5 small suggestions for LED lighting design

The appearance of LED has broken the traditional light source design method and the mentality, at present has two kinds of newest design idea.

Scene lighting: in order to create a kind of beautiful, gorgeous lighting environment, to set off the scene effect, make people feel the atmosphere of the scene.

Emotional lighting: Lighting Design Based on human needs. Emotional lighting is based on people's emotions, from the perspective of human beings to create a mood like lighting environment. Emotional lighting and scene lighting is different, emotional lighting is dynamic, can meet the spiritual needs of the lighting, people feel the mood. The scene lighting is static, it can only emphasize the needs of the scene lighting, but can not express people's emotions, in a sense, emotional lighting covers the scene lighting.

Emotional lighting contains four aspects: first, environmental protection and energy saving, two is healthy, the three is intelligent, and the other is human nature.

5 small suggestions for LED lighting design

In order to do a good job in the design of LED lighting key in the following areas:

1, do not use bipolar power devices

The bipolar power devices cheaper than MOSFET, is generally about 2 cents a, so some designers in order to reduce the LED driving costs and the use of bipolar power devices, this will seriously affect the reliability of the circuit, because with the LED drive circuit board temperature increase, the effective working range of bipolar devices will rapidly shrink, it will lead to the rise in temperature when the device fault which affects the reliability of the LED lamp, the correct approach is to use MOSFET MOSFET device, the service life of the device is much longer than the bipolar devices.

2, do not use the pressure 600V MOSFET

The breakdown voltage of 600V MOSFET is cheaper, many believe that the input voltage of LED lamp is generally 220V, so the pressure 600V is enough, but a lot of the time circuit voltage to 340V, when there is a surge, 600V MOSFET is very easy to breakdown, thus affecting the lifetime of the LED lamps, the actual selection of 600V MOSFET may be saved but some of the cost paid is the cost of the entire circuit board, therefore, "do not use 600V voltage of MOSFET, the best selection pressure of more than 700V MOSFET." he stressed.

3, try not to use electrolytic capacitor

LED drive circuit in the end do not use electrolytic capacitors? At present there are proponents and opponents, supporters believe that if the temperature control circuit board, in order to reach the purpose of prolonging life of electrolytic capacitor, electrolytic capacitor with 105 degrees high temperature such as the life of 8000 hours, according to the passage of the electrolytic capacitor life estimation formula of "temperature every 10 degrees lower, life is doubled, then it operates at 95 degrees under the environment of life for 16000 hours, at 85 degrees under the environment of working life for 32000 hours, at 75 degrees under the environment of working life is 64000 hours, if the working temperature is lower, then life will be longer! In view of this, as long as the use of high quality electrolytic capacitors on the power supply life is not affected!

There are supporters of low frequency from high ripple current without electrolytic capacitor has caused flicker caused by physical discomfort for some eye, low frequency ripple amplitude will lead to some digital camera equipment difference frequency flashing light dark grid. Therefore, the high quality light source lamps or electrolytic capacitors. But opponents believe that the electrolytic capacitor will naturally aging, in addition, the temperature of the LED lamp is very difficult to control, so the life of electrolytic capacitors will be reduced, thus affecting the life of LED lamps.

In this regard, famous personage explanation, driving circuit of input part in LED can be considered without electrolytic capacitor, actually using PI LinkSwitch-PH can save electrolytic capacitors, PI single-stage PFC/ constant flow design designers can avoid the large capacitance, in an output circuit with high voltage ceramic capacitor instead of electrolytic capacitor so as to enhance the reliability, some people in the design of the two stage circuit, the electrolytic capacitor at the output of a 400V, which will seriously affect the reliability of the circuit, the proposed single-stage circuit ceramic capacitor can. It is not recommended to design electrolytic capacitors for industrial applications that do not pay much attention to dimming, high temperature and high reliability.

4, try to use integrated MOSFET

If the LED lamp power design is not very high, recommend the use of integrated drive LED MOSFET, because the benefits of doing so is to integrate MOSFET on resistance less than the heat generated by the separation of the less, in addition, is the integration of MOSFET controller and FET together, generally have thermal shutdown function in MOSFET, overheating will automatically turn off the circuit to protect the LED lamp, it is very important for LED lamps, LED lamps for general is very small and difficult to carry out air cooling.

5, try to use a single level architecture circuit

If the efficiency of PFC is 95%, and the efficiency of the DC/DC part is 88%, the efficiency of the whole circuit will be reduced to 83.6%! PI's LinkSwitch-PH device integrates a PFC/CC controller, a 725 V MOSFET, and a MOSFET driver into a single package, boosting the efficiency of the drive circuit to 87%. However, such a device can greatly simplify the layout design of the circuit board, which can save up to 25 components used in the traditional isolation flyback design. The required components include high voltage large capacity electrolytic capacitor and optical coupler. LED two level architecture is suitable for the use of second constant current drive circuit to make the PFC drive LED constant current drive. These designs are out of date and no longer cost effective, so in most cases it is best to use a single level design.