Research on energy-saving LED display

The design of the power supply is a relatively mature field, and another design idea can be used to realize the power supply of the display screen, such as synchronous rectification technology. Q10 is a power MOSFET. During the positive half cycle of the secondary voltage, Q10 is turned on and Q10 is rectified. In the negative half cycle of the secondary voltage, Q10 is turned off. The power loss of the synchronous rectifier circuit mainly includes the conduction loss of Q10 and the gate. Drive loss. When the switching frequency is lower than 60KHz, the conduction loss is dominant; when the switching frequency is higher than 60KHz, the gate driving loss is dominant. Synchronous rectification technology can significantly improve power efficiency, even up to 95%, when designing AC/DC or DC/DC converters with low voltage and high current output. When driving a higher power synchronous rectifier, a CMOS high speed power MOSFET driver can also be used when the gate peak drive current IG(PK) ≥ 1A is required. Of course, using this technology to power the LED display can reduce the voltage to the required voltage value, and the efficiency of the power supply can also reach the value of the general switching power supply voltage. Therefore, the use of synchronous rectification technology to power the led display can be achieved. With the effect of energy saving, there will definitely be some increase in power costs.

Secondly, we can carefully study the LED screen driver IC, control the output port to open or open, the output port voltage drop is VDS=0.65V, which is determined by the process and materials, to reduce the VDS to 0.2V, or even 0.1 V, the area required by itself must increase. It can be seen in the structure of the MOS transistor that there is a parasitic capacitance between GS and GD, and the driving of the MOS transistor is actually charging and discharging the capacitor. This charging and discharging process takes a while. If the area increases, the parasitic capacitance on the MOS tube will also increase. As a result, the port response speed of the entire IC decreases, which is for an LED screen driver IC. Will be a fatal weakness.

Therefore, it is difficult to achieve the process by starting from the IC, reducing the cornering voltage and making the driving IC have sufficient response speed. Some people think that other design principles can be used, but if it is a constant current IC, the internal circuit may be different, but the switching tube of the channel port must exist, so even if other design principles are adopted, the purpose of achieving voltage drop is also Hard to achieve.

Summarizing the above factors, we can find that in the energy-saving collection of LEDs, the main thing is to start from the power supply, that is, in the state of driving IC constant current must reduce the input of the power supply voltage, and the red, green and blue cores Separate power supply can also achieve energy savings, but such costs will increase. It is indeed quite difficult to start from the IC, that is, the energy-saving realization of LED has nothing to do with IC, it is just an innovation on the power supply. In fact, it is equivalent to using a power supply on an ordinary driver IC. In fact, it can also achieve energy-saving effects.