Use mobile phone charger for LED light power circuit diagram

MOS power IC full range

It adopts 1W high-power white LED with heat-dissipating aluminum sheet (the on-voltage is 3.2V; the maximum working current is 300mA). The appearance is shown in Figure 1.

There are more than 10 mobile phone chargers, both constant current source and switching power supply. Usually, the output voltage of mobile phone charger is 4.2V~5V/500mA. Therefore, only one 1W LED can be powered. Can the output voltage be increased for multiple LEDs? After disassembling a number of mobile phone chargers for analysis, it is considered that the circuit is completely feasible.

The input voltage of the mobile phone charger is AC IOOV~240V/130mA, and the output voltage is 9W0.6A. Secondary connected regulator circuit TIA31 (TLA31 pin arrangement shown in Figure 2). Try to use the 1kΩ resistor on the upper voltage divider resistor R17 of the TIA31R to increase the output voltage to 11V, and then drop it to 10V after the load. It can be used for the above 1W LED lamp 3 [10V>3x3.2V (LED turn-on voltage -9.6) V], the restructuring is completed. The schematic diagram of the principle is shown in Figure 3.

Installation: 3 IwLEDs are connected in series and directly glued into the reflector of the original incandescent lamp (the heat dissipation effect is better). The mobile phone charger is insulated and placed in the base of the desk lamp, and the original wire in the snakeskin hose of the desk lamp is used as the + and - power cord; the center pillar of the lamp base and the outer spiral copper ring are welded +, - The power cord is connected to the LED.

Debugging: As shown in Figure 4, adjust the current limiting resistor R* to make the operating current of the circuit 260mA (3.3n, IW for this example R*).

R ※ power selection: power consumption = 12R = (0.26A) 2x3.3 Ω ≈ 0.22W, so R ※ should be selected (2 ~ 3 times) power consumption = (2 ~ 3) x 0.22W - 0.5W - 1W (This example uses a 1W resistor).

Use effect: The brightness of the modified LED high-power white light lamp is about 40W incandescent lamp brightness. It is used for one month and often turns on and off repeatedly. For the circuit of Figure 5, replace the Zener diode D8 with 11V, and adjust R12 to make the working current flowing through the Zener diode 5mA. Then its output voltage rises to 12V (Zener diode 11V + optocoupler turn-on voltage 1.2V), up to about 15V.

Note: Before the transformation, the charging indicator LED1 (see Figure 5) is soldered. After the LED is adjusted, if the indicator needs to be retained, the indicator current limiting resistor R13 should be adjusted so that the current flowing through the indicator is 3mA (old type). Just fine. The modified mobile phone charger is easy to use with the 1W LED on the ceiling lamp. If 3 sets (9 pieces) of the above LED lights are used instead of IOOW incandescent lamps; 4 sets (12 pieces) of LED lights can replace 150W incandescent lamps or replace fluorescent tubes.

Tip: Because the brightness is too high after changing to high-brightness LED lights, milk white or frosted glass lampshade should be added to avoid harmful to the human eye, especially infants and young children should always be more supine.

For the single 1W LED test used in the above modification, when the applied voltage reaches 3.2V (with no current limiting resistor), the operating current is 200mA, which is very bright. (After reaching a certain brightness, the operating current is increased. Sometimes the human eye can hardly see it. There is a change in brightness). Therefore, when adjusting the current, try to take a low value. It does not have to reach about 250 mA. It is subject to eye comfort and can be taken according to the test.