Switching Power Supplies

Switching power supply, or switched-mode power supply (SMPS), is to utilize the electronic switching devices (such as transistor, MOFET, thyristor, etc.) for constantly switching on and off through the control circuit to make input voltage pulse modulation, so as to achieve DC/AC, DC/DC voltage conversion, output voltage adjustable and automatic voltage regulator. The SMPS power supplies are now widely applied to electronic devices by virtue of its outstanding performance in small size, light weight and high efficiency.
The switching power supplies on ATO.com can convert universal AC input to 5V/15V/12V/24V/48V DC output with short circuit, overload and overvoltage protection, complying with safety & EMC standards. High quality 50W ~ 400W SMPS power supply is an ideal choice for switching on & off LED light strips, computers, printers and other power tools, office devices, household appliances or industrial equipment.

What are the components of switch mode power supply?

1. Main Circuit

• Inrush current limiter: Limit the inrush current on the input side when the power is turned on.
• Input filter: Its function is to filter the clutter existing in the grid and prevent the clutter generated by the machine from being fed back to the grid.
• Rectification and filtering: rectify the AC power of the grid directly into a smoother DC power.
• Inverter: Convert the rectified direct current into high-frequency alternating current, which is the core part of the high-frequency switching power supply.
• Output rectification and filtering: Provide stable and reliable DC power according to the needs of the load.

2. Control circuit

On the one hand, take samples from the output end, compare with the set value, and then control the inverter to change its pulse width or frequency to stabilize the output. The control circuit performs various protection measures for the power supply.

3. Detection circuit

Provides various parameters and various instrument data in operation in the protection circuit.

4. Auxiliary power supply

Realize the software (remote) startup of the power supply, and supply power for the protection circuit and the control circuit (chips such as PWM).

How to choose a SMPS power supply?

1. Select the appropriate output voltage.
2. Select appropriate power. To extend life span of a switching power supply, it is suggested to select one with 30% more than the rated output power.
3. Take load characteristics into cosideration. In case of motors, bulbs or capacitive load, users should select an appropriate switching power supply to prevent overload caused by large current at startup. In case of motors, users should consider backward flow of voltage when the device is halted.
4. Users should consider the working temperature of SMPS power supply and whether the additional auxiliary cooler is needed. Output of the SMPS power supply shall be reduced in higher temperature conditions.
5. Choose the features of SMPS power supply according to demands
   Protective features: overvoltage protection, over temperature protection, and over load protection etc.
   Application features: signal functions (indication of normal and failure status), remote control, remote measuring, and parallel connection etc.
6. Comply with the applicable safety certification and EMC certification.
   
   

How to use a switching power supply properly?

1. Confirm whether specifications of input or output voltage comply with nominal value of the power supply before use.
2. Check whether input and output leads are correctly connected before powering on for prevention of equipment damages.
3. Check whether various components are tightened up. Check whether there are contacts between screws and electrical parts of power panel. Measure insulation resistance between shell and input or output leads for prevention of electric shock.
4. Make sure the ground terminal is properly connected to the ground to grantee safety and reduce noise waves.
5. Multiplexed output refers to a power supply with primary and secondary output. The primary output performs better than secondary output. In general conditions, the one with larger current is the primary output. To ensure adjustment rate and dynamic indicators of output load, it is required to at least carry 10% of its load. If using secondary output instead of the primary one, users should exert dummy load on the primary output. Please refer to the specifications of different models for more details.
6. Please note that the frequent switching of power supply will have negative influence on its life span.
7. Operating environment and on-load level will influence life span of switching power supply.