If you encounter problems using Mingwei power products, please search for the following common problems first to solve your problems. If the answers listed do not satisfy your question, please contact your nearest Mingwei distributor, our distributor will reply you as soon as possible!

MEAN WELL is a professional standard power supply manufacturer, which develops various types of power supply products in response to market needs. Choosing the right power supply product where relevant specifications, electrical functions, or product reliability are your focus. Therefore, the following common questions have been compiled, please refer to it!

Functional aspects


Notes on choosing POWER SUPPLY?


  1. In order to increase the life of POWER SUPPLY, it is recommended to select a model with an output power rating that is 30% more. For example, if the system requires a 100W power supply, it is recommended to choose a model with an output power rating greater than 130W, and so on, which can effectively improve the life of POWER SUPPLY.
  2. In addition, the working ambient temperature of POWER SUPPLY and the need for additional auxiliary heat dissipation equipment need to be considered. At excessively high ambient temperatures, POWER SUPPLY needs to be derated. Please refer to the product specifications for the derating curve of ambient temperature to output power.
  3. Select functions according to application needs:
• Protection function: Over Voltage Protection (OVP), Over Temperature Protection (OTP), Over Load Protection (OLP), etc.
• Application function: signal function (POWER GOOD, POWER FAIL), remote control function, telemetry function, parallel function, etc.
• Special functions: power factor correction (PFC), uninterruptible power supply (UPS).

4. Select the required safety regulations and electromagnetic compatibility (EMC) certification.


May the power of Mingwei be used for 45 ~ 440Hz, if it is, is there any other influence?


MEAN WELL's standard products can generally be used in this frequency range. However, the use frequency is too low, which will cause the efficiency to decrease. For example: When the SP-200-24 operates at an input voltage of 230VAC and a rated load, when the input AC frequency is 60Hz, its efficiency is 84%, but if the input AC frequency decreases It is 50Hz, and its efficiency is 83.8%; when it is too high, the PF value of models with PFC function will decrease, and it will also increase the leakage current. For example: SP-200-24 operates at 230VAC and At rated load, when the frequency of input AC power is 60Hz, the power factor is 0.93 and the leakage current is 0.7mA; while when the frequency of input AC power is 440Hz, the power factor decreases to 0.75, and the leakage current increases to 4.3mA.


What is the minimum load requirement? And how do I get this information from the data sheet?


MEAN WELL's multiple output power supplies (for example, 2 output or more) have minimum load requirements. Therefore, it is particularly recommended that you read the product specifications before use. In order for multiple sets of output power supplies to work properly, each set of outputs still requires a minimum current, otherwise the output voltage will be unstable or exceed a defined voltage error range. This minimum load requirement can refer to the "current range" in the specification, as shown in the following table: CH1 requires a minimum current consumption of 2A, CH2 requires 0.5A, CH3 requires 0.1A, and CH4 can be a minimum of 0A.


Why does the power supply crash during use, and can it be operated again after being turned off?


Generally, there are two reasons that cause the power supply to be down during use. The first may be overload protection caused by momentary overload of the power supply. It is recommended to increase the output power of the power supply or modify the design of the overload. The second is excessive temperature rise and over-temperature protection. phenomenon. The above situation will cause the power supply to crash due to entering the protection state, and the situation will be restored when the power is turned off.


For a power supply with a cooling fan, what are the control conditions for its fan operation?


Compared with other parts in the power supply, the cooling fan has a relatively short life (usually an average failure time of about 5,000 to 100,000 hours); therefore, it can extend the life if it can change its operation mode. Generally speaking, the fan control method has the following two designs:

  1. Temperature control: When the temperature switch detects that the internal temperature of the power supply exceeds its set value, the cooling fan will run at full speed; conversely, when it is lower than its set value, it will stop running or at half its speed. Speed operation. In addition, in some power supplies, the cooling fan is controlled by a non-linear control method to change its speed synchronously with different internal temperatures.
  2. Load control: When the load of the power supply exceeds its set value, the cooling fan will run at full speed; conversely, when it is lower than its set value, it will stop running or run at half the speed.


What is Inrush Current? Is there anything I should pay attention to?


The switching power supply will have a short current (1/2 ~ 1 power cycle, EX: 60Hz power supply 1/120 ~ 1/60 seconds) at the moment of input power supply power (approximately 20 ~ 100A according to product design) (Please refer to the product specifications). After the product is turned on, the normal current input is restored. It will appear at the moment when power is supplied to the power input terminal. This is normal and will not cause damage to the power supply. However, it is not recommended to continuously power on / off the power supply. It should also be noted that if multiple power supplies are turned on at the same time, the protection switch of the system power distribution may be tripped. It is recommended that multiple power supplies should be turned on one at a time or use the remote control function of the power supply to perform the product. On / off.


What is PFC?


PFC (Power Factor Correction) power factor correction is mainly to improve the ratio of the effective power and the apparent power of the AC input of the power supply. Generally, models without PFC line have a power factor of only 0.4 ~ 0.6 at the input end, while active PFC lines can reach above 0.9. The correlation is as follows: Apparent power = Input voltage x Input current (VA) Effective power = Input voltage x input current x power factor (W)
From an environmental protection point of view: the power company's power plant must generate more power than the apparent power, so that its generator set can stably supply the market's power demand, and the actual use of power is effective power. If the power factor is 0.5, it means that the generator set emits more than 2VA power, so that it can safely supply 1W of power, and its energy operation efficiency is poor. On the contrary, if the power factor is improved to 0.95, as long as the power company's generator set emits more than 1.06VA power, there is no problem in supplying 1W of electrical energy, and the operating efficiency of energy is better.
Active PFC can be divided into single-stage PFC and dual-stage PFC according to the line architecture. For comparison, refer to the table below.

PFC architecture advantage Disadvantage Application restrictions
Single-stage PFC low cost
Simple line
Low power efficiency
Ripple is too big
Feedback is not easy to adjust and affect PF
1.No hold up time directly affects the output of the AC power supply.
2.High Ripple current easily affects the life of LED lamps (direct drive
3.Slow feedback response, great influence on load characteristics
Two-stage PFC High power design
Good PFC characteristics
Feedback compensation is easy to adjust
Good load characteristics
high cost
Complicated line
Can be used in most environments with general power, without special restrictions


What is the difference between -V or COM on the negative terminal of the output of MEAN WELL power supply?


COM (COMMON) refers to the common ground. The output attributes of MEAN WELL products are described as follows:
Single output: positive (+ V), negative (-V)
Multiple sets of outputs (common ground): positive (+ V1, + V2.), Negative (COM)


There are AC or DC inputs on the input terminals of the MEAN WELL power supply catalog. What is the difference?


a. 85 ~ 264VAC; 120 ~ 370VDC
b. 176 ~ 264VAC; 250 ~ 370VDC
c. 85 ~ 132VAC / 176 ~ 264VAC by Switch; 250 ~ 370VDC

    • When the product specifications indicate the input power range of items a and b above, the power supply can work normally whether it is sending AC or DC power. But please also pay attention to the design of some models. The direct power input (+) is connected to AC / L, and the negative (-) is connected to AC / N power supply. The AC / L can only be turned on. If the wiring is wrong, but it is not turned on, it can work normally by reversing it, and the power supply will not have other problems.
    • The product specification is marked as item c above. The 115 / 230V switch must be switched to the "230V" position to input 250 ~ 370VDC. If the switch is in the "115V" position and 250 ~ 370VDC is input, the power supply will be damaged. Be sure to pay attention.


What is MTBF? How is it different from Life Cycle? What is DMTBF?


MTBF and Life Cycle are important indicators of product reliability. At present, the more commonly used estimation methods of MTBF are the part count method and stress analysis method. The most important laws and regulations to follow are:
MIL-HDBK-217F Notice 2 and TELCORDIA SR / TR-332 (Bellcore), of which MIL-HDBK-217F Notice 2 is US military regulations and TELCORDIA SR / TR-332 (Bellcore) is general commercial regulations. At present, the company still uses MIL-HDBK-217F Notice 2 (Stress Analysis) as the calculation and compliance regulations. The so-called MTBF (Mean Time Between Failure) average failure time is the expected value of reliability estimation, which refers to the average time that the reliability of the product drops to 36.8% after continuous work for a period of time. MEAN WELL MTBF currently adopts the MIL-HDBK-217F standard and uses stress analysis to estimate the expected value of product reliability (excluding fans), which refers to the probability that the product will still work normally after continuous use reaches the counted time It was 36.8% (e -1 = 0.368). If the product continuously uses twice the counted MTBF, the probability that it can still work normally is 13.5% (e -2 = 0.135). And Life Cycle refers to the temperature rise of the electrolytic capacitor under the highest operating ambient temperature, and calculates the reference value of the electrolytic capacitor life. For example, the product RSP-750-24 MTBF = 109.1 K hours (25 ° C), the internal C110 capacitor Life Cycle = 213 K hours (Ta = 50 ° C).

DMTBF (Demonstration Mean Time Between Failure) empirical mean time to failure is a way to verify MTBF. Please refer to the following formula to calculate the total verification time.

Total verification time

among them

MTBF: mean time to failure

X 2 : Data can be obtained by looking up the table in the chi-square distribution table

N: number of samples

AF: acceleration factor, which can be calculated from the formula of the acceleration factor

Ae = 0.6

K (Boltzmann Constant) = 8.625 * 10 -5 (eV / k)

T1: refers to the rated temperature of the specification; calculated in absolute temperature

T2: refers to the temperature used for acceleration during verification; it is calculated as absolute temperature during calculation. However, this temperature must not cause any changes in the physical properties of the product.


What are "Power Good" and "Power Fail" signals? And how to use it?


Some power supplies will send "Power Good" or "Power Fail" signals for monitoring and control when they are turned on or off.
Power Good: refers to sending a TTL signal after a delay of tens to hundreds of ms after the output reaches 90% of the rated voltage.
Power Fail: before the output is lower than 90% of the rated voltage, the TTL signal is turned off more than 1ms in advance.


I have a TN-1500 inverter. Why is the AC power input already provided, but the AC IN LED does not light up?


According to the mains voltage in different countries, the output of the 110VAC version of the TN-1500 inverter can be changed to 100/110/115 / 120VAC, and the output of the same 220VAC version of the TN-1500 inverter can be changed to 200/220/230 / 240VAC. When the inverter is set to UPS mode and the fluctuation of the mains voltage exceeds ± 15% of the set value of the AC output voltage, the power source of the inverter will be switched from the mains to the battery to maintain the AC output Voltage accuracy; at the same time, the AC IN indicator on the front panel will be turned off.


What are the forms of overcurrent / overload protection?


When the output current of the power supply exceeds the rated current, the protection circuit operates to reduce or cut off the output power.
The overcurrent characteristics are divided into the following types:
Protection method:
The output current capability will decrease when it is overloaded, and generally drops below 20% of the rated current, as shown by curve a in the figure.
During overload, the current stays within the defined range, and the output voltage will decrease, as shown by curve b in the figure.
The higher the current during overload, the lower the voltage in proportion, as shown by curve c in the figure.
When the load is over, the voltage and current will drop rapidly and cut off the output, but it will recover automatically.
When the load is overloaded, the output will be cut off, and the output voltage and output current will approach zero.

Reply method:
(1) After the over-current (over-load) state is released, the system automatically recovers (Auto Recovery).
(2) After releasing the over-current (over-load) status, restart (Re-Power-On).
Note: Please avoid long-term overload or short circuit, which will shorten the life of the power supply or damage it. The overload or short-circuit protection design of some models is a composite type. The protection method is as described above. The current limiting (or Foldback Current Limiting or Over Power Limiting) will be turned off (or Hiccup Current Limiting) after a certain time.


What is Ripple Noise? How to measure?


The waveform of the AC component contained in the output DC voltage of SPS is as follows:

There are two kinds of components in SPS ripple noise, one is the octave frequency of AC input voltage, and the other is the switching frequency of SPS itself. Because it is high frequency noise, when measuring, the bandwidth of the oscilloscope should be set at 20MHz, and the probe should be measured at the shortest distance; and a small capacitor (0.1uF) should be added to the end to be tested to filter out noise interference, as shown in the figure As shown.


What is the definition of IPxy dust and water resistance? What is the definition of MEAN WELL's IP68?


The design of MEAN WELL power and dustproof is mainly based on the IEC60529 international standard. The relevant standards are described in the following table:
(Note: Models above IP64 level are suitable for occasions with humid indoor or outdoor rain)

* IP64-IP66 grade models are suitable for indoor wet environments or outdoor rain-covered places. For restrictions on actual installation, please refer to the definition of IP grade test.
* All products cannot be left in water for a long time.
* The definition of Mingwei IP68 is that the product to be tested is placed 1 meter under the water surface, and the dynamic test is performed for 1 month.
Dynamic test: Perform 12-hour AC TURN ON; 12-hour AC TURN OFF burn-in test.


How to choose Mingwei LED power supply?



  1. Determine the appropriate wattage according to the customer's system requirements and application methods, including the power safety margin to be designed, and consider the system's drive mode design.
    1. Use Mingwei power supply to "direct drive" LED lamps. For the main points, please refer to questions (A2) and (A3).
    2. Using Mingwei's power supply and LED driver IC with constant current source to achieve more accurate constant current drive. For the main points, please refer to questions (A2) and (A3).
  2. Confirm the working environment of the LED power supply, choose the appropriate waterproof and dustproof (IP) level, or the appropriate model structure (metal case, plastic case, PCB type).
  3. Do you need to have a power factor correction (PFC) function: Models with a single-stage PFC architecture can only be used for LED loads, and those with a dual-stage PFC architecture can be used for general loads.
  4. If the system design uses a power supply to drive the LED directly, do you need a model that can adjust the output voltage / current or a model that has a dimming function.
    1. * Please refer to the following website for detailed model comparison table: http://www.meanwell.com.tw/product/images/led/LED_comparison_chart_tw.pdf
      * For products with power factor correction, if you want to use single-stage PFC products, please refer to the description of LED power supply application problem (D1) .


What are the application methods of LED lighting system configuration? What are its advantages and disadvantages?



Cautions when choosing an LED power supply?


  1. Directly driven design of lighting system
    1. The sum of the upper and lower limits of the LED operating voltage range must be within the output voltage range of the LED power supply. For example, the LED specification is 3.4 ~ 3.6V, and the 6-string series voltage is 20.4 ~ 21.6V. At this time, the output must be selected It is a 24V (18 ~ 24V constant current range) model.
    2. For models with power factor correction function, if the PF value is required to be greater than 0.9, the load must be greater than the PFC definition range of the specification. The relationship between the power factor and output load is shown in Figure (1), which will be different according to the model definition. The general design value Over 75% LOAD.
    3. If it is used in the place where the input voltage is unstable, such as using generator equipment or in heavy industrial areas, please select the "General-purpose" product in Table 1.
  2. Constant current IC design for lighting system
    1. The startup voltage design of the driver IC needs to be close to the output voltage of the LED power supply.
    2. The driver IC has higher requirements for voltage stability, and it is recommended to use the "generic general purpose" products in Table 1.
    3. For models with power factor correction function, the load must be greater than the range defined in the PFC specification. The relationship between power factor and output load is shown in Figure (1), which will be different according to the model definition. Generally, the design value is above 75% LOAD.
    4. The use of driver ICs may cause EMI collocation problems. The EMI design needs to be confirmed again. If there are EMI problems, please refer to LED Power Supply Application Problems (11).


What are the CV, CC, CV + CC mentioned in the LED power supply specifications?



How is ELN-30 / 60-XXD (P) dimming function applied?


As shown in (11) and (12), adding DC voltage control (D Type) or PWM control signal (P Type) between "DIM +" and "DIM-" can be controlled by adjusting the output current of the power supply. LED current, because this control signal and output current are not directly linear and have a certain error, it is recommended to apply to dimming control that does not require accuracy.


Can the output voltage and current of the Mingwei LED power supply be fine-tuned by the user?


Customers who want to modify the output voltage and current can refer to the V / I adjustment field in Table 1 "Ming Wei LED Power Supply Product Comparison Table" and select the LED power supply according to the adjustment voltage and current requirements. Please refer to the product specifications for the adjustment range. The output voltage and current trimming of Mingwei LED power supply is adjusted by internal variable resistors. Except for the PLN and ELN series models, the cover must be removed as shown in Figure (9) and adjusted by SVR1 / SVR2, which can be directly adjusted as Figure (10) adjusts the Io ADJ and Vo ADJ hole positions on the housing. In addition, after adjusting the voltage and current, you need to confirm that the total output power cannot be greater than the output rating. It is also necessary to confirm that the upper cover and waterproof plug must be assembled correctly after adjustment.


    What is the definition of the IP level (such as the IP67 of CLG-100) in the Mingwei LED power supply specifications?


    MEAN WELL LED power supplies mostly have dust-proof and waterproof design, which are mainly based on the IEC60529 international standard. The content is described in the following table:

    * IP64-IP66 grade models are suitable for indoor wet environments or outdoor rain-covered places. For restrictions on actual installation, please refer to the definition of IP grade test.
    * All products cannot be left in water for a long time.


    If you want to design LED street lights, what kind of solution can we provide?



    What is the difference between 1 ~ 10V and 0 ~ 10V dimming control?


    The main difference is that 0 ~ 10V can be used to turn off the LED power output, and 1 ~ 10V can only achieve 10% dimming.


    What is the output current accuracy of Mingwei LED power products?


    The output current error of Mingwei LED power products is mainly defined by spec. For pure constant current models, please refer to spec. Current accuracy. For constant voltage + constant current models, please refer to spec. Overcurrent protection range.


    What is the difference between unipolar and bipolar power converters?


    The active power factor correction circuit can be divided into two types: single-stage and dual-stage. Single-stage power converter integrates the front-stage power factor correction circuit and the post-stage DC-to-DC converter circuit. The two-stage power converter is Separate design. Compared to single-stage converters, the two-stage architecture is more complicated and costly. However, single-stage converters have the disadvantages of being easily affected by poor input power quality and excessive output ripple. This type is only suitable for LED driving applications where the input voltage is stable. The two-stage type can be used for LED driving in harsh environments or can be regarded as a general power supply application.


      What are the characteristics and errors defined by the dotted lines in the LED product VI characteristic curve?


      LED product specifications have VI characteristic curves. According to the curve description, they can be divided into "constant current" and "constant current + constant voltage". Constant current models are only applicable to LED applications, and constant current + constant voltage models are applicable to LEDs. Or general application, non-suitable for LED driving interval will be indicated by dashed line. According to the protection method, it can be divided into hiccup and constant current mode. The interval only represents this current characteristic. There is no defined current value error. The short-circuit current can be selected as the hiccup mode. If there is a motor or a capacitive load, the interval protection mode can be selected as a constant current model.