[Source: High-tech LED "LED Good Products" magazine February issue] LED lighting drive power, in order to reduce costs, must be easy to mass production. Drivers of drive power are constantly innovating and exploring to find drive power that meets market needs. Switched-supply LED lighting driver power supplies with isolated and non-isolated topologies require transformers or inductors. The circuit structure is relatively complex and cannot be automated in batch production.
The linear constant current LED lighting driver power supply not only meets the above requirements, but also can easily realize the thyristor dimming function.
Ming Microelectronics Co., Ltd. introduces SM2082B single-channel LED linear constant current driver chip, OUT is high voltage resistant port, output current is adjustable from 5mA to 60mA, set by external Rext resistor, output current does not change with OUT port voltage change, built-in over temperature protection Function, power-on soft-start function (can guarantee that the LED light will not be burned when the system is over-punched), the circuit is simple, transformer and inductor are no longer needed, and mass production can be realized. SM2082B supports single application, also supports parallel application, and also supports thyristor dimming application. It is suitable for LED lighting fields such as T8/T5, flat panel lamp, ceiling lamp, etc. It is easy to pass 3C, UL, CE and other certification standards.
SM2082B single application program
The system design of the SM2082B is described in detail below with reference to FIG. When we select the type of lamp bead (such as 3014, 2835, etc.), the output current is almost set, and the output current is related to the resistance Rext:
Iout =1.2/Rext
Its output power Pout,
Pout =Iout ·n ·VLED
Wherein, VLED represents the on-voltage drop corresponding to the LED lamp, and n represents the number of LED lamps connected in series. The design of n needs to consider the following two aspects:
(1) Meet the minimum OUT voltage of the driver IC.
In the circuit of Figure 1, the OUT port voltage Vout, Vout=Vin-n·VLED, in order to ensure the normal operation of the chip, it is necessary to ensure that the OUT port voltage Vout is greater than the minimum allowable port voltage; since the grid input voltage has a 20% fluctuation, it is necessary The chip is guaranteed to operate normally at low input voltages.
(2) The lower the voltage of the OUT port of the chip, Vout, the higher the system efficiency.
Under normal operating conditions, the lower the voltage at the OUT terminal, the lower the consumption of the driver IC, and the higher the efficiency of the system.
Therefore, the output current and the number n of LED lamps are set, and the output power is also determined. The following figure is a physical diagram of a single application T8 LED fluorescent lamp. The LED is connected in series with 80 3014 beads. The rated working voltage is 220Vac, the conversion efficiency is 92.5%, and the input power is 8W (for reference only).
SM2082B parallel application scheme
Medium and high power applications can be realized by paralleling multiple SM2082Bs. The parallel application works in the same way as a single application. Figure 3 shows a schematic diagram of a parallel application scheme, and Figure 4 shows a physical diagram of a 35W ceiling light.
The 35W ceiling lamp solution uses 2835 lamp beads 90 strings 3 and has a rated working voltage of 220Vac, a conversion efficiency of 91.3%, and a lumen efficiency of 102lm/W (for reference only).
Unfinished: For more information, please check the February issue of Gaogong LED's "LED Good Products" magazine.
The linear constant current LED lighting driver power supply not only meets the above requirements, but also can easily realize the thyristor dimming function.
Ming Microelectronics Co., Ltd. introduces SM2082B single-channel LED linear constant current driver chip, OUT is high voltage resistant port, output current is adjustable from 5mA to 60mA, set by external Rext resistor, output current does not change with OUT port voltage change, built-in over temperature protection Function, power-on soft-start function (can guarantee that the LED light will not be burned when the system is over-punched), the circuit is simple, transformer and inductor are no longer needed, and mass production can be realized. SM2082B supports single application, also supports parallel application, and also supports thyristor dimming application. It is suitable for LED lighting fields such as T8/T5, flat panel lamp, ceiling lamp, etc. It is easy to pass 3C, UL, CE and other certification standards.
SM2082B single application program
The system design of the SM2082B is described in detail below with reference to FIG. When we select the type of lamp bead (such as 3014, 2835, etc.), the output current is almost set, and the output current is related to the resistance Rext:
Iout =1.2/Rext
Its output power Pout,
Pout =Iout ·n ·VLED
Wherein, VLED represents the on-voltage drop corresponding to the LED lamp, and n represents the number of LED lamps connected in series. The design of n needs to consider the following two aspects:
(1) Meet the minimum OUT voltage of the driver IC.
In the circuit of Figure 1, the OUT port voltage Vout, Vout=Vin-n·VLED, in order to ensure the normal operation of the chip, it is necessary to ensure that the OUT port voltage Vout is greater than the minimum allowable port voltage; since the grid input voltage has a 20% fluctuation, it is necessary The chip is guaranteed to operate normally at low input voltages.
(2) The lower the voltage of the OUT port of the chip, Vout, the higher the system efficiency.
Under normal operating conditions, the lower the voltage at the OUT terminal, the lower the consumption of the driver IC, and the higher the efficiency of the system.
Therefore, the output current and the number n of LED lamps are set, and the output power is also determined. The following figure is a physical diagram of a single application T8 LED fluorescent lamp. The LED is connected in series with 80 3014 beads. The rated working voltage is 220Vac, the conversion efficiency is 92.5%, and the input power is 8W (for reference only).
SM2082B parallel application scheme
Medium and high power applications can be realized by paralleling multiple SM2082Bs. The parallel application works in the same way as a single application. Figure 3 shows a schematic diagram of a parallel application scheme, and Figure 4 shows a physical diagram of a 35W ceiling light.
The 35W ceiling lamp solution uses 2835 lamp beads 90 strings 3 and has a rated working voltage of 220Vac, a conversion efficiency of 91.3%, and a lumen efficiency of 102lm/W (for reference only).
Unfinished: For more information, please check the February issue of Gaogong LED's "LED Good Products" magazine.
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