the art without creative labor based on the embodiment of the utility model belong to the protection scope of the utility model.

[0044] Embodiment:

[0045] As Figure 2 indicated, the utility model provides a kind of external high-precision direct current dimming circuit, comprising:

[0046] Signal generator 10, switching circuit 20 and IC 30;

[0047] The signal generator 10 provides direct current dimming signal, and the direct current dimming signal is transmitted to the switching circuit 20;

[0048] The IC 30 internally provides reference voltage, and the reference voltage is transmitted to the switching circuit 20;

[0049] When the direct current dimming signal is high level, the reference voltage is outputted high level to the IC after the switching circuit 20;

[0050] When the direct current dimming signal is low level, the reference voltage is outputted low level to the IC after the switching circuit 20.

[0051] The utility model embodiment is provided in the above-mentioned technical scheme, introduces stable reference voltage in circuit, such as the reference voltage of 6V in the utility model can be used, and direct current dimming signal is fluctuating square wave signal, such as, the PWM square wave signal of the dimming frequency of 20KHZ, voltage range is 0V-3.3V.When the direct current dimming signal is high level (3.3V), the reference voltage is outputted high level to the IC after the switching circuit;When the direct current dimming signal is low level (0V), the reference voltage is outputted low level to the IC after the switching circuit. So that the signal inputted to IC also realizes 0-3.3V switching along with the change of dimming signal, and switching frequency is same as the dimming frequency of direct current dimming signal, avoid the influence of line loss and ground wire voltage floating high, thereby improve the precision of direct current dimming, realize that can satisfy + / -5% dimming current change requirement.

[0052] As a preferred embodiment of the utility model, as Figure 3 indicated, the switching circuit includes first voltage divider circuit, first triode Q306, second voltage divider circuit and second triode Q307;

[0053] The direct current dimming signal is transmitted to the first voltage divider circuit after the ADIM-1 pin of the signal generator;

[0054] The reference voltage is transmitted to the second voltage divider circuit after the VREF pin of the IC;

[0055] When the direct current dimming signal is high, the direct current dimming signal is divided by the first voltage dividing circuit, so that the first triode Q306 is turned on and the second triode Q307 is turned off, and the reference voltage is divided by the second voltage dividing circuit and outputted as high level (3.3V) to the ADIM-2 pin of the IC.

[0056] When the direct current dimming signal is low, the direct current dimming signal is divided by the first voltage dividing circuit, so that the first triode Q306 is turned off and the second triode Q307 is turned on, and the reference voltage is divided by the second voltage dividing circuit and directly grounded through the second triode Q307, and outputted as low level (0V) to the ADIM-2 pin of the IC.

[0057] Specifically, in the embodiment of the utility model, when the direct current dimming signal is high (3.3V), the direct current dimming signal is divided by the first voltage dividing circuit, so that the first triode Q306 is turned on and the second triode Q307 is turned off, and the reference voltage is divided by the second voltage dividing circuit and outputted as high level (3.3V) to the ADIM-2 pin of the IC; when the direct current dimming signal is low (0V), the direct current dimming signal is divided by the first voltage dividing circuit, so that the first triode Q306 is turned off and the second triode Q307 is turned on, and the reference voltage is divided by the second voltage dividing circuit and directly grounded through the second triode, and outputted as low level (0V) to the ADIM-2 pin of the IC.

[0058] As a preferred embodiment of the utility model, the direct current dimming signal is a PWM square wave signal with a dimming frequency of 20KHZ and a voltage range of 0V-3.3V.

[0059] As a preferred embodiment of the utility model, as shown in the figure, Figure 3 The first voltage dividing circuit comprises a jumper JP19, a resistor R348 and a resistor R383 connected in series.

[0060] The direct current dimming signal is inputted at the jumper JP19 end.

[0061] As a preferred embodiment of the utility model, as shown in the figure, Figure 3 One end of the resistor R383 is connected with the resistor R348 and the B electrode of the first triode Q306 at the same time.

[0062] The other end of the resistor R383 is connected with the E electrode of the first triode Q306 and grounded at the same time.

[0063] Therefore, the direct current dimming signal is added to the B pole (base pole) of the first triode Q306 after being divided by the ADIM-1 pin, the jumper JP19 and the resistance R348, and the first triode Q306 is turned on when the direct current dimming signal is 3.3V, and the first triode Q306 is turned off when the direct current dimming signal is 0V.

[0064] As a preferred embodiment of the utility model, as shown in the figure, Figure 3 The second voltage dividing circuit includes a jumper J3, a resistance R387, a resistance R384, a resistance R385, a resistance R386 and a resistance R341.

[0065] One end of the jumper J3 is connected to the VREF pin, and the other end of the jumper J3 is connected to one end of the resistance R387, one end of the resistance R384 and one end of the resistance R385.

[0066] The other end of the resistance R387 is connected to the B pole of the first triode Q306.

[0067] The other end of the resistance R384 is connected to the C pole of the first triode Q306 and the B pole of the second triode Q307.

[0068] The other end of the resistance R385 is connected to one end of the resistance R386 and the C pole of the second triode Q307.

[0069] The other end of the resistance R386 is connected to one end of the resistance R341.

[0070] The other end of the resistance R341 is grounded.

[0071] As a preferred embodiment of the utility model, the E pole of the second triode Q307 is grounded.

[0072] Therefore, when the direct current dimming signal is 3.3V, the first triode Q306 is turned on after voltage division, the B electrode voltage of the second triode Q307 is pulled down to the ground, the second triode Q307 is cut off, and the voltage of the reference voltage provided from the VREF pin (preferably 6V in the utility model) after voltage division and transmitted to the ADIM-2 pin is 3.3V; when the direct current dimming signal is 0V, the first triode Q306 is cut off, the voltage of the reference voltage provided from the VREF pin after voltage division and reaching the B electrode of the second triode Q307 is high level, so that the second triode Q307 is turned on, and the reference voltage is pulled down to the ground through the resistor R385 and the C electrode of the second triode Q307, therefore, the C electrode voltage of the second triode Q307 will be 0V, and the voltage transmitted to the ADIM-2 pin is also 0V. In summary, the circuit provided in the utility model realizes accurate switching of 0-3.3V, avoids the influence of line loss and ground voltage floating, thereby improving the precision of direct current dimming, and realizing that the + / -5% dimming current change requirement can be met.

[0073] As a preferred embodiment of the utility model, the filter circuit is further included;

[0074] The filter circuit is used for filtering the square wave signal transmitted to the ADIM-2 pin.

[0075] As a preferred embodiment of the utility model, as shown in Figure 3 The filter circuit includes a capacitor C329.

[0076] One end of the capacitor C329 is connected with the ADIM-2 pin, and the other end of the capacitor C329 is grounded.

[0077] As a preferred embodiment of the utility model, as shown in Figure 3 The filter circuit includes a capacitor C315.

[0078] One end of the capacitor C315 is connected with the ADIM-2 pin, and the other end of the capacitor C315 is grounded.

[0079] The setting of the filter circuit makes the square wave signal transmitted to the ADIM-2 pin smoother.

[0080] The working principle of the high-precision direct current dimming circuit in the utility model embodiment is as follows:

[0081] Reference Figure 3The direct current dimming signal is added to the B pole (base pole) of the first triode Q306 after being divided by the ADIM-1 pin, the jumper JP19 and the resistance R348. The direct current dimming signal in the utility model is a PWM square wave signal with a dimming frequency of 20 KHZ and a voltage range of 0V-3.3V, and the reference voltage provided by the VREF pin is 6V.

[0082] When the direct current dimming signal is 3.3V, the first triode Q306 is turned on after being divided, the B pole voltage of the second triode Q307 is pulled down to the ground, the second triode Q307 is cut off, and the voltage of the ADIM-2 pin after being divided from the reference voltage provided by the VREF pin (preferably 6V in the utility model) is 3.3V.

[0083] When the direct current dimming signal is 0V, the first triode Q306 is cut off, the voltage of the B pole of the second triode Q307 after being divided from the reference voltage provided by the VREF pin is a high level, the second triode Q307 is turned on, the reference voltage is pulled down to the ground through the resistance R385 and the C pole of the second triode Q307, therefore, the C pole voltage of the second triode Q307 is 0V, and the voltage of the ADIM-2 pin is also 0V. In summary, the circuit provided in the utility model realizes accurate switching of 0-3.3V, avoids the influence of line loss and ground voltage floating, thereby improving the accuracy of direct current dimming and meeting the + / -5% dimming current change requirement.

[0084] The above is only a preferred embodiment of the utility model patent, but the protection scope of the utility model patent is not limited to this, any skilled person in the art can make equivalent replacement or change according to the technical scheme and the utility model concept of the utility model patent within the scope disclosed by the utility model patent, and it belongs to the protection scope of the utility model patent.

Claims

1. An external high-precision direct-current dimming circuit, characterized by comprising: Comprising: a signal generator, a switching circuit and an IC; the signal generator provides a direct current dimming signal, which is transmitted to the switching circuit; the IC internally provides a reference voltage, which is transmitted to the switching circuit; when the direct current dimming signal is high, the reference voltage is outputted to the IC as high level after passing through the switching circuit; when the direct current dimming signal is low, the reference voltage is outputted to the IC as low level after passing through the switching circuit.

2. The high-precision DC dimming circuit according to claim 1, characterized in that The switching circuit comprises a first voltage dividing circuit, a first transistor Q306, a second voltage dividing circuit and a second transistor Q307; the direct current dimming signal is transmitted to the first voltage dividing circuit through the ADIM-1 pin of the signal generator; the reference voltage is transmitted to the second voltage dividing circuit through the VREF pin of the IC; when the direct current dimming signal is high, the direct current dimming signal is divided by the first voltage dividing circuit, which makes the first transistor Q306 conductive and the second transistor Q307 non-conductive, and the reference voltage is divided by the second voltage dividing circuit and outputted to the ADIM-2 pin of the IC as high level; when the direct current dimming signal is low, the direct current dimming signal is divided by the first voltage dividing circuit, which makes the first transistor Q306 non-conductive and the second transistor Q307 conductive, and the reference voltage is divided by the second voltage dividing circuit and directly grounded through the second transistor Q307, which is outputted to the ADIM-2 pin of the IC as low level.

3. The high precision DC dimming circuit of claim 2, wherein, The direct current dimming signal is a PWM square wave signal with a dimming frequency of 20KHZ and a voltage range of 0V-3.3V.

4. The high precision DC dimming circuit of claim 3, wherein, The first voltage dividing circuit comprises a jumper JP19, a resistor R348 and a resistor R383 connected in series; the direct current dimming signal is inputted at the jumper JP19.

5. The high-precision direct current dimming circuit according to claim 4, wherein one end of the resistor R383 is connected to the resistor R348 and the B electrode of the first transistor Q306; the other end of the resistor R383 is connected to the E electrode of the first transistor Q306 and grounded.

6. The high-precision DC dimming circuit of claim 5, wherein, The second voltage dividing circuit comprises a jumper J3, a resistor R387, a resistor R384, a resistor R385, a resistor R386 and a resistor R341; one end of the jumper J3 is connected to the VREF pin, and the other end of the jumper J3 is connected to one end of the resistor R387, one end of the resistor R384 and one end of the resistor R385; the other end of the resistor R387 is connected to the B electrode of the first transistor Q306; the other end of the resistor R384 is connected to the C electrode of the first transistor Q306 and the B electrode of the second transistor Q307; the other end of the resistor R385 is connected to one end of the resistor R386 and the C electrode of the second transistor Q307; the other end of the resistor R386 is connected to one end of the resistor R341; the other end of the resistor R341 is grounded.

7. The high-precision DC dimming circuit of claim 6, wherein, the E electrode of the second transistor Q307 is grounded.

8. The high precision DC dimming circuit of claim 7, wherein, Further comprising a filter circuit; The filter circuit is used for filtering the square wave signal transmitted to the ADIM-2 pin.

9. The high precision DC dimming circuit of claim 8, wherein, The filter circuit comprises a capacitor C329. One end of the capacitor C329 is connected to the ADIM-2 pin, and the other end of the capacitor C329 is grounded.

10. The high precision DC dimming circuit of claim 9, wherein, The filter circuit comprises a capacitor C315. One end of the capacitor C315 is connected to the ADIM-2 pin, and the other end of the capacitor C315 is grounded.

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