Controller integrated circuit and energy storage lighting fixtures

Abstract

The present invention discloses a controller integrated circuit for a lighting fixture equipped with an energy storage battery. The controller integrated circuit includes a charge management circuit, a discharge control circuit, and a discharge time extension circuit. While ensuring the initial brightness of the lighting fixture is at its maximum when the energy storage battery is fully charged, the present invention can automatically and continuously adjust the lighting brightness based on the remaining energy in the energy storage battery, significantly extending the duration of the stored energy lighting.

Description

Technical Field

[0001] The present invention relates to an LED lighting controller, and in particular to a controller integrated circuit suitable for an LED lighting fixture with an energy storage battery, and an energy storage lighting fixture comprising the controller integrated circuit. Background Art

[0002] As a new generation of lighting sources, LEDs have gained widespread adoption. Currently, a special category of LED lamps exists on the market: those that incorporate energy storage batteries. These include solar-powered lamps, AC emergency lighting fixtures, and low-voltage emergency lighting fixtures. These lamps are referred to here as energy storage lamps. Their defining characteristic is that they contain internal energy storage batteries (such as lithium batteries). These lamps utilize different external power sources. For example, solar-powered lamps charge their lithium batteries through photoelectric conversion using photovoltaic panels; AC emergency lighting fixtures charge their lithium batteries directly from the 110V / 220V AC grid; and low-voltage emergency lighting fixtures typically charge their lithium batteries via a USB port or a 5V adapter.

[0003] Figure 1 and Figure 2 The circuit structure of the energy storage lighting fixture in the prior art is shown. Figure 1 The PMOS tube is used as the discharge switch tube 103, and Figure 2 The NMOS transistor is used as the discharge switch 205, and the control logic of the two is opposite. When the discharge switch is turned on, the lithium battery 013 discharges to the LED load 012 after the current is limited by the resistor 011. The brightness of the lamp is determined by the current through the LED load 012, as shown in the following formula (1):

[0004] I LED =(BAT-V LED ) / R (1)

[0005] BAT is the BAT node voltage of the lithium battery 013, and the general LED conduction voltage V LED At around 2.8V, R is the resistance of the series current limiting resistor 011; the discharge switch PMOS tube 103 and the NMOS tube 205 can both be regarded as ideal switches.

[0006] Energy storage batteries usually account for the largest proportion of the total cost of a lamp, so their capacity is relatively limited. For example, a typical low-power outdoor solar lamp or emergency lamp only contains a 2000mAH 18650 lithium battery. As can be seen from the above formula (1), the load current of a typical energy storage lighting fixture is not constant, and changes in battery voltage will also cause changes in the load current. During the discharge process, as the battery voltage decreases, the load current will also decrease linearly, thus extending the lighting time. If a constant current output is used, to achieve the same lighting time, the cost of the energy storage battery will increase significantly, making it unacceptable to the end market. In particular, solar outdoor lighting fixtures have high requirements for lighting time. This type of lamp lights up after dark and needs to continue until dawn the next day; if it is cloudy or rainy, the energy storage battery is not fully charged, and this is not easy to achieve. It is likely that the battery energy storage will be exhausted before 10 pm. For solar outdoor lighting, continuous lighting on cloudy nights is a problem that has not yet been completely solved.

[0007] The continuous lighting time of energy storage lighting fixtures is also related to the initial brightness. After the energy storage battery is fully charged (charging does not necessarily mean the battery is fully charged), the brightness when the light is first turned on is called the initial brightness. There is a special case, that is, when the energy storage battery is fully charged, according to the above formula (1), the LED load current is the largest when the light is first turned on, and only the resistance value of R determines its size. The brightness at this time is called the maximum initial brightness. It can be seen that the initial brightness is less than or equal to the maximum initial brightness. The former can be selected, while the latter is a fixed constant (assuming that the R value remains unchanged). The greater the initial brightness of this type of lamp, the shorter the continuous lighting time will be; conversely, if the continuous lighting time is to be longer, the initial brightness of the lamp must be smaller. It can be seen that the initial brightness and the lighting duration are contradictory.

[0008] In the prior art, there is a method for extending the duration of energy storage lighting. This method extends the duration of energy storage lighting by selecting the initial brightness of the lamp at different levels. In other words, to extend the duration of energy storage lighting fourfold, it is necessary to manually select a level where the initial brightness when the energy storage battery is fully charged is one-quarter of the maximum initial brightness. The initial brightness levels are generally divided into three levels, with a maximum of four levels. This method is indeed effective, but it has two shortcomings. First, the initial brightness of the lamp when the energy storage battery is fully charged needs to be changed, which may be far less than the maximum initial brightness, resulting in a poor user experience. Second, manual selection is required. Manual selection is not very friendly to the elderly and children, and manual participation in solar outdoor lighting is also unrealistic.

[0009] Another method extends lighting duration by reducing the brightness of stored energy. For example, the lamp initially operates at maximum brightness. After 10 minutes, the brightness is automatically reduced to 75% using PWM. After 40 minutes, the brightness is automatically reduced to 50% using PWM. After 2 hours, the brightness is automatically reduced to 25% using PWM. Because the brightness level and shift times are fixed, this is a semi-automatic method. This method is relatively simple, can be implemented using an inexpensive MCU, and can indeed extend lighting duration. However, its drawback is that the algorithm is inflexible and cannot dynamically adjust the discharge algorithm. Therefore, it still cannot solve the problem of solar outdoor lighting on cloudy nights. Summary of the Invention

[0010] The purpose of the present invention is to address the above-mentioned defects of energy storage lighting fixtures in the prior art, and to ensure that the initial brightness when the energy storage battery is fully charged adopts the maximum initial brightness without increasing costs, and to significantly increase the duration of energy storage lighting without the need for manual intervention, thereby basically solving the problem of solar outdoor lighting that continues to illuminate all night on cloudy days.

[0011] According to a first aspect of the present invention, a controller integrated circuit is provided for a lighting fixture having an energy storage battery. The energy storage battery is connected to the drain of an NMOS discharge tube via an LED load and a current-limiting resistor, and the source of the NMOS discharge tube is connected to a reference ground. The controller integrated circuit is internally provided with a charge management circuit, a discharge control circuit, and a discharge time extension circuit. The charge management circuit has one end connected to an external power supply and the other end connected to a BAT node between the energy storage battery and the LED load for charging the energy storage battery. After discharge begins, the discharge time extension circuit generates a PWM dimming signal with a continuously decreasing duty cycle based on the continuously decreasing BAT node voltage of the energy storage battery. In response to an enable signal generated by the discharge control circuit, the discharge time extension circuit outputs the PWM dimming signal to the gate of the NMOS discharge tube.

[0012] According to a second aspect, an energy storage lighting fixture is provided, comprising a controller integrated circuit as described in the first aspect above, an energy storage battery, an LED load, a current limiting resistor, and an NMOS discharge tube, wherein the energy storage battery is connected to the drain of the NMOS discharge tube via the LED load and the current limiting resistor, and the source of the NMOS discharge tube is connected to a reference ground.

[0013] According to a third aspect, a controller integrated circuit is provided for a lighting fixture having an energy storage battery, wherein the energy storage battery is connected to the drain of a PMOS discharge tube, and the source of the PMOS discharge tube is connected to a reference ground via an LED load and a current-limiting resistor. The controller integrated circuit is internally provided with a charge management circuit, a discharge control circuit, and a discharge time extension circuit, wherein one end of the charge management circuit is connected to an external power supply and the other end is connected to a BAT node between the energy storage battery and the drain of the PMOS discharge tube, for charging the energy storage battery. After discharge begins, the discharge time extension circuit generates a PWM dimming signal with a continuously decreasing duty cycle based on the continuously decreasing BAT node voltage of the energy storage battery. In response to an enable signal generated by the discharge control circuit, the discharge time extension circuit outputs an inverted PWM dimming signal to the gate of the PMOS discharge tube.

[0014] According to a fourth aspect, an energy storage lighting fixture is provided, comprising a controller integrated circuit, an energy storage battery, an LED load, a current limiting resistor, and a PMOS discharge tube as described in the third aspect above, wherein the energy storage battery is connected to the drain of the PMOS discharge tube, and the source of the PMOS discharge tube is connected to a reference ground via the LED load and the current limiting resistor.

[0015] According to the present invention, while ensuring the initial brightness of the lamp is at its maximum when the energy storage battery is fully charged, the lighting brightness is innovatively automatically and steplessly adjusted based on the remaining energy in the energy storage battery. This significantly extends the duration of stored energy lighting, thus completely resolving the problem of continuous solar outdoor lighting on cloudy nights. Furthermore, the present invention utilizes a low-cost CMOS semiconductor process to integrate the charging management circuitry into a single chip, eliminating the need for an MCU. This not only improves system performance, but also reduces system cost and enhances system reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] For a better understanding of the present invention, the present invention is further described below with reference to embodiments and accompanying drawings. In the accompanying drawings:

[0017] Figure 1 The circuit structure of the energy storage lighting fixture using a PMOS discharge tube in the prior art;

[0018] Figure 2 The circuit structure of the energy storage lighting fixture using NMOS discharge tube in the prior art;

[0019] Figure 3 Shows the corresponding relationship between battery voltage, remaining energy percentage SOC and discharge PWM duty cycle;

[0020] Figure 4 This is a circuit diagram of an energy storage lighting fixture according to an example of the present invention;

[0021] Figure 5 The corresponding relationship between battery voltage, remaining energy percentage SOC and discharge PWM duty cycle after the parameters are changed is shown;

[0022] Figure 6 This is a circuit diagram of another example of an energy storage lighting fixture of the present invention;

[0023] Figure 7 This is a circuit diagram of another example of an energy storage lighting fixture of the present invention. DETAILED DESCRIPTION

[0024] The inventors considered that, under the premise of ensuring that the initial brightness of the lamp's energy storage battery is the maximum initial brightness when it is fully charged, if the lighting brightness is to be automatically and steplessly lowered according to the remaining power of the energy storage battery, two problems need to be solved: one is how to measure the remaining power of the energy storage battery at a low cost; the other is how to achieve stepless brightness reduction.

[0025] Taking the 18650 ternary lithium battery, which is the most commonly used in energy storage lighting fixtures, as an example, the battery voltage B when fully charged is MAX The inventors have found through testing that after the discharge begins, the remaining energy of the lithium battery gradually decreases, and the corresponding battery voltage also decreases approximately linearly; when the battery voltage drops to B MIN When the voltage is about 3V, the remaining energy of the lithium battery is less than 5%, which is approximately zero. In other words, the remaining energy percentage SOC and the battery voltage BAT are approximately linearly related, as shown in the following formula (2):

[0026] SOC(%)≈(BAT-B MIN ) / (B MAX -B MIN )(2)

[0027] On this basis, the circuit generates a dimming PWM pulse signal with a duty cycle that is approximately equal to the percentage of remaining power. The duty cycle D(PWM) is determined according to the following formula (3):

[0028] D(PWM)≈(BAT-B MIN ) / (B MAX -B MIN )(3)

[0029] Next, the PWM pulse signal is used to control the on and off of the discharge power tube, which can automatically adjust the average operating current I of the LED load. LED I LED Determined by the following formula (4):

[0030] I LED =D(PWM)x(BAT-V LED ) / R (4)

[0031] Among them, V LED It is still the LED conduction voltage, and R is the resistance of the series current limiting resistor.

[0032] It can be seen that by adopting the above current reduction scheme, the discharge PWM duty cycle decreases proportionally as the lithium battery voltage decreases, thereby achieving automatic stepless brightness adjustment, thereby extending the night lighting duration of the solar lamp.

[0033] Reference Figure 3 , Figure 3 The corresponding relationship between battery voltage, remaining energy percentage (SOC), and discharge PWM duty cycle is shown. This relationship between SOC and battery voltage is the result of a linear fit of actual measured data. It is only an approximation and not very accurate, which is limited by the low-cost requirements of the present invention. Professional battery energy metering technology is complex and costly, making it unsuitable for the present invention.

[0034] To simplify the mathematical processing, we assume that energy is released uniformly throughout the discharge process. Under this assumption, mathematical processing yields data on the extended nighttime lighting duration under various SOC conditions, as shown in the table below.

[0035]

[0036] In this table, the first row shows the initial battery voltage before discharge, which reflects the daytime light intensity. The second row shows the percentage of the battery's actual charge after daytime charging, which is directly related to the first row. The third row shows the length of discharge time without the above scheme at different initial battery voltages, where T is the corresponding discharge time without the scheme after the battery is 100% fully charged. The fourth row shows the length of discharge time with the above scheme. It can be seen that under various SOC conditions, the lighting time with the current reduction scheme is twice that without the scheme. It should be noted that in actual discharge, the release of battery energy cannot be uniform. The above equation (1) theoretically shows that the higher the battery voltage, the faster the energy release; the lower the battery voltage, the slower the energy release. Therefore, the actual discharge time extension of the above current reduction scheme is more than twice.

[0037] The following describes how to implement the above current reduction scheme in circuit. Figure 4 , Figure 4 This is a circuit diagram of an energy storage lighting fixture according to an example of the present invention. The lighting fixture includes a controller 300, an energy storage battery 013, an LED load 012, a current-limiting resistor 011, and an NMOS discharge tube 205. The energy storage battery 013 is connected to the drain of the NMOS discharge tube 205 via the LED load 012 and the current-limiting resistor 011. The source of the NMOS discharge tube 205 is connected to a reference ground.

[0038] The controller 300 can be implemented as an integrated circuit. In addition to the integrated charge management circuit 301, the chip also includes a discharge control circuit 302 and a discharge time extension circuit 310. The charge management circuit 301 is connected to an external power source at one end and to the BAT node between the energy storage battery 013 and the LED load 012 at the other end, thereby charging the energy storage battery 013. Once the energy storage battery 013 begins discharging, the discharge time extension circuit 310 generates a PWM dimming signal with a decreasing duty cycle based on the continuously decreasing BAT node voltage of the energy storage battery. In response to the enable signal EN generated by the discharge control circuit 302, the discharge time extension circuit 310 outputs this PWM dimming signal to the gate of the NMOS discharge tube 205.

[0039] like Figure 4 As shown, the discharge time extension circuit 310 includes a subtractor 311, an oscillator 312, a comparator 313 and an AND gate 314. The subtractor 311 detects the remaining power of the energy storage battery 013. One input terminal of the subtractor is connected to the BAT node voltage of the energy storage battery 013; the other input terminal is connected to a reference voltage. Here, the energy storage battery 013 is, for example, a ternary lithium battery. MIN (The battery voltage corresponding to the residual energy being close to zero) is about 3V, so the reference voltage is selected to be 3V. The subtraction result is sent to the comparator 313 and compared with the sawtooth wave or triangle wave generated by the oscillator 312; the peak value of the sawtooth wave or triangle wave is B MAX The difference between the current (4.2V) and the reference voltage (3V) (i.e., 1.2V) is zero, and the frequency is generally greater than 15kHz but less than 200kHz. The comparison between the two generates a pulse width modulation signal (PWM). The mathematical relationship between the power measurement, PWM duty cycle, and LED load current is completely determined by the above equations (2), (3), and (4).

[0040] The discharge control circuit 302 outputs an enable signal EN (high level is valid) to the AND gate 314, performs a logic AND operation with the output result of the comparator 313, and finally outputs the above-mentioned PWM dimming signal to control the lighting on and off. Different energy storage lighting fixtures have different corresponding discharge control circuits 302. For example, in terms of solar lighting fixtures, the basic requirement is to turn on the lights at night (EN changes from low level to high level) and turn off the lights at dawn (EN changes from high level to low level). In the case of AC emergency lighting fixtures, the change of the enable signal EN is achieved through the physical switch of the lamp in the power outage state. For low-voltage emergency lighting fixtures, the on and off control of energy storage lighting can be achieved simply by using a push button switch.

[0041] Due to the high cost of energy storage batteries, the maximum free, unconfigured discharge time (T) for solar outdoor lighting fixtures is only about four hours. Using the aforementioned two-fold discharge method, with a fully charged battery, the maximum discharge time is 2T, or only about eight hours. A typical night lasts 10 hours, which is barely sufficient. However, considering the possibility of a full charge on a cloudy day, for example, with only a 30% charge, the two-fold discharge time is only 0.6T, resulting in a lighting duration of only about 2.4 hours, significantly short of the 10-hour requirement. Therefore, a two-fold discharge method is insufficient; a higher discharge multiplier, at least four times or more, is required. A higher multiplier yields a longer continuous lighting duration. However, excessively high multipliers are also not recommended, as they can significantly reduce average lighting brightness. Generally, a multiplier of less than ten times is appropriate.

[0042] To increase the discharge multiple, we also need to start with theoretical analysis. Figure 3 In the figure, the battery voltage corresponding to a discharge duty cycle of zero is 3.0V. When this battery voltage is moved up to 3.6V, it can be seen that the rate at which the discharge duty cycle decreases has doubled. Figure 5 The duty cycle D(PWM) is determined according to the following formula (5):

[0043] D(PWM)≈(BAT-B PWM0 ) / (B MAX -B PWM0 )(5)

[0044] Wherein, BAT represents the BAT node voltage of the energy storage battery; MAX Indicates the voltage of the energy storage battery when it is fully charged; B PWMO Indicates the energy storage battery voltage corresponding to the predetermined PWM duty cycle of zero, and B PWMO Greater than or equal to B MIN , but smaller than B MAX In B PWMO The value is B MIN In the case of , the above formula (5) is the same as formula (3).

[0045] Figure 5 In the corresponding B PWM0 is 3.6V, D(PWM)≈(BAT-3.6) / 0.6, Figure 3 The speed of duty cycle decrease is doubled, that is, the night lighting time can be extended to 4T in theory. If the maximum extension time is to be 6T, then B PWM0 The value should be around 3.8V.

[0046] Figure 5 The discharge duty cycle is selected to become zero when the battery voltage is 3.6V, that is, B PWMOis 3.6V. This means that the battery cannot be discharged below 3.6V, which is obviously not the best solution. Preferably, a minimum discharge duty cycle is added. The minimum duty cycle can select a predetermined value greater than zero, and this predetermined value is preferably 5% to 30%. For example, 16% can be selected as the minimum duty cycle, and the corresponding battery voltage is 3.7V. Of course, the minimum duty cycle can be freely selected, and the size of the minimum duty cycle will also affect the length of the discharge time. The smaller the minimum duty cycle, the longer the lighting time, but the lower the average brightness. Refer again Figure 5 , Figure 5 If 16% is selected as the minimum duty cycle, the maximum discharge time can be extended to 6T in theory; 4.2V can be selected as B PWMO , which means that after the lithium battery is fully charged, the initial discharge duty cycle is the minimum duty cycle, which can extend the discharge time to 6T. It should be noted that B PWMO The selection of minimum duty cycle for discharge and discharge is independent of each other.

[0047] Reference Figure 6 , Figure 6 This is a circuit diagram of another example of an energy storage lighting fixture of the present invention. Figure 4 Based on the example, this example adds the option of the minimum discharge duty cycle. Accordingly, inside the controller 400, the discharge time extension circuit 410 and Figure 4 There are some differences. Figure 6 As shown, the discharge time extension circuit 410 includes a subtractor 411, an oscillator 312, a comparator 313, a comparator 415, an OR gate 416 and an AND gate 314. Figure 4 Similarly, the subtractor 411 still detects the remaining power of the lithium battery 013, and the reference voltage REF1 is selected as the above B PWMO The subtraction result is amplified by the amplifier and sent to the comparator 313 to be compared with the sawtooth wave or triangle wave generated by the oscillator 312. Figure 4 There is no change compared to the reference voltage REF2. The sawtooth wave or triangle wave is also sent to the comparator 415 and compared with the reference voltage REF2. Here, the relationship between the minimum duty cycle of the PWM dimming signal and the reference voltage REF2 is as follows:

[0048] D MIN (PWM) = REF2 / 1.2 (6)

[0049] Therefore, the reference voltage REF2 is selected as the product of a predetermined minimum duty cycle and the peak value of the sawtooth or triangle wave (e.g., 1.2 V). The outputs of comparator 313 and comparator 415 are logically ORed together, and then logically ANDed together with the enable signal EN output by the discharge control circuit 302 to ultimately output the PWM dimming signal.

[0050] Figure 6 In the exemplary discharge time extension circuit 410, a K-fold amplifier is connected between the subtractor 411 and the comparator 313. The duty cycle of the output signal pulse of the comparator 313 is equal to K*(BAT-REF1) / 1.2. Substituting into the above equation (5) can be used to obtain K, as shown in the following equation (7):

[0051] K=1.2 / (B MAX -REF1) (7)

[0052] When REF1 is 3V, K is 1. In addition, if the peak value of the sawtooth wave or triangle wave output by the oscillator 312 is changed to 1.0V, for example, the number 1.2 in equations (6) and (7) should be changed to 1.0. The peak value of the sawtooth wave or triangle wave corresponding to K being equal to 1 can also be obtained according to equation (7). Figure 6 The K-fold amplifier in this example can be omitted, and the subtraction result of subtractor 411 can be directly sent to comparator 313. For example, when REF1 is selected to be 3.6V, the sawtooth wave or triangle wave peak value corresponding to K equal to 1 is 0.6V. For different REF1 values, the sawtooth wave or triangle wave peak value corresponding to K equal to 1 is also different.

[0053] The present invention can be implemented in a variety of circuit modes. Figure 4 or Figure 6 The example is just one example. Figure 4 and Figure 6 In the circuit, the discharge tube adopts NMOS tube, but PMOS tube can also be used as the discharge tube. Figure 7 , Figure 7 The circuit structure of an energy storage lighting fixture using a PMOS discharge tube is shown. In this lighting fixture, the energy storage battery 013 is connected to the drain of the PMOS discharge tube 505, and the source of the PMOS discharge tube 505 is connected to the reference ground via the LED load 012 and the current limiting resistor 011. In the controller 500, the charging management circuit 301 is connected to the external power supply at one end and to the BAT node between the energy storage battery 013 and the drain of the PMOS discharge tube 505 at the other end. The discharge time extension circuit 510 is connected to the external power supply at the other end. Figure 6 On the basis of the corresponding circuit, an inverter 501 is added to logically invert the PWM dimming signal output by the AND gate 314 , and the inverted PWM dimming signal is output to the gate of the PMOS discharge tube 505 . Figure 7 The rest of the circuit structure of the example is the same as Figure 6 Same, no more details.

[0054] In the above examples, the NMOS and PMOS discharge tubes are located outside the controller chip, but those skilled in the art will appreciate that, depending on actual application requirements, the discharge tubes may also be placed inside the controller chip.

[0055] The above article uses ternary lithium battery as an example to explain the theory and technology, but the present invention is also applicable to other types of energy storage batteries, such as lithium iron phosphate battery, polymer lithium battery, sodium ion battery, lead acid battery and nickel metal hydride battery. MAX The voltage is about 4.2V, B MIN The voltage is about 3.0V. MAX Voltage about 3.6V, B MIN The voltage is about 3.0V.

[0056] While the preceding description primarily uses solar outdoor lighting as an example, the present invention is also applicable to AC emergency lighting and low-voltage emergency lighting. For these two types of emergency lighting, the present invention significantly extends the lighting duration at a low cost, making it highly practical. This is particularly relevant in underdeveloped countries and regions where power infrastructure is poor and power outages are common.

[0057] It is obvious that many variations are possible in the invention described herein without departing from the spirit and scope of the invention. Therefore, all variations obvious to those skilled in the art are intended to be included within the scope of the appended claims.

Claims

1. A controller integrated circuit for a lighting fixture with an energy storage battery, wherein the energy storage battery is connected to the drain of an NMOS discharge tube via an LED load and a current-limiting resistor, and the source of the NMOS discharge tube is connected to a reference ground; the controller integrated circuit is internally provided with a charge management circuit, a discharge control circuit, and a discharge time extension circuit, wherein: A charging management circuit, one end of which is connected to an external power supply, and the other end of which is connected to a BAT node between the energy storage battery and the LED load, for charging the energy storage battery; The discharge time extension circuit generates a PWM dimming signal with a continuously decreasing duty cycle based on the continuously decreasing BAT node voltage of the energy storage battery after the discharge starts; and outputs the PWM dimming signal to the gate of the NMOS discharge tube under the action of the enable signal generated by the discharge control circuit. The duty cycle of the PWM dimming signal is determined according to the following formula: D(PWM)≈(BAT-B PWM0 ) / (B MAX -B PWM0 ) Wherein, BAT represents the BAT node voltage of the energy storage battery; MAX Indicates the voltage of the energy storage battery when it is fully charged; B PWMO Indicates the energy storage battery voltage corresponding to the predetermined PWM duty cycle of zero, and B PWMO Greater than or equal to the energy storage battery voltage corresponding to the residual energy close to zero, but less than B MAX .

2. The controller integrated circuit according to claim 1, wherein: The discharge time extension circuit includes a subtractor, an oscillator, a comparator and an AND gate, wherein: a subtractor, having one input terminal connected to the BAT node voltage of the energy storage battery, another input terminal connected to a first reference voltage, and an output terminal connected to an input terminal of the comparator; an oscillator, whose output end is connected to the other input end of the comparator and is used to generate a sawtooth wave or a triangle wave; An AND gate has one input end connected to the enable signal generated by the discharge control circuit, the other input end connected to the output end of the comparator, and an output end of the AND gate outputs the PWM dimming signal.

3. The controller integrated circuit according to claim 2, wherein: The first reference voltage is selected as the B PWMO Voltage; the peak value of the sawtooth wave or triangle wave is the B MAX The difference between the voltage and the first reference voltage has a valley value of zero.

4. The controller integrated circuit according to claim 1, wherein: The discharge time extension circuit selects a predetermined value greater than zero as the minimum duty cycle of the PWM dimming signal.

5. The controller integrated circuit according to claim 4, wherein: The predetermined minimum duty cycle of the PWM dimming signal is 5% to 30%.

6. The controller integrated circuit according to claim 5, wherein: The discharge time extension circuit includes a subtractor, an oscillator, a first comparator, a second comparator, an OR gate and an AND gate, wherein: a subtractor, having one input terminal connected to the BAT node voltage of the energy storage battery, another input terminal connected to a first reference voltage, and an output terminal connected to an input terminal of the first comparator; an oscillator, whose output end is connected to the other input end of the first comparator and one input end of the second comparator, and is used to generate a sawtooth wave or a triangle wave; a second comparator, the other input terminal of which is connected to the second reference voltage, and the output terminal of which is connected to an input terminal of the OR gate; an OR gate, the other input of which is connected to the output of the first comparator, and the output of which is connected to an input of the AND gate; The AND gate has another input terminal connected to the enable signal generated by the discharge control circuit, and an output terminal outputting the PWM dimming signal.

7. The controller integrated circuit according to claim 6, wherein: The first reference voltage is selected as the B PWMO Voltage; the peak value of the sawtooth wave or triangle wave is the B MAX The difference between the voltage and the first reference voltage has a valley value of zero.

8. The controller integrated circuit according to claim 7, wherein: The second reference voltage is selected as the product of the predetermined minimum duty cycle and the peak value of the sawtooth wave or the triangle wave.

9. The controller integrated circuit according to claim 6, wherein: The discharge time extension circuit further includes an amplifier connected between the subtractor and the first comparator, and configured to amplify an output signal of the subtractor and provide the amplified output signal to the first comparator.

10. A controller integrated circuit for a lighting fixture with an energy storage battery, wherein the energy storage battery is connected to the drain of a PMOS discharge tube, and the source of the PMOS discharge tube is connected to a reference ground via an LED load and a current-limiting resistor; the controller integrated circuit is internally provided with a charge management circuit, a discharge control circuit, and a discharge time extension circuit, wherein: A charging management circuit, one end of which is connected to an external power supply, and the other end of which is connected to the BAT node between the energy storage battery and the drain of the PMOS discharge tube, for charging the energy storage battery; The discharge time extension circuit generates a PWM dimming signal with a continuously decreasing duty cycle based on the continuously decreasing BAT node voltage of the energy storage battery after the discharge starts; and outputs the inverted PWM dimming signal to the gate of the PMOS discharge tube under the action of the enable signal generated by the discharge control circuit. The duty cycle of the PWM dimming signal is determined according to the following formula: D(PWM)≈(BAT-B PWM0 ) / (B MAX -B PWM0 ) Wherein, BAT represents the BAT node voltage of the energy storage battery; MAX Indicates the voltage of the energy storage battery when it is fully charged; B PWMO Indicates the energy storage battery voltage corresponding to the predetermined PWM duty cycle of zero, and B PWMO Greater than or equal to the energy storage battery voltage corresponding to the residual energy close to zero, but less than B MAX .

11. An energy storage lighting fixture, comprising a controller integrated circuit according to any one of claims 1 to 9, an energy storage battery, an LED load, a current limiting resistor, and an NMOS discharge tube, wherein: The energy storage battery is connected to the drain of the NMOS discharge tube via an LED load and a current limiting resistor, and the source of the NMOS discharge tube is connected to a reference ground.

12. An energy storage lighting fixture, comprising the controller integrated circuit according to claim 10, an energy storage battery, an LED load, a current limiting resistor, and a PMOS discharge tube, wherein: The energy storage battery is connected to the drain of the PMOS discharge tube, and the source of the PMOS discharge tube is connected to the reference ground via the LED load and the current limiting resistor.

Images