TW201528874A - Control circuit and control method for light-emitting diode module, and light-emitting diode device - Google Patents

Abstract

Control techniques for light-emitting diode module are disclosed. A current sensor generates a feedback current between a difference calculation node and a ground terminal based on light emission of a light-emitting diode module. A reference current generator outputs a reference current to be coupled to the difference calculation node via a control switch that is for a current difference calculation. The control switch for the current difference calculation is turned on and off synchronously with an output current control switch within the light-emitting diode module. A filter has an input terminal that is coupled to the difference calculation node. A pulse signal generator generates a pulse-width modulation signal whose duty cycle is adjusted in accordance with a signal at an output terminal of the filter. The output current control switch is turned on and off in accordance with the pulse signal and thereby the light emission of the light-emitting diode module reaches to a level corresponding to the current level of the reference current.

Description

Light-emitting diode module control circuit and control method, and light-emitting diode device

The embodiment of the present invention relates to a control circuit and a control method for a Light-Emitting Diode (LED) module, and a light-emitting diode device including the LED module and the control circuit.

Light-emitting diodes are commonly used light-emitting semiconductor electronic components. Generally, a plurality of LEDs are used in series, and the current flowing thereon determines the amount of light, which can be adjusted by pulse width modulation (PWM).

An important subject in the art is to implement the above pulse width modulation with a low price and simple architecture.

The embodiment of the present invention discloses a control circuit and a control method for a light emitting diode module, and a light emitting diode device including the light emitting diode module and the control circuit.

A light-emitting diode module control circuit implemented according to an embodiment of the present invention includes: a current sensor; a reference current source; a current difference calculation control switch; a filter; and a pulse generator. Current sensing The device generates a feedback current according to the amount of illumination of a light-emitting diode module, and is reflected between a feedback operation connection point and a ground end. The reference current source outputs a reference current coupled to the feedback calculation connection point by the current difference calculation control switch. The current difference calculation control relationship is started and closed synchronously with a current control switch in the LED module. The filter has an input coupled to the feedback connection point and has an output. The pulse generator is configured to generate a pulse width modulation signal whose duty cycle is adjusted with the signal at the output end of the filter to control activation and deactivation of the current control switch in the LED module. The amount of illumination of the LED module reaches the setting corresponding to the reference current.

In this case, a further embodiment discloses a light-emitting diode package. The device includes the above-mentioned light emitting diode module and the LED module control circuit.

Light-emitting diode module realized according to an embodiment of the present invention The control method includes: generating, by a current sensor, a feedback current according to the illuminating quantity of the LED module, reflected between a feedback operation connection point and a ground end; and outputting a reference by using a reference current source The current is controlled by a current difference calculation control switch coupled to the feedback operation connection point, and the current difference calculation control open relationship is started and closed synchronously with a current control switch in the LED module; a filter, wherein the filter has an input coupled to the feedback connection point and has an output; and a pulse generator generates a pulse whose duty cycle is adjusted with a signal at the output of the filter And a width modulation signal for controlling activation and deactivation of the current control switch in the LED module, so that the illumination quantity of the LED module reaches a setting corresponding to the reference current.

The invention is described in detail below with reference to the accompanying drawings.

100‧‧‧Lighting diode device

102‧‧‧Lighting diode module

104‧‧‧Lighting diode

106‧‧‧Inductance

108‧‧‧ diode

110‧‧‧current control switch

112‧‧‧ Current Sensor

114‧‧‧ Current difference calculation control switch

116‧‧‧ Filter

118‧‧‧Pulse generator

120‧‧‧Resistance-Controlled Current Generator

122, 126‧‧‧Operational Amplifier

124‧‧‧N type gold oxide half field effect transistor

128‧‧‧RS forward and reverse

130‧‧‧buffer

A1, A2‧‧‧I_sense, I_adj integral amount in working area Ton C1, C2‧‧‧ capacitor

D, S, G‧‧‧N-type gold-oxygen half-field effect transistor, drain, source, gate I_adj‧‧‧ reference current (source)

I_adj_nf‧‧‧ calculates the reference current after the current switch is controlled by the current difference

I_out‧‧‧ Current output from the source S of the current control switch 110

I_sense‧‧‧Responding current

nL1, nL2‧‧‧ first and second ends of the inductor 106

R, Rs‧‧‧ resistance

S302...S308‧‧‧Steps

SW_on‧‧‧ pulse width modulation signal

Ton‧‧ working area

VIN‧‧‧ power supply

Vref‧‧‧ reference potential

1 is a diagram showing a light emitting diode device 100 according to an embodiment of the present invention; and FIG. 2 is a view showing a signal waveform of the first FIG. The value of the reference current I_adj will determine the amount of illumination of the LED module 102; and FIG. 3 is a flow chart illustrating a method of controlling the LED module 102 according to the architecture of FIG.

The following description sets forth various embodiments of the invention. The following description sets forth the basic concepts of the invention and is not intended to limit the invention. The scope of the actual invention shall be defined in accordance with the scope of the patent application.

1 illustrates a light emitting diode device 100 including a light emitting diode module 102 according to an embodiment of the present invention, and other components in the figure belong to a light emitting diode module control circuit.

The LED module 102 includes a plurality of LEDs 104 connected in series, an inductor 106, a diode 108, and a current control switch 110. The current control switch 110 is an N-type gold-oxygen half-field effect transistor (not intended to be limited to operation only by this element), the gate G thereof can be a control end, and the two connection ends thereof are the drain D and the source S. . The drain D of the current control switch 110 can be coupled to the first end nL1 of the inductor 106. The light emitting diodes 104 are connected in series between a power source VIN and a second terminal nL2 of the inductor 106. The diode 108 has an anode coupled to the inductor 106 The first end nL1 has a cathode coupled to the power source VIN. The gate G of the current control switch 110 is configured to receive the pulse width modulation signal SW_on to control the light emission state of the light emitting diodes 104, and determine the amount of light emitted by the light emitting diode module 102.

The other parts of FIG. 1 further show the disclosed LED module control circuit, comprising: a current sensor 112; a reference current source I_adj; a current difference calculation control switch 114; a filter 116; A pulse generator 118.

The current sensor 112 generates a feedback current I_sense (I_sense=I_out/K, I_out is the current output by the source S of the current control switch 110) according to the amount of illumination of the LED module 102, which is reflected in A feedback operation is between the connection point nf and a ground terminal (GND). One embodiment uses a current mirror technique to generate a current of I_out/K value at a mirroring ratio of 1/K (eg, designing the aspect ratio of the current mirror transistor) as the feedback current I_sense. The reference current source I_adj can output a reference current (also denoted by I_adj). The current difference calculation control switch 114 is coupled to the feedback operation connection point nf. The current difference calculation control switch 114 can be started and turned off synchronously with the current control switch 110 in the LED module 102; for example, both are controlled by the pulse width modulation signal SW_on. As a result, the amount of current actually flowing into the feedback calculation connection point nf by the reference current I_adj is I_adj_nf. The filter 116 has an input coupled to the feedback connection point nf and has an output. The input of the filter 116 filters the current difference (I_adj_nf-I_sense). The pulse generator 118 can be configured to generate a pulse width modulation signal (ie, SW_on) whose duty cycle is adjusted with the signal at the output of the filter 116 to control the light-emitting diode module 102. The current control switch 110 is turned on and off, so that the amount of light emitted by the LED module 102 reaches the setting corresponding to the reference current I_adj.

In this case, the case can collect the feedback signal in the form of current, that is, the current I_sense is returned. In addition, the sensed feedback current I_sense may be first calculated by the difference (I_adj_nf-I_sense) (or (I_sense-I_adj_nf)) of the current I_adj_nf after the pulse width modulation signal SW_on is switched, and then the difference value (I_adj_nf- I_sense) (or (I_sense-I_adj_nf)) for filtering. In the past, the current collected is first converted into a voltage through a set resistor, and then compared to a reference voltage through a comparator. In another conventional method, the resistor is a high-standard sensing resistor (Rsense) for sensing the current flowing through the LED (LED), and the sensing resistor (Rsense) at this time. The current of about 1 ampere (A) needs to be sensed, so the ability to withstand current needs to be high, so the price of the sense resistor (Rsense) is very expensive. However, since the current can be directly collected and the current is calculated in this case, in this case, it is not necessary to additionally provide a resistor and a comparator, so that the process of performing the difference calculation and then filtering in the form of current can make the light-emitting diode of the present case The pulse width modulation control architecture of the module 102 is simple, saves the cost of configuring the comparator and the resistor, and reduces power loss.

In an embodiment, the ratio K of the current I_out output by the current control switch 110 relative to the feedback current I_sense can be set such that the feedback current I_sense is controlled at a microamperes (uA) level. For example, the K value may be 2000x56, such that when the current I_out is 1120 mA, the feedback current I_sense is 10 uA, which is a microampere rating. As such, the filter 116 can be implemented with low cost components. In addition, the reference current I_adj outputted by the reference current source I_adj can thus be controlled at such a microampere level as 10uA, and the reference current I_adj can also be used in a low-cost circuit frame. Constructed. In addition, since the feedback signal is collected by the permeable current, and the feedback current I_sense is in the micro ampere level, the power loss can be reduced.

As shown, filter 116 is a low pass filter that includes capacitors C1, C2 and resistor R. The capacitor C1 is coupled to the input end of the filter 116 to the ground. The capacitor C2 is coupled to the output of the filter 116 to the ground. A resistor R is coupled between the input of the filter 116 and the output. The implementation of the filter 116 is not limited to that shown in FIG. 1, and can be implemented in other circuit configurations.

As shown, the reference current I_adj outputted by the reference current source I_adj is mirrored from a resistance-controlled current generator 120. The resistance control type current generator 120 includes an operational amplifier 122, a resistor Rs, and an N-type MOS field effect transistor 124. The operational amplifier 122 has a positive input (reference '+') that receives a reference potential Vref and has a negative input (reference '-') and an output. The resistance value of the resistor Rs is also denoted as Rs for inputting the negative terminal of the operational amplifier 122 '-' to ground. The N-type MOS field-effect transistor 124 has a drain D coupled to a power supply, a gate G coupled to the output of the operational amplifier 122, and a source S coupled to the negative terminal of the operational amplifier 122. Enter '-'. The reference current I_adj output by the reference current source I_adj is proportional to the current value Vref/Rs (for example, mirrored from the resistance-controlled current generator 120 using a current mirror technique). With this architecture, the resistor Rs can be designed to be a ohm-ohm grade, such as 100K ohms, which is a relatively inexpensive component. In other considerations, the resistance control type current generator 120 of FIG. 1 can be implemented by other circuit configurations.

This paragraph discusses the architecture of pulse generator 118, which may include an operational amplifier 126, an RS flip-flop 128, and a buffer 130. The operational amplifier 126 has a positive input (label '+') to receive a triangular reference wave, a negative terminal An input (reference '-') is coupled to the output of the filter 116 and has an output. The RS flip-flop 128 is coupled to the output of the operational amplifier 126 by a reset input (reference 'R') and coupled to the input of the buffer 130 with an output (reference 'Q'). The output end of the buffer 130 is supplied with the pulse width modulation signal SW_on to the control terminal G of the current control switch 110. The current control switch 110 can be located in the LED module 102. The higher the amount of DC filtered by the filter 116 (which is output through the output of the filter 116), the longer the duty cycle of the pulse width modulation signal SW_on. In particular, the pulse generator 118 of FIG. 1 can be implemented in other circuit configurations.

Taking the filter 116 as an example, it filters the current difference value (I_adj_nf-I_sense) (or (I_sense-I_adj_nf)) to output a DC reference wave in which the DC portion is supplied to the positive terminal of the operational amplifier 126 and the positive terminal of the operational amplifier 126. . The larger the difference between the feedback current I_sense and the target set value, the larger the current difference (I_adj_nf-I_sense) (or (I_sense-I_adj_nf)), the higher the DC portion filtered by the filter 116, the less likely the output of the operational amplifier 126 is The reset input end of the RS flip-flop 128 (reference numeral 'R') is moved, so that the longer the duty cycle of the pulse width modulation signal SW_on is, the light-emitting time of the light-emitting diode 104 is increased, and the amount of illumination set by the reference current I_adj is approached. .

Figure 2 illustrates a signal waveform illustrating the architecture of Figure 1. The value of the reference current I_adj determines the amount of illumination of the LED module 102. Since the current difference calculation control switch 114 can be turned on and off with the high and low levels of the pulse width modulation signal SW_on, the current amount of the reference current I_adj actually flowing into the feedback operation connection point nf is I_adj_nf. The LED module control circuit disclosed in the embodiment of the invention can adjust the working interval of the pulse width modulation signal SW_on Ton, the integral value A1 of the feedback current I_sense in the range of the working range Ton is equal to the integral value A2 of the reference current I_adj in the range of the working range Ton. When the above conditions are satisfied, the amount of light emitted by the LED module 102 can correspond to the setting of the reference current I_adj.

FIG. 3 is a flow chart showing a control method of the LED module 102 according to the structure of FIG. In step S302, the current sensor 112 generates a feedback current I_sense according to the amount of light emitted by the LED module 102, and is reflected between the feedback operation connection point nf and a ground end. This embodiment further relates to the reference current source I_adj outputting the reference current I_adj. The reference current I_adj may be coupled to the feedback operation connection point nf by the current difference calculation control switch 114 such that the amount of current actually flowing into the feedback operation connection point nf is I_adj_nf, wherein the current difference calculation control switch 114 is The current control switch 110 in the LED module 102 is turned on and off by the pulse width modulation signal SW_on. Step S304 is for calculating the current difference value (I_adj_nf-I_sense). Step S306 may filter the current difference value (I_adj_nf-I_sense) through the filter 116. Step S308, the pulse generator 118 generates a pulse width modulation signal SW_on adjusted by the signal on the output end of the filter 116 through the pulse generator 118 to control the current control switch in the LED module 102. The activation and deactivation of 110 enables the illuminating amount of the illuminating diode module 102 to reach a setting corresponding to the reference current I_adj output by the reference current source I_adj. The flow shown in Figure 3 is normally performed in a loop mode. After step S308, the flow returns to step S302. As discussed above, the embodiment of the present invention (for example, the LED module control circuit of FIG. 1 or the LED module control method of FIG. 3) does not need to have a resistor (for example, a high price). /Specsal resistance (Rsense) for current-voltage conversion of large current, but directly for current Collect and current calculations (eg, steps S302...S306). The process of performing the feedback calculation and then filtering in the form of current can make the pulse width modulation control structure of the LED module simple, save the cost of configuring the comparator and the resistor, and reduce the power loss.

While the invention has been described above by way of example, the invention is not intended to be construed as limiting the scope of the invention.

100‧‧‧Lighting diode device

102‧‧‧Lighting diode module

104‧‧‧Lighting diode

106‧‧‧Inductance

108‧‧‧ diode

110‧‧‧current control switch

112‧‧‧ Current Sensor

114‧‧‧ Current difference calculation control switch

116‧‧‧ Filter

118‧‧‧Pulse generator

120‧‧‧Resistance-Controlled Current Generator

122‧‧‧Operational Amplifier

124‧‧‧N type gold oxide half field effect transistor

126‧‧‧Operational Amplifier

128‧‧‧RS forward and reverse

130‧‧‧buffer

C1, C2‧‧‧ capacitor

D, S, G‧‧‧N-type gold oxide semi-transistor, drain, source, gate

I_adj‧‧‧reference current (source)

I_adj_nf‧‧‧Switch 114 adjusted reference current

I_out‧‧‧ Current output from the source S of the current control switch 110

I_sense‧‧‧Responding current

nL1, nL2‧‧‧ first and second ends of the inductor 106

R, Rs‧‧‧ resistance

SW_on‧‧‧ pulse width modulation signal

VIN‧‧‧ power supply

Vref‧‧‧ reference potential

Claims (14)

A light-emitting diode module control circuit includes: a current sensor, generating a feedback current according to a light-emitting amount of a light-emitting diode module, reflected between a feedback operation connection point and a ground end; a reference current source and a current difference calculation control switch, wherein the reference current source outputs a reference current to be coupled to the feedback calculation connection point by the current difference calculation control switch, and the current difference calculation control is turned on The relationship is started and closed synchronously with a current control switch in the LED module; a filter having an input coupled to the feedback connection point and having an output; and a pulse generator for generating a pulse width modulation signal adjusted by a signal on the output end of the filter to control activation and deactivation of the current control switch in the LED module to enable the LED module The amount of illuminance reaches the setting corresponding to the reference current. The illuminating diode module control circuit of claim 1, wherein: the feedback current generated by the current sensor and reflected between the feedback computing connection point and the ground end It is one-k of the current output by the current control switch of the light-emitting diode module; the K value is such that the feedback current is controlled at the microampere level. The light-emitting diode module control circuit of claim 1, wherein: the reference current source outputs the reference current mirrored from a resistance-controlled current generator; and the resistance-controlled current generation The device includes: An operational amplifier having a positive terminal input receiving a reference potential Vref and having a negative terminal input and an output terminal; a resistor having a resistance value Rs, the negative terminal input of the operational amplifier being grounded; and an N-type gold An oxygen half field effect transistor having a drain coupled to a power supply, a gate coupled to the output of the operational amplifier, and a source coupled to the negative input of the operational amplifier; and the reference current source output The reference current is proportional to the current value Vref/Rs. The illuminating diode module control circuit of claim 3, wherein the resistor has a resistance value Rs of 仟 ohms. The light-emitting diode module control circuit of claim 1, wherein the filter is a low-pass filter. The illuminating diode module control circuit of claim 5, wherein the filter comprises: a first capacitor coupled between the input end of the filter and the ground; a second capacitor And coupling the output end of the filter to the ground end; and a resistor coupled between the input end of the filter and the output end. The light-emitting diode module control circuit of claim 1, wherein the pulse generator comprises: an operational amplifier having a positive-end input receiving a triangular reference wave and a negative-end input coupled to the filter The output end and an output end; An RS-reactor having a reset input coupled to the output of the operational amplifier; and a buffer having an input coupled to the output of the RS flip-flop and having an output coupled to the output The control terminal of the current control switch in the LED module. A light-emitting diode device comprising: the light-emitting diode module control circuit according to claim 1; and the light-emitting diode module controlled by the light-emitting diode module control circuit. The illuminating diode device of claim 8, wherein the illuminating diode module comprises: the current control switch; an inductor having a first end coupled to a connecting end of the current control switch And having a second end; a plurality of light emitting diodes connected in series between a power source and the second end of the inductor; and a diode having an anode coupled to the first end of the inductor, And having a cathode coupled to the power source. A method for controlling a light-emitting diode module includes: generating, by a current sensor, a feedback current according to a light-emitting amount of a light-emitting diode module, which is reflected between a feedback operation connection point and a ground end; And outputting a reference current by a reference current source, wherein the reference current is coupled to the feedback operation connection point by a current difference calculation control switch, and the current difference is The value calculation control relationship is started and closed synchronously with a current control switch in the LED module; a filter is provided, wherein the filter has an input coupled to the feedback connection point and has an output end And a pulse width modulation signal that is adjusted by a pulse generator with a signal on the output end of the filter to control activation and deactivation of the current control switch in the LED module. The illuminating amount of the illuminating diode module is set to correspond to the reference current output by the reference current source. The method for controlling a light-emitting diode module according to claim 10, wherein: the feedback current system reflected between the feedback calculation connection point and the ground end and the current difference calculation control switch The reference current coupled to the feedback connection point is coupled to the input of the filter. The method for controlling a light-emitting diode module according to claim 10, further comprising: causing the current sensor to generate and reflect the feedback between the feedback operation connection point and the ground end The current is one-k of the current output by the current control switch of the LED module; wherein the K value is such that the feedback current is controlled at a microampere level. The method for controlling a light-emitting diode module according to claim 10, further comprising: causing the reference current source outputted by the reference current source to be mirrored from a resistance-controlled current generator. The method for controlling a light-emitting diode module according to claim 10, comprising implementing the filter with a low-pass filter.