CN201001215Y - A sound and light control constant current LED lighting lamp - Google Patents

Abstract

The utility model discloses a sound-light control constant-current LED lighting lamp, which comprises an LED array, an AC/DC conversion rectification circuit and a control circuit, wherein the control circuit is composed of a sound-light control circuit and a PWM voltage/current converter. The feature is that the output end of the sound and light control circuit is connected with the pulse output enabling pin (PWM_D) of the HV series PWM control chip (HV9910) in the PWM voltage/current converter. The LED lighting lamp of the utility model has the following remarkable effects: 1. It is directly powered by AC 220V mains, which can directly replace the existing sound and light control corridor lights; 2. Wide voltage (AC90-265V) constant current drive, and the current is continuous , The ripple coefficient is small, the LED has high luminous efficiency and long life; 3. All control circuits are powered by the DC power supply provided by the HV series PWM control chip, the circuit is obviously simplified, and the power saving is remarkable.

Description

A sound and light control constant current LED lighting lamp

technical field

The utility model relates to a circuit device for a general electric light source, in particular to a sound and light control LED lighting lamp.

Background technique

The advent of high-brightness and high-power LEDs has brought new opportunities for the development of electric light sources. Due to the non-linear I-V characteristics of LEDs, a small change in the forward voltage VF will also cause a large change in the forward current IF, which can shorten the life of the LED, reduce the brightness of the LED, and burn the LED if it is serious. Therefore, various constant current drives The programs have been launched successively. Among them, the more successful one is the HV series PWM driver chip launched by Supertex Corporation of the United States. With this chip as the core, a simple peripheral circuit configuration can be connected to a PWM constant current control circuit, and then combined with a voltage/current conversion circuit to drive LEDs with constant current. The product brochure published by Supertex Company of the United States discloses a specific solution, in which the main circuit of the voltage/current conversion circuit is composed of an LED array, an inductor, a power field effect tube, and a current sampling resistor connected in series, and the LED array is connected in parallel with the inductor in series. The freewheeling diode on the loop feeds the electric energy stored in the inductor to the LED when the power field effect tube is closed for half a cycle, thereby providing continuous DC power for the LED; furthermore, a capacitor is connected in parallel to the LED array to smooth the output current , to reduce the current ripple factor. However, the technical solution mentioned in the product manual does not involve the control of the LED power supply, and still cannot meet the requirements of avoiding permanent lights, needing to be off during the day, light on with noise at night, and light off without noise (such as corridors, public toilets, etc.).

A utility model patent for a "voice-activated step light with light-emitting diodes as light source" (notification number: 2702577) authorized and announced by the State Intellectual Property Bureau on May 25, 2005. One of the embodiments of the patented solution is a joint control scheme of sound and light, which consists of a sound sensor, an amplifier, a light control circuit, a single-chip microcomputer and multiple groups of LED connections. When the ambient light is dark, the light control circuit outputs a high level , the sound signal received by the sensor is amplified and sent to the single chip microcomputer for processing and output high level to drive one or more groups of control electronic switches to make the LED light; when the ambient light is bright, the light control circuit outputs low level, the sensor The received sound signal is amplified and then sent to the single chip microcomputer for processing and outputting a low level, and the electronic switch remains off. It can be seen that although this patented scheme can carry out joint control of sound and light to avoid the constant lights in the corridor, it has the following disadvantages: 1. There is no AC/DC conversion circuit, which is not suitable for direct AC power supply; 2. There is neither voltage regulation nor constant DC power supply, the brightness of the LED fluctuates with the power supply, if the power supply voltage is too high, it will affect the life of the LED.

A utility model patent for "LED Sound and Light Control Emergency Corridor Light" (No. 2753092) authorized and announced by the State Intellectual Property Bureau on January 18, 2006. The main difference between this patent scheme and the above-mentioned patent is that the single-chip microcomputer for AND processing is replaced with a NAND gate circuit, so that the circuit cost is reduced, but it is obvious that there are still deficiencies in the 2702577 patent scheme.

Contents of the invention

In view of the above disadvantages in the prior art, the purpose of this utility model is to provide an improved sound and light control LED lighting lamp, which not only can be directly powered by AC or DC high voltage, but also has high luminous efficiency and long life.

The technical solution that the present invention realizes above-mentioned purpose is:

A sound and light control constant current LED lighting lamp, which includes an LED array, an AC/DC conversion and rectification circuit and a control circuit, wherein the control circuit is composed of a sound and light control circuit and a PWM voltage/current converter, and is characterized by sound, light The output terminal of the light control circuit is connected with the pulse output allowing pin PWMD of the HV series PWM control chip in the PWM voltage/current converter.

The PWM voltage/current converter described in the utility model is mainly composed of a main circuit and a control circuit, wherein the main circuit is composed of an LED array, an inductor, a power field effect tube and a current sampling resistor connected in series in sequence, and a current smoothing filter capacitor is connected in parallel with the LED On the array, a Schottky freewheeling diode is connected in parallel on the loop of the LED array and the inductor in series; the control circuit is composed of HV series PWM chips and their peripheral components, in which the current feedback pin CS of the HV series PWM chips and the upper end of the current sampling resistor Connection, the PWM output pin GATE is connected to the control pole of the power FET. The PWM voltage/current converter is a known technology, and those skilled in the art can refer to the product specification of the HV series PWM type DC-DC step-down conversion dedicated IC published by Supertex Corporation of the United States to carry out deformation design.

The sound and light control circuit of the utility model can be designed with reference to the utility model patent scheme whose authorized announcement number is 2753092.

In the sound-light control constant-current LED lighting lamp described in the utility model, the power supply input ends of the sound-light control circuit are respectively connected to the power supply voltage pin V _DD of the HV series PWM control chip in the PWM voltage/current converter. Connect to common ground GND. Furthermore, a current-limiting resistor is connected in series between the positive pole of the power input terminal of the sound and light control circuit and the supply voltage pin (V _DD ) of the HV series PWM control chip in the PWM voltage/current converter, and the current-limiting resistor is connected to the ground. An energy storage capacitor is bridged to form a power circuit of the sound and light control circuit. Its purpose is not only to ensure the instantaneous high-current operation of the sound and light control circuits, but also to ensure the stable operation of the HV series PWM control chip.

Compared with the prior art, the utility model has the following advantages:

1. Directly powered by AC 220V city electricity, it can directly replace the existing sound and light control corridor lights;

2. Wide voltage (AC90～265V) constant current drive, continuous current, small ripple coefficient, high luminous efficiency and long life of LED;

3. All the control circuits in the further improvement scheme of the utility model are powered by the DC power supply provided by the HV series PWM control chip, which not only greatly simplifies the circuit of the whole device, but also significantly saves electric energy.

Description of drawings

Fig. 1 is the electric schematic diagram of a kind of specific embodiment of PWM voltage/current converter described in the utility model;

Fig. 2 is an electrical schematic diagram of a specific embodiment of the sound and light control circuit described in the present invention.

Detailed ways

Fig. 1 and Fig. 2 are the electrical schematic diagram of a specific embodiment of the sound and light control constant current LED lighting lamp described in the utility model, wherein Fig. 1 is the electrical schematic diagram of the PWM voltage/current converter, and Fig. 2 is the acoustic 1. The electrical schematic diagram of the light control circuit, the same-named ends of the two circuits shown in Fig. 1 and Fig. 2 are connected.

Referring to Fig. 1, the AC/DC conversion and rectification circuit is composed of a full bridge B1, filter capacitors C1 and C2. The PWM voltage/current converter is mainly composed of a main circuit and a control circuit, wherein the main circuit is composed of an LED array, an inductor L, an N-channel power type field effect transistor Q1 and a current sampling resistor Rfb connected in series in sequence, and a current smoothing filter The capacitor Co is connected in parallel to the LED array, and a Schottky freewheeling diode D1 is connected in parallel to the loop of the LED array and the inductor L in series; the control circuit is composed of the PWM chip HV9910 and its peripheral voltage stabilizing capacitor C3 and the pulse frequency adjustment resistor Rosc. The current feedback pin CS of the PWM chip HV9910 is connected to the upper end of the current sampling resistor Rfb, and the PWM output terminal GATE is connected to the control pole of the N-channel power field effect transistor Q1. The specific working process of the circuit shown in Figure 1 is as follows:

After the voltage is rectified by the rectifier bridge B1 (if it is powered by DC mode, the rectifier circuit can also be _omitted ), it is filtered by capacitors C1 and C2 to form a DC voltage. The device provides the working voltage V _DD for HV9910. When the PWM_D pin of HV9910 is high level, HV9910 is allowed to generate a fixed switching frequency on the GATE pin by the frequency setting resistor Rosc on the RT pin and the internal oscillator capacitor. The PWM pulse is output, and the duty cycle of the PWM pulse is adjusted by comparing the feedback voltage on the CS pin with the internal constant reference voltage Vref. When the PWM pulse voltage output by HV9910 is applied to the gate level of N-channel power field effect transistor Q1, the LED array is lit. When the gate-level voltage of Q1 is at a high level, Q1 is turned on, and the DC voltage starts to be across the LED array and the inductor L, and the LED array is lit by the electric energy provided by the power supply, and the inductor L stores electric energy at the same time; when the gate-level voltage of Q1 When the level is low, Q1 is turned off, and the energy stored in the inductor L continues to provide current to the LED array through the fast recovery Schottky freewheeling diode D1. It can be seen that no matter in the positive half cycle or the negative half cycle of the PWM pulse, there is a pulsating voltage applied to both ends of the LED array. After the voltage is smoothed by the capacitor Co, the LED array can obtain a continuous and smooth current. Since the LED array always works in a continuous constant current mode, it is not only beneficial to improve the luminous efficiency of the LED, but also beneficial to prolong the service life of the LED.

Referring to Fig. 2, the described sound and light control circuit is made up of a power supply circuit, an acoustic-electric converter, a photoelectric converter, an audio amplifier, an AND-non-logic circuit, and a delay output circuit. Among them, the power circuit is composed of a current limiting resistor R1 connected to the power supply voltage pin V _DD of HV9910 and an energy storage capacitor C4 connected between the current limiting resistor R1 and the ground; the acoustic-electric converter consists of an electret microphone MIC The photoelectric converter is composed of resistor R4 and photoresistor RG in series; the audio amplifier is mainly composed of a NAND gate CD4011A, a DC blocking capacitor connected in series at the input end of CD4011A, and a feedback resistor R3 connected across the input and output ends of CD4011A; and - The non-logic circuit is served by the NAND gate CD4011B; the delay output circuit is composed of the NAND gate CD4011C and the diode D2 connected in series between the output terminal of CD4011B and the input terminal of CD4011A, and connected across the current limiting resistor R1 and the energy storage capacitor C4 Composed of resistor R6 and capacitor C8 between the point and the CD4011C input. The working process of the circuit shown in Figure 2 is as follows:

At night (when the ambient light is dark), the series junction of resistor R4 and photoresistor RG always outputs a high level, that is, the next input terminal of the NAND gate CD4011B is high level. changes with changes in the input level at the terminal. Once there is a sound (such as human footsteps), the sound is converted into an audio signal by the electret microphone MIC, which is amplified by the audio amplifier composed of CD4011A and sent to the other input terminal of CD4011B, so that CD4011B outputs a pulsating AC signal. Then charge the energy storage capacitor C1 through D2 until the CD4011C flips the level, and the CD4011C outputs a high level and sends it to the pulse output enable pin PWM_D of the HV9910 in the circuit shown in Figure 1, so that the PWM voltage/current converter works and lights up LED array. After the sound is over, the capacitor C8 is discharged through the resistor R6, and when CD4011C flips the level, the LED goes out, waiting for the next sound.

During the day (when the ambient light is bright), the series node of the resistor R4 and the photoresistor RG always outputs a low level, that is, the lower input terminal of the NAND gate CD4011B is low level, and at this time the input voltage of the upper input terminal of the CD4011B is low. Whether it is high level or low level, CD4011B always outputs high level, that is, no matter whether there is sound or not, CD4011B always outputs high level, CD4011C can never turn over, keep low level output, and the LED array is always in the off state.

Claims (3)

1. A sound and light control constant current LED lighting lamp, which includes an LED array, an AC/DC conversion and rectification circuit and a control circuit, wherein the control circuit is composed of a sound and light control circuit and a PWM voltage/current converter, and is characterized in that The output end of the sound and light control circuit is connected with the pulse output enabling pin (PWM_D) of the HV series PWM control chip (HV9910) in the PWM voltage/current converter. 2. The sound-light control constant current LED lighting lamp according to claim 1, characterized in that the power supply input terminals of the sound-light control circuit are respectively connected with the HV series PWM control in the PWM voltage/current converter. The power supply voltage pin (V _DD ) of the chip (HV9910) is connected to the common ground (GND). 3. According to claim 2, a sound-light control constant-current LED lighting lamp is characterized in that the positive pole of the power input end of the sound-light control circuit is connected to the HV series PWM control chip (HV9910) in the PWM voltage/current converter. ) between the power supply voltage pins (V _DD ) in series with a current-limiting resistor (R1), and the current-limiting resistor (R1) is connected across the ground with an energy storage capacitor (C1) to form a power circuit for sound and light control circuits.

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