CN112638000A

CN112638000A - Voltage regulating circuit and light regulating circuit

Info

Publication number: CN112638000A
Application number: CN202011429886.3A
Authority: CN
Inventors: 梅永建
Original assignee: Chengdu Jimi Technology Co Ltd
Current assignee: Chengdu Jimi Technology Co Ltd; Chengdu XGIMI Technology Co Ltd
Priority date: 2020-12-09
Filing date: 2020-12-09
Publication date: 2021-04-09
Anticipated expiration: 2040-12-09
Also published as: CN112638000B

Abstract

The application relates to the technical field of voltage regulating circuits, in particular to a voltage regulating circuit and a dimming circuit, wherein the voltage regulating circuit comprises a first unit, a second unit and a third unit for changing the working states of the first unit and the second unit; the output end of the first unit is respectively connected with the output end of the second unit and the output end of the third unit, and the second unit and the third unit are connected in parallel; when the switch tube of the third unit is conducted, the first unit and the second unit are invalid, and the input of the third unit is changed for carrying out voltage intermittent regulation; when the switch tube of the third unit is cut off, the first unit and the second unit are effective, and the input of the first unit is changed for continuous voltage regulation; the method adopts discrete elements and a simple PWM control mode, realizes cost control, simplifies the control mode, and meets the output requirement of a large voltage range; the diversity of the voltage control mode enlarges the application field range of the circuit.

Description

Voltage regulating circuit and light regulating circuit

Technical Field

The application relates to the technical field of voltage regulating circuits, in particular to a voltage regulating circuit and a dimming circuit.

Background

The existing light-emitting diode dimming circuit is realized by switching on and off the lamp with constant current and different PWM duty ratios, and the method has high feasibility and is simple to operate. However, the impact on the light emitting diode lamp is large, and the service life of the light emitting diode lamp is greatly shortened when no effective buffer exists.

Disclosure of Invention

An object of the embodiments of the present application is to provide a voltage regulating circuit and a dimming circuit to solve the above problems.

A voltage regulating circuit comprises a first unit, a second unit and a third unit for changing the working states of the first unit and the second unit;

the output end of the first unit is respectively connected with the output end of the second unit and the output end of the third unit, and the second unit and the third unit are connected in parallel;

when the switch tube of the third unit is conducted, the first unit and the second unit are invalid, and the input of the third unit is changed for carrying out voltage intermittent regulation; when the switch tube of the third unit is cut off, the first unit and the second unit are effective, and the input of the first unit is changed to carry out voltage continuous adjustment.

Preferably, when the switching tube of the third unit is turned off, and the first input signal level of the first unit is valid, the voltage at the output terminal of the second unit or the third unit is V _ OUT — K1 × VREF, and when the first input signal level of the first unit is invalid, the voltage at the output terminal of the second unit or the third unit is V _ OUT — K2 × VREF, VREF representing the reference voltage of the second unit, K1 representing the voltage division coefficient calculated by the resistors in the first unit and the second unit, and K2 representing the voltage division coefficient calculated by the resistors in the second unit.

Preferably, the first unit includes an isolation element, the first unit is connected in parallel with the second unit when the isolation element is turned on, and the first unit is isolated from the second unit when the isolation element is turned off.

Preferably, the isolation element is a triode or a MOS tube; and the switching tube of the third unit adopts a triode or an MOS tube.

Preferably, the third unit outputs a minimum voltage Vmin when the first input signal level of the third unit is active; when the first input signal level of the third unit is invalid, the third unit output voltage V _ OUT is K3 VREF, VREF represents the reference power supply of the second unit, and K3 represents the voltage division coefficient calculated by the resistors in the first unit and the second unit or represents the voltage division coefficient calculated by the resistor in the second unit.

Preferably, the first unit includes isolation element, second resistance and third electric capacity, when isolation element adopted first triode, first input signal was connected to first triode base, first triode emitter ground, the one end of second resistance is connected to first triode collecting electrode, the one end of third electric capacity is connected to the other end of second resistance, the other end ground of third electric capacity, the output of second unit is connected after the other end of second resistance and the one end of third electric capacity are connected.

Preferably, when the input signal of the third unit is invalid and the input signal of the first unit is valid, the loop formed by the second resistor and the first triode is connected with the second unit in parallel, and the voltage of the output end of the third unit is connected with the second unit in parallel

When the input signal of the third unit is invalid and the input signal of the first unit is invalid, the loop where the second resistor and the first triode are positioned fails, the second resistor and the first triode are separated from the second unit, and the voltage of the output end of the third unit is equal to the voltage of the output end of the third unit

R2 denotes a resistance value of the second resistor, R3 denotes a resistance value of the third resistor, R5 denotes a resistance value of the fifth resistor, and VREF denotes a reference power source.

Preferably, the second unit includes a reference power supply, a third resistor and a fifth resistor, the reference power supply is connected to one end of the third resistor, the other end of the third resistor is connected to one end of the fifth resistor, the other end of the fifth resistor is grounded, and the other end of the third resistor and one end of the fifth resistor are respectively connected to the output end of the first unit and the output end of the third unit.

Preferably, when the switch tube adopts a triode, the third unit comprises a first resistor and a second triode, one end of the first resistor is connected with the output end of the second unit, the other end of the first resistor is connected with the collector electrode of the second triode, the base electrode of the second triode is connected with a second input signal, and the emitter electrode of the second triode is grounded.

Preferably, the first unit comprises a first-stage first unit and a second-stage first unit, the first-stage first unit and the second-stage first unit are connected in parallel, the output ends of the first-stage first unit and the second-stage first unit are both connected with the output end of the second unit, the input end of the first-stage first unit is connected with the first PWM signal, and the input end of the second-stage first unit is connected with the second PWM signal.

Preferably, the third unit includes a first-stage third unit and a second-stage third unit, the first-stage third unit and the second-stage third unit are connected in parallel, the output ends of the first-stage third unit and the second-stage third unit are both connected with the output end of the second unit, the input end of the first-stage third unit is connected with the first level signal, and the input end of the second-stage third unit is connected with the second level signal.

Preferably, the second unit includes first order second unit and second level second unit, first order second unit and second level second unit parallel connection, the third unit includes first order third unit and second level third unit, first order second unit output is connected to first order second unit input, first order second unit output is connected first order third unit, the first unit output is connected to the input of second level second unit, the output of second level second unit is connected the second level third unit.

Preferably, the first unit includes an isolation element, a second resistor and a third capacitor, when the isolation element adopts a first MOS transistor, the gate of the first MOS transistor is connected with a first input signal, the source of the first MOS transistor is grounded, the drain of the first MOS transistor is connected with one end of the second resistor, the other end of the second resistor is connected with one end of the third capacitor, the other end of the third capacitor is grounded, and the other end of the second resistor and one end of the third capacitor are connected with the output end of the second unit.

Preferably, when the switching tube adopts an MOS tube, the third unit includes a first resistor and a second MOS tube, one end of the first resistor is connected to the output end of the second unit, the other end of the first resistor is connected to the drain of the second MOS tube, the gate of the second MOS tube is connected to the second input signal, and the source of the second MOS tube is grounded.

Preferably, the output end of the first unit is connected with the output end of the third unit, the output end of the third unit is connected with the output end of the second unit, and the output end of the second unit outputs the voltage regulation voltage;

or the output end of the first unit is connected with the output end of the second unit, the output end of the second unit is connected with the output end of the third unit, and the output end of the third unit outputs the voltage regulation voltage.

On the other hand, the application provides a dimming circuit, including constant current chip, emitting diode and voltage regulating circuit, voltage regulating circuit adopts foretell voltage regulating circuit, voltage regulating circuit output connects the constant current chip input, the emitting diode is connected to the constant current chip output.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings that are required to be used in the embodiments of the present application will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present application and therefore should not be considered as limiting the scope, and that those skilled in the art can also obtain other related drawings based on the drawings without inventive efforts.

Fig. 1 is a circuit diagram of embodiment 1 of the present application.

Fig. 2 is a schematic block diagram of a circuit in embodiment 1 of the present application.

Fig. 3 is a voltage pattern diagram of embodiment 1 of the present application.

Fig. 4 is a circuit diagram 1 of embodiment 2 of the present application.

Fig. 5 is a circuit diagram 2 of embodiment 2 of the present application.

Fig. 6 is a circuit diagram 3 according to embodiment 2 of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application. Furthermore, it should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, it need not be further defined and explained in subsequent figures.

Example 1

The existing voltage regulating circuit comprises an upper computer for sending a regulating instruction, wherein a signal output end of the upper computer is connected with an input end of an FPGA control circuit for receiving the regulating instruction, an output end of the FPGA control circuit is connected with an input end of a DAC (digital-to-analog converter) circuit, an output end of the DAC circuit is connected with an input end of a constant current driving circuit for outputting a corresponding current value according to the regulating instruction, and an output end of the constant current driving circuit is connected with a light emitting diode lamp arranged on a light emitting diode light source plate, so that dimming is realized. The existing voltage regulating circuit is realized by adopting a DAC chip, and has high cost, high implementation complexity and small output voltage range. Referring to fig. 1, a voltage regulator circuit according to an embodiment of the present application is provided to overcome the problem of the conventional voltage regulator circuit.

The voltage regulating circuit of the embodiment comprises a first unit, a second unit and a third unit, wherein the first unit is used for enlarging the voltage regulating range of the second unit through isolation; the output end of the first unit is connected with the output end of the second unit, the output end of the second unit is connected with the output end of the third unit, and the output end of the third unit is connected with the constant current chip; when the switch tube of the third unit is conducted, the first unit and the second unit do not work, and the input of the third unit is changed for carrying out voltage intermittent adjustment; when the switch tube of the third unit is cut off, the first unit and the second unit work, and the input of the first unit is changed to carry out voltage continuous adjustment.

If the switching tube of the third unit adopts a triode,

the first unit is a PWM filtering unit and includes an isolation element, a second resistor R2 and a third capacitor CD 3. The isolation element employs a first triode QA 1.

The base of the first triode QA1 is connected to a first input signal LED _ Dimming, the emitter of the first triode QA1 is grounded, i.e., connected to a GND pin, the collector of the first triode QA1 is connected to one end of a second resistor R2, the other end of the second resistor R2 is connected to one end of a third capacitor CD3, the other end of the third capacitor CD3 is grounded, i.e., connected to the GND pin, and the other end of the second resistor R2 and one end of the third capacitor CD3 are connected to a second unit after being connected.

The circuit also comprises a fourth resistor R4, wherein R4 is a protection resistor and has the value range of 1K-4.7K; the QA1 proposes to set a protection resistor when BJT is used, and it is not used if MOS transistor is used.

The second cell is a reference cell and comprises a reference power source VREF, a third resistor RD3 and a fifth resistor RD5, wherein the reference power source VREF is connected with one end of a third resistor RD3, the other end of the third resistor RD3 is respectively connected with one end of a fifth resistor RD5, one end of a third capacitor CD3 and the other end of a second resistor R2, and one end of the fifth resistor RD5 is connected with a GND pin. The voltage range of the second unit output is 0-VREF.

The third unit is a voltage control unit and comprises a first resistor RD1 and a second triode QA2, one end of the first resistor RD1 is connected with the output end of the second unit and the constant current chip, the other end of the first resistor RD1 is connected with the collector electrode of the second triode QA2, the base electrode of the second triode QA2 is connected with a second input signal LED _ OFF, and the emitter electrode of the second triode QA2 is connected with a GND pin. The three-phase inverter further comprises a third resistor R3, one end of the third resistor R3 is connected with an input signal, the other end of the third resistor R3 is connected with a base electrode of a second triode QA2, and the third resistor is combined with BJT devices such as triodes for use, so that the system stability can be improved. The first resistor RD1 may adjust the magnitude of the minimum voltage value.

When the second triode QA2 of the third unit is turned off, and the LED _ Dimming level of the first unit is active, the voltage at the output end of the second unit or the third unit is V _ OUT ═ K1 × VREF, and when the LED _ Dimming level of the first unit is inactive, the voltage at the output end of the second unit or the third unit is V _ OUT ═ K2 × VREF, VREF represents the reference voltage of the second unit, K1 represents the voltage division coefficient calculated by the resistors in the first unit and the second unit, and K2 represents the voltage division coefficient calculated by the resistors in the second unit.

The method comprises the following specific steps: when the input signal of the third unit is invalid (such as LED _ OFF low level), the third unit fails, the voltage regulating circuit comprises a first unit and a second unit, the voltage regulating circuit enters a voltage continuous regulating mode, when the input signal of the first unit is valid (such as LED _ Dimming high level), a first loop formed by a second resistor R2 and a first triode QA1 is connected with the second unit in parallel, and the voltage of the output end of the third unit is connected with the voltage of the output end of the second unit

When the input signal of the third unit is invalid (for example, when the LED _ OFF is at a low level) and the input signal of the first unit is invalid (for example, when the LED _ Dimming is at a low level), the loop where the second resistor R2 and the first triode QA1 are located fails, the second unit is disconnected, and the voltage at the output end of the third unit is disconnected

R2 denotes a resistance value of the second resistor, R3 denotes a resistance value of the third resistor, R5 denotes a resistance value of the fifth resistor, and VREF denotes a resistance value of the reference power supply.

The first triode in the first unit is an isolation element, the first unit is connected with the second unit in parallel when the isolation element is conducted, and the first unit is isolated from the second unit when the isolation element is cut off. The isolation element can also adopt an MOS tube.

When the input signal level of the third unit is effective (for example, when the LED _ OFF is at a high level), the first unit and the second unit are invalid, the voltage regulating circuit comprises a third unit, the voltage regulating circuit enters a voltage intermittent regulating mode, and the third unit outputs a minimum voltage Vmin; when the input signal level of the third unit is invalid (for example, when the LED _ OFF is at a low level), the third unit output voltage V _ OUT is K3 VREF, VREF represents the reference power supply of the second unit, and K3 represents the voltage division coefficient calculated by the resistors in the first unit and the second unit or represents the voltage division coefficient calculated by the resistor in the second unit. The voltage of V3 is affected by the PWM duty cycle of the first unit and the resistance of R2, and the maximum value of V3 is affected only by the resistances RD3 and RD 5.

The input signal of the first unit is a specific frequency PWM signal which is represented as high-level active at QA1, and when the base of QA1 is high-level, the R2 circuit is effectively connected with CD3 in parallel to realize voltage division in the whole circuit; that is, V _ OUT — V1 — V2 — V3 depends on VREF and the voltage dividing coefficient formed by R2, RD3, RD 5; when the QA1 base is low, R2 and CD3 fail, and it is considered to be OUT of the whole circuit, i.e., V _ OUT-V2-V3 depends on the voltage dividing coefficient and VREF composed of RD3 and RD 5. The third unit comprises a second triode QA2 and a first resistor RD1, the RD1 is a current-limiting resistor, and the current-limiting resistor is not set or set, if VREF is too large, the current-limiting resistor needs to be set, and the amplitude of the minimum voltage value can be adjusted; no matter the LED _ Dimming network level state, the LED _ OFF network is high, QA2 is turned on, and V1 ═ V2 ═ V3 ═ 0; first, the two cells fail and output a minimum voltage of 0 or close to 0 directly (with a current-limiting resistor). When the LED _ OFF is at a low level, V3 is in a proportional relation with VREF, the LED _ OFF high-low level switching realizes a discontinuous mode, the duty ratio of LED _ OFF is changed, the high-low level period can be changed, the corresponding load is a voltage brightness period, and if multiple loads are connected in parallel, the color gamut change (the RGB color voltage is different, and the combined result is inconsistent in light color) can be realized.

The orderly combination of the three unit structures can meet the effective regulation of the reference voltage. Compared with the DAC module scheme, the scheme has the advantages of low application cost and strong practical feasibility.

The circuit principle is as follows: as shown in fig. 3, in the voltage discontinuous operation mode, as shown in fig. 3(a), the voltage value is switched between 0V and the voltage V, at this time, the first unit input signal LED _ Dimming is a fixed PWM signal, the LED _ OFF level is high, the QA2 is turned on, and V1 ═ V2 ═ V3 ═ 0; the first unit and the second unit fail and directly output the minimum voltage of 0 or close to 0 (when the current-limiting resistor is used); when the LED _ OFF level is at a low level, V3 is in a proportional relation with VREF (when the LED _ Dimming level is at a high level, QA1 is turned on, and when the LED _ Dimming level is at a low level, QA1 is turned on and OFF; the output of the first unit is stabilized at a certain voltage value due to the effect of a capacitor CD3, so that the high voltage amplitude in the intermittent mode is stabilized). The LED _ OFF high and low levels are matched to realize intermittent operation of voltage, parameters such as PWM duty ratio, LED _ OFF duty ratio and the like are dynamically adjustable, and the LED _ OFF duty ratio dimming circuit is used for general voltage dimming. As shown in fig. 3(b), in the voltage continuous mode, the voltage value does not return to the 0V position, and the voltage can be continuously and dynamically adjusted and always maintained in a certain range. In the voltage continuous mode, the LED _ OFF level is low, the QA2 is turned OFF, the third unit is failed, the LED _ Dimming level is high, the QA1 is turned on, and the whole circuit comprises a first unit and a second unit; the voltage continuous mode voltage regulation range calculation formula is as follows:

when the LED _ Dimming is always in a high level, QA1 is turned on to obtain Vmin; when the LED _ Dimming is always low, QA1 is turned off, the output voltage is determined by RD3, RD5, VREF, and Vmax is obtained as RD5/(RD3+ RD 5); the step change value can be adjusted by changing the PWM signal, and continuous adjustment is realized. In the circuit, the parameter of R2 determines the lower limit value of linear voltage regulation, and the CD3 determines the response speed of voltage regulation and the lowest frequency of PWM signals. The isolation element QA1 constitutes an isolation circuit, and the value range of the power source VREF existing in the QA1 is larger, so that the aim of controlling large voltage division by small voltage signals is achieved, and the application range of the circuit is enlarged. R2 and CD3 form a first-order RC low-pass filter which passes low frequency and blocks high frequency. When the PWM signal passes through the CD3, the DC stable voltage output after the amplitude limiting of the PWM signal is realized by utilizing the charge-discharge characteristic of the capacitor.

Based on the above embodiment, the triodes in the first unit and the third unit can be replaced by MOS transistors, and the corresponding circuit connections are correspondingly changed; the second unit is unchanged.

The first unit comprises a first MOS tube, a second resistor and a third capacitor, wherein a grid electrode of the first MOS tube is connected with an input signal, a source electrode of the first MOS tube is connected with a GND pin, a drain electrode of the first MOS tube is connected with one end of the second resistor, the other end of the second resistor is connected with one end of the third capacitor, the other end of the third capacitor is connected with the GND pin, and the other end of the second resistor and one end of the third capacitor are connected with the back of the second unit.

The third unit includes first resistance and second MOS pipe, and second unit output and load are connected to the one end of first resistance, the first resistance other end is connected the second MOS pipe drain electrode, second input signal is connected to second MOS pipe grid, the GND pin is connected to the second MOS pipe source.

The level validity is defined according to the actual situation, and can be valid at a high level and valid at a low level; the high level is defined as a voltage of 3.3V or 5V, and the low level is defined as a voltage of 0V.

Therefore, the isolation element of the first unit and the switch tube of the third unit both adopt a triode or an MOS tube, or the first unit adopts a triode or an MOS tube, and the third unit adopts an MOS tube or a triode. When the triode is of an NPN type, the corresponding connection is as described above; when the MOS tube adopts an N-MOS tube, the corresponding connection is as described above. In summary, the switching tubes of the first unit and the third unit only need to adopt devices with switching functions to realize on or off. The corresponding connection mode is changed correspondingly, and is not described herein again.

On the other hand, the second unit and the third unit are sequentially replaceable; the output end of the first unit is connected with the output end of the third unit, the output end of the third unit is connected with the output end of the second unit, and the output end of the second unit is connected with a load or an output voltage; the connections between the cells are correspondingly changed and the connections of the devices within the cells are unchanged.

Similarly, if the GND pin of the second unit is changed into-VREF, the voltage regulating range is wider; the RC device of the first unit can also adopt multi-stage RC, and the voltage stability of the circuit is improved.

Example 2

Based on embodiment 1, when the first unit, the second unit, and the third unit of this embodiment are multi-level, it is beneficial to improve the control range and optimize the control mode.

As shown in fig. 4, when the first unit includes a first-stage first unit and a second-stage first unit, the first-stage first unit and the second-stage first unit are connected in a consistent manner, the first-stage first unit and the second-stage first unit are connected in parallel, the output ends of the first-stage first unit and the second-stage first unit are both connected to the second unit, the input end of the first-stage first unit is connected to a first PWM signal LED _ Dimming1, the input end of the second-stage first unit is connected to a second PWM signal LED _ Dimming2, signals at the input ends of the first-stage first unit and the second-stage first unit are changed, and the control mode and the voltage regulation range of the first unit are correspondingly changed, such as master-slave control.

As shown in fig. 6, when the third unit includes a first-stage third unit and a second-stage third unit, the first-stage third unit and the second-stage third unit are connected in a consistent manner, the first-stage third unit and the second-stage third unit are connected in parallel, the output ends of the first-stage third unit and the second-stage third unit are both connected to the second unit, the first-stage third unit is connected to the first level signal LED _ OFF, the second-stage third unit is connected to the second level signal LED _ OFF1, single-input multi-output is realized, signals at the input ends of the first-stage third unit and the second-stage third unit are changed, and the control mode and the voltage regulation range of the third unit are correspondingly changed.

As shown in fig. 5, the second unit includes a first-stage second unit and a second-stage second unit, the first-stage second unit and the second-stage second unit are connected in a consistent manner, the first-stage second unit and the second-stage second unit are connected in parallel, the third unit includes a first-stage third unit and a second-stage third unit, the input end of the first-stage second unit is connected to the first unit, the output end of the first-stage second unit is connected to the first-stage third unit, the input end of the second-stage second unit is connected to the first unit, the output end of the second-stage second unit is connected to the second-stage third unit, so as to implement multiple input and multiple output, change the reference voltages of the first-stage second unit and the second-stage second unit, and correspondingly change the output voltage of the third unit.

If the first unit adds a level of control, as shown in fig. 4, LED _ Dimming and LED _ Dimming1 can control V _ OUT output together, so that V _ OUT has a wider adjustment range and finer voltage variation steps. When the LED _ Dimming is low, the circuit formed by QA3, R7 and CD1 is disabled and controlled by LED _ Dimming1, and the subsequent control principle corresponds to the circuit principle of embodiment 1. When the LED _ Dimming1 is at low level, the circuit formed by QA5, R10 and CD2 is disabled and controlled by the LED _ Dimming, and the subsequent control principle corresponds to the above principle.

If the second unit is added with one stage (corresponding to the addition of the third unit with one stage), as shown in fig. 5, the voltage division of the two stages of the second units RD7, RD9, RD10, RD16 is different, so that one-way control of multiple outputs of different voltage values can be realized.

If the third unit is added by one stage, as shown in fig. 6, the multiplexing of the third unit of the circuit can realize the master-slave relationship between LED _ OFF and LED _ OFF 1. When LED _ OFF goes high, LED _ OFF1 is masked and LED _ OFF1 does not affect the V _ OUT output anyway. When LED _ OFF1 goes high, LED _ OFF cannot control anything and there is a latch-up.

Therefore, the first unit, the second unit and the third unit can be multiplexed, the number of multiplexing stages is set according to specific requirements, and the corresponding circuit principle is correspondingly changed as in embodiment 1.

Based on the embodiment 1, the triodes in the first unit and the third unit can be replaced by MOS tubes, and the corresponding circuit connection is correspondingly changed; the second unit is unchanged. Therefore, the switching tubes of the first unit and the third unit can both adopt a triode or an MOS tube, or the first unit adopts a triode or an MOS tube, and the third unit adopts an MOS tube or a triode. When the triode is of an NPN type, the corresponding connection is as described above; when the MOS tube adopts an N-MOS tube, the corresponding connection is as described above. In summary, the switching tubes of the first unit and the third unit only need to adopt devices with switching functions to realize on or off. The corresponding connection mode is changed correspondingly, and is not described herein again.

As shown in fig. 2, firstly, a PWM signal is input, the PWM signal is filtered into a dc voltage with a reduced amplitude through the first unit RC filter circuit, the dc voltage passes through the reference voltage dividing circuit formed by the second unit and the third unit, the maximum/small voltage value can be output when the reference voltage dividing circuit is started, the maximum/small voltage and the RC filter circuit output voltage value are used for voltage processing, finally, a required voltage value is output, the voltage value is subsequently received by the constant current chip, and the constant current chip is connected to the light emitting diode lamp, thereby realizing brightness adjustment of the light emitting diode.

The voltage regulating circuit of the embodiment can be applied to dimming of the light emitting diode, the output end of the voltage regulating circuit is connected with the constant current chip, and the output end of the constant current chip is connected with the light emitting diode; the constant current chip adopts TPS92641/TPS92640, the output end of the voltage regulating circuit is connected with the 6 th pin of the chip, and the voltage change regulates the output current change at the rear end, so that the brightness of the light-emitting diode lamp is automatically regulated. On the other hand, the voltage regulating circuit of the embodiment is simple and universal in component device, can adopt a plurality of voltage regulating circuits to be connected in parallel, and is connected with a plurality of light emitting diodes after being connected with a constant current chip, so that the adjustment of the multicolor lamp is realized. In a similar way, the voltage regulating circuit of the application not only comprises the field of light emitting diode regulation, but also is applicable to various circuits needing voltage regulation. The method solves the problems of high cost and small output voltage range of the DAC chip, realizes cost control and simplification of a control mode by adopting discrete elements and a simple PWM control mode, and meets the output requirement of a large voltage range; the diversity of the voltage control mode enlarges the application field range of the circuit. In the aspect of dimming application, the service life of the light emitting diode is better improved in a mode of continuously changing current compared with an intermittent dimming circuit.

The above description is only an example of the present application and is not intended to limit the scope of the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Moreover, it is noted that, in this document, relational terms such as "first," "second," "third," and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Claims

1. A voltage regulating circuit is characterized by comprising a first unit, a second unit and a third unit for changing the working states of the first unit and the second unit;

2. The voltage regulation circuit of claim 1, wherein when the switch of the third unit is turned off, and the first input signal level of the first unit is active, the voltage at the output terminal of the second unit or the third unit is V _ OUT — K1 — VREF, and when the first input signal level of the first unit is inactive, the voltage at the output terminal of the second unit or the third unit is V _ OUT — K2 — VREF, VREF represents the reference voltage of the second unit, K1 represents the voltage division coefficient calculated by the resistors in the first unit and the second unit, and K2 represents the voltage division coefficient calculated by the resistors in the second unit.

3. The voltage regulator circuit according to claim 2, wherein the first unit comprises an isolation element, the first unit is connected in parallel with the second unit when the isolation element is turned on, and the first unit is isolated from the second unit when the isolation element is turned off.

4. The voltage regulating circuit according to claim 3, wherein the isolation element is a triode or a MOS tube; and the switching tube of the third unit adopts a triode or an MOS tube.

5. The voltage regulating circuit according to claim 1, wherein when the first input signal level of the third unit is active, the third unit outputs a minimum voltage Vmin; when the first input signal level of the third unit is invalid, the third unit output voltage V _ OUT is K3 VREF, VREF represents the reference power supply of the second unit, and K3 represents the voltage division coefficient calculated by the resistors in the first unit and the second unit or represents the voltage division coefficient calculated by the resistor in the second unit.

6. The voltage regulating circuit according to claim 1, wherein the first unit comprises an isolating element, a second resistor and a third capacitor, when the isolating element is a first triode, the base of the first triode is connected with a first input signal, the emitter of the first triode is grounded, the collector of the first triode is connected with one end of the second resistor, the other end of the second resistor is connected with one end of the third capacitor, the other end of the third capacitor is grounded, and the other end of the second resistor and one end of the third capacitor are connected and then connected with the output end of the second unit.

7. The voltage regulator circuit according to claim 6, wherein the second resistor and the first triode form a loop in parallel with the second unit when the input signal of the third unit is inactive and the input signal of the first unit is active, and the voltage of the output terminal of the third unit is lower than the voltage of the output terminal of the second unit

8. The voltage regulating circuit according to claim 1, wherein the second unit comprises a reference power supply, a third resistor and a fifth resistor, the reference power supply is connected with one end of the third resistor, the other end of the third resistor is connected with one end of the fifth resistor, the other end of the fifth resistor is grounded, and the other end of the third resistor and one end of the fifth resistor are respectively connected with the output end of the first unit and the output end of the third unit.

9. The voltage regulating circuit according to claim 1, wherein when the switching tube is a triode, the third unit comprises a first resistor and a second triode, one end of the first resistor is connected to the output end of the second unit, the other end of the first resistor is connected to the collector of the second triode, the base of the second triode is connected to the second input signal, and the emitter of the second triode is grounded.

10. The voltage regulating circuit according to claim 1, wherein the first unit comprises a first stage first unit and a second stage first unit, the first stage first unit and the second stage first unit are connected in parallel, the output ends of the first stage first unit and the second stage first unit are both connected with the output end of the second unit, the input end of the first stage first unit is connected with the first PWM signal, and the input end of the second stage first unit is connected with the second PWM signal.

11. The voltage regulating circuit according to claim 1, wherein the third unit comprises a first stage third unit and a second stage third unit, the first stage third unit and the second stage third unit are connected in parallel, the output ends of the first stage third unit and the second stage third unit are both connected with the output end of the second unit, the input end of the first stage third unit is connected with the first level signal, and the input end of the second stage third unit is connected with the second level signal.

12. The voltage regulating circuit according to claim 1, wherein the second unit comprises a first-stage second unit and a second-stage second unit, the first-stage second unit and the second-stage second unit are connected in parallel, the third unit comprises a first-stage third unit and a second-stage third unit, an input end of the first-stage second unit is connected with an output end of the first unit, an output end of the first-stage second unit is connected with the first-stage third unit, an input end of the second-stage second unit is connected with an output end of the first unit, and an output end of the second-stage second unit is connected with the second-stage third unit.

13. The voltage regulating circuit according to claim 1, wherein the first unit comprises an isolating element, a second resistor and a third capacitor, when the isolating element adopts a first MOS transistor, the gate of the first MOS transistor is connected to the first input signal, the source of the first MOS transistor is grounded, the drain of the first MOS transistor is connected to one end of the second resistor, the other end of the second resistor is connected to one end of the third capacitor, the other end of the third capacitor is grounded, and the other end of the second resistor and one end of the third capacitor are connected to the output end of the second unit.

14. The voltage regulating circuit according to claim 1, wherein when the switching tube is an MOS tube, the third unit includes a first resistor and a second MOS tube, one end of the first resistor is connected to the output end of the second unit, the other end of the first resistor is connected to the drain of the second MOS tube, the gate of the second MOS tube is connected to the second input signal, and the source of the second MOS tube is grounded.

15. The voltage regulating circuit according to claim 1, wherein the first unit output terminal is connected to a third unit output terminal, the third unit output terminal is connected to a second unit output terminal, and the second unit output terminal outputs a regulating voltage;

16. A dimming circuit is characterized by comprising a constant current chip, a light emitting diode and a voltage regulating circuit, wherein the voltage regulating circuit adopts the voltage regulating circuit of claims 1-15, the output end of the voltage regulating circuit is connected with the input end of the constant current chip, and the output end of the constant current chip is connected with the light emitting diode.