What Is an LED Power Supply?

LED power supply is a kind of power supply, a device that provides power to electronic equipment, and also a power supply. It is a device that converts AC power to DC power through a transformer and a rectifier. This device is called a rectified power supply, also called a drive power supply. An electronic device capable of providing a signal is called a signal source. Lithium batteries, dry batteries, rectified power sources, and signal sources are sometimes called power sources. The battery is divided into ± grades.

Convert other forms of energy into

LED power supplies are widely used

The LED chip and the power supply are installed together. Generally, the space is small and the heat dissipation conditions are poor. How to ensure the quality and life of the LED power supply must be considered before designing to avoid the LED power supply failing quickly. It can be said that the life of the LED power supply is restricting the LED The key to development.

This is a comprehensive issue that requires system design and consideration.

We believe that the performance that affects the life of the LED power supply includes environmental characteristics, components and power pending, and has the following aspects:

1. Impact of practical application environment: high humidity environment, high temperature environment, dusty environment, strong magnetic environment, vibration environment

2. The influence of lighting temperature environment: the internal temperature of the lighting is less than 65 degrees, the lighting shell is less than 75 degrees, and the power supply temperature is less than 60 degrees

3, the impact of the power supply grid: the voltage input of the unstable grid will cause impact on the components of the LED power supply, thereby affecting the service life of the LED driver.

4, the impact of insulation and installation: the correct installation of the product and good insulation will enhance the application of LED power.

5, the impact of electrolytic capacitors: the sealed part of electrolytic capacitors will leak gasified electrolyte, this phenomenon will accelerate as the temperature rises, it is generally believed that each 10 ° C temperature rise, the leakage rate will increase twice.

Therefore, it can be said that the electrolytic capacitor determines the life of the power supply device.

If a 105-degree high-temperature electrolytic capacitor with a lifetime of 10,000 hours is selected, according to the commonly used electrolytic capacitor life estimation formula "every 10 degrees is reduced, the life is doubled", then it is at 95 degrees

1. Driver chip: IC

The core of the driving power supply is the IC, and the quality of the IC directly affects the entire power supply.

The driver ICs of large manufacturers are all looking for large packaging factories to package; while the driver IC technology of small factories is to directly copy the driver design scheme of large factories to find small packaging factories to package, which cannot guarantee the consistency of the entire batch of IC And stability, resulting in inexplicable failure of the drive power supply after a period of use.

Therefore, the IC on the LED power supply is refused to be polished, so that the lamp manufacturers can understand the IC solution and the cost of the driver, so that they can purchase power products at a reasonable price.

2.Transformer

The control chip can be regarded as the brain center of the power supply, and the transformer that determines power and temperature resistance is a transformer.

The transformer is responsible for completing "AC-Magnetic-DC", and the energy overload will saturate the bomber.

The core of the transformer is the magnetic core and the wire package.

The quality of the magnetic core is the core of the transformer, but like porcelain, it is extremely difficult to distinguish.

The simple appearance can be distinguished as: the appearance is crisp, dense and bright, while those with air holes polished on the back are top grade.

The wire package is made of copper wire winding. The quality of using copper wire is the key to the life of the transformer.

Copper-clad aluminum wires of the same length are 1/4 of the price of pure copper wires. Due to cost pressures, transformer manufacturers often have transformers with copper-clad aluminum wires in them.

As a result, the transformer will burn out when the temperature of the transformer rises, resulting in failure of the power supply and the entire lamp. Therefore, many lamps, especially those with built-in power supplies, tend to be explosive for about 6 months after shipment.

And how to tell if this copper wire is pure copper wire or copper clad aluminum? Use a lighter to ignite it and burn it out quickly to become copper-clad aluminum.

It can also be identified by measuring the coil resistance.

3.Electrolytic capacitors and SMD ceramic capacitors

In fact, the life of the output capacitor greatly affects the life of the power supply.

The output terminal has a switching frequency of up to 60,000 times per second, which causes the parasitic resistance of the capacitor to heat up, generating scale-like substances, and finally the electrolyte warms up and explodes.

Recommended Output Electrolytic Capacitor: Uses LED-specific electrolytic capacitors. General models begin with L.

Ceramic capacitor: The material is divided into X7R, X5R and Y5V, and the actual capacitance value of Y5V can only reach the actual 1/10, the nominal capacitance value only refers to working at 0 volts. Therefore, this tiny chip resistor and poor selection will also lead to cost differences and greatly shorten the life of the power supply.

4.Circuit design and welding process of power products

Judgment of design advantages and disadvantages: Aside from the professional perspective, it can be distinguished by some intuitive methods, such as neat, generous, orderly, and bright and straightforward soldering.

Welding process: manual welding and wave soldering process. As everyone knows, the quality of wave soldering process by mechanization is definitely better than manual welding. Identification method: whether there is red glue on the back. (The solder paste process + soldering fixture can also achieve wave soldering, but the fixture cost is high).

SMD solder joint inspection instrument: AOI.

This equipment can detect the phenomenon of false welding, false welding and missing welding during the placement process.

A flashing phenomenon occurs when the lamp is used for a period of time, which is basically caused by the power supply or the welding of the lamp beads.

The false solder detection of this product is extremely difficult to pass the aging test, so it is necessary to rely on AOI to detect the quality of the power supply.

5. Batch inspection of aging racks and high-temperature aging rooms for power products

The best power products controlled by materials and production processes still need to detect aging.

It is difficult to control the incoming inspection of electronic components and transformers.

Only through the aging of the entire batch of power supplies and high-temperature sampling in high-temperature rooms, can we check the quality stability of this batch of power supplies and whether the materials have potential safety hazards.

The role of high-volume high-temperature spot checks: power failures are between 1 / 1000th and 1%, and such failures can only be discovered by high-temperature aging of thousands.

The high-temperature room can simulate the harsh environment of power supply operation. Sampling inspection under strict conditions can find batch problems, such as irrational design, poor raw materials, deduction of failures in lamps, high-voltage switch shock, etc.

Aging at room temperature for a long time: screening out random failures such as false welding, missing welding, and collision, filtering out early failures of components, and effectively reducing the failure rate of finished products (1% to 1/1000).

That is, the UPS allows the range of the mains voltage to change, because the local voltage fluctuations directly affect the operation of the UPS, especially in some areas, the power grid is relatively bad, and the voltages during the day and night are very different.

If the UPS is to work 24 hours, in such a wide range of changes, whether the UPS can work is very important. If it does not work, only the battery is switched. This means that the battery is not used for real power failure. Second, frequent battery switching will affect the battery life.

If the UPS's battery transfer device is a relay, the damage to the relay is particularly serious, which greatly increases the failure rate of the UPS.

Voltage protection level (Up)

The peak value of the standard lightning pulse breakdown voltage, the residual voltage of the protected terminal under the rated discharge current Isn, for the power system arrester, according to the overvoltage classification (1,2,3,4), the protection level determines its installation position For information system protectors, the level of protection must match the compatibility of the system and equipment to be protected.

Operating Voltage

The working voltage refers to the voltage required by the CPU to work normally. With the increase of the CPU manufacturing process and the main frequency, the operating voltage of the CPU has a gradual decline. Low voltage can solve the problem of excessive power consumption and excessive heat generation, which is especially important for notebook computers.

input resistance

Impedance is the resistance of a circuit or device to AC current. Input impedance is the impedance measured at the entrance. One input is placed on the load of the signal source that drives it.

High input impedance is also ideal because it reduces signal variations when the circuit is connected. The smallest impedance at a given voltage is the smallest input impedance. As an alternative or supplement to the input current, it determines the input power requirements.

Voltage level (Uc)

The maximum voltage that can be applied to the specified terminal without causing changes in characteristics and activating protection components.

Power factor

This value is usually between 0 and 1, and its value must never be greater than 1. It is the ratio between the W (real power) and VA (virtual power) values. The higher and lower the ratio, the more the ratio The higher the efficiency of the appliance itself, and the lower the ratio, the greater the energy consumed by the appliance itself and the more power it consumes.

Instant response

When the input voltage changes greatly within an instant (within the allowable range), the time it takes for the output stable voltage value to return to normal is also the ability of the power supply to respond to abnormal conditions.

Power fan

The power supply fan is an important part of the power supply and is responsible for extracting hot air from the power supply. When the power is turned on, you can see that there are two large heat sinks. The performance and limit parameters of the high-power tube on the heat sink directly affect the safe carrying power of the power supply and the product cost.

In addition, the two sockets at the rear of the power supply are used to connect external power and provide sockets for the display, and the male socket is generally a power socket. There is a voltage setting switch between the two sockets for switching between 110V and 220V voltage systems. The 220V voltage system is commonly used in China. If it is set incorrectly in the 110V range, it will cause damage to the power supply.

Overcurrent protection

When the load of the protected line increases and the rated current is greater than 1.4 times, the protector cuts off the line after a delay.

System certification

As a total solution for professional users, workstations need to be certified for the entire system to ensure that the system can handle the heat generated by dual CPUs, multiple high-speed rotating disks and graphics cards, and ensure that the power supply can meet the startup and high-speed rotating disks and graphics cards. The stable voltage requirements ensure that the product can run stably under the most demanding environments.

Power

The smaller the power of the power supply, the less heat is generated by the machine, so the continuous projection time of the machine is longer.

For safety, projectors are generally equipped with overheating protection.

Overvoltage protection

The ATX power supply has a 3.3V voltage group more than the traditional AT power supply. Some motherboards directly use 3.3V to supply power to some of the motherboard s devices without voltage-stabilizing components. Even for circuits with voltage-stabilizing devices, there is an upper limit on the input voltage. Powered equipment may cause severe irreversible physical damage. Therefore, the overvoltage protection of the power supply is very important to prevent trouble before it happens.

Noise and filtering

This indicator requires a professional instrument to visually quantify the judgment. The main reason is that 220V AC power is converted into various low-voltage DC power by filtering and stabilizing the switching power supply. The noise indicates the smoothness of the output DC power. The level of filtering quality is directly related to the output DC power The level of the AC component is also called the ripple coefficient. The smaller the coefficient, the better.

At the same time, the capacity and quality of the filter capacitor are also related to the stability of the voltage when there is a large change in current.

Power management

Refers to how to effectively distribute power to the different components of a system. Power management is critical for mobile devices that rely on battery power. By reducing the energy consumption of components when they are idle, a superior power management system can extend battery life by two or three times.

impedance

Impedance: Pay attention to the difference between resistance and resistance. In the world of direct current (DC), the role of objects in blocking current is called resistance, but in the field of alternating current (AC), in addition to resistance, it will block current, and capacitance and inductance. It will also hinder the flow of current. This effect is called reactance, and the impedance we call everyday is the sum of resistance and reactance on the vector.

Power consumption management

IEEE802.11 also defines the signaling method of the MAC layer, which enables mobile users to have the longest battery life through the control of power management software. Power management puts the network to sleep (low power or power down) when no data is being transmitted, which can result in packet loss.

To solve this problem, IEEE802.11 stipulates that the AP should have a buffer to store information, and mobile users who are sleeping will wake up periodically to recover the information.

Return loss

In high-frequency situations, it reflects the proportion of traveling waves reflected at the transition point of the protective equipment.

Under this parameter, we can directly measure the matching degree between the protection device and the surge impedance of the system.

For data transmission systems, in order to prevent bit errors, the return loss of the system must be greater than 20dB.

effect

Does not irritate the eyes, saves power, saves energy and environmental protection, and softens the eyes.