Linear IC driver – Mainstream design
What's led power supply or led driver?
The LED driver power supply is a power converter that can converts AC to a specific DC voltage and current to drive the LED sources.
It can be divided into isolated and non-isolated power supplies according to safety.
The non-isolated led driver is designed with input and output in the same GND, and there is the possibility of electric shock and clutter interference.
1. Which type will be more safety?
The non-isolated led driver is designed with input and output in the same GND, and there is the possibility of electric shock and clutter interference.
The isolated led driver uses a 1:1 transformer to isolate the input and output, and the output terminal is suspended to the GND.
It's not directly connected to GND of AC input, can not make a loop on circuit to avoid risk of electric shock and interference.
2. Which type will be more suitable?
Although the isolated led driver is extremely safe, it's difficult to apply to the ultra-thin floodlight due to its large size.
In order to solve this issue, we use a non-isolated linear IC constant current driver solution. The non-isolated linear IC driver have solved volume problems and reducing costs.
Linear IC LED Floodlight
Let's talk about the advantages and disadvantages of non-isolated linear IC constant current driver?
Advantages
a. High PF value >0.98 High efficiency >90%, low harmonic THD <15%.
b. No need to place any capacitors or inductors to meet the requirements of EMC and Energy Star.
c. The circuit part, all use solid-state components, to avoid the use of electrolytic capacitors in high temperature for a long time. lifespan is longer and more reliable.
d. LED driver and led chips are integrated, reducing processing costs.
e. The cost can be greatly reduced under the same conditions of export safety standards and quality requirements.
f. Has automatic over-temperature protection and over-voltage protection, can better guarantee the lifespan of the driver and the whole lamp.
Disadvantage
a. Grid voltage fluctuations
When the voltage fluctuates greatly and the voltage rises, the led driver of whole lamp will be raised rapidly to cause the temperature increased of IC and led chips.
In order to solve this problem, should use IC with automatically adjust the influence of voltage fluctuations.
It can effectively ensure within 5% of power stability , within 10% of light effect changes.
b. Strobe problem
The linear IC driver solution belongs to the AC direct-drive LED light source, a 100Hz strobe is generated. Should need to added a solid capacitor for ripple absorption.
At the same time, the frequency of voltage is amplified from 50HZ to 500 or 1000HZ to solve the stroboscopic problem in the design.
c. Insulation problem
Due to this led driver solution uses non-isolated AC input and metal shell, to ensure insulation is necessary.
How to achieve a better linear IC driver?
1. Safety and insulation issues must be considered.
2. Choose IC with voltage fluctuation adjudication function.
3. Need to reserve the heat dissipation of the IC in structure design.
4. For high-power floodlights, it is necessary to increase the design of lightning protection and surge protection circuits.