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DC/DC converters are not reverse polarity protected. They will be irreparably damaged if connected the wrong way around. If it is possible or likely that the converter could be reverse polarity connected, then a diode must be used to protect the converter (refer to the Application Notes).

All DC/DC converters can withstand occasional short-duration over-voltage transients (<100ms), but repeated over-voltage conditions can lead to failure. Unregulated DC/DC converters can cope with longer input over-voltage conditions as long as the supply voltage does not exceed the component ratings. The output voltage will also be too high. Regulated DC/DC converters will attempt to regulate an input over-voltage condition so will be more stressed, nevertherless some converters like the REC3.5 and REC6 can withstand 60s input over-voltage conditions (refer to datasheet for limits)

All DC/DC converters can withstand occasional short-duration brown-outs, but repeated under-voltage conditions can lead to failure. For a constant power load, the input current rises exponentially as the input voltage decreases. Unregulated DC/DC converters can cope with longer input under-voltage conditions as long as the increased input current does not exceed the component ratings. The output voltage will also be too low. Unregulated converters do not have an Under-Voltage Lock-Out (UVLO) function. Regulated DC/DC converters will attempt to regulate an input under-voltage condition so will be more stressed, some series are available with an Under-Voltage Lock-Out (UVLO) function, either as standard or as an /X1 option, which disables the converter if the input current is too high. This also stops the converter from attempting to start up too early before the supply voltage has stabilized.

The ratio refers to the input voltage range. For example, a 24V input DC/DC converter with 1:1 input range is specified with 24Vinput +/-10% (21.6V to 26.4V). A 24V input DC/DC converter with 2:1 input range is specified over a two-to-one input voltage range of 18V-36V and a 24V input DC/DC converter with 4:1 input range is specified over a four-to-one input voltage range of 9V-36V.

A non-isolated or switching regulator converter can efficiently reduce or boost a DC input voltage to a lower or higher output voltage.

A switching regulator has the following advantages over an isolated DC/DC converter:

1. As a transformer is not used and the input and output share a common ground, the efficiencies can be very high (>97%). These low losses allow a wider operating temperature and a higher power density compared with isolated converters.
2. A switching regulator can vary the internal on/off duty cycle over a wider range to compensate for changes in load and/or input voltage, thus the converter can work efficiently over an extended input voltage range (7:1 or more) and load range (100:1).
3: Switching regulators often uses a cycle-by-cycle controller IC, so the reaction time to dynamic load changes or short circuit conditions is very fast.

An isolated DC/DC converter will translate a DC input voltage to the same or a different DC output voltage which is electrically isolated from the input via an internal transformer. It is commonly used for the following reasons:

1: To break ground loops. Electrical interference on the power rails is blocked from affecting other parts of the circuit, for example, a DC/DC used in a motor controller circuit can provide a low-noise, stable output from a noisy DC supply.
2: To change the reference point of a supply. For example to generate a +5V rail from a -48V telecoms power supply.
3. For safety. For example in medical applications to protect the patient from power supply faults
4: For supply security. For applications with multiple channels, isolating each channel power supply with a separate DC/DC converter means that if any channel is faulty or short-circuited, the remaining channels are unaffected.

A DC/DC converter can have the following connections:

The supply pins, Vin+ and Vin –
The output pins, Vout + and Vout- (plus a common pin for +/- outputs)
A remote control on/off, enable or control pin (usually labelled "CTRL")
A trim pin (to adjust the output voltage up or down)
Sense pins (to compensate for any cable or track resistance losses)
Power OK pin (an output signal to indicate that the output voltage is stable)

There are many reasons why you should use a DC/DC converter, but the most common applications are:

• To match the loads to the power supply (e.g. to generate higher, lower or dual outputs from a single source, or to invert a supply rail.)
• To isolate primary and secondary circuits (e.g. for safety reasons or to protect a sensitive circuit from interference)
• To simplify power supplies (e.g. multiple output converters or one converter per rail (point-of-load) can reduce power supply complexity, overall cost and board space requirements while at the same time increasing flexibility, reliability and system efficiency.)

산업용 전원은 신뢰성, 넓은 입력 전압 범위, 각종 보호 기능, 고효율을 최우선으로 고려해야 합니다. 또한 일반적인 산업 환경 온도 범위인 -40℃ ~ +85℃에서 안정적으로 동작해야 합니다.

마이크로컨트롤러에는 매우 안정적인 전압 레일을 제공하는 저노이즈 DC/DC 컨버터 또는 선형 레귤레이터를 사용해 전원을 공급하는 것이 일반적입니다. 마이크로컨트롤러의 입력 전류는 연산 부하 변화에 따라 급격하게 변동하기 때문에, 부하가 갑자기 변해도 안정성을 유지할 수 있도록 빠른 과도 응답 특성이 요구됩니다.

신뢰성은 부품 품질, 열 관리, 보호 기능 구현, 적절한 전기적 설계에 따라 좌우됩니다.

Although some of our DC/DC converters contain Class A or Class B EMC filters built in, many of our low cost DC/DC converters contain only simple input filters. The customer can then decide to add an EMC filter individually or for all of the converters together to save costs. External EMI filter suggestions are given in our Application Notes for both Class A and Class B levels. All of our AC/DC converters contain a built-in Class B EMC filter as standard.

The UKCA (UK Conformity Assessed) marking is a new UK product marking that is used for products being placed on the market in Great Britain (England, Wales and Scotland). It applies to the same products that are currently CE marked. The circumstances in which self-declaration of conformity for UKCA marking can be used are the same as for CE marking. Based on current UK rules, RECOM is eligible to self-declare for the UKCA Declaration of Conformity (DoC) as long as the EU and UK regulations remain aligned.
RECOM will make available a separate UKCA Declaration of Conformity (DoC) based on the existing CE Declaration of Conformity (DoC) and test reports (self-declaration). CE marking remains valid for goods placed on the market in Great Britain until 1 January 2023. The UKCA marking must be used for placing goods on the market in Great Britain after this date. RECOM will continue to actively monitor any changes to the UKCA rules based on UK government guidance and react accordingly.
We will also instigate a program to successively add the UKCA mark to our CE marked products to fulfil our obligations as manufacturer. For further information or enquiries regarding our UKCA policy, contact TechSupport

RECOM prides itself on having a comprehensive certification portfolio, with full third party UL/IEC/EN certifications (not just 'designed to meet'). Certifications cover Industrial, Medical, LED lighting, Household, Railway and Automotive standards, depending on the application area of the converter.

We provide many medical grade converters with UL/IEC/ EN-60601-1 certifications (3rd Ed.), including risk assessment documentation.

Refer to the instructions given by the conformal coating supplier regarding the recommended process for washing and drying the boards before applying the conformal coating. We have never received any complaints of chemical incompatibility or any other problems with conformal coating our products.

Ultrasonically cleaning can cause damage to sensitive electronic components, so it is not recommended. Nevertheless, some RECOM parts can be cleaned without harm, so if ultrasonic cleaning is necessary, please contact Recom Technical Support for advice.

DC/DC 컨트롤러 IC는 MOSFET, 인덕터, 트랜스포머 등 외부 전력 부품의 스위칭 동작을 제어하는 소자입니다.

동기식 컨버터는 기존 정류 다이오드를 MOSFET로 대체하여 도통 손실을 줄이고 효율을 크게 향상시킵니다.

벅 컨버터는 고주파 하이사이드 또는 로우사이드 스위치, 인덕터, 정류기, 출력 필터를 이용해 입력 전압을 더 낮은 출력 전압으로 강하시킵니다.

벅-부스트 컨버터는 하나 이상의 인덕터, 하이사이드 또는 로우사이드 스위치, 정류기, 출력 필터를 활용하여 입력 전압 대비 출력 전압을 승압 및 강하 모두 할 수 있는 토폴로지입니다.

입력 전압이 목표 출력 전압보다 높거나 낮게 변동하는 환경에서 벅-부스트 컨버터를 주로 사용합니다. 예를 들어 충전 및 방전 과정에서 전압이 변동하는 12V 배터리로부터 안정적인 12V 전압을 유지해야 할 경우 해당 토폴로지가 최적입니다.

부스트 컨버터는 인덕터, 로우사이드 스위치, 정류기, 출력 필터를 이용해 입력 전압을 더 높은 출력 전압으로 승압시킵니다.

비동기식 컨버터는 정류기로 다이오드를 사용하기 때문에 회로 구조가 간단하지만 동기식 제품에 비해 일반적으로 효율이 낮습니다.

중요한 파라미터로는 입력 전압 범위, 출력 전압, 최대 부하 전류, 스위칭 주파수, 효율, 크기, 방열 성능이 있습니다. 어플리케이션의 특정 요구사항을 만족하도록 이 요소들을 균형 있게 고려하여 선정하며, PCB 실장 면적을 최소화하는 동시에 IC가 전기적·열적 안전 동작 범위 내에서 구동하도록 보장해야 합니다.

컨버터 IC는 일반적으로 파워 스위치를 내장하고 있어 더 콤팩트한 솔루션을 제공합니다. 반면 컨트롤러 IC는 MOSFET, 인덕터, 트랜스포머 등 외부 전력 부품의 스위칭 동작을 관리합니다.

푸시-풀과 풀브릿지 토폴로지는 별도의 전압 안정화 기능이 없는 경우가 많아, 입력 전압이 일정하게 제어되는 전원 레일에 사용하기 적합합니다. 푸시-풀은 입력 전류가 여러 스위칭 트랜지스터에 분산되므로 작은 IC 패키지에서 더 큰 전력을 출력할 수 있어 3.3V, 5V 입력 레일에 선호됩니다. 풀브릿지는 입력 전압 스트레스가 스위칭 트랜지스터들에 분산되므로 높은 입력 전압을 효율적으로 스위칭할 수 있어 5V~24V 입력 레일에 적합합니다. 출력 전압 안정화, 넓은 입력 전압 범위 또는 고출력 전력이 요구되는 어플리케이션의 경우, 활용 범위가 넓고 갈바닉 절연 기능을 구현할 수 있는 장점으로 인해 플라이백 토폴로지가 가장 선호됩니다.

디스크리트 전원은 컨트롤러, 스위칭 트랜지스터, 트랜스포머, 인덕터, 커패시터 등 개별 부품들을 조합하여 컨버터를 구성하는 방식입니다. 해당 설계 방식은 높은 설계 유연성를 제공하며, 엔지니어가 열 관리, 높은 전력 밀도, 저비용 등 특정 성능 목표에 맞춰 각 부품을 선정하여 최적화할 수 있습니다.

손실이 적은 부품 선정, 스위칭 주파수 최적화, 동기 정류 기법 적용을 통해 효율을 개선할 수 있습니다.

높은 설계 자유도, 맞춤형 레이아웃 구현, 성능 최적화 또는 대량 생산 시 비용 절감 효과가 필요할 때 디스크리트 설계를 선호합니다.

일반적인 보호 기능으로는 과전류 보호, 과전압/저전압 보호, 열 차단, 단락 보호가 있습니다.

대표적인 토폴로지로는 벅, 부스트, 벅-부스트, 플라이백, 포워드, 하프브릿지, 풀브릿지 컨버터가 있습니다.

데드타임은 스위칭 동작 사이에 삽입되는 짧은 지연 시간으로, 브릿지 구조의 상하단 트랜지스터가 동시에 도통하는 현상을 방지하거나 푸시-풀 구조에서 코어 에너지를 완전히 방출하기 위해 설정합니다.

구동 능력이 충분한 게이트 드라이버는 온·오프 상태 간의 빠르고 안정적인 전환을 구현해 스위칭 손실을 저감합니다. 게이트 전압을 최적의 양전압 및 음전압으로 구동함으로써 스위칭 트랜지스터의 본래 전력 성능을 최대한 활용할 수 있습니다.

부트스트랩 회로는 전원 전압보다 높은 전압을 생성하여 하이사이드 스위치를 구동하는 데 사용합니다.

게이트 전하량은 트랜지스터를 턴온·턴오프하는 데 필요한 전하량을 의미하며, 게이트 드라이버에 요구되는 구동 전류를 결정합니다. 스위칭 속도를 좌우하는 핵심 지표이므로 매우 중요합니다.

트랜지스터 게이트에는 정해진 스위칭 임계 전압과 큰 기생 커패시턴스가 존재하기 때문에 빠르고 효율적인 스위칭을 위해 충분한 구동 전류가 필요합니다. 완전한 턴온 상태를 구현하기 위해 게이트 구동 전압은 통상 수 볼트 수준인 임계 전압보다 높은 +15~+20V까지 상승할 수 있습니다. 안정적인 턴온 특성을 확보하기 위해서는 게이트 구동 전압을 -3~-9V 수준의 음전압으로 인가해야 하는 경우도 있습니다.

하프브릿지 게이트 드라이버는 하프브릿지 구조로 배치된 두 개의 스위칭 소자를 제어해 출력을 능동적으로 풀업·풀다운하는 역할을 수행합니다.

All RECOM production batches are burn-in tested in our factory before being shipped to the customer.

The inrush current is dependent on the converter, the load (especially the capacitive load) and the impedance of the primary power supply. Therefore, there is no recommended value for the inrush limiting inductor as this need to be individually worked out for each application. Having said that, usually 22µH~100µH is a good starting point.
A CMC is a good inrush current limiter because the core does not go into saturation with high currents (the +ve inrush current is balanced out by the -ve inrush current), so it has a dual purpose: EMC filter and inrush limiting. However, for high power converters it is sometimes better to use a low inductance, high current, choke that is selected to reduce inrush rather than a high inductance choke selected for the best EMC filtering because otherwise too much power could be lost through the choke's resistance during normal operation.

Recom does not offer this feature in any of its DC/DC converters. Synchronizing the oscillators in several converters is a useful technique where beat frequencies must be avoided at the cost of an increased amount of interference at the main frequency. Usually effective results can be achieved by individually filtering each converter without creating a strongly interfering main frequency.

In theory, yes, but in practice it is very non-linear. Adjusting the output voltage using an external voltage or current can also affect the regulation and short circuit behaviour, so it is not recommended.

Our AC/DC converters usually incorporate input surge protection, although some series require an external suppression MOV to meet all operating conditions. Our DC/DC converters do not usually incorporate surge protection, although an electrolytic capacitor placed close to the input pins is usually sufficient to meet the requirements of 61000-4-5.

Reverse polarity protection is not built inside any of the converters. It needs to be added externally. We recommend adding an external MOSFET for higher power converters or a simple blocking diode for lower power, non-critical applications.

RECOM has one of the largest selection of non-isolated DC/DC products on the market. Our search engine allows searches for non-isolated converters only.

An isolated DC/DC converter has no electrical connection between the input and output. So it does not matter if Vin+ is connected to a positive supply and Vin- is connected to ground or if Vin+ was connected to ground and Vin- was connected to a negative supply. This is useful in the telecommunications industry, for example, where a standard -48V supply can be used to generate a +5V output (Vin+ = ground, Vin- = -48V, Vout + = 5V, Vout- = ground).
This does not apply to non-isolated switching regulators, but the R-78 series can be configured to generate a negative output voltage from a positive input voltage (refer to the Application Notes).

The main problem with a 12 battery as a power source is that it can deliver very high inrush currents. Normally with lower power converters (under 20W), this is not a problem, but for the higher power converters the inrush current can damage the converters or extzernal components. The other issue with batteries is if the end-user connects the battery the wrong way around, this will instantly destroy any converter. To avoid these problems, an external blocking diode or FET can be fitted and either a soft-start circuit or an inrush current filter can be added. Please contact Recom Technical Support for suggested circuits and component values.

The unregulated converters have a deviation curve depending on the load. The lower the load is, the higher the output voltage. Please check the graphs included in our Datasheets about Deviation/Load. Usually, these converters need at least 20% load.

RECOM prides itself on having comprehensive datasheets, but there may be a parameter or operating characteristic that it not listed.

We offer local Technical Support through our offices in Austria, Germany, USA, Singapore, Japan and China, or you can contact your local RECOM contact or distributor to ask us for more information.

The converters have a derating curve that starts usually between 70°C and 85°C. From that temperature point onwards the load must be reduced to limit the internal heat dissipation. You can use a heat sink to move this temperature point up a few degrees, but if your application doesn’t have an adequate cooling system, even a large heat sink may not be effective. Plastic cased converters cannot be effectively heatsinked. Use a higher power converter instead to increase the derating.

You can use a dual 15V output converter (+/-15V), omitting the common pin and using only the +Vout pin and –Vout pins. Dual output converters regulate between the +ve and –ve output rails only, so connection to the common pin is unnecessary for the converter to work normally. This is true of any dual output converter, so +/-5V = 10V, +/-9V = 18V, +/-12V = 24V and +/-15V = 30V.

If isolation is not required, the –ve output pin can be connected back to the +ve input pin to boost a supply voltage. For example, a 24V supply feeding an isolated 24Vin, 24V out DC/DC converter wired up this way will generate a 48V output voltage with double the power: 24V@1A (24W) from the supply + 24V@1A (24W) from the converter = 48V@1A (48W)

The Remote On/Off or Control pin is commonly used for the following reasons:
To control a high-power converter using a low-power signal. The input power of a control pin is typically only a few milliwatts, but it can enable or disable a converter of as much as a hundred watts. This means that the low power output of a microcontroller or logic IC can be used to control a system without the need of extra amplifiers or bulky relays.
To power-up or power-down a system of several converters in the right sequence. Many complex power supplies need to start up or shut down in a certain order to be safe. An example could be a computer-based controller where the microprocessor should be up and running before the peripherals are powered up. Another example is where one power supply feeds another. The primary power supply often should have reached a stable output voltage before the secondary power supplies are turned on.
To save energy. A control pin can be used to turn off the power completely to parts of a circuit during standby mode, while leaving a central watchdog circuit still active. This is especially important for battery powered circuits because all DC/DC converters draw some power even when they are not loaded.
To reduce the inrush current. In a system of several parallel sub-systems, it is often useful to stagger the start-up of each sub-system so as not to overload the primary power supply or cause the main fuse to trip or blow on switch-on.

The trim pin (if fitted) can be used to increase or decrease the regulated output voltage over a limited range (typically +/-10% or -20%, +10%). Some switching regulators offer a Vadj. pin which can adjust the output voltage over a wider range (up to +/-50%).
Connecting a resistor between trim (or Vadj,) and the Vout+ pin will reduce the output voltage. Connecting a resistor between trim (or Vadj,) and the Vout- or Gnd pin will increase the output voltage.
Trimming is typically used to help compensate for the voltage drop along a long cable or PCB track by increasing the output voltage, or to reduce the output voltage to avoid over-voltage stress on the load under worst-case conditions.
Voltage trim is also useful to match different battery chemistries. A 12V lead acid battery can be trickle charged using a 12V converter trimmed up to 13.2V (+10%) or a LiPo Battery safely charged from a 5V converter trimmed down to 4.6V (-8%).

The sense pins (Sense + and Sense-) are used by the DC/DC converter to regulate the output voltage as delivered to the load, not as measuresd directly across the output pins. The converter uses four connections, Vout+ and Vout- delivering a high current and two low current connections, Sense+ and Sense- for feedback. The advantage of using the sense pins compared with simply trimming up the output voltage to compensate for the volt-drop along the connection is that sense pins regulate the load voltage at both low and high load currents, thus avoiding too high a load voltage when lightly loaded. Sense pins can also be used by some load sharing controllers to allow two or more DC/DC converters to be connected in parallel to increase the power.

Some unregulated bipolar converters feature power sharing, where all or some of the load can be taken from just one output pin.
Regulated dual output converters regulate the difference between Vout+ and Vout- and allow the common pin to float. So if a +/-15V is asymmetrically loaded with, say +80%, -20%, then the output voltage difference will stay 30V, but the common pin will drift so that the output voltage will measure +13, -17V. If a balanced output is required with unbalanced load, then use post-regulation to stabilize the outputs.

When a control pin voltage is rising, the switching point (threshold) is higher than when the voltage is falling. The difference between the rising voltage trigger point and the falling voltage trigger point is the hysteresis. For example, a converter with negative control logic could switch on as soon as the control pin voltage exceeds 3V but once started, only switches off again when the voltage drops below 1V. The 2V difference is the hysteresis and stops the converter from switching on-and-off erratically with a slowly rising or falling control voltage.

Some RECOM converters, like the R-78AA series, have a two level control pin function. If the control pin voltage drops below 2.6V, the main power stage is switched off, but the internal oscillator and voltage regulator is kept running. This allows a very rapid restart from standby to full power. For ultra-low power mode, the control pin voltage must be below 1.6V. Then the main oscillator is also turned off and the converter draws only 20µA from the input. Start-up will be slower from deep sleep than from standby.

Negative control logic means that logic 0 (low) enables the converter and logic 1 (high) disables the converter. If the pin is left unconnected, it will be logic 0 and the converter will start up as soon as power is applied.
Positive control logic means that logic 0 (low) disables the converter and logic 1 (high) enables the converter. If the pin is left unconnected, it will be logic 0 and the converter will not start up when power is applied, but wait for a positive signal before starting. For many safety-critical systems, this is an important feature.

Quiescent or standby current is the current drawn by the converter from the supply when it is unloaded (the converter is active and has an output voltage, but no output current). The shutdown current is the residual current drawn by the converter from the supply while it is disabled by using the control pin. The control pin current is the current drawn by converter through the control pin in order to keep it in the disabled state.

The maximum allowed control pin voltage varies from converter series to converter series. Most DC/DC converters allow up to 5V and some up to 12V or more. Refer to the datasheets for guidance. Do not connect an unused control pin to +Vin unless this is expressly permitted in the datasheet.

All RECOM products will not be damaged if used without s load, although in some families some specifications may be out of range below 10% load.

Nickel plated copper or aircraft-grade aluminium, depending on the converter series.

We use a number of tin whisker mitigation strategies, all following the Jedec JP002 guidelines:

Through Hole Devices
The pins used in all of our through-hole converters are made of hard silver-copper alloy. The pins are then Nickel underplated to 0.5µm before being pure tin electroplated to 6µm thickness. This thickness of overplating is a compromise between reasonable manufacturing costs and having a thick enough coating to impair tin whisker formation. The surface is not ‘brightened’, also to mitigate tin whisker formation. Finally the pins are annealed according to JIS C3101. This reduces any residual forming stresses, which is one of the other potential causes of tin whisker formation.

Surface Mount Devices:
The carrier frames used in our SMD converters are made from DF42N nickel alloy which is pure tin plated. The pins are then hot dipped in Sn-Ag-Cu solder to mitigate tin whisker formation.

The converters are not vacuum potted because we use a special process to remove the air bubbles (voids). The epoxy potting process is as follows:
1- The two-component epoxy is mixed and placed under a vacuum for 1 minute to remove any air bubbles created by the mixing process.
2- The plastic case is 1/3 filled and allowed to rest.
3- The pre-tested converter pcb is inserted into the case and 2/3 filled and allowed to rest.
4- The part completed converters are placed in a warm oven (30°C) for 20 minutes to allow any air bubbles to rise to the top.
5- The case is sealed with a harder grade of epoxy and baked at 50°C for one hour to cure.
6- In addition, spot checks are made with our X-ray machine to monitor and ensure that air voids are not present in any of our converters.
The silicone rubber potting process is as follows:
1- The pre-mixed silicone rubber compound is injected into the case
2- The case is placed on to a shaker and vibrated to encourage any air bubbles to rise to the surface
3- The case is topped up to the fill level
4- The converters are put aside to cure at room temperature.

An unregulated converter is a cheaper solution but offers less output voltage stability. The output voltage can change depending on both the load and the input voltage variations. Therefore, the input voltage range is restricted to +/-5% or +/-10% , so it is recommended to use unregulated DC/DC cpnverters only with a regulated supply voltage. The output voltage can rise substantially during no-load conditions, but, even an unregulated converter offers a low output voltage variation over a 20% to 100% load range.

Regulated converters offer a much better load and line voltage regulation, typically less than 1%, so the output voltage is not dependant on the load or input voltage. In particular, the output voltage remains stable under low load or no load conditions. In addition, the input voltage range is higher (2:1, 4:1 or up to 7:1 with non-isolated converters), so regulated converters are suitable for use with variable input voltage supplies such a batteries or multiple supply voltages (e.g, 12V or 24V supplies)

The current drawn by the converter when it is idle (not loaded). All converters contain oscillators that absorb power even if no power is being drawn from the converter.

At a certain ambient temperature the internal heat dissipation makes it impossible for the converter to supply 100% of its power and the load must be derated (reduced) as the temperature goes higher. The derating curve shows the maximum power that the converter can deliver over the full operating temperature range. Some AC/DC converters allso have a low-temperature derating. This is due to increased losses caused by reduced efficiency at very low temperatures.

Different converters have different on/off control voltages. Please check the datasheets carefully before connecting the on/off pin to ground or +Vin as this can damage the converter. Some on/off pins may require additional external components if driven with a TTL level signal.

The higher power converters are optimized to run with the highest efficiency at full load. This means, for example, that the switching transistors need to switch very rapidly to avoid wasting power in the region between fully on and fully off. With no load, the switching drivers still run at full power which makes the converters run warm.

Low power converters that uses post-regulation must be designed so that at the minimum input voltage there is enough output voltage headroom that the linear regulator can regulate properly. This means that with the nominal input voltage, there will be a higher voltage drop across the linear regulator, which in turn will increase the quiescent current drawn by the converter.

Higher power converters often use synchronous rectification on the output. The switching transistors still run at full power even under no-load conditions, so this can lead to a high quiescent current.

Yes, if they are derated (not used at full power). However, the simpler low cost converters have no overtemperature protection. If they are used outside of the temperature specification for a long period of time, they may fail. Our higher power DC/DC and AC/DC converters are fitted with over temperature protection. If they overheat they will simply shut down.

The isolation is tested with the inputs shorted together and the outputs shorted together and then the test voltage is applied between the input and output side. In this way the insulation is tested for all possible pathways between input and output, so the value applies equally for the low side and high side input.

Isolation refers to the electrical separation (galvanic isolation) between the input and the output of the converter. This means that the output of an isolated converter is not linked to the input and any electrical interference, voltage differences and fault currents are blocked. This is extremely important in applications where the output circuit is connected to the “real” world and the main circuit must be separated from anything that happens to the output circuit. DC/DC converters are usually specified with the DC isolation for 1 second, AC/DC converters are usually specified with the AC isolation for 1 minute.

The isolation voltage given in the datasheets is valid for 1 second flash test only. If an isolation barrier is required for longer or infinite time the Rated Working Voltage has to be used. Recom provides an isolation conversion calculator on the website to indicate the equivalence bewtween DC and AC isolation for 1s, 60s or continuous.
It is very important that you compare the same type of isolation when comparing our products with the competitors to avoid misunderstandings.

Yes, our RACVxx series offer constant voltage outputs. The difference between a lighting CV driver and an industrial CV power supply is that the RACV's have full LED lighting certifications. (note: industial power supplies need PFC only above 75W. LED lighting regulations specify PFC from 25W. It is not permitted to use non-PFC power supplies above 25W)

Yes, for our AC input drivers we offer 0-10V analog dimming, TRIAC dimming and Thermal dimming.

The analog voltage is used to control an internal PWM circuit.

The controller chip has a multi-stage shutdown:
On : Open or 0V < Vr < 0.6V
minimum quiescent current - all circuits shut down - slowest restart response time
Off (Standby) : 0.6V < Vr < 2.9V
output power stage and PWM oscillator off - medium restart response time
Off (Shutdown) : 2.9V < Vr < 6V
output power stage off, all other circuits active - quickest restart response time

The RCD-24 series is step-down (buck) converter. You always need a higher input voltage than the output voltage required. A high power LED usually has a forward voltage drop of around 3.4V, so only three LEDs can be drivenin series from a 12V source. If the input voltage is increased to 24V, seven LEDs can be in the chain and if the input voltage is 36V, then ten LEDs can be driven.
However, it is possible to connect chains of LEDs in parallel, so a RCD-24-7.0 can drive two chains of three 350mA LEDs connected in parallel.
Remember that this part is a constant current converter, so the output voltage is variable depending on the power needed, but it will always be lower than the input voltage.

The RCD series is a All-in-One solution in a small package with high efficiency, wide input range, two different ways of dimming Analog and Digital (PWM), high operating temperature range, and it’s fully tested. You don’t have to worry about all different suppliers of all the components of your discrete solution.

The linearity outside the 10~90% range of the PWM dimming is not perfect, but still pretty good. The Analog dimming can be used in a 0~100% range.

The MTBF (Mean Time Between Failures) is a calculated figure based on the chances of a random failure causing the converter to stop working - ignoring all of the real-life stress factors such as over voltage stress, under voltage stress, thermal stress, switching stress or component aging. It should not be confused with operational lifetime. For comparison, the MTBF of a 25-year old healthy person is around 800 years - meaning if that person never got ill, lived an ideal, unstressed lifestyle and never aged - so that the only cause of death would be accidental injury- then that person would theoretically live 8 centuries. MTBF is a comparative measure of reliabilty, but not an absolute measure.

The standard environment for MIL STD 217F calculations is Ground Benign.
The correction factors for other environments are:

Ground Benign (GB) = 1.00
Ground Mobile (GM) = 0.61
Naval Sheltered (GNS) = 0.61
Aircraft Inhabited Cargo (AIC) = 0.61
Space Flight (SF) = 1.00
Missile Launch (ML) = 0.32

MTBF (Mean Time Between Failures) of different components in a system can be added up to give overall board-level reliability. As MTBF is a standard measure used for all electronic components, it is useful to also have the figure for the DC/DC converter in the datasheets.
MTBF figures can also be used to compare the reliability of two different DC/DC products. The product with the highest MTBF will, in general, have the highest reliability. Care must be taken when comparing MTBF figures between different manufacturers as the way they are calculated may differ significantly.

노이즈와 전압 리플을 최소화하기 위해 IC 전원 핀에 최대한 가깝게 배치해야 합니다.

최적화된 PCB 레이아웃, 올바른 접지 설계, 차폐 처리, 필터 적용, 스위칭 전환 구간 제어를 통해 EMI를 억제할 수 있습니다.

적절한 PCB 레이아웃은 기생 인덕턴스를 최소화하고 노이즈를 저감하며 방열 성능을 개선하고 컨버터의 안정적인 동작을 보장합니다.

PCB 구리 면적 확장, 방열 비아 사용, 효율 최적화, 충분한 공기 흐름 확보 등을 통해 열 관련 문제를 줄일 수 있습니다.

대표적인 종류로는 DC/DC 컨버터 IC, PWM 컨트롤러 IC, 게이트 드라이버 IC, PMIC, 선형 레귤레이터, 배터리 관리 IC가 있습니다.

전원 IC는 일반적으로 더 많은 외부 부품이 필요하며 정밀한 PCB 설계가 요구됩니다. 추가적인 외부 부품과 복잡한 레이아웃 설계로 인해 전체 개발 난이도가 높아집니다.

전원 IC는 고효율 스위칭 토폴로지, 최적화된 제어 알고리즘, 고속 스위칭 주파수를 구현하여 전력 손실을 최소화합니다.

전원 IC(파워 집적회로)는 전력을 조절하거나 변환하기 위해 설계된 반도체 소자입니다. 피드백 제어, 스위칭 제어, 보호 기능, 전원 관리 등 필수 기능을 단일 칩에 집적하고 있습니다.

전원 IC는 산업용 전자기기, 통신 시스템, 가전제품, 차량용 시스템, IoT 기기에 사용됩니다.

PMIC는 복잡한 전자 시스템 내 전력 분배를 관리하는 집적회로입니다. 일반적으로 다수의 전압 레귤레이터, 전원 시퀀싱, 배터리 관리, 시스템 모니터링 기능을 하나의 반도체 소자에 통합합니다.

설계자에게 최대한의 설계 자유도, 대량 생산 시 낮은 비용, 고도로 맞춤화된 전원 아키텍처가 필요할 때 전원 IC를 자주 활용합니다.

주요 장점으로는 높은 집적도, 작은 실장 면적, 향상된 효율이 있습니다. 집적형 전원 IC를 통해 설계자는 각 어플리케이션 특성에 맞는 최적화된 전원 솔루션을 구현할 수 있습니다.

파워 스위칭 트랜지스터는 주로 구동 방식, 스위칭 속도, 최대 스위칭 전압 및 허용 전력 용량에 따라 차이가 있습니다. 주요 종류로는 MOSFET(최대 100kHz, 600V, 1kW), SiC(최대 500kHz, 3.3kV, 100kW), GaN(최대 1MHz, 900V, 10kW), IGBT(최대 50kHz, 6.5kV, 1MW)가 있습니다.

MOSFET은 가격이 저렴하고 집적화가 용이하기 때문에 스위칭 전원 장치에 가장 많이 사용됩니다. SiC와 GaN은 고주파 스위칭 분야에 활용되며, IGBT는 초고전력 또는 고전압 스위칭 용도에 선호됩니다.

The enable pin has two functions: Below 2.6V, the converter is OFF (the output power stage is switched off, but the converter oscillator is still running). Below 1.6V, the converter is in ultra-low power mode ( 20µA shutdown mode)

The enable pin on the ROF-78 has a max voltage of 5VDC.
1.25V is the threshold voltage, below that voltage the converter should be OFF. Above 1.25 the converter will be ON. The 0.9V and 1.55V values are recommended safety values to ensure that below 0.9 it will be OFF, and 1.55V it will be ON.
In short, if you want to ensure that the device is on continuously, apply >1.55V to the EN pin all the time

It is recommended that the R-78 series of switching converters is used with a minimum load of 6mA to guarantee that the output is stable under all operating conditions.

As long as the output current is below the preset value the LED driver operates in CV (constant voltage mode). When the output current is lower than the preset current the drivers switches to CC (constant current) mode.

The RAC04 family already works at -40degC (extended temperature), so it doesnt need the additional suffix (-E).

The datasheets specify the maximum capacitive load. If the combined capacitive load is higher, the converter may go into short circuit protection on power-up.
For switching regulators, but the output capacitor may discharge back into the output of the converter if the input supply is suddenly removed and damage the converter. Fitting protection diodes can avoid this reverse current flow.

No. Switching regulators function differently than linear regulators and this “trick” does not work. They need a very good ground connection to function properly.

All of our DC/DC converters contain a built-in input capacitor filter, so an external capacitor is not required for normal operation, unless specified in the datasheet. An input capacitor may also be required to meet surge requirements or to smooth the DC supply at the point of load. If several DC/DCs are powered from the same rail, then input capacitors placed close to the input pins are recommended.

No external components are needed. An input capacitor is recommended only if the input voltage exceeds 26V. An output capacitor helps reduce output ripple further, but the ripple is relatively low anyway.

The Innoline series all use intelligent controllers that measure the output current on each switching cycle (Current Mode Control). If the output is overloaded, the converter will deliver the over-current until either the converter overheats and shuts itself down (thermal protection) or the load current exceeds the safe limits. If the output is short circuited, the controller shuts down the output drive circuitry. The output condition is continuously monitored and the converter automatically restarts.

Type is not critical. Actually, a lower quality, relatively high ESR capacitor on the input is actually an advantage as its internal resistance helps damp down any switch-on surge oscillations.
A combination of tantalum or electrolytic in parallel with an MLCC on the input or output combines the advantages of both types (high ESR to reduce ringing, low ESR to filter noise).

The R-78 costs more than a linear regulator because it is intelligent. It may look similar to a three-pin linear regulator, but it is far more efficient and inside is a controller chip that protects the converter against overload, over temperature and short circuits. This makes it very robust and hard-to-kill.
Even if the converter itself costs more, the savings that can be made in the primary power supply (because it needs less output current), assembly (because there is no fiddly heatsink, screw, nut and thermal paste to worry about) and inventory (one part rather than 7 parts with the linear regulator + heatsink + mounting + input and output capacitors) mean that the overall power supply cost can be lower with the R-78 than with the ""cheaper"" linear regulator.

파워 트랜스포머는 자기 결합을 통해 회로 간 에너지를 전달하는 부품으로, 주로 전압 변환과 절연 목적으로 사용됩니다. 코어 내 자속을 매개로 에너지를 전달하며 코어에 에어갭을 설치할 필요가 없습니다.

갈바닉 절연은 안전성을 높이고 그라운드 루프를 차단하며 민감한 회로를 고전압으로부터 보호합니다. 입출력 간 직접적인 도통 경로를 차단하기 때문에 상용 전압으로부터 사용자를 보호하고, 노이즈나 서지로 저전압 제어 전자기기가 파손되는 것을 막는 핵심 요소입니다.

절연 트랜스포머는 안전 확보와 노이즈 저감을 위해 입력 회로와 출력 회로 사이에 갈바닉 절연을 제공합니다.

트랜스포머는 두 개 이상의 권선을 구비하고 회로 간 에너지를 전달하는 반면, 인덕터는 단일 권선으로 자기장에 에너지를 축적하는 부품입니다.

대표적인 소재로는 페라이트 코어와 분말 철 코어가 있으며, 자기 특성과 스위칭 주파수 특성에 따라 선택하여 적용합니다.

포워드 트랜스포머는 스위칭 사이클의 온 구간에 1차 권선에서 2차 권선으로 직접 에너지를 전달합니다. 플라이백 트랜스포머와 다르게 코어에 에너지를 축적하지 않으며, 스위치 오프 상태에서 전류 흐름을 유지하기 위해 출력 인덕터에 에너지를 저장하는 방식을 채택합니다.

플라이백 트랜스포머는 플라이백 토폴로지에서 에너지를 축적·전달하는 데 사용됩니다. 일반 트랜스포머와 달리 스위치 온 구간에 에너지를 저장하기 위해 코어 에어갭이 필요하며, 스위치 오프 시 축적된 에너지를 출력측으로 방출합니다. 또한 회로 가동 후 컨트롤러에 전원을 공급하는 보조 권선이 포함되는 경우가 많습니다.