what is a 24 volt power supply ?

November 21, 2023

24 volt power supply is to use the circuit control switch tube for high-speed on-off and off. The conversion of direct current into high frequency alternating current is provided to the transformer for voltage change, thus generating one or more sets of 24V voltage required.

AC input 100-240V; DC output: 24V power supply. The reason why the 24 Volt power supply is converted to high-frequency AC is that the efficiency of high-frequency AC in the transformer transformer circuit is much higher than that of 50HZ. So the switching transformer can be made very small, and the work is not very hot!! The cost is very low. If you don’t change 50HZ to high frequency, the switching power supply is meaningless!! 24 Volt power supply can be generally divided into isolated and non-isolated two types, isolated type must have switching transformers, but not isolated may not have.

What circuits and components do 24 Volt power supply have?

EMI filter circuit
The main function of the EMI filter circuit is to filter out the interference of high-frequency pulses from the external power grid to the power supply, and also to reduce the electromagnetic interference of the switching power supply itself to the outside world. High-quality power supplies generally have two-pole EMI filter circuits.
Level 1 EMI circuit
The AC power socket is welded to a first-levelEMI power filter circuit. This is an independent circuit board, which is used after the AC input The first set of circuits it passes through, this low-pass network composed of chokes and capacitors, can filter out high-frequency clutter and in-phase interference signals on the power line. It also shields the interference signals inside the power supply, forming a power supply. The first line of defense against electromagnetic interference.
Secondary EMI circuit
After the mains power enters the power board, it first passes through the power fuse, and then passes through the second EMI circuit composed of inductors and capacitors to fully filter out high-frequency noise, and then enters the high-voltage rectifier and filter circuit through the current-limiting resistor.
Bridge rectifiers and high voltage filtering
After EMI filtering, the mains power becomes high-voltage direct current after full-bridge rectification and capacitor filtering. Convert the alternating current at the input end into pulsed direct current. In 2018, there are two forms. One is a full bridge, which is to package four diodes together. The other is to use four discrete diodes to form a bridge rectifier circuit. The function is the same and the effect is also Same.
PFC circuit
The PFC circuit is called a power factor correction or compensation circuit. The higher the power factor, the greater the power utilization.
Switching transistors and switching transformers
As the name suggests, the core of switching power supply is the word switch. The switching transistor and switching transformer are the core components of the switching power supply. The switching transistor is made to work in the saturated and cut-off (i.e. on and off) states through self-excitation or other excitation, thereby inducing high-frequency voltage on the secondary winding of the switching transformer. After rectification, filtering and voltage stabilization, various DC voltages are output.
Low voltage rectifier filter circuit
The pulsating voltage after being stepped down by the high-frequency starting transformer also needs to be rectified and filtered using diodes and capacitors. However, the working frequency during rectification is very high at this time, so Schottky rectifier diodes with fast recovery function must be used. Ordinary rectifier diodes It is difficult to do this, and the capacitor used in the rectifier part cannot have too large an AC impedance, otherwise it will not be able to filter out the high-frequency AC components. Therefore, the selected capacitor must not only have a large capacity, but also have a low AC resistance. , in addition, you can see 1 or 2 large inductor coils with magnetic cores, which together with the filter capacitors filter out high-frequency AC components to ensure the output of pure DC power.
Voltage stabilization and protection circuit
The voltage stabilizing circuit usually samples a part of the voltage from the output voltage of the power supply and compares it with the standard voltage. The difference is amplified and used to drive the switching transistor to adjust the duty cycle of the switching tube to achieve voltage stability. The function of the protection circuit is to detect changes in the output voltage or current at each end. When short circuit, overvoltage, overcurrent, overload, undervoltage, etc. occur at the output end, the protection circuit will act, cut off the excitation signal of the switching tube, and cause the switching tube to When the vibration stops, the output voltage and current are zero, which plays a protective role.

Electrical characteristics

1.0 safety standards.
2.0 Mechanical Properties:
2.1 Stress test: Each lead terminal of the product can withstand an axial pulling force of 2 kilograms, lasting 60 seconds, without loosening, blocking, or other damage.
2.2Drop test: The product is dropped from a height of 90CM, once in each direction of X-Y-Z, onto a pine board with a thickness of 1CM. No abnormality, insulation resistance test, minimum 10M ohm. Refer to GB/T 4857.
2.3 Wire swing test: The wire hoisting weight is 200 grams, the left and right swing angle is 120 degrees, and it must still be conductive after 300 rounds. Refer to UL-817/JISC8306.
3.0 Appearance:
The general appearance of the product is that it has been exposed to no deformation, cracks or rust.
4.0 Input and output characteristics
4.1INPUT VOLTAGE input voltage:
100VAC 50/60Hz
110VAC 50/60Hz
264VAC 50/60Hz
4.2 OUTPUT VOLTAGE Output voltage:
240mVP-P MAX
4.3INPUT CURRENT input current:
AC 100V 50/60Hz     AC 110V 50/60Hz           AC 264V 50/60Hz
50mA Max
2000mA Max
4.4 Input power: no-load 0.5W maximum, input voltage 100-240VAC50/60Hz. Load: 150W maximum.
4.6TEMPERATURE RISING Temperature rise: 65℃ MAX.
4.7 INSULATION RESISTANCE Insulation resistance: 500VDC100 MΩ MIN.
4.8 Withstand voltage test: 5mA 3000VAC for 1 minute, between input and output, input and shell, for one minute. When choosing to increase the withstand voltage by 5%, the application time is 1 second.
4.9 -1 Power factor: 0.91 MIN.
5.0 ENVIRONMENTAL Environment:
5.1 Working environment temperature range: -29 ℃ TO + 45.5 ℃.
5.2 Storage environment temperature range: -40 ℃ TO + 75 ℃.
5.3 Heat resistance: The tested product is placed in a high temperature chamber at 105℃±3℃ and tested after 16 hours. The product must meet the voltage resistance test requirements of item 4.7. Insulation resistance: 500VDC is not less than 10 M ohm. Between input and output, input and shell.
5.4 Moisture resistance: Place it for 8 hours at an ambient temperature of 40 ℃ ± 2 ℃ and a relative humidity of 90% ~ 95%. Take it out and test it after 10 minutes. The product must meet the voltage resistance requirements of item 4.7. Insulation resistance: input to output , under 500VDC conditions, minimum 10M ohms.
6.0 Reliability:
Rated full load, operating temperature 25°C. Product life is within 30,000 hours.
7.0 Protection:
7.1 Current protection: The product has a built-in current fuse, type 250V 3A, fixed in the input circuit.
7.2 Short circuit protection: Withstand continuous short circuit and automatic recovery capabilities.
8.0 Inspection:
8.1100% inspection items: no-load voltage, load voltage, ripple voltage, input current, withstand voltage test and general appearance inspection.
8.2 In addition to 100% inspection items, sampling inspection also includes insulation resistance and audible sound inspection.
8.3 Submit each batch of sampling inspection reports and 100% withstand voltage test reports.
8.4 Sampling inspection item level: MIL-STD-105EII fatal flaw 0, major flaw 0.25, minor flaw 1.0.
9.0 Main measuring equipment
9.1 AC SOURCE/AC input power supply: AFC-500W, external calibration once a year
9.2 POWER METER/power meter: CHROMA 2100, external calibration once a year
9.3 ELECTRONIC LOAD/electrical load: PRODIGIT 3310C, external calibration once a year
9.4 OSCILLOSCOPE/Storage Oscilloscope: TDS-2012B, external calibration once a year
9.5 DIGITAL MULTIMETER/Digital multimeter; Fluke 4.5, external calibration once a year
9.6 DC POWER/DC input power supply: WYK-6030, external calibration once a year
9.7 HI-POT TESTER/withstand voltage tester LANKE ELECTRONICS 7112, external calibration once a year
9.8 INSULATIONRASISTANCE TESTER/Insulation resistance meter: YD2681A, external calibration once a year
10.0 Obtain certification
10.1 Refer to the certification column of Fuyuan official website to download.
10.2 Certificate
United States/Canada UL, cUL, FCC, NrCAN, CEC
Europe/Germany TUV/GS, CE, ErP, CB, RoHS, LVD, EMC British BS,
Australia SAA, C-Tick, MEPS
Korea KC
Japan PSE
China CCC
power supply 24v5a (2)
Application of 24V5A, QXP-PAD-2405000 power adapter
Lead-acid batteries, electric toys, humidifiers, air purifiers, motor massage and beauty equipment, security monitoring systems, precision testing and measuring instruments , electronic information product peripherals, printing and imaging equipment, audio amplifiers, LED indoor lighting, digital communication appliances, LCD, LED LCD monitors, LED outdoor lighting fixtures, etc.


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