CN101951717B

CN101951717B - Environment-adaptive solar LED (light-emitting diode) driving circuit and control method

Info

Publication number: CN101951717B
Application number: CN201010507663.4A
Authority: CN
Inventors: 褚以人
Original assignee: SUZHOU YINGNUOHUA MICRO-ELECTRONICS Co Ltd
Current assignee: SUZHOU YINGNUOHUA MICRO-ELECTRONICS Co Ltd
Priority date: 2010-06-11
Filing date: 2010-10-15
Publication date: 2014-12-17
Anticipated expiration: 2030-10-15
Also published as: CN101951717A

Abstract

The invention discloses an environment-adaptive solar LED driving circuit, comprising a comparator, a charge capacity detection circuit, a current adjustment circuit, and an LED constant-current driving circuit, wherein the comparator controls the voltage output Vout of the whole driving circuit through level; the charge capacity detection circuit consists of a photovoltaic cell detector, a voltage control oscillator, a counter and an NMOS transistor M, the output frequency of the voltage control oscillator changes linearly along with the voltage change of the source S and drain D of the NMOS transistor M, the counter is reset from the falling edge of the input signal of the comparator CE, and the output of the counter is the output of the charge capacity detection circuit; the current adjustment circuit comprises a 2-order analogue-digital converter ADC and a 6-order digital-analogue converter DAC, the high order of the 6-order digital-analogue converter DAC is connected with the output of the 2-order analogue-digital converter ADC and the low four orders thereof is connected with the output of the counter; the LED constant-current driving circuit is converted from a synchronous BOOST circuit, the output current of the LED constant-current driving circuit is determined by the reference voltage Vref of the 6-order digital-analogue converter DAC and a sampling feedback resistance in a peripheral circuit, and the feedback resistance is connected to the FB end of the synchronous BOOST circuit.

Description

Environment self-adaption solar LED drive circuit and control method

Technical field

The present invention relates to a kind of solar LED drive circuit, particularly relate to a kind of method of environment self-adaption solar LED drive circuit and realization control LED discharging current thereof.

Background technology

As a kind of novel outdoor light fixture, LED Solar lamp has a lot of significantly advantage.But it is innately affected by environment, winter undercharge, but required lighting hours is long, and battery long-term work is at deficient electricity condition; Charging interval in summer is long, and required lighting hours is short, and the long-term work of battery possibility is at full power state; Battery cannot be operated in poised state, therefore, needs to carry out overcharge and over to battery.For the LED solar lawn lamp of extra low voltage, additives for overcharge protection is difficult to realize.In actual design, usually realize preventing overcharge with the method strengthening battery capacity.But owing to cannot realize discharge and recharge balance, this can only reduce the probability of overcharge, cannot ensure not overcharge.Like this, just increase cost, reduce the reliability of light fixture simultaneously.

Summary of the invention

For above-mentioned prior art, the invention provides a kind of environment self-adaption solar LED drive circuit, utilize this drive circuit, LED discharging current can be determined according to charge volume, to make discharge and recharge balance, reach and make LED solar energy lamp brighter for summer, the longer effect of lighting hours in winter.Fundamentally ensure in different regional markets, useful life that different environments for use can extend LED solar energy lamp.

In order to solve the problems of the technologies described above, the technical scheme that environment self-adaption solar LED drive circuit of the present invention is achieved is: comprise charge capacity testing circuit, matrix current adjustment circuit and constant current driver circuit for LED, one comparator, an incoming level of described comparator controls the voltage output Vout of whole drive circuit; Described charge capacity testing circuit is made up of photovoltaic cell detector, voltage controlled oscillator, counter and nmos pass transistor M; The output frequency of described voltage controlled oscillator makes linear change with the change of described nmos pass transistor source S and drain D voltage; Described counter is resetted by the trailing edge of the input CE signal of described comparator, and the output of described counter is the output of described charge volume testing circuit; Described matrix current adjustment circuit comprises two analog to digital converter ADC and six figure place weighted-voltage D/A converter DAC, a high position of described six figure place weighted-voltage D/A converter DAC connects the output of described two analog to digital converter ADC, low 4 outputs connecing described counter of described six figure place weighted-voltage D/A converter DAC; Described constant current driver circuit for LED is transformed by synchronous BOOST booster circuit, the output current of described constant current driver circuit for LED is determined by the sampling feedback resistance in the reference voltage Vref of described six figure place weighted-voltage D/A converter DAC and peripheral circuit, and this feedback resistance receives the FB end of this synchronous BOOST booster circuit.

The method of a kind of control LED of the present invention discharging current, comprise: an incoming level of described comparator controls the voltage output Vout of whole drive circuit, when an incoming level of comparator is high level, start Vout and export, comparator CE trailing edge is by counter resets; Wherein, the output ICON of comparator is as the signal of regulating impulse frequency;

Because described nmos pass transistor M is operated in linear zone, the negative pole S-of photovoltaic cell is directly proportional to charging current and voltage controlled oscillator 3 output frequency to the potential difference between earth terminal GND, and therefore, described voltage controlled oscillator output frequency is directly proportional to the electric current of photovoltaic cell; When the negative pole S-of photovoltaic cell is lower than earth terminal GND, the output of described photovoltaic cell detector 2 controls nmos pass transistor M and opens, and starts charging; Meanwhile, control voltage controlled oscillator work, described counter starts counting, and the counting of described counter 4 is directly proportional to charge capacity; When the negative pole S-of photovoltaic cell is higher than earth terminal GND, the output of described photovoltaic cell detector controls nmos pass transistor M and turns off, and stops charging; Meanwhile, described counter stops counting;

Described two ADC6 are for detecting the voltage of photovoltaic cell, setting its low pressure from drop lock UVLO is 0.9V, corresponding 4 State-outputs of described two ADC, described one of four states exports and represents below 0.9V, 0.9 ~ 1.10V, 1.10V ~ 1.35V, more than 1.35V respectively; When the magnitude of voltage detected lower than described low pressure from drop lock time, synchronous rectified boost LED constant current circuit quits work; When the magnitude of voltage detected is equal to or higher than described low pressure from drop lock, described synchronous rectified boost LED constant current circuit work;

Described synchronous BOOST booster circuit is the constant-current drive circuit of synchronous rectified boost LED, supply voltage Vbat is elevated to the forward voltage higher than photovoltaic cell, keep constant current output, its output current is determined by the sampling feedback resistance in the reference voltage Vref of six figure place weighted-voltage D/A converter DAC5 and peripheral circuit; Reference voltage Vref needed for six figure place weighted-voltage D/A converter DAC5 drive for generation of LED constant current, wherein, described two ADC6 export as high two, and described counter 4 exports as low four.

Compared with prior art, the invention has the beneficial effects as follows:

The present invention has the solar LED drive circuit of environment self-adaption ability, constant current driver circuit for LED is wherein 200810052442.5 at number of patent application, invention and created name is on the basis of " pulse width frequency modulation mode DC-DC booster circuit ", add the matrix current adjustment circuit that charge capacity detects and realizes brightness adjustment, be set as that third gear cell voltage adjusts by one or six figure place weighted-voltage D/A converter DAC, this drive circuit achieves the design of same solar LED (Light Emitting Diode) lamp and is issued to discharge and recharge balance in different environments for use.

Accompanying drawing explanation

Fig. 1 is the circuit block diagram of environment self-adaption solar LED drive circuit of the present invention;

Fig. 2 is the flow chart utilizing drive circuit shown in Fig. 1 to realize control LED discharging current.

Embodiment

Below in conjunction with the drawings and specific embodiments, the present invention is described in further detail.

As shown in Figure 1, a kind of environment self-adaption solar LED of the present invention drive circuit, comprise charge capacity testing circuit, matrix current adjustment circuit, constant current driver circuit for LED and a comparator, the voltage of the whole drive circuit of input signal CE Automatic level control of described comparator 1 exports Vout; Described charge capacity testing circuit is made up of photovoltaic cell detector 2, voltage controlled oscillator 3, counter 4 and nmos pass transistor M; The output frequency of described voltage controlled oscillator 3 makes linear change with the change of described nmos pass transistor M source S and drain D voltage; Described counter 4 is resetted by the trailing edge of the enabling signal of the input signal CE of comparator 1, and the output of described counter 4 is the output of described charge volume testing circuit; The output ICON of comparator 1 is as the signal of regulating impulse frequency.Described matrix current adjustment circuit comprises two analog to digital converter ADC6 and six figure place weighted-voltage D/A converter DAC5, a high position of described six figure place weighted-voltage D/A converter DAC5 connects the output of described two analog to digital converter ADC6, low 4 outputs connecing described counter 4 of described six figure place weighted-voltage D/A converter DAC; Described constant current driver circuit for LED 7 is transformed by synchronous BOOST booster circuit, the output current of described constant current driver circuit for LED 7 is determined by the sampling feedback resistance in the reference voltage Vref of described six figure place weighted-voltage D/A converter DAC5 and peripheral circuit, and this feedback resistance receives the FB end of this synchronous BOOST booster circuit.The technical scheme of above-mentioned synchronous BOOST booster circuit is shown in that number of patent application is 200810052442.5, and its invention and created name is pulse width frequency modulation mode DC-DC booster circuit, and the detailed content for this technical scheme does not repeat them here.

In the present invention, so-called three-gear voltage is adjusted to: the voltage signal detecting Vbat, with 0.9,1.10,1.35 three magnitudes of voltage for separation, form three voltage gears i.e. four regions and be respectively: below 0.9V, 0.9 ~ 1.10V, 1.10V ~ 1.35V, more than 1.35V.

As shown in Figure 2, the method utilizing above-mentioned drive circuit to realize LED discharging current is:

When voltage output Vout, the CE of the whole drive circuit of input signal CE Automatic level control of described comparator 1 are high level, start Vout and export, the trailing edge of CE is by counter resets; Wherein, the output ICON of comparator 1 is as the signal of regulating impulse frequency;

Because described nmos pass transistor M is operated in linear zone, the negative pole S-of photovoltaic cell and the potential difference between earth terminal GND become with charging current and voltage controlled oscillator 3 output frequency is directly proportional, therefore, described voltage controlled oscillator 3 output frequency is directly proportional to the electric current of photovoltaic cell; When the negative pole S-of photovoltaic cell is lower than earth terminal GND, the output of described photovoltaic cell detector 2 controls nmos pass transistor M and opens, and starts charging; Meanwhile, control voltage controlled oscillator 3 and work, described counter 4 starts counting, and the counting of described counter 4 is directly proportional to charge capacity; When the negative pole S-of photovoltaic cell is higher than earth terminal GND, the output of described photovoltaic cell detector 2 controls nmos pass transistor M and turns off, and stops charging; Meanwhile, described counter 4 stops counting;

Described two ADC6 are for detecting the voltage of photovoltaic cell, setting its low pressure from drop lock UVLO is 0.9V, corresponding 4 State-outputs of described two ADC, described one of four states exports and represents below 0.9V, 0.9 ~ 1.10V, 1.10V ~ 1.35V, more than 1.35V respectively; When the magnitude of voltage detected lower than described low pressure from drop lock time, described synchronous rectified boost LED constant current circuit quits work; When the magnitude of voltage detected is equal to or higher than described low pressure from drop lock, described synchronous rectified boost LED constant current circuit work;

Although invention has been described for composition graphs above; but the present invention is not limited to above-mentioned embodiment; above-mentioned embodiment is only schematic; instead of it is restrictive; those of ordinary skill in the art is under enlightenment of the present invention; when not departing from present inventive concept, can also make a lot of distortion, these all belong within protection of the present invention.

Claims

1. an environment self-adaption solar LED drive circuit, comprise charge capacity testing circuit, matrix current adjustment circuit and constant current driver circuit for LED, it is characterized in that: also comprise a comparator (1), the voltage of the whole drive circuit of described comparator (1) Automatic level control exports Vout;

Described charge capacity testing circuit is made up of photovoltaic cell detector (2), voltage controlled oscillator (3), counter (4) and nmos pass transistor (M); The output frequency of described voltage controlled oscillator (3) makes linear change with the change of described nmos pass transistor (M) source S and drain D voltage;

Described counter (4) is resetted by the trailing edge of the enabling signal of described comparator (1), and the output of described counter (4) is the output of described charge volume testing circuit;

Described matrix current adjustment circuit comprises one two analog to digital converter ADC (6) and six figure place weighted-voltage D/A converter DAC (5), a high position of described six figure place weighted-voltage D/A converter DAC (5) connects the output of described two analog to digital converter ADC (6), low 4 outputs connecing described counter (4) of described six figure place weighted-voltage D/A converter DAC;

Described constant current driver circuit for LED (7) is transformed by synchronous BOOST booster circuit, the output current of described constant current driver circuit for LED (7) is determined by the sampling feedback resistance in the reference voltage Vref of described six figure place weighted-voltage D/A converter DAC (5) and peripheral circuit, and this feedback resistance receives the FB end of this synchronous BOOST booster circuit.