LED in series. LED Flexi Strip

 Two works:

LED Bulb Resistor R3 is constant , the voltage drop across R3 to control the use of a switch TL432 , in the use of a switch 432 to control the Q1 of output current so as to achieve the purpose , the purpose of selection is to use 432 432 on the basis of 1.21V to reduce the loss on R3 . Constant current value is 1.21/R3, R1 selected according to the magnification of Q1 to select .

3 Applications Notes : LED Module

This circuit is recommended applications in a single voltage input , the output current low current LED power driver on , such as bulb , T tubes, etc., is generally recommended under 100mA output current . While the output voltage, the more close to the input would be better, so to avoid excessive pressure drop of Q1 and cause loss is too large , the efficiency is low , so it is best to use the LED in series.   LED Flexi Strip

Three constant current diode drive circuit

1 as typical circuit ( Figure 3, Figure 4 )

Figure 3

Figure 4

2 Working Principle

Ideal current source is an infinite resistance of the device, regardless of what the value of the voltage across , which never changes the current flowing through . Of course, this device could not exist . The actual equivalent to a constant current diode in a voltage range of 25-100V for example, the current is constant for a particular value, e.g. 20mA. The equivalent circuit is shown in Figure 5