CN214125566U

CN214125566U - LED dimming circuit, LED driving system and electronic equipment

Info

Publication number: CN214125566U
Application number: CN202023287956.4U
Authority: CN
Inventors: 吴允栋; 张旭光; 胡金玺; 孙炜
Original assignee: BCD Shanghai Micro Electronics Ltd
Current assignee: BCD Shanghai Micro Electronics Ltd
Priority date: 2020-12-30
Filing date: 2020-12-30
Publication date: 2021-09-03
Anticipated expiration: 2030-12-30

Abstract

The utility model discloses a LED dimming circuit, LED actuating system and electronic equipment, come to carry out size judgement to the input voltage of adjusting luminance through first comparison module and second comparison module, and gate suitable signal output according to the judged result through the gating module, when the input voltage of adjusting luminance is less than first threshold voltage, can export the dimming signal of relative accuracy through the voltage division module, it is not accurate to avoid current LED dimming circuit to exist and the size is indefinite all the time and lead to flowing LED's electric current when input voltage Vref _ Dim is low partially because of its operational amplifier's maladjustment voltage Vos, LED lamp luminance can not reach the problem of the index requirement of the precision of adjusting luminance. The technical scheme of the utility model can improve LED precision of adjusting luminance, satisfy the demand that the high accuracy was adjusted luminance.

Description

LED dimming circuit, LED driving system and electronic equipment

Technical Field

The utility model relates to a LED drive technical field especially relates to a LED dimmer circuit, LED actuating system and electronic equipment.

Background

The LED lighting technology has been gradually popularized due to its low power consumption, long service life, high lighting effect, and the like, and becomes the mainstream lighting technology, and due to its characteristics of fast response speed and light emitting intensity in direct proportion to the driving current, the LED dimming technology has the basic application conditions.

Referring to fig. 1, a conventional LED dimming circuit includes: an input resistor R0, a zener diode Z, an operational amplifier OPA, an offset voltage source Vos, a switch tube Mo (P type), a resistor R1, a resistor R2 and an error amplifier EA, wherein, a dimming input voltage Vref _ Dim is input into the LED dimming circuit from one end of the resistor R0, the other end of the resistor R0 is grounded through the cathode and the anode of the zener diode Z in turn, the other end of the resistor R0 is also connected with the positive input end of the operational amplifier OPA, the output end of the operational amplifier OPA is connected with the grid of the switch tube M0, the switch tube M0, the resistor R1 and the resistor R2 are connected in series between the working voltage Vp and the ground in turn, the offset voltage source Vos has one end connected with the reverse input end of the operational amplifier OPA, the other end connected with the series node of the switch tube M0 and the resistor R1, the series node of the resistor R1 and the resistor R2 is connected with the positive input end of the error amplifier EA and inputs voltage to the error amplifier EA, the curve of the voltage Vp varying with the dimming input voltage Vref _ Dim is shown in fig. 2; the inverting input terminal of the error amplifier EA is connected to a feedback terminal FB, a feedback voltage Vfb connected to the feedback terminal FB is related to the dimming input voltage Vref _ Dim, the output terminal Out of the error amplifier EA transmits a dimming signal to the corresponding LED, and the LED is usually grounded by connecting an external resistor Rfb (not shown) in series, and the current flowing through the LED can be set by adjusting the resistance value of the external resistor Rfb. Namely: i _ Led is Vfb/Rfb, typically Vfb is 0 to 0.4V, Vfb is K Vref Dim, and Vref Dim is typically in the range of 0 to 5V.

When Vref _ Dim is greater than 2.5V, Vfb ═ Vp ═ 0.4V, and the error in Vfb voltage is:

when Vref _ Dim is in the range of 0-Vk (wherein Vk is less than 0.8V), Vfb is Vp, namely 0-0.4V; the error in the Vfb voltage is:

from the relationships Accuracy1_ Vfb and Accuracy2_ Vfb, Accuracy2_ Vfb determines the final error amount.

If Vk is 0.8V, assuming Vos is 8mV, the final error:

if Vk is 0.1V, assuming Vos is 8mV, the final error:

when the LED dimming circuit structure shown in fig. 1 is used to realize LED dimming, since the offset voltage Vos of the operational amplifier OPA is always present and has an indefinite magnitude, when the input voltage Vref _ Dim is low, the current flowing through the LED is inaccurate, and the brightness of the LED lamp cannot meet the index requirement of the dimming precision, which results in that the requirement of high-precision LED dimming cannot be met.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a LED dimmer circuit, use its LED actuating system and electronic equipment, can avoid current LED dimmer circuit to exist all the time and the size is indefinite and lead to the not accurate, the LED lamp luminance can not reach the index requirement's of the precision of adjusting luminance problem of the electric current that flows LED when input voltage Vref _ Dim is low partially because of its operational amplifier's maladjustment voltage Vos.

In order to achieve the above object, the utility model provides a LED dimming circuit, include:

the first comparison module is used for judging whether the dimming input voltage is smaller than a first threshold voltage or not;

the second comparison module is used for judging whether the dimming input voltage is larger than a second threshold voltage or not;

the effective input signal generating module is used for generating corresponding effective input signals according to the judgment results of the first comparing module and the second comparing module;

the output module is used for outputting a dimming signal according to the effective input signal; wherein the second threshold voltage is greater than the first threshold voltage,

the input ends of the first comparison module and the second comparison module are connected to a dimming voltage input end for receiving the dimming input voltage, the output ends of the first comparison module and the second comparison module are respectively connected to the corresponding input ends of the effective input signal generation module, and the output end of the effective input signal generation module is connected to the input end of the output module.

Optionally, the valid input signal generating module comprises:

the voltage division module is used for dividing the output voltage of the first comparison module;

the buffer module is used for buffering the output voltage of the second comparison module;

a gating module for selecting the output of the voltage dividing module as an active input signal when the dimming input voltage is less than the first threshold voltage and selecting the output of the buffering module as an active input signal when the dimming input voltage is greater than the second threshold voltage;

the voltage dividing module and the buffer module are a preceding stage circuit or a subsequent stage circuit of the gating module, wherein when the voltage dividing module and the buffer module are the preceding stage circuit of the gating module, a control end of the gating module is connected with an output end of the first comparison module, an input end of the voltage dividing module is connected with an input end of the dimming voltage, an input end of the buffer module is connected with an output end of the second comparison module, output ends of the voltage dividing module and the buffer module are both connected with corresponding input ends of the gating module, and an output end of the gating module is connected with an input end of the output module; when the voltage division module and the buffer module are the rear-stage circuit of the gating module, the input end of the voltage division module and the input end of the buffer module are both connected with the output end of the gating module, and the output end of the voltage division module and the output end of the buffer module are both connected with the input end of the output module.

Optionally, the gating module includes an inverter, a first switching unit, and a second switching unit;

the output end of the first comparison module is respectively connected with the input end of the phase inverter and the control end of the second switch unit, the output end of the second comparison module is connected with the input end of the second switch unit, the output end of the phase inverter is connected with the control end of the first switch unit, the input end of the first switch unit is connected with the dimming voltage input end, and the output ends of the first switch unit and the second switch unit are the output ends of the gating module; alternatively, the first and second electrodes may be,

the output of first comparison module connects respectively the input of phase inverter with the control end of first switch element, the output of second comparison module connects the input of buffering module, the output of buffering module connects the input of second switch element, the input of partial pressure module is connected the input of first switch element, the output of phase inverter connects the control end of second switch element, the output of first switch element with the output of second switch element does the output of gating module.

Optionally, the first switch unit is an MOS transistor, a triode, a single-pole single-throw switch with a control end, or a transmission gate; the second switch unit is respectively an MOS tube, a triode, a single-pole single-throw switch with a control end or a transmission.

Optionally, the buffer module is a circuit separate from the voltage dividing module, or the buffer module and the voltage dividing module share the same circuit; the voltage division module comprises a first resistor and a second resistor which are connected in series, one end of the first resistor, which is connected in series with the second resistor, is an output end of the voltage division module, and the other end of the first resistor is an input end of the voltage division module; and/or, the buffer module comprises a third resistor and a fourth resistor which are connected in series, wherein one end of the third resistor, which is connected in series with the fourth resistor, is the output end of the buffer module, and the other end of the third resistor is the input end of the buffer module.

Optionally, the second comparing module includes an input resistor, a voltage stabilizing unit, a first operational amplifier, and a first switching tube; one end of the input resistor is connected with the dimming voltage input end, and the other end of the input resistor is connected with one end of the voltage stabilizing unit and the positive input end of the first operational amplifier; the other end of the voltage stabilizing unit is grounded; the output end of the first operational amplifier is connected with the control end of the first switch tube, one end of a conduction path of the first switch tube is connected with working voltage, and the other end of the conduction path of the first switch tube is connected with the corresponding input end of the effective input signal generation module.

Optionally, the second comparing module further includes an offset voltage source, one end of the offset voltage source is connected to the inverting input terminal of the first operational amplifier, and the other end of the offset voltage source is connected to the corresponding input terminal of the effective input signal generating module or the other end of the conduction path of the first switching tube.

Optionally, the voltage stabilizing unit includes a voltage stabilizing diode, one end of the voltage stabilizing diode is connected to a connection node between the input resistor and the forward input end of the first operational amplifier, the other end of the voltage stabilizing diode is grounded, and a reverse breakdown voltage of the voltage stabilizing diode is the second threshold voltage; alternatively, the first and second electrodes may be,

the voltage stabilizing unit comprises a second operational amplifier and a second switching tube, wherein the reverse input end of the second operational amplifier and one end of a conducting circuit of the second switching tube are respectively connected to the connecting node of the input resistor and the forward input end of the first operational amplifier, the forward input end of the second operational amplifier is connected to the second threshold voltage, the output end of the second operational amplifier is connected with the control end of the second switching tube, and the other end of the conducting circuit of the second switching tube is grounded.

Based on same utility model the design, the utility model also provides a LED driving system, including the signal input circuit who is used for producing the input voltage that adjusts luminance and if LED dimming circuit, signal input circuit's output with LED dimming circuit's dimming voltage input end is connected.

Based on same utility model the design, the utility model also provides an electronic equipment, including LED lamp and connection if the utility model discloses LED actuating system.

Compared with the prior art, the technical scheme of the utility model following beneficial effect has:

the technical scheme of the utility model, carry out the size judgement to the incoming voltage of adjusting luminance through first comparison module and second comparison module, and produce the module through effective input signal and produce suitable effective input signal output according to the judged result, when the incoming voltage of adjusting luminance is less than first threshold voltage, can come according to the effective input signal output relatively accurate dimming signal who produces through output module, it is not accurate to avoid current LED dimming circuit to exist and the size is indefinite all the time and lead to flowing LED's electric current when incoming voltage Vref _ Dim is low partially because of its operational amplifier's maladjustment voltage Vos, LED lamp luminance can not reach the problem of the index requirement of the precision of adjusting luminance. The technical scheme of the utility model can improve LED precision of adjusting luminance, satisfy the demand that the high accuracy was adjusted luminance.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

Fig. 1 is a schematic circuit diagram of a conventional LED dimming circuit;

fig. 2 is a graph of a voltage Vp of the LED dimming circuit shown in fig. 1 varying with a dimming input voltage Vref _ Dim;

fig. 3 is a schematic diagram of functional modules of an LED dimming circuit according to an embodiment of the present invention;

fig. 4A is a schematic circuit diagram of an embodiment of the LED dimming circuit shown in fig. 3;

fig. 4B is a graph of the voltage Vp of the LED dimming circuit shown in fig. 4A varying with the dimming input voltage Vref _ Dim;

fig. 5 is a schematic diagram of another specific circuit structure of the LED dimming circuit shown in fig. 3;

fig. 6 is a schematic diagram of another specific circuit structure of the LED dimming circuit shown in fig. 3;

fig. 7 is a schematic diagram of functional modules of an LED dimming circuit according to another embodiment of the present invention;

fig. 8 is a schematic diagram of a specific circuit structure of the LED dimming circuit shown in fig. 7.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without creative efforts belong to the protection scope of the present invention. As used herein, "and/or" means either or both.

Referring to fig. 3, an embodiment of the present invention provides an LED dimming circuit, which includes a first comparing module 11, a second comparing module 12, an effective input signal generating module 13, and an output module 14. The valid input signal generating module 13 is configured to generate a corresponding valid input signal Vp according to the determination results of the first comparing module 11 and the second comparing module 12, and specifically includes a gating module 131, a voltage dividing module 132, and a buffering module 133.

The first comparing module 11 is configured to determine whether a dimming input voltage Vref _ Dim (generally ranging from 0V to 5V) is smaller than a first threshold voltage Vk (Vk is between 0V and 0.8V); the second comparing module 12 is configured to determine whether the dimming input voltage Vref _ Dim is greater than a second threshold voltage Vq (e.g., 2.5V); the voltage dividing module 132 is configured to divide the output voltage of the first comparing module 11; the buffer module 133 is configured to buffer the output voltage of the second comparing module 12; the gating module 131 is configured to select the output of the voltage dividing module 132 as the valid input signal Vp when the dimming input voltage Vref _ Dim is smaller than the first threshold voltage Vk, and select the output of the buffering module 133 as the valid input signal Vp when the dimming input voltage Vref _ Dim is greater than the second threshold voltage Vq; the output module 14 is configured to output a dimming signal out according to the valid input signal Vp.

In this embodiment, the voltage dividing module 132 and the buffering module 133 are both used as a post-stage circuit of the gating module 131, the input terminals of the first comparing module 11 and the second comparing module 12 are both connected to the dimming voltage input terminal In for receiving the dimming input voltage Vref _ Dim, the output terminals of the first comparing module 11 and the second comparing module 12 are respectively connected to the corresponding input terminals of the gating module 131, the voltage dividing module 132 and the buffering module 133 may be two separate circuits, at this time, the corresponding output terminals of the gating module 131 are respectively connected to the input terminals of the voltage dividing module 132 and the input terminals of the buffering module 133, and the output terminals of the voltage dividing module 132 and the buffering module 133 are both connected to the input terminal of the output module 14.

Referring to fig. 4A and fig. 5, when the LED dimming circuit of the present embodiment is specifically applied, in order to simplify the circuit, the voltage dividing module 132 and the buffering module 133 may multiplex the same circuit segment, at this time, the output terminal of the gating module 131 is connected to the input terminal of the same circuit segment, and the output terminal of the same circuit segment is connected to the input terminal of the output module 14.

Specifically, in a specific application of the embodiment, referring to fig. 4A, the first comparing module 11 includes a comparator Comp, the second comparing module 12 includes an input resistor R0, a zener diode Z (i.e., a voltage stabilizing unit), a first operational amplifier OPA1, a first switching tube M0 and an offset voltage source Vos, the gating module 131 includes a first switch K1, an inverter inv and a second switch K2, the voltage dividing module 132 and the buffer module 133 multiplex a same circuit, the same circuit includes a first resistor R1 and a second resistor R2 connected in series, and the output module 14 includes an error amplifier EA. The first switch K1 and the second switch K2 are single-pole single-throw switches with control ends, and can be switched on or switched off under the action of signals received by the control ends; the positive input end of the comparator Comp is connected to the dimming voltage input end In to connect the dimming input voltage Vref _ Dim, the negative input end of the comparator Comp is connected to the first threshold voltage Vk, Vk is 0.8V In fig. 4A, and the output end of the comparator Comp is connected to the input end of the inverter inv and the control end of the second switch K2; one end of the input resistor R0 is connected to the dimming voltage input terminal In to receive the dimming input voltage Vref _ Dim, and the other end of the input resistor R0 is connected to the positive input terminal of the first operational amplifier OPA1 and the cathode of the zener diode Z; the anode of the zener diode Z is grounded, the reverse breakdown voltage Vz of the zener diode Z is Vq (Vq may be equal to 2.5V), and the zener diode Z is mainly used for voltage stabilization and voltage division by the input resistor R0 to generate an input voltage required by the OPA1, thereby achieving the determination of whether the dimming input voltage Vref _ Dim of the OPA1 is greater than Vq; the switch tube M0 is a PMOS tube, the gate of the switch tube is a control end, and is connected to the output end of the first operational amplifier OPA1, the drain of the switch tube is one end of a conduction path for connecting to the working voltage Vdd, and the source of the switch tube is the other end of the conduction path, and is connected to the input end of the second switch K2; the positive pole of offset voltage source Vos is connected to the inverting input terminal of first operational amplifier OPA1, and the negative pole of offset voltage source Vos is connected to the output terminal of second switch K2, in other embodiments of the present invention, the negative pole of offset voltage source Vos can also be replaced by the source electrode connected to M0; the output end of the inverter inv is connected with the control end of the first switch K1, the input end of the first switch K1 is connected with the dimming voltage input end In, the output end of the first switch K1 is connected with the output end of the second switch K2 and one end of the first resistor R1, and the node formed by connecting the first resistor R1 and the second resistor R2 In series outputs an effective input signal Vp; the forward input end of the error amplifier EA is connected to a node where the first resistor R1 and the second resistor R2 are connected in series to receive the valid input signal Vp, the reverse input end of the error amplifier EA is connected to a feedback end FB for feeding back the LED voltage to access a feedback voltage Vfb related to the LED lighting condition, the output end of the error amplifier EA outputs a dimming signal out to an LED lamp, and the LED lamp is usually grounded by connecting an external resistor Rfb (not shown) in series, and the current flowing through the LED can be set by adjusting the resistance of the external resistor Rfb. Namely: i _ Led is Vfb/Rfb, typically Vfb is 0 to 0.4V, Vfb is K Vref Dim, and Vref Dim is typically in the range of 0 to 5V. The curve of Vp as a function of Vref _ Dim is shown in FIG. 4B.

Referring to fig. 4A and 4B, when Vref _ Dim is greater than 2.5V, the first switch K1 is opened, the second switch K2 is closed, and after voltage division is performed by the first resistor R1 and the second resistor R2, Vp is 2.5V n2, n2 is a proportionality constant, and the error Accuracy1_ Vfb of the Vfb voltage:

the error Accuracy1_ Vfb is the same as the error Accuracy1_ Vfb in the conventional LED dimming circuit shown in fig. 1.

With reference to fig. 4A and 4B, when Vref _ Dim is 0 to 0.8V, the first switch K1 is closed and gated, the second switch K2 is opened, and after voltage division is performed by the first resistor R1 and the second resistor R2, Vp is Vfb is Vref _ Dim n 1; n1 is related to the ratio between the first resistor R1 and the second resistor R2, the error of Vfb voltage is determined by the ratio between the first resistor R1 and the second resistor R2, and the error of Vfb voltage Accuracy2_ Vfb is less than or equal to 0.1%, thus, when the dimming input voltage Vref _ Dim is in the range of 0V to 0.8V, Accuracy2_ Vfb is greatly reduced compared with Accuracy1_ Vfb, that is, the error of Vfb voltage (i.e., Accuracy2_ Vfb) is greatly reduced. That is, the circuit design shown in FIG. 4A can make the total error (i.e., Accuracy2_ Vfb) less than 1% when Vref _ Dim is in the range of 0V to 2.5V.

Therefore, the LED dimming circuit of the embodiment judges the dimming input voltage through the first comparison module and the second comparison module, and gates a proper signal output through the gating module according to the judgment result, when the dimming input voltage is lower than the first threshold voltage, a relatively accurate dimming signal can be output through the voltage dividing module, thereby avoiding the problems that the current flowing through the LED is inaccurate when the dimming input voltage Vref _ Dim is low and the brightness of the LED lamp cannot meet the index requirement of the dimming accuracy due to the fact that the offset voltage Vos of the operational amplifier of the existing LED dimming circuit is always present and has an indefinite magnitude. The technical scheme of the utility model can improve LED precision of adjusting luminance, satisfy the demand that the high accuracy was adjusted luminance.

It should be noted that the circuit configuration of the gating module 131 is not limited to the above configuration. Specifically, in other application embodiments of the present invention, the first switch K1 and the second switch K2 may be replaced by electronic components or circuits having equivalent functions, respectively. For example, please refer to fig. 5, In another embodiment of the present invention, the first switch K1 is replaced by a first transmission gate TG1 having a control end, the second switch K2 is replaced by a second transmission gate TG2 having a control end, the first transmission gate TG1 and the second transmission gate TG2 can be turned on or off under the action of a signal received by the control end, the input end of the first transmission gate TG1 is connected to the dimming voltage input end In, the control end of the first transmission gate TG1 is connected to the output end of the inverter inv, the output end of the first transmission gate TG1 is connected to one end of the first resistor R1 and the output end of the second transmission gate TG2, the input end of the second transmission gate TG 35 2 is connected to the source of the switch M0, and the control end of the second transmission gate is connected to the output end of the comparator Comp; other circuit portions of the LED dimming circuit in this application embodiment are the same as corresponding circuit portions of the LED dimming circuit in the application embodiment shown in fig. 4, and reference may be made to the above description, and details are not repeated here. For another example, in other embodiments of the present invention, the single-pole single-throw switches (the first switch K1 and the second switch K2) having the control terminal may be replaced by MOS transistors or triodes, respectively.

The circuit configuration of the second comparing module 12 is not limited to the above configuration. In other embodiments of the present invention, the offset voltage source Vos can be omitted, and the zener diode Z thereof can also be replaced by a circuit design of the voltage stabilizing unit having the same function. For example, referring to fig. 5, in an embodiment of the present invention, the voltage stabilizing unit of the second comparing module 12 includes a second operational amplifier OPA2 and a second switching tube M1, the second switching tube M1 is an NMOS tube, the inverting input terminal of the second operational amplifier OPA2 and the source terminal of the second switching tube M1 (i.e., one end of the M1 conducting circuit) are respectively connected to the connection node of the input resistor R1 and the forward input terminal of the first operational amplifier OPA1, the forward input terminal of the second operational amplifier OPA2 is connected to the second threshold voltage Vq (Vq is 2.5V in fig. 5), the output terminal of the second operational amplifier OPA2 is connected to the gate terminal (i.e., the control terminal) of the second switching tube M1, and the drain terminal of the second switching tube M1 (i.e., the other end of the M1 conducting circuit) is grounded; other circuit portions of the LED dimming circuit in this application embodiment are the same as corresponding circuit portions of the LED dimming circuit in the application embodiment shown in fig. 4, and reference may be made to the above description, and details are not repeated here. When Vk is 0.8V, Vq is 2.5V, and Vref _ Dim is in the range of 0.8V to 2.5V, the second operational amplifier OPA2 outputs a high level, so that M1 is turned on, Vp rises with the rise of the dimming input voltage Vref _ Dim, and Vp is 0.4V when Vref _ Dim rises to 2.5; when Vk is 0.8V, Vq is 2.5V, and Vref _ Dim is greater than 2.5V, the second operational amplifier OPA2 outputs a low level, so that M1 is turned off, the first operational amplifier OPA1 outputs a high level, M0 is turned on, TG2 is turned on, and Vp is 2.5V.

In the embodiment shown in fig. 4A and fig. 5, the buffering module 133 and the voltage dividing module 132 multiplex the same circuit, but in other embodiments of the present invention, the buffering module 133 and the voltage dividing module 132 may be two circuits separated from each other. Specifically, referring to fig. 6, in the LED dimming circuit according to another embodiment of the present invention, the output end of the second switch K2 is connected to the input end of the buffering module 133, the output end of the first switch K1 is connected to the input end of the voltage dividing module 132, the output ends of the buffering module 133 and the voltage dividing module 132 are both connected to the positive input end of the error amplifier EA, and the voltage dividing module 132 includes a first resistor R1 and a second resistor R2 connected in series; other circuit portions of the LED dimming circuit in this application embodiment are the same as corresponding circuit portions of the LED dimming circuit in the application embodiment shown in fig. 4, and reference may be made to the above description, and details are not repeated here.

In addition, in the above embodiment, the voltage dividing module 132 and the buffer module 133 are used as the post-stage circuit of the gating module 131, and therefore the first comparing module 11 and the second comparing module 12 are connected to the gating module 131 first, and then the gating module 131 gates the corresponding branch to output the corresponding Vp, but the technical solution of the present invention is not limited to this, please refer to fig. 7, in another embodiment of the present invention, the voltage dividing module 132 and the buffer module 133 may also be used as the pre-stage circuit of the gating module 131, at this time, the first comparing module 11 is connected to the voltage dividing module 132 first, the second comparing module 12 is connected to the buffer module 133 first, the gating module 131 is connected to the voltage dividing module 132 and the buffer module 133 and gates the voltage dividing module 132 or the buffer module 133 to output the corresponding Vp, and the same technical effect as the circuit shown in fig. 3 can also be achieved. Referring to fig. 7, the LED dimming circuit includes a first comparing module 11, a second comparing module 12, an effective input signal generating module 13 and an output module 14, wherein the effective input signal generating module 13 includes a gating module 131, a voltage dividing module 132 and a buffering module 133. The input terminals of the first comparing module 11 and the second comparing module 12 are both connected to a dimming voltage input terminal In for receiving the dimming input voltage Vref _ Dim, the output terminal of the first comparing module 11 is connected to the control terminal of the gating module 131, the input terminal of the voltage dividing module 132 (i.e., one terminal of the first resistor R1) is connected to the dimming voltage input terminal In, the output terminal of the second comparing module 12 is connected to the input terminal of the buffer module 133 (i.e., one terminal of the third resistor R3), the output terminals of the voltage dividing module 132 and the output terminal of the buffer module 133 are both connected to the corresponding input terminals of the gating module 131, and the output terminal of the gating module 131 is connected to the input terminal of the output module 14.

Referring to fig. 8, in an embodiment of the present invention, the first comparing module 11 includes a comparator Comp, the second comparing module 12 includes an input resistor R0, a zener diode Z (i.e., a zener unit), a first operational amplifier OPA1 and a first switch M0, the gating module 131 includes a first transmission gate (i.e., a first switch unit) TG1, an inverter inv and a second transmission gate (i.e., a second switch unit) TG2, the output module 14 includes an error amplifier EA, the voltage dividing module 132 and the buffer module 133 are separate circuits, specifically, the voltage dividing module 132 includes a first resistor R1 and a second resistor R2 connected in series, and the buffer module 133 includes a third resistor R3 and a fourth resistor R4 connected in series. The positive input end of the comparator Comp is connected with the dimming voltage input end In to access the dimming input voltage Vref _ Dim, the reverse input end of the comparator Comp is connected with a first threshold voltage Vk, Vk is between 0 and 0.8V, and the output end of the comparator Comp is connected with the input end of the inverter inv and the control end of the first transmission gate TG 1; one end of the input resistor R0 is connected to the dimming voltage input terminal In to receive the dimming input voltage Vref _ Dim, and the other end of the input resistor R0 is connected to the positive input terminal of the first operational amplifier OPA1 and the cathode of the zener diode Z; the anode of the zener diode Z is grounded, the reverse breakdown voltage Vz of the zener diode Z is Vq (Vq may be equal to 2.5), the zener diode Z is mainly used for voltage stabilization and voltage division with the input resistor R0 to generate the input voltage required by the OPA1, thereby achieving the determination of whether the dimming input voltage Vref _ Dim of the OPA1 is greater than Vq; the switch tube M0 is a PMOS tube, the gate of which is a control end and is connected to the output end of the first operational amplifier OPA1, the drain of which is one end of a conduction path for connecting the working voltage Vdd, and the source of which is the other end of the conduction path and is connected to one end of the third resistor R3 (as the input end of the buffer module 133); the other end of the third resistor R3 is connected to one end of the fourth resistor R4 as the output end of the buffer module 133, one end of the first resistor R1 (as the input end of the voltage dividing module 132) is connected to the dimming voltage input end In to receive the dimming input voltage Vref _ Dim, and the other end of the first resistor R1 is connected to one end of the second resistor R2 as the output end of the voltage dividing module 132; the other end of the second resistor R2 and the other end of the fourth resistor R4 are both grounded; an output end (i.e., a serial node of the first resistor R1 and the second resistor R2) of the voltage dividing module 132 is connected to an input end of a first transmission gate TG1, an output end (i.e., a serial node of the third resistor R3 and the fourth resistor R4) of the buffer module 133 is connected to an input end of a second transmission gate TG2, and an output end of the first transmission gate TG1 and an output end of the second transmission gate TG2 are both connected to a positive input end of the error amplifier EA, so as to input an effective input signal Vp to the positive input end of the error amplifier EA; the inverting input end of the error amplifier EA is connected with a feedback end FB for feeding back the LED voltage, so as to access a feedback voltage Vfb related to the LED lighting condition, and the output end of the error amplifier EA outputs a dimming signal out.

Based on same utility model conceive, an embodiment of the utility model provides a still provides a LED actuating system, including the signal input circuit (not shown) that is used for producing the input voltage that adjusts luminance and as LED dimmer circuit, an output of signal input circuit with LED dimmer circuit's dimming voltage input end is connected, be used for to LED dimmer circuit's dimming voltage input end provides input voltage Vref _ Dim of adjusting luminance. The other output end of the signal input circuit is a feedback end FB for feeding back LED voltage, is connected with the reverse input end of an error amplifier EA of the LED dimming circuit, and is used for providing feedback voltage Vfb related to the LED light-emitting condition for the reverse input end of the error amplifier EA. The signal input circuit may include an ac source, a rectifier, and a control chip connected in sequence. The rectifier receives an alternating current signal from an alternating current source, outputs a direct current signal after rectification, and the control chip generates dimming input voltage Vref _ Dim and feedback voltage Vfb according to the direct current signal.

Based on same utility model the design, an embodiment of the utility model provides an electronic equipment still is provided, including LED lamp and connect if the utility model discloses LED actuating system. The electronic device may be a lighting device, a charger, a portable communication device, etc.

The utility model discloses a LED actuating system and electronic equipment owing to have the utility model discloses a LED dimmer circuit, consequently have the utility model discloses an all technological effects that LED dimmer circuit brought.

The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An LED dimming circuit, comprising:

2. The LED dimming circuit of claim 1, wherein the valid input signal generation module comprises:

3. The LED dimming circuit of claim 2, wherein the gating module comprises an inverter, a first switching unit, and a second switching unit;

4. The LED dimming circuit of claim 3, wherein the first switching unit is a MOS transistor, a triode, a single-pole single-throw switch with a control terminal, or a transmission gate; the second switch unit is respectively an MOS tube, a triode, a single-pole single-throw switch with a control end or a transmission.

5. The LED dimming circuit of claim 2, wherein the buffer module is a circuit separate from the voltage divider module or a circuit multiplexed with the voltage divider module; the voltage division module comprises a first resistor and a second resistor which are connected in series, one end of the first resistor, which is connected in series with the second resistor, is an output end of the voltage division module, and the other end of the first resistor is an input end of the voltage division module; and/or, the buffer module comprises a third resistor and a fourth resistor which are connected in series, wherein one end of the third resistor, which is connected in series with the fourth resistor, is the output end of the buffer module, and the other end of the third resistor is the input end of the buffer module.

6. The LED dimming circuit according to any one of claims 1 to 5, wherein the second comparing module comprises an input resistor, a voltage stabilizing unit, a first operational amplifier, a first switching tube; one end of the input resistor is connected with the dimming voltage input end, and the other end of the input resistor is connected with one end of the voltage stabilizing unit and the positive input end of the first operational amplifier; the other end of the voltage stabilizing unit is grounded; the output end of the first operational amplifier is connected with the control end of the first switch tube, one end of a conduction path of the first switch tube is connected with working voltage, and the other end of the conduction path of the first switch tube is connected with the corresponding input end of the effective input signal generation module.

7. The LED dimming circuit of claim 6, wherein the second comparison module further comprises an offset voltage source, one end of the offset voltage source is connected to the inverting input terminal of the first operational amplifier, and the other end of the offset voltage source is connected to the corresponding input terminal of the active input signal generation module or the other end of the conduction path of the first switch tube.

8. The LED dimming circuit of claim 6, wherein the voltage regulator unit comprises a zener diode, one end of the zener diode is connected to a connection node of the input resistor and the forward input end of the first operational amplifier, the other end of the zener diode is grounded, and a reverse breakdown voltage of the zener diode is the second threshold voltage; alternatively, the first and second electrodes may be,

9. An LED driving system comprising a signal input circuit for generating a dimming input voltage and an LED dimming circuit as claimed in any one of claims 1 to 8, an output of the signal input circuit being connected to a dimming voltage input of the LED dimming circuit.

10. An electronic device comprising the LED lamp and the LED driving system according to claim 9 connected thereto.