What is the difference between LED switching power supply and drive power supply?

2019-12-20 17:40:46

 

Is the led light drive power the same as the switch power? For the LED lamp drive power supply with AC220V input voltage, the AC220V input voltage is firstly rectified and filtered to become dc high voltage, and then the dc high voltage is converted to constant current output by special constant-current drive IC (such as HV9910). As we know, the LED lamp bead is a kind of nonlinear components, after the lamp bead conduction, lamp beads at the ends of the forward voltage with small fluctuations, forward current through the lamp bead will have big change, so the LED lamp bead are generally adopts constant current drive, so whether drive power/ LED drive a lamp bead or dozens of lamp bead, is a constant current through the lamp bead.

For the switching power supply whose input voltage is AC220V, its input circuit also rectifies and filters AC220V to become dc high voltage first, but then USES special voltage regulator IC to convert the dc high voltage into the required stable voltage. Since the output voltage of the switching power supply is constant and the output current varies with the load, this power supply cannot be directly connected to the LED lamp bead, otherwise the lamp bead will be damaged due to the excessive current flowing through.

LED drivers are also a kind of switching power supply (see there is a constant current chip driver that does not stick to the edge of the electronic transformer).

1. The voltage output forms designed as electronic transformers are 3.2v, 6.4v. This voltage is not constant, but varies with the load to achieve the purpose of constant current.

2. Its output current is constant. The ideal circuit is that no matter how the LED characteristic curve changes, the current of the driving power remains unchanged. However, limited to the component precision, there will still be a small number of changes, and this change is also an important parameter to judge whether the driver circuit is excellent. The LED conduction and voltage function is a nonlinear "three-section" relationship, so it is very important to maintain a constant current.

3. Its starting is soft. Since the consistency of LED is very poor, and the activity of internal PN junction changes instantaneously during conduction, the drive of LED is generally designed as soft start to avoid this defect.

So LED drive is constant current mode of work, electronic transformer is fixed, the two are different