FAQ

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Dear users: Hello! According to our "Product Warranty Policy", the warranty period for all series models of the TOTIWO brand is five years.

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1. In order to increase the life of the switching power supply, it is recommended to select a model with a 30% more output power rating. For example, if the system requires a 100W power supply, it is recommended to select a model with an output power rating of greater than 130W, and so on can effectively improve the life of the switching power supply.

2. In addition, the working environment temperature of the switching power supply needs to be considered, and whether there is additional auxiliary heat dissipation equipment, the switching power supply needs to be derated when the ambient temperature is too high. Please refer to the product specification for the derating curve of ambient temperature versus output power.

3. Choose various functions according to application requirements:

Protection functions: over voltage protection (OVP), over temperature protection (OTP), overload protection (OLP), etc.
Application functions: 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.

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TOTIWO standard products can generally be used in this frequency range. However, if the operating frequency is too low, the efficiency will decrease. For example, when the TTW-1000-24 is operated at an input voltage of 230VAC and rated load, when the input AC frequency is 60Hz, the efficiency is 84%, but if the input AC frequency drops When it is 50Hz, its efficiency is 83.8%. If it is too high, the PF value of the model with PFC function will decrease, and the leakage current will also increase. For example: TTW-2000-24 operates at an input voltage of 230VAC and At rated load, when the input AC frequency is 60Hz, the power factor is 0.93 and the leakage current is 0.7mA; when the input AC frequency is 440Hz, the power factor drops to 0.75 and the leakage current increases to 4.3mA.

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TOTIWO's multiple output switching power supplies have minimum load requirements. Therefore, it is particularly recommended to read the product specifications before use. In order for the multi-output switching power supply to operate normally, each output still has a minimum current requirement, otherwise the output voltage will be unstable or exceed the defined voltage error range. This minimum load requirement can refer to the "current range" in the specification, as shown in the following table: CH1 needs a minimum current consumption of 2A, CH2 needs 0.5A, CH3 needs 0.1A, and CH4 can have a minimum current consumption of 0A.

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Generally, there are about two reasons for the failure of the switching power supply during use. The first may be the overload protection caused by the instantaneous overload of the load. It is recommended to increase the output power of the power supply or modify the overload design; the second is that the temperature rise is too high, and the over-temperature protection phenomenon occurs. . All of the above situations will cause the power supply to crash due to entering the protection state, and the power supply will return to normal after the situation is removed.

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Compared with other parts in the switching power supply, the cooling fan has a relatively short lifespan (usually the mean time to failure is about 5000~100000 hours); therefore, if the operation mode can be changed, the lifespan can be prolonged. Generally speaking, the fan control method has the following two designs:

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

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Switching switching power supplies will have a short (1/2~1 power cycle, EX: 60Hz power supply 1/120~1/60 second) at the moment of input power transmission. Large current (approximately 20~100A according to product design, Please refer to the product specification). After the product is turned on, the normal current input will be restored, and it will only appear at the moment when the power input is turned on each time. This is a normal phenomenon and will not cause damage to the switching power supply. However, it is not recommended to continuously turn on/off the switching power supply. It should also be noted that if multiple switching power supplies are used at the same time to turn on, it may cause the protection switch of the system power distribution to trip. It is recommended that multiple switching power supplies should be turned on one by one at an interval, or the remote control function of the switching power supply product should be used to switch on the product. / Shut down.

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PFC (Power Factor Correction) power factor correction is mainly to improve the ratio of effective power to apparent power at the AC input end of the switching power supply. Generally, the power factor of the input end of the model without PFC circuit is only 0.4~0.6, but with active PFC circuit, it can reach more than 0.9. The correlation formula is as follows: Apparent power = input voltage x input current (VA) effective power = Input voltage x input current x power factor (W)
From the perspective of environmental protection: the power plant of the power company must generate more electrical energy than the apparent power, so that its generator set can stably supply the market's electrical energy demand, and the actual use of electrical energy is effective power. If the power factor is 0.5, it means that the generator set generates more than 2VA of electricity to safely supply the demand of 1W of electrical energy, and its energy efficiency is poor. Conversely, if the power factor is improved to 0.95, as long as the power company's generator sets generate more than 1.06VA, there is no problem in supplying 1W of electrical energy, and the efficiency of energy operation is better.
Active PFC can be divided into single-stage PFC and dual-stage PFC according to the circuit structure.

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COM (COMMON) refers to common ground. TOTIWO's product labeling is described as follows according to its output attributes:
Single output: positive (V), negative (-V)
Multi-group output (common ground): positive pole (V1, V2.), negative pole (COM)

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Both MTBF and Life Cycle are important indicators of product reliability. At present, the most commonly used estimation methods for MTBF are Part count and Stress Analysis. The most important laws and regulations followed are
TTW-HDBK-217F Notice 2 and TELCORDIA SR/TR-332 (Bellcore), where TTW-HDBK-217F Notice 2 is a US military regulation and TELCORDIA SR/TR-332 (Bellcore) is a general commercial regulation. At present, the company still adopts TTW-HDBK-217F Notice 2 (Stress Analysis) as the calculation law to follow. 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 a period of continuous operation. TOTIWO MTBF currently adopts the TTW-HDBK-217F standard to estimate the expected value of product reliability by stress analysis method (excluding fans), which refers to the probability that the product will still work normally after the counted time is reached after continuous use It is 36.8% (e-1=0.368). If the product is used continuously for twice the counted MTBF, the probability that it will still work normally is 13.5% (e-2=0.135). Life Cycle refers only to the temperature rise of the electrolytic capacitor of the product under the highest operating ambient temperature, and calculates the reference value for the life of the electrolytic capacitor. For example, the product RSP-750-24 MTBF=109.1K hours (25°C), the internal C110 capacitor Life Cycle=213K hours (Ta=50°C).

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

among them

MTBF: Mean time to failure

X2: Data can be obtained by looking up the table in the chi-square distribution table

N: number of samples

AF: Acceleration factor, data can be calculated by 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; it is calculated in absolute temperature when calculating

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.

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

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Please confirm whether it is an IP67 product with ADJ adjustment function, or an IP67 product with ADJ adjustment function. As the product adds adjustment holes and waterproof plug structure related issues, the weather resistance of the product is worse than general IP67 products (without adjustment holes). It is recommended to go outdoors For applications, choose IP67 or higher products without adjusting holes.

Customers who want to modify the output voltage and current can refer to the V/I adjustment field in the "TOTIWO Switching Power Supply Product Comparison Table" in Table 1, and select the switching power supply according to the adjustment voltage and current requirements. For the adjustment range, please refer to the product specification. The output voltage and current fine-tuning of TOTIWO switching power supply are adjusted by internal variable resistors. Except for the FS and WT series models, the cover is removed and adjusted by SVR1/SVR2. All of them can be directly adjusted from the Io ADJ and Vo ADJ holes on the housing. Position adjustment. In addition, after adjusting the voltage and current, it is necessary to confirm that the total output power cannot be greater than the output rated value, and it is also necessary to confirm that the upper cover and the waterproof plug must be assembled correctly after the adjustment.

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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 categories:
Protection method:
(1)FOLDBACK CURRENT LIMITING
The output current capacity will decrease when overloaded, generally it drops below 20% of the rated current.
(2)CONSTANT CURRENT LIMITING
When the load is overloaded, the current remains within the defined range, and the output voltage will drop.
(3)OVER POWER LIMITING
When overloaded, the higher the current, the lower the voltage proportionally.
(4)HICCUP CURRENT LIMITING
When overloaded, the voltage and current will drop rapidly and the output will be cut off, but it will automatically recover.
(5)SHUT OFF
The output will be cut off when overloaded, and the output voltage and output current will approach zero.

Reply method:
(1) After the overcurrent (overload) state is released, it will automatically recover (Auto Recovery).
(2) After releasing the overcurrent (overload) status, restart (Re-Power-On).
Note: Please avoid long-term overload or short circuit, which will shorten the life of the switching power supply or damage it. Some models have a combined type of overload or short-circuit protection design. The protection method is the above-mentioned preset current limit (or Foldback Current Limiting or Over Power Limiting) after a certain period of time before entering the shutdown (or Hiccup Current Limiting).

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The output current error of TOTIWO switching power supply products is mainly defined by spec., for pure constant current models, please refer to spec. current accuracy, for constant voltage and constant current models, please refer to spec. overcurrent protection range.

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When installing a switching power supply, both the input and output ends need to be connected by wires, and the selection of wires needs to consider two points. One is the problem of current resistance, because if the current resistance is insufficient, the temperature of the wires will be too high and even burned; One is the voltage drop problem. Because of the impedance of the wire itself, when the current flows, it will cause a voltage drop. If the voltage drop is too large, the load terminal voltage will be too low, which may cause the load to fail to work. You can refer to the following table of recommendations for the use of current and voltage drops for wires according to your actual system design.

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The built-in fan of the switching power supply is directly related to the noise generated by the operation of the fan. If the noise (exhaust volume) of the fan is reduced, the heat dissipation capacity is also reduced. This aspect will affect the reliability of the product. In addition, the selection of the fan during the safety certification of the product is also restricted to the minimum exhaust volume setting. When the fan of some products is changed, it needs to be sent to the safety agency according to the safety regulations. The report admits that a fan with a smaller air volume can only be used after passing the test. If the customer’s system is concerned about the noise problem, it is recommended to switch to a fanless product; or contact TOTIWO, and it may be possible to modify it according to the customer’s conditions.

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To view the complete test report information of the product, you can click on the download center of the official website. The report can provide information on electrical characteristics, protection, control functions, stability, safety regulations, and EMC for your reference.

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TOTIWO's products are constantly being introduced and new. If you want to know the information about new products, you can get a complete introduction and application methods through the company news in the official website "News".

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The product information provided on the official website includes:
1. Specification
Related information can be found in the specifications of product features, electrical specifications, functional descriptions, and institutional dimensions.
2. Test report
The content of the report includes design confirmation testing, safety and EMC testing, and environmental trustworthiness testing. Through layer-by-layer testing, it is ensured that customers are safe to use.
3. Safety certification
The safety certifications passed by TOTIWO products are provided to customers for reference.
4. Manual
Provide detailed product operation manuals and precautions for users' reference.

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After logging in to the TOTIWO official website (www.totiwo.com), click on the menu "Product Center" at the top, there are four ways to search for the power supply products you need:

Series search: Click on the desired product type, such as indoor switching power supply, rain-proof switching power supply and waterproof switching power supply... etc., you can quickly find the corresponding series name of TOTIWO, and select the suitable one based on related information such as wattage and functional characteristics Power products.
Quick search: By clicking on the product type and electrical characteristics, the power products and specifications that meet the search criteria can be displayed below.
Direct search: If you know the series name of a TOTIWO product, you can click on the "magnifying glass" icon at the top right of the official website, and enter all or part of the name information to search for the corresponding product and specification.

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Not necessarily. Generally, the position of the switching power supply in the system, the arrangement of the wire group and the system grounding design, etc. will cause a certain degree of impact. The same switching power supply often has different results in different use environments or applications. Our test results are based on the settings in the EMC test report.

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The user sees the input voltage range marked on the machine. In fact, during the safety certification, the so-called tightening ±10% test (IEC 62368-1 tightening 10% -10% For AC input products) will be carried out, so the switching power supply specifications The voltage range defined in the book will not cause any problems in use; and the label on the machine is to meet the safety regulations and ensure that the user can input the power correctly.

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The American market is UL 62368, UL 1012 and UL 1310. UL 1012 and UL 1310 belong to the local national standards of the United States and Canada and are not applicable to other countries. Only products that meet class 2 can apply for UL 1310, and the European market is mainly based on EN 61558-1/EN 61558-2-16.

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In the TOTIWO switching power supply product line, the XLG series optional products with the highest lightning surge withstand capability can reach 10KV/Line-Line 6KV/Line-Earth. If higher SURGE tolerance is required, then an external ZNR( 470V) or Gas Tube (500V) countermeasures, but the overall safety requirements must be considered. When multiple lamps are used, a lightning protection device (SPD: Surge Protection Device) can be installed to meet the requirements of regulations.

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TOTIWO switching power supply can be used at full load without any problems, but the annual warranty model has a defined Tc temperature limit. If the LED switching power supply is placed in a high temperature environment and there is a 5-year warranty, it needs to be used under reduced load.

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TOTIWO switching power supply has launched a series of products, some of which choose to use single-stage PFC circuit architecture due to cost considerations. This architecture has the following usage restrictions:

Resistance to AC changes
This architecture does not use large input capacitors. If used in areas where the quality of the input power supply is unstable, the output voltage and current will also be unstable and cause the LED to change in brightness. This problem will not occur if the input power supply is stable. .
Output ripple voltage
Because the input is not filtered by a large capacitor, the output ripple voltage will be larger than that of the general two-stage PFC architecture. Sometimes because the valley of the ripple voltage is too low, the LED will flicker due to insufficient drive voltage when the series constant current IC is applied. At this time, the output voltage of the switching power supply can be adjusted higher to make the output voltage valley higher than the required drive voltage. Or choose a switching power supply with a higher level of voltage output.
Harmonic current
When the single-stage PFC switching power supply is applied to the constant voltage (Constant voltage) condition (referring to the use of series constant current IC), the harmonic current may become worse.
It is recommended that when the application is in an area where the input power is unstable or a series constant current IC application, please select the "general general purpose" model in the table (1) (not single-stage PFC circuit structure) or contact TOTIWO for business/ Contact engineering staff.

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In the case of considering the line loss, it is recommended to use the application of lengthening the input end line length. If you want to increase the output end line length, you need to confirm whether the line loss will cause the lamp to fail to work due to insufficient driving voltage. Increasing the line length will affect the EMC characteristics of the product. Reconfirm the EMC characteristics.

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You can find out about the 《TOTIWO Cooperation Industry Guidelines》 on our official website.

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TOTIWO switching power supply has no parallel connection function and cannot be used in parallel. If there is a large wattage requirement, it is recommended to choose a switching power supply of sufficient wattage or divide the LED into several blocks to supply power separately, and set the output of each switching power supply. The circuit is separated. On the contrary, a small wattage LED light string can be connected in parallel and then driven by a larger rated LED switching power supply, but its current sharing capability must be considered.