The study of energy saving led screen

     First of all, from the point of power supply, if you reduce power supply from 5 V to 4 V, so, schottky positive proportion of pressure drop on the output voltage would increase, this also let the switch power supply output voltage decreases, the higher the proportion of rectifier schottky positive voltage (pressure drop their X = V decrease /V output,the output from 5 V to 4 V, to join its pressure drop is 0.5 V, the proportion will rise from 0.1 to 0.125, increased by 25%), the lower the output power efficiency, the LED screen on the overall energy saving is not too obvious.So use this power supply design principle is clearly is unable to achieve the power to promote the efficiency of work.At the same time, the 5 v is nominal voltage value, in use in the market it has been quite mature, if the new power supply voltage is enabled, while reduces the efficiency, increase the cost, but among the quality it is difficult to secure and so there are problems to achieve such a practice. 

    The design of the power supply is a relatively mature field, we can use another kind of design idea to realize display of power supply, such as synchronous rectification technology.Q10 for power MOSFET, the secondary voltage of the positive half cycle, Q10 conduction,Q10 plays a role during rectifier .In the secondary voltage of the negative half cycle, Q10 shut off, synchronous rectifier circuit power loss mainly include Q10 conduction loss and gate drive loss.When the switching frequency is lower than 60 KHZ, conduction loss dominant;Switching frequency is higher than 60 KHZ, give priority to with gate drive loss.In the design of low output voltage, high current AC/DC or DC/DC converter, the synchronous rectifier technology can significantly improve the efficiency of power supply as high as 95%.When driving a high-power synchronous rectifier, require grid peak drive current IG (PK) 1 a or higher,also can use CMOS high speed power MOSFET driver.Adopting this technology to the led display power supply voltage drop can be to the needed voltage value, at the same time, the efficiency of power supply can reach general value of voltage switching power supply, so by using synchronous rectifier technology for the led display power supply can achieve significant energy saving effect, the power cost can decline.

    Second, we can carefully study the led screen driver IC, control output port closed or open, the output port pressure drop the VDS = 0.65 V, which are determined by the technology and material,if reduce VDS to 0.2 V, even 0.1 V, even itself required area is bound to increase.In the structure of the MOS tube you can see, in the GS, GD between parasitic capacitance, and MOS tube, is actually charging and discharging of capacitance.The charging and discharging process need time, if area increase,parasitic capacitance on the MOS tube will also increase, so, the consequences is a fall in the whole IC port response speed, thus for a LED screen driver IC can be fatal weakness.

    So,if want to start from the IC, the turning point to reduce voltage,making the driver IC has enough response speed the same time, the difference is technology, it is difficult to achieve.Some people think that can use other design principle, but if it is a constant current IC, the internal circuit is may not be same,but the switch tube channel port is must exist, so that even if use other design principle, in order to achieve the voltage drop,it is also difficult to achieve.
Sum up the above factors, we can found that the issues in LED screen energy saving,we still should start from the power supply, that is to say, under the condition driver IC constant-current must  reduce power supply voltage input,and the red, green and blue each tube core is separated supply the power supply,in this way also can achieve energy saving, but the cost will increase.And it is very difficult to start from the IC,which LED the implementation of energy-saving and IC doesn't have a relationship,it is merely an innovation on the power supply.It is equivalent that we will be a power supply to use on the average driver IC,actually,also can achieve the result of energy saving requirements.