Application Application Notes Notes Contents ECONOLINE (General Apps.) ● No Load Over Voltage Lock-Out POWERLINE DC-DC Terminology Long Distance Supply Lines ● EMC Filter Suggestion Input Range LCD Display Bias ● General Test Set-Up Load Regulation Pre- and Post Regulation ● Input Voltage Range Line Voltage Regulation EIA-232 Interface ● PI Filter Output Voltage Accuracy 3V/5V Logic Mixed Supply Rails ● Output Voltage Accuracy Input and Output Ripple and Noise Isolated Data Acquisition System ● Voltage Balance EMC Considerations ● Line Regulations Insulation Resistance Power Supply Considerations ● Load Regulation Efficiency at FulI Load Interpretation of DC-DC Converter EMC Data ● Efficiency Temperature Drift Conducted and Radiated Emissions ● Switching Frequency Switching Frequency Line Impedance Stabilisation Network (LISN) ● Output Ripple and Noise No Load Power Consumption Shielding ● Output Ripple and Noise (continued) Isolation Capacitance Line Spectra of DC-DC Converters ● Transient Recovery Time Input to Output Isolation ● Mean Time Between Failure (MTBF) ● Temperature Performance of DC-DC Converters ● Current Limiting Noise ● Transfer Moulded (SMD) DC-DC Converters ● Fold Back Current Limiting Operating Temperature Range Production Guideline Application Note ● Isolation Calculation of Heatsinks Component Materials ● Break-Down Voltage Isolation Component Placement ● Temperature Coefficient Isolation Voltage vs. Rated Working Voltage Component Alignment ● Ambient Temperature ● Isolation mode in IGBT Driver Circuits Solder Pad Design ● Operating Temperature Range ● Connecting DC-DC Converters in Series Solder Reflow Profile ● Storage Temperature Range ● Connecting DC-DC Converters in Parallel Recommended Solder Reflow Profile ● Output Voltage Trimming ● Filtering Adhesive Requirements ● Heat Sinks Output Filtering Calculation Adhesive Placement ● Limiting Inrush Current Cleaning ● Maximum Output Capacitance Vapour Phase Reflow Soldering ● Settling Time ● Isolation Capacitance and Leakage Current ● Application Examples INNOLINE Overload Protection ● EMC Filter Suggestion Input Voltage Drop-Out (brown-outs) ● Soft Start Circuit ● Positve - to - Negative Converters ● www.recom-international.com ● BLOCK DIAGRAMS Tin Whisker Mitigation 2008 227 DC-DC Converter Applications Terminology The data sheet specification for DC-DC converters contains a large quantity of information. This terminology is aimed at ensuring that the user can interpret the data provided correctly and obtain the necessary information for their circuit application. Input Range The range of input voltage that the device can tolerate and maintain functional performance over the Operating Temperature Range at full load. Load Regulation The change in output voltage over the specified change in output load. Usually specified as a percentage of the nominal output voltage, for example, if a 1V change in output voltage is measured on a 12V output device, load voltage regulation is 8.3%. For unregulated devices the load voltage regulation is specified over the load range from 10% to 100% of full load. Line Voltage Regulation The change in output voltage for a given change in input voltage, expressed as percentages. For example, assume a 12V in-put, 5V output device exhibited a 0.5V change at the output for a 1.2V change at the input, line regulation would be 1%/1%. Output Voltage Accuracy The proximity of the output voltage to the specified nominal value. This is given as a tolerance envelope for unregulated devices with the nominal input voltage applied. For example, a 5V specified output device at 100% load may exhibit a measured output voltage of 4.75V, i.e. a voltage accuracy of –5%). Input and Output Ripple and Noise The amount of voltage drop at the input, or output between switching cycles. The value of voltage ripple is a measure of the storage ability of the filter capacitors. The values given in the datasheets include the higher frequency Noise interference superimposed on the ripple due to switching spikes.The measurement is limited to 20MHz Bandwidth. Input to Output Isolation The dielectric breakdown strength test between input and output circuits. This is the isolation voltage the device is capable of withstanding for a specified time, usually 1 second (for more details see chapter “Isolation Voltage vs. Rated Working Voltage”). 228 Insulation Resistance The resistance between input and output circuits. This is usually measured at 500V DC isolation voltage. Efficiency at FulI Load The ratio of power delivered from the device to power supplied to the device when the part is operating under 100% load conditions at 25°C. Temperature Drift The change in voltage, expressed as a percentage of the nominal, per degree change in ambient temperature. This parameter is related to several other temperature dependent parameters, mainly internal component drift. Switching Frequency The nominal frequency of operation of the switching circuit inside the DC-DC converter. The ripple observed on the input and output pins is usually twice the switching frequency, due to full wave rectification and the push-pull configuration of the driver circuit. No Load Power Consumption This is a measure of the switching circuits power cunsumption; it is determined with zero output load and is a limiting factor for the total efficiency of the device. Isolation Capacitance The input to output coupling capacitance. This is not actually a capacitor, but the parasitic capacitive coupling between the transformer primary and secondary windings. Isolation capacitance is typically measured at 1 MHz to reduce the possibility of the on-board filter capacitors affecting the results. Mean Time Between Failure (MTBF) RECOM uses MIL-HDBK-217F standard for calculation of MTBF values for +25°C as well as for max. operating temperature and 100% load. When comparing MTBF values with other vendor's products, please take into account the different conditions and standards i.e. MILHDBK-217E is not as severe and therefore values shown will be higher than those shown by RECOM. (1000 x 10³ hours =1000000 hours = 114 years!) These figures are calculated expected device lifetime figures using the hybrid circuit model of MIL-HDBK-217F. POWERLINE converters also can use BELLCORE TR-NWT-000332 for calculation of MTBF. The hybrid model has various accelerating factors for operating environment (πE), maturity (πL), screening (πQ), hybrid function (πF) and a summation of each individual component characteristic (λC). 2008 The equation for the hybrid model is then given by: λ = Σ (NC λC) (1 + 0.2πE) πL πF πQ (failures in 106 hours) The MTBF figure is the reciprocal of this value. In the data sheets, all figures for MTBF are given for the ground benign (GB) environment (πE = 0.5); this is considered the most appropriate for the majority of applications in which these devices are likely to be used. However, this is not the only operating environment possible, hence those users wishing to incorporate these devices into a more severe environment can calculate the predicted MTBF from the following data. The MIL-HDBK-217F has military environments specified, hence some interpretation of these is required to apply them to standard commercial environments. Table 1 gives approximate cross references from MIL-HDBK-217F descriptions to close commercial equivalents. Please note that these are not implied by MILHDBK-217F, but are our interpretation. Also we have reduced the number of environments from 14 to 6, which are most appropriate to commercial applications. For a more detailed understanding of the environments quoted and the hybrid model, it is recommended that a full copy of MIL-HDBK-217F is obtained. It is interesting to note that space flight and ground benign have the same environment factors. It could be suggested that the act of achieving space flight should be the determining environmental factor (i.e. missile launch). The hybrid model equation can therefore be rewritten for any given hybrid, at a fixed temperature, so that the environmental factor is the only variable: λ = k (1 + 0.2 πE) The MTBF values for other environment factors can therefore be calculated from the ground benign figure quoted at each temperature point in the data book. Hence predicted MTBF figures for other environments can be calculated very quickly. All the values will in general be lower and, since the majority of the mobile environments have the same factor, a quick divisor can be calculated for each condition. Therefore the only calculation necessary is to devide the quoted MTBF fig. by the divisor given in table 2. www.recom-electronic.com DC-DC Converter Applications Environment Ground Benign πE Symbol GB Ground Mobile GM Naval Sheltered NS Aircraft Inhabited Cargo AIC Space Flight SF Missile Launch ML MIL-HDBK-271F Description Non-mobile, temperature and humidity controlled environments readily accessible to maintenance Equipment installed in wheeled or tracked vehicles and equipment manually transported Sheltered or below deck equipment on surface ships or submarines Typical conditions in cargo compartments which can be occupied by aircrew Earth orbital. Vehicle in neither powered flight nor in atmospheric re-entry Severe conditions relating to missile launch Commercial Interpretation or Examples Laboratory equipment, test instruments, desktop PC's, static telecomms In-vehicle instrumentation, mobile radio and telecomms, portable PC's Navigation, radio equipment and instrumentation below deck Pressurised cabin compartments and cock-pits, in flight entertainment and non-safety critical applications Orbital communications satellite, equipment only operated once in-situ Severe vibrational shock and very high accelerating forces, satellite launch conditions a) Single Output b) Dual Output c) Twin Isolated Outputs Table 1: Interpretation of Environmental Factors Figure 1: Standard Isolated Configurations Environment Ground Benign Ground Mobile Naval Sheltered Aircraft Inhabited Cargo Space Flight Missile Launch πE Symbol GB GM GNS πE Divisor Value 0.5 1.00 4.0 1.64 4.0 1.64 AIC 4.0 1.64 SF ML 0.5 12.0 1.00 3.09 Table 2: Environmental Factors Noise Input conducted noise is given in the line conducted spectra for each DC-DC converter (see EMC issues for further details). Noise is affected significantly by PCB layout, measurement system configuration, terminating impedance etc., and is difficult to quote reliably and with any accuracy other than via a spectrum analysis type plot. There will be some switching noise present on top of the ripple, however, most of this is easily reduced by use of small capacitors or filter inductors, as shown in the application notes. Operating temperature range: Operating temperature range of the converter is limited due to specifications of the components used for the internal circuit of the converter. www.recom-international.com The diagram for temperature derating shows the safe operating area (SOA) within which the device is allowed to operate. At very low temperatures, the specifications are only guaranteed for full load. Up to a certain temperature 100% power can be drawn from the device, above this temperature the output power has to be less to ensure function and guarantee specifications over the whole lifetime of the converter. These temperature values are valid for natural convection only. If the converter is used in a closed case or in a potted PCB board, higher temperatures will be present in the area around thermal converter because the convection may be blocked. If the same power is also needed at higher temperatures either the next higher wattage series should be chosen or if the converter has a metal case, a heatsink may be considererd. a) Non-lsolated Dual Rails b) Non-lsolated Negative Rail c) Dual Isolated Outputs (U/T) Calculation of heatsinks: All converters in metal-cases can have a heatsink mounted so the heat generated by the converters internal power dissipation Pd can be removed. The general specification of the whole thermal system incl. heatsink is it’s thermal resistance Power dissipation Pd: Pd = Pin - Pout = Pd - Pout RTH case-ambient RTHcase-ambient = Tcase - Tambient Pd 2008 Figure 2: Alternative Supply Configurations Efficiency 229 DC-DC Converter Applications Example: RP30-2405SEW starts derating without heatsink at +65°C but the desired operation is 30W at +75°C so the size of the heatsink has to be calculated. Pout = 30W Efficiency = 88% max. Pd = Pout Efficiency - Pout = 30W - 30W = 4.1W 88% Tcase = 100°C (max. allowed case temperature) Tambient = 75°C RTHcase-ambient = Tcase-Tambient = 100°C-75°C PD 4.1°C =6.1°C/W So it has to be ensured that the thermal resistance between case and ambient is 6,1°C/W max. When mounting a heatsink on a case there is a thermal resistance RTH case-heatsink between case and heatsink which can be reduced by using thermal conductivity paste but cannot be eliminated totally. RTHcase-ambient = RTHcase-heatsink + RTHheatsink-ambient Isolation One of the main features of the majority of Recom DC-DC converters is their high galvanic isolation capability. This allows several variations on circuit topography by using a single DC-DC converter. Heatsink mounted on case without thermal conductivity paste Heatsink mounted on case with thermal conductivity paste RTH case-heatsink = ca. 0,5…1 °C/W Heatsink mounted on case with thermal conductivity paste and electrical-isolation-film RTH case-heatsink = ca. 1…1,5 °C/W If a heatsink is mounted on the converter it’s thermal resistance has to be at least: RTHcase-ambient = RTHcase-heatsink + RTHheatsink-ambient = 6.1°C/W - 1°C/W = 5.1°C/W Using this value, a suitable heat sink can be selected. Adding a fan increases the efficiency of any additional heat sinking, but adds cost and power loading. bias, resistor feed). Having an alternative return path can upset the regulation and the performance of the system may not equal that of the converter. The basic input to output isolation can be used to provide either a simple isolated output power source, or to generate different voltage rails, and/or dual polarity rails (see figure 1). These configurations are most often found in instrumentation, data processing and other noise sensitive circuits, where it is necessary to isolate the load and noise presented to the local power supply rails from that of the entire system. Usually local supply noise appears as common mode noise at the converter and does not pollute the main system power supply rails. The isolated positive output can be connected to the input ground rail to generate a negative supply rail if required. Since the output is isolated from the input, the choice of reference voltage for the output side can be arbitrary, for example an additional single rail can be generated above the main supply rail, or offset by some other DC value (see figure 2). Regulated converters need more consideration than the unregulated types for mixing the reference level. Essentially the single supply rail has a regulator in its +Vout rail only, hence referencing the isolated ground will only work if all the current return is through the DC-DC and not via other external components (e.g. diode 230 RTH case-heatsink = ca. 1…2 °C/W In most cases choosing the next higher wattage-series and using dissipation reduction via derating may be the more efficient solution. Isolation Voltage vs. Rated Working Voltage The isolation voltage given in the datasheet is valid for 1 second flash tested only. If a isolation barrier is required for longer or infinite time the Rated Working Voltage has to be used. Conversion of Isolation Voltage to Rated Working Voltage can be done by using this table or graph. Figure 5: IEC950 Test Voltage for Electrical Strength Tests Isolation Test Voltage (V) Rated Working Voltage (V) 1000 130 1500 230 3000 1100 6000 3050 Table 2: Typical Breakdown Voltage Ratings According to IEC950 2008 www.recom-electronic.com DC-DC Converter Applications The graph and table above show the requirements from IEC950. According to our experience and in-house tests, we can offer the following conversion tables: Isolation Test Voltage (1 second) 500 VDC 1000 VDC 1500 VDC 2000 VDC 2500 VDC 3000 VDC 4000 VDC 5000 VDC 6000 VDC Isolation Test Voltage (1 minute) 400 VDC 800 VDC 1200 VDC 1600 VDC 2000 VDC 2400 VDC 3200 VDC 4000 VDC 4800 VDC Isolation Test Voltage (1 minute) 250 VAC 500 VAC 750 VAC 1000 VAC 1250 VAC 1500 VAC 2000 VAC 2500 VAC 3000 VAC Isolation Test Voltage (1 minute) 350 VAC 700 VAC 1050 VAC 1400 VAC 1750 VAC 2100 VAC 2800 VAC 3500 VAC 4200 VAC Isolation Test Voltage (1 minute) 565 VDC 1130 VDC 1695 VDC 2260 VDC 2825 VDC 3390 VDC 4520 VDC 5650 VDC 6780 VDC Table 1 : D.C. Isolation Voltage test vs different conditions Isolation Test Voltage (1 second) 500 VAC 1000 VAC 1500 VAC 2000 VAC 2500 VAC 3000 VAC 4000 VAC 5000 VAC 6000 VAC Table 2 : A.C. Isolation Voltage test vs different conditions Isolation mode in IGBT driver circuits An application for DC/DC converters is to isolate driver circuits for IGBT stacks. In these applications, the maximum DC voltage applied across the isolation gap is not the only factor to be considered because the highly dynamic switching waveforms are an additional stressing factor (typical switching transients can exceed 20kV/µs.) Taking into account that both factors mean a permanent stress on the converter, it is recommended to over specify the converter in terms of isolation voltage and coupling capacitance. Even if a 3kVDC product seems to be appropriate if you just look at the rated working voltage that is required, it is still recommended to choose a product which is specified to 5.2kVDC or 6kVDC to also cover the high dv/dt rates. The higher the isolation voltage rating for a DC/DC converter is, the lower the coupling (isolation) capacitance and a low coupling capacitance is essential in AC or highly dynamic switched DC usage. This will ensure a safe usage and avoid a shortened lifetime in such a highly demanding situation. www.recom-international.com 2008 231 DC-DC Converter Applications Connecting DC-DC Converters in Series So there is potential danger that if the loading is asymmetrical, that one of the converters starts to be overloaded while the others have to deliver less current. The over-loaded converter may then drop out of circuit leading to power supply oscillation. Galvanic isolation of the output allows multiple converters to be connected in series, simply by connecting the positive output of one converter to the negative of another (see figure 3). In this way non-standard voltage rails can be generated, however, the current output of the highest output voltage converter should not be exceeded. When converters are connected in series, additional filtering is strongly recommended, as the converters switching circuits are not synchronised. As well as a summation of the ripple voltages, the output could also produce relatively large beat frequencies. A capacitor across the output will help, as will a series inductor (see filtering). Figure 3: Connecting DC-DC Converters in Series Connecting DC-DC Converters in Parallel Connecting the outputs of DC/DC converters in parallel is possible but not recommended. Usually DC/DC converters have no possibility to balance out the output currents. Figure 4: Paralleled DC-DC Converters with Balance Function. The only possibility to balance out the individual currents is to use a special balance function (like in R-5xxx) or use converters with SENSE function and additional load-share controllers (as can be done for the RP40-SG and RP60-SG, for example). Refer to figure 5 below. If two or more converters are operated from a common supply voltage (inputs in parallel), then input decoupling via LC-filters is recommended (see input filters in figure 5). This helps to avoid hard-to-handle conducted EMI caused by totally un-synchronized oscillators. Also inrush current peaks are lowered. Having several smaller filters, one for each converter, is recommended instead of using one common filter for all converters, as this helps to reduce the possibility of the converters beating against each other. Figure 5: Paralleled DC-DC Converters using Load Share Controllers 232 2008 www.recom-electronic.com DC-DC Converter Applications Filtering When reducing the ripple from the converter, at either the input or the output, there are several aspects to be considered. Recom recommend filtering using simple passive LC networks at both input and output (see figure 6). A passive RC network could be used, however, the power loss through a resistor is often too high.The self-resonant frequency of the inductor needs to be significantly higher than the characteristic frequency of the device (typically 1OOkHz for Recom DC-DC converters). The DC current rating of the inductor also needs consideration, a rating of approximately twice the supply current is recommended. However, depending on your application design and loadsituation may interfer with the calculated filter so testing in the final application and re-adjustment of the component’s values may be necessary. If we consider the circuit without the series inductor, then the input current is given by; When choosing a value for the filtering capacitor please take care that the maximum capacitive load is within the specifications of the converter. When the component is initially switched on (i.e. t=O) this simplifies to; i=V R This would imply that for a 5V input, with say 50mOhm track and wire resistance, the inrush current could be as large as 1OOA. This could cause a problem for the DC-DC converter. Output Filtering calculation: Better results in filtering can be achieved if common mode chokes are used instead of a single choke. Common mode chokes are multiple chokes sharing a core material so the common mode rejection (Electrical noise which comes through one power line and returns to the noise source through some type of ground path is common mode noise.) is higher. Please refer to our page "Common Mode Chokes for EMC" also part of these application notes. These can be used for input filtering as well as for the output side. Calculating of the filtering components can be done using Limiting Inrush Current The DC resistance of the inductor is the final consideration that will give an indication of the DC power loss to be expected from the inductor. Using a series inductor at the input will limit the current that can be seen at switch on (see figure 7). This frequency should be significant lower than the switching frequency of the converter. Example - RC series: Operating frequency = 85kHz max. then, fc =10 % of 85 kHz = 8,5 kHz ( ) i = V exp – t R RC A series input inductor therefore not only filters the noise from the internal switching circuit, but also limits the inrush current at switch on. Short Circuit Protection in 0.25W - 2W Econoline converters In the low wattage, unregulated converter Portfolio we offer continuous short circuit protection (option /P). Especially in applications where the output of converters is connected via a plug and socket to an external module, the chances of having a short circuit across the output is quite high. A conventional unregulated converter can withstand a short circuit across the outputs for only a limited time. The same condition can occur with high capacitive loads if they have a low ESR. RECOM uses balancing between transformer core saturation ratings and the maximum electrical ratings of the switching transistors in the primary side oscillator to create a converter that can withstand a continuous short circuit (<1 Ohm) across the outputs without failing. Figure 7: Input Current & Voltage at Switch On However, this is NOT an overload protection. If the coverters are over-loaded but not short circuited, the converters may still overheat and fail. Figure 6: Input and Output Filtering www.recom-international.com 2008 233 DC-DC Converter Applications Maximum Output Capacitance A simple method of reducing the output ripple is simply to add a large external capacitor. This can be a low cost alternative to the LC filter approach, although not as effective. There is, however, also the possibility of causing start up problems, if the output capacitance is too large. With a large output capacitance at switch on, there is no charge on the capacitors and the DC-DC converter immediately experiences a large current demand at its output. The inrush current can be so large as to exceed the ability of the DC-DC converter, and the device can go into current limit or an undefined mode of operation. In the worst case scenario the device continuously oscillates as it tries to start, goes into overload shutdown and then retries again. The DC-DC converter may not survive if this condition persists. For the Powerline the maximum capacitive loads are specified. For Econoline please refer to the tables below. If instead of single capacitors on outputs an L-C-filter is used, the maximum capacitive laod can be higher because the choke is preventing too high rising speed of the current peak. However the practical maximum capacitive load is dependent on the quality of the filter and the ESR of the capacitors used. Settling Time The main reason for not fitting a series inductor internally, apart from size constraints, is that many applications require a fast switch on time. When the input voltage is a fast ramp, Single Output then the output can respond within 500µs of the input reaching its target voltage (measured on a range of RA/RB and RC/RD converters under full output load without external filters). The use of external filters and additional input or output capacitance will slow this reaction time. It is therefore left to the designer to decide on the predominant factors important for their circuit: settling time or noise performance. Isolation Capacitance and Leakage Current The isolation barrier within the DC-DC converter has a capacitance, which is a measure of the coupling between input and output circuits. Providing this is the largest coupling source, a calculation of the leakage current between input and output circuits can be calculated. Dual Output Unregulated 0.25W Unregulated 0.5W 22µF max. Unregulated 1W Regulated 0.5W 33µF max. 10µF max. Unregulated 2W Regulated 1W 47µF max. 33µF max. Max. capacitive load for unregulated Econoline models Max. capacitive load Max. capacitive load Single output 3W , 5W Dual output 3.3V 2200µF 5.0V 1000µF 9.0V 470µF 12.0V 220µF 15.0V 120µF ±5.0V ±470µF ±9.0V ±220µF ±12.0V ±100µF ±15.0V ±68µF Single output 7.5W Dual output 3300µF 5.0V 2200µF 9.0V 680µF 12.0V 330µF 15.0V 220µF ±5.0V ±1000µF ±9.0V ±330µF ±12.0V ±160µF ±15.0V ±100µF Max. capacitive load for REC7.5 series Max. capacitive load for REC3 and REC5 series 234 3.3V 2008 www.recom-electronic.com DC-DC Converter Applications Assuming we have a known isolation capacitance (Cis - refer to datasheet) and a known frequency for either the noise or test signal, then the expected leakage current (iL) between input and output circuits can be calculated from the impedance. The general isolation impedance equation for a given frequency (f) is given by: Zf = ___1___ j 2 π C is For an RB-0505D, the isolation capacitance is 18pF, hence the isolation impedance to a 50Hz test signal is: Z50 = ___1_______ = 177 M Ω j 2 π 50 18 pf If using a test voltage of 1kVrms, the leakage current is: iL = Vtest = _1000V_ = 5.65 µA 177 M Ω Zf If there is an intelligent power management system at the input, using a series resistor (in place of the series inductor) and detecting the voltage drop across the device to signal the management system can be used. A similar scheme can be used at the output to determine the output voltage, however, if the management system is on the input side, the signal will need to be isolated from the controller to preserve the system isolation barrier (see figure 10). Unregulated RECOM DC/DC converters usually are short circuit protected only for a short time, e.g. 1 second. By option they can be continous short circuit protected (option /P), then their design is able to withstand the high output current in a short circuit situation without any need for extra circuit protection. All Recom DC-DC converters which include an internal linear regulator have a thermal overload shutdown condition which protects these devices from excessive over-load. There are several other current limiting techniques that can be used to detect an overload situation, the suitability of these is left to the designer. The most important thing to consider is how this information will be used. If the system needs to signal to a controller the location or module causing the overload, some form of intelligence will be needed. If the device simply needs to switch off, a simple fuse type arrangement will be adequate. If this condition is to be used to signal a power management system, the most suitable arrangement is the output voltage detector (see figure 10a), since this will fall to near zero on shut-down. Wide input range regulated converters offer overload protection / short circuit protection via an internal circuit that interfers with the primary oscillator so the switching is regulated back in situations of overload or output short circuit. It can be easily observed from these simple equations that the higher the test or noise voltage, the larger the leakage current, also the lower the isolation capacitance, the lower the leakage current. Hence for low leakage current, high noise immunity designs, high isolation DC-DC converters should be selected with an appropriate low isolation capacitance. Figure 8: Simple Overload Protection Application Examples Overload Protection Although the use of filtering will prevent excessive current at power-on under normal operating conditions, many of the lower cost converters have no protection against an output circuit taking excessive power or even going short-circuit. When this happens, the DC-DC converter will take a large input current to try to supply the output. Eventually the converter will overheat and destroy itself if this condition is not rectified (short circuit overload is only guaranteed for 1 s on an unregulated part). a) Series Resistor for Input Current Measurement There are several ways to prevent overload at the outputs destroying the DC-DC converter. The simplest being a straight forward fuse. Sufficient tolerance for inrush current is required to ensure the fuse does not blow on power-on (see figure 8). Another simple scheme that can be applied is a circuit breaker. There is also the potential to add some intelligence to the overload scheme by either detecting the input current, or the output voltage (see figure 9). www.recom-international.com b) Ground Current Monitor Choose current limit (ILIMIT) and ground resistor (RGND) so that : 0.7V = RGND x ILIMIT. Figure 9: Input Monitored Overload Protection 2008 235 DC-DC Converter Applications Input Voltage Drop-Out (brown-outs) When the input voltage drops, or is momentarily removed, the output circuit would suffer similar voltage drops. For short period input voltage drops, such as when other connected circuits have an instantaneous current demand, or devices are plugged in or removed from the supply rail while 'hot', a simple diode-capacitor arrangement can prevent the output circuit from being effected. Opto-Isolated Overload Detector (On overload +VO falls and the LED switches off, the VOL. line is then pulled high.) Figure 10 : Ouput Monitored Overload Protection The circuit uses a diode feed to a large reservoir capacitor (typically 47µF electrolytic), which provides a short term reserve current source for the converter, the diode blocking other circuits from draining the capacitor over the supply rail. When combined with an in-line inductor this can also be used to give very good filtering. The diode volt drop needs to be considered in the power supply line under normal supply conditions. A low drop Schottky diode is recommended (see figure 11). No Load Over Voltage Lock-Out Unregulated DC-DC converters are expected to be under a minimum of 10% load, hence below this load level the output voltage is undefined. In certain circuits this could be a potential problem. The easiest way to ensure the output voltage remains within a specified tolerance, is to add external resistors, so that there is always a minimum 10% loading on the device (see figure 12). This is rather inefficient in that 10% of the power is always being taken by this load, hence only 90% is available to the additional circuitry. Zener diodes on the output are another simple method. It is recommended that these be used with a series resistor or inductor, as when the Zener action occurs, a large current surge may induce signal noise into the system. Figure 11 : Input Voltage Drop-out Figure 12: No Load over Voltage Lock-Out 236 2008 www.recom-electronic.com DC-DC Converter Applications Long Distance Supply Lines When the supply is transmitted via a cable, there are several reasons why using an isolated DC-DC converter is good design prac-tice (see figure 13). The noise pick up and EMC susceptibility of a cable is high compared to a pcb track. By isolating the cable via a DC-DC converter at either end, any cable pick-up will appear as common mode noise and should be self-cancelling at the converters. Another reason is to reduce the cable loss by using a high voltage, low current power transfer through the cable and reconverting at the terminating circuit. This will also reduce noise and EMC susceptibility, since the noise voltage required to affect the rail is also raised. For example, compare a system having a 5V supply and requiring a 5V, 500mW output at a remote circuit. Assume the connecting cable has a 100 Ohm resistance. Using an RO-0505 to convert the power at either end of the cable, with a 100mA current, the cable will lose 1W (I2R) of power. The RO would not be suitable, since this is its total power delivery; hence there is no power available for the terminating circuit. Using a RB-0512D to generate 24V and a RA-2405D to regenerate 5V, only a 21 mA supply is required through the cable, a cable loss of 44mW. Figure 13: Long Distance Power Transfer Pre- and Post Regulation The usefulness of many DC-DC converters can be enhanced by pre- or post-regulation. The usual input voltage range of a DC-DC converter is either fixed, 2:1 or 4:1 depending on the converter technology used inside the device. Switching regulators have typically a much wider input voltage range - up to 8:1, but do not have the advantage of the DC-DC converter’s galvanic isolation. By combining the two techniques and using a switching regulator as a pre-regulator, an ultra-wide range, isolated DC-DC converter supply can be built (see Figure 15a) Post regulation is useful to combine the advantages of a linear regulator’s low noise output with the ability of a DC-DC converter to boost a lower input voltage to a higher output voltage. Figure 15b: Post-Regulation Example LCD Display Bias A LCD display typically requires a positive or negative 24V supply to bias the crystal. The RO-0524S converter was designed specifically for this application. Having an isolated OV output, this device can be configured as a +24V supply by connecting this to the GND input, or a –24V supply by connecting the +Vo output to GND (see figure 14). In this example, a low cost RAA unregulated converter is used to boost a 5V supply up to 10V so that a low drop out linear regulator can produce a low noise, regulated 9V output. EIA-232 Interface Figure 15a: Pre-Regulation Example In a mains powered PC often several supply rails are available to power a RS232 interface. However, battery operated PC’s or remote equipment having a RS232 interface added later, or as an option, may not have the supply rails to power a RS232 interface. Using a RB-0512S is a simple single chip solution, allowing a fully EIA-232 compatible interface to be implemented from a single 5V supply rail, and only 2 additional components (see figure 16a). Figure 14: LCD Display Bias www.recom-international.com 2008 237 DC-DC Converter Applications 3V/5V Logic Mixed Supply Rails There has been a lot of attention given to new l.C.'s and logic functions operating at what is rapidly emerging as the standard supply level for notebook and palmtop computers. The 3.3V supply is also gaining rapid acceptance as the defacto standard for personal telecommunications, however, not all circuit functions required are currently available in a 3.3V powered IC. The system designer therefore has previously had only two options available; use standard 5V logic or wait until the required parts are available in a 3V form, neither being entirely satisfactory and the latter possibly resulting in lost market share. There is now another option, mixed logic functions running from separate supply rails. A single 3.3V line can be combined with a range of DC-DC converters from Recom, to generate voltage levels to run virtually any standard logic or interface IC. The Recom range includes dual output parts for powering analogue bipolar and amplifier functions (RA/RB series), as well a single output function for localised logic functions (RL/RM, RN/RO series). A typical example might be a RS232 interface circuit in a laptop PC using a 3.3V interface chip (such as the LT1330), which accepts 3.3V logic signals but requires a 5V supply (see figure 16b). Recom has another variation on this theme and has developed two 5V to 3.3V step down DC-DC converters (RL053.3 and R0-053.3). These have been designed to allow existing systems to start incorporating available 3.3V l.C.’s without having to redesign their power supply. Figure 16a: Optimised RS232 Interface This is particularly important when trying to reduce the overall power demand of a system, but not having available all of the functions at the 3.3V supply. The main application for this range of devices are system designers, who want to provide some functionality that requires a higher voltage than is available from the supply rail, or for a single localised function. Using a fully isolated supply is particularly useful in interface functions and systems maintaining separate analogue and digital ground lines. Figure 16b: RS232 Interface with 3V Logic 238 2008 www.recom-electronic.com DC-DC Converter Applications Isolated Data Acquisition System Any active system requiring isolation will need a DC-DC converter to provide the power transfer for the isolated circuit. In a data acquisition circuit there is also the need for low noise on the supply line; hence good filtering is required. The circuit shown (see figure 17) provides a very high voltage isolation barrier by using an RH converter to provide the power isolation and opto isolators for the data isolation. An overall system isolation of 2.5kV is achieved. EMC Considerations: When used for isolating a local power supply and incorporating the appropriate filter circuits as illustrated in Fig. 17), DC-DC converters can present simple elegant solutions to many EMC power supply problems. The range of fixed frequency DC-DC converters is particularly suitable for use in EMC problem situations, as the stable fixed switching frequency gives easily characterised and easily filtered output. The following notes give suggestions to avoid common EMC problems in power supply circuits. Figure 17: Isolated Serial ADC System Power Supply Considerations ● Eliminate loops in supply lines (see figure 18). ● Decouple supply lines at local boundaries (use LC filters with low Q, see figure 19). ● Place high speed sections close to the power line input, slow speed sections furthest away (reduces power plane transients, see figure 20). ● Isolate individual systems where possible (especially analogue and digital systems) on both power supply and signal lines (see figure 21). An isolated DC-DC converter can provide a significant benefit to help reduce susceptibility and conducted emission due to the isolation of both power rail and ground from the system supply. Recom primarily uses toroidal transformers in our DC-DC converters and as such they have negligible radiated EMI, but all DC-DC converters are switching devices and as such will have a characteristic switching frequency, which may need some additional filtering. Figure 18: Eliminate Loops in Supply Line Interpretation of DC-DC Converter EMC Data Figure 19: Decouple Supply Lines at Local Boundaries Electromagnetic compatibility (EMC) of electrical and electronic products is a measure of electrical pollution. Throughout the world there are increasing statutory and regulatory requirements to demonstrate the EMC of end products. In Europe the EC directive 89/336/EEC requires that any product sold after 1 January 1996 complies with a series of EMC limits, otherwise the product will be prohibited from sale within the EEC and the seller could be prosecuted and fined. Although DC-DC converters are generally exempt from EMC restrictions on the grounds that they are components, it is the belief of Recom that information on the EMC of these components can help designers plan ahead so that their end products can meet the relevant statutory EMC requirements. It must be remembered however, that a DC-DC converter is unlikely to be the only com-ponent in the power supply chain, hence the information quoted needs interpretation by the circuit designer to determine its impact on the final EMC performance of their system. www.recom-international.com 2008 239 DC-DC Converter Applications Hence, the EC directive covers the frequency spectrum 150kHz to 1GHz, but as two separate and distinct modes of transmission. The Recom range of DC-DC converters feature toroidal transformers. These have been tested and proved to have negligible radiated noise. The low radiated noise is primarily due to toroidal shaped transformers maintaining the magnetic flux within the core, hence no magnetic flux is radiated by design. Due to the exceptionally low value of radiated emission, only conducted emissions are quoted. Figure 20: Place High Spead Circuit Close to PSU Conducted emissions are measured on the input DC supply line. Unfortunately no standards exist for DC supplies, as most standards cover mains connected equipment. This poses two problems for a DC supplied device, firstly no standard limit s can be directly applied, since the DC supplied device does not directly connect to the mains, also all refer e n c e material uses the earth-ground plane as reference point. In a DC system often the OV is the reference, however, for EMC purposes, it is probably more effective to maintain the earth as the reference, since this is likely to be the reference that the shielding is connected to. Consequently all measurements quoted are referenced to the mains borne earth. Figure 21 : Isolate Individual Systems Line Impedance Stabilisation Network (LISN) It is necessary to ensure that any measurement of noise is from the device under test (DUT) and not from the supply to this device. In mains connected circuits this is important and the mains has to be filtered prior to supply to the DUT. The same approach has been used in the testing of DC-DC converters and the DC supply to the converter was filtered, to ensure that no noise from the PSU as present at the measuring instrument. Figure 22: Filtered Supply to DC-DC Converter The notes given here are aimed at helping the designer interpret the effect the DC-DC converter will have on the EMC of their end product, by describing the methods and rationale for the measurements made. Where possible CISPR and EN standards have been used to determine the noise spectra of the components, however, all of the standards reference to mains powered equipment and interpretation of these specifications is necessary to examine DC supplied devices. 240 Conducted and Radiated Emissions There are basically two types of emissions covered by the EC directive on EMC: radiated and conducted. Conducted emissions are those transmitted over wire connecting circuits together and covers the frequency spectrum 150kHz to 30MHz. Radiated are those emissions transmitted via electromagnetic waves in air and cover the frequency spectrum 30MHz to 1GHz. 2008 A line impedance stabilisation network (LISN) conforming to CISPR 16 specification is connected to both positive and negative supply rails and referenced to mains earth (see figure 22). The measurements are all taken from the positive supply rail, with the negative rail measurement point terminated with 50 Ohm to impedance match the measurement channels. www.recom-electronic.com DC-DC Converter Applications 2 100 Conducted Emission (dBuV) and the full rectified spectra, at twice the fundamental switching frequency (even line spectra). Quasi-resonant converters, such as the Recom range, have square wave switching waveforms, this produces lower ripple and a higher efficiency than soft switching devices, but has the drawback of having a relatively large spectrum of harmonics. 4 1 80 8 6 12 10 3 60 5 7 9 11 13 40 20 0 0 100 300 200 400 500 Frequency (kHz) Figure 23: Individual Line Spectra Figure 24: Frequency Voltage Dependency The conducted emissions are measured under full load conditions in all cases. Under lower loads the emission levels do fall, hence full load is the worst case condition for conducted line noise. 100 Conducted Emission (dBuV) The EC regulations for conducted interference covers the bandwidth 150kHz to 30MHz. Considering a converter with a 100kHz nominal switching frequency, this would exhibit 299 individual line spectra. There will also be a variation of absolute switching frequency with production variation, hence a part with a 90kHz nominal frequency would have an additional 33 lines over the entire 30MHz bandwidth. Absolute input voltage also produces slight variation of switching frequency (see figure 24). Hence, to give a general level of conducted noise, we have used a 100kHz resolution bandwidth (RBW) to examine the spectra in the data sheets. This wide RBW gives a maximum level over all the peaks, rather than the individual line spectra. This is easier to read as well as automatically compensating for variances in switching frequency due to production variation or differences in absolute input voltage (see figure 25). 80 60 40 Temperature Performance of DC-DC Converters 20 0 100kHz 1MHz 10MHz 100MHz Frequency Figure 25 : V Spectrum The temperature performance of the DC-DC converters detailed in this book is always better than the quoted operating temperature range. The main reason for being conservative on the operating temperature range is the difficulty of accurately specifying parametric performance outside this temperature range. Shielding At all times the DUT, LlSN’s and all cables connecting any measurement equipment, loads and supply lines are shielded. The shielding is to prevent possible pick-up on cables and DUT from external EMC sources (e.g. other equipment close by). The shielding is referenced to mains earth (see figure 22). Line Spectra of DC-DC Converters All DC-DC converters are switching devices, hence, will have a frequency spectra. www.recom-international.com Fixed input DC-DC converters have fixed switching frequency, for example the RC/RD range of converters has a typical switching frequency of 50kHz. This gives a stable and predictable noise spectrum regardless of load conditions. If we examine the noise spectrum closely (see figure 23) we can see several distinct peaks, these arise from the fundamental switching frequency and its harmonics (odd line spectra) 2008 There are some limiting factors which provide physical barriers to performance, such as the Curie temperature of the core material used in the DC-DC converter (the lowest Curie temperature material in use at Recom is 125°C). Ceramic capacitors are used almost exclusively in the DC-DC converters because of their high reliability and extended life properties, however, the absolute capacity of these can fall when the temperature rises above 85°C (i.e. the ripple will increase) 241 DC-DC Converter Applications Component Alignment The components can be aligned by either optical recognition or manual alignment. If using manual alignment it should be ensured that the tweezers press on the component body and not on the pins. The components themselves are symmetrical along their axis, hence relatively easy to align using either method. Figure 26: Typical Switching Frequency vs. Temperature Other considerations are the power dissipation within the active switching components, although these have a very high temperature rating. Their current carrying capacity derates as temperature exceeds 100°C. Therefore this allows the DC-DC converters to be used above their specified operating temperature, providing the derating of power delivery given in the specification is adhered to. Components operating outside the quoted operating temperature range cannot be expected to exhibit the same parametric performance that is quoted in the specification. An indication of the stability of a device can be obtained from the change in its operating frequency, as the temperature is varied (see figure 26). A typical value for the frequency variation with temperature is 0.5% per °C, a very low value compared to other commercial parts. This illustrates the ease of filtering of Recom DC-DC converters, since the frequency is so stable across load and temperature ranges. Transfer Moulded (SMD) DC-DC Converters Production Guideline Application Note The introduction by Recom of a new and innovative method of encapsulating hybrid DC-DC converters in a transfer moulded (TM) epoxy molding compound plastic has enabled a new range of surface mount (SMD) DC-DC converters to be brought to market, which addresses the component placement with SOIC style handling. With any new component there are of course new lessons to be learned with the mounting technology. With the Recom SMD DC-DC converters, the lessons are not new as such, but may require different production techniques in certain applications. 242 Component Materials Recom SMD converters are manufactured in a slightly different way than the through-hole converters. Instead of potting the PCB board inside a plastic case with conventional epoxy the whole package is molded around the PCB board with epoxy molding compound plastic. This ensures better thermal conductivity from the heat generating components like semiconductors, transformer, etc. inside to the surface from where it can dissipate via convection. This makes them ideal for reflow processes also under the stricter conditions of lead-free soldering temperatures that meet the requirements of the ROHS regulation. All materials used in RECOM lead-free products are ROHS compliant, thus the total amount of the restricted materials (lead, mercury, cadmium, hexavalent chromium, PBBs and PBDEs) are below the prescribed limits. Detailed chemical analysis reports are available. Component Placement Recom SMD DC-DC converters are designed to be handled by placement machines in a similar way to standard SOIC packages. The parts are available either in tubes (sticks) or in reels. The parts can therefore be placed using machines with either vibrational shuttle, gravity feeders, or reel feeders.The vacuum nozzle for picking and placing the components can be the same as used for a standard 14 pin or 18 pin SOIC (typically a 5 mm diameter nozzle). An increase in vacuum pressure may be beneficial, due to the heavier weight of the hybrid compared to a standard SOIC part (a typical 14 pin SOIC weighs 0.1g, the Recom SMD DCDC converter weighs 1.5 ~ 2,7g). It is advisable to consult your machine supplier on the best choice of vacuum nozzle if in doubt. If placing these components by hand, handle the components only by the central body area where there are no component pins. 2008 Solder Pad Design The Recom SMD DC-DC converters are designed on a pin pitch of 2,54mm (0.1") with 1,20 mm pad widths and 1,80 mm pad lengths. This allows pads from one part to be used within a PCB CAD package for forming the pad layouts for other SMD converters. These pads are wider than many standard SOIC pad sizes (0.64mm) and CAD packages may not accommodate these pins with a standard SOIC pad pattern. It should be remembered that these components are power supply devices and as such need wider pads and thicker component leads to minimise resistive losses within the interconnects. Solder Reflow Profile RECOM’s SMD converters are designed to withstand a maximum reflow temperature of 245°C (for max. 30seconds) in accordance with JEDEC STD-020C. If multiple reflow profiles are to be used (i.e. the part is to pass through several reflow ovens), it is recommended that lower ramp rates be used than the maximum specified in JEDEC STD-020C. Continual thermal cycling to this profile could cause material fatigue, if more than 5 maximum ramp cycles are used. In general these parts will exceed the re-flow capability of most IC and passive components on a PCB and should prove the most thermally insensitive component to the reflow conditions. www.recom-electronic.com DC-DC Converter Applications shock and vibration testing, then using adhesive attachment is essential to ensure the parts pass these environmental tests. The Recom SMD DC-DC converters all have a stand-off beneath the component for the application of adhesive to be placed, without interfering with the siting of the component. The method of adhesive dispensing and curing, plus requirements for environmental test and in-service replacement will determine suitability of adhesives rather than the component itself. However, having a thermoset plastic body, thermoset epoxy adhesive bonding between board and component is the recommended adhesive chemistry. If the reflow stage is also to be used as a cure for a heat cure adhesive, then the component is likely to undergo high horizontal acceleration and deceleration during the pick and place operation. The adhesive must be sufficiently strong in its uncured (green) state, in order to keep the component accurately placed. Adhesive Placement The parts are fully compatible with the 3 main methods of adhesive dispensing; pin transfer, printing and dispensing. The method of placing adhesive will depend on the available processes in the production line and the reason for using adhesive attachment. For example, if the part is on a mixed though-hole and SMD board, adhesive will have to be placed and cured prior to reflow. If using a SMD only board and heat cure adhesive, the reflow may be used as the cure stage. If requiring adhesive for shock and vibration, but using a conformal coat, then it may be possible to avoid a separate adhesive alltogether, and the coating alone provides the mechanical restraint on the component body. Recommended Solder Reflow Profile: The following 2 graphs show the typical recommended solder reflow profiles for SMD and through-hole ROHS compliant converters. reflow. The adhesive prevents the SMD parts being ”washed off“ in a wave solder, and being ”vibrated off“ due to handling on a double sided SMD board. The exact values of the profile’s peak and it’s maximum allowed duration is also given in the datasheet of each converter. As mentioned previously, the Recom range of SMD DC-DC converters are heavier than standard SOIC devices. The heavier weight is a due to their size (volume) and internal hybrid construction. Consequently the parts place a larger than usual stress on their solder joints and leads if these are the only method of attachment. Using an adhesive between component body and PCB can reduce this stress considerably. If the final system is to be subjected to Adhesive Requirements If SM surface mount components are going to be wave soldered (i.e. in a mixed through hole and SMD PCB) or are to be mounted on both sides of a PCB, then it is necessary to use an adhesive to fix them to the board prior to www.recom-international.com 2008 Patterns for dispensing or printing adhesive are given for automatic lines. If dispensing manually after placement the patterns for UV cure are easily repeated using a manual syringe (even if using heat cure adhesive).If dispensing manually, dot height and size are not as important, and the ad-hesive should be applied after the components have been reflowed. When dispensing after reflow, a chip underfill formulation adhesive would be the preferred choice. These types 'wick' under the component body and offer a good all round adhesion from a single dispensed dot. The patterns allow for the process spread of the stand-off on the component, but do not account for the thickness of the PCB tracks. 243 DC-DC Converter Applications If thick PCB tracks are to be used, a grounded copper strip should be laid beneath the centre of the component (care should be exercised to maintain isolation barrier limits). The adhesive should not retard the pins reaching their solder pads during placement of the part, hence low viscosity adhesive is recommended. The height of the adhesive dot, its viscosity and slumping properties are critical. The dot must be high enough to bridge the gap between board surface and component, but low enough not to slump and spread, or be squeezed by the component, and so contaminate the solder pads. If wishing to use a greater number of dots of smaller diameter (common for pin transfer methods), the dot pattern can be changed, by following a few simple guidelines. As the number of dots is doubled their diameter should be halved and centres should be at least twice the printed diameter from each other, but the dot height should remain at 0.4mm. The printed dot should always be positioned by at least its diameter from the nearest edge of the body to the edge of the dot. The number of dots is not important, provided good contact between adhesive and body can be guaranteed, but a minimum of two dots is recommended. Cleaning The thermoset plastic encapsulating material used for the Recom range of surface mount DC-DC converters is not fully hermetically sealed. As with all plastic encapsulated active devices, strongly reactive agents in hostile environments can attack the material and the internal parts, hence cleaning is recommended in inert solutions (e.g. alcohol or water based solvents) and at room temperature in an inert atmospheres (e.g. air or nitrogen). A batch or linear aqueous cleaning process would be the preferred method of cleaning using a deionised water solution. on a pcb, 230°C and shorter dwell times will still deliver good results. After discussions with various contract manufacturers, we recommended that the temperature gradients used during preheat and cooling phases are between 0.5 K/s up to 3 K/s. Other form factors than 8-pin or 10-pin SMDpackages have not been tested under vapour phase conditions. Please contact RECOM in this case. Custom DC-DC Converters In addition to the standard ranges shown in this data book, Recom have the capability to produce custom DC-DC converters designed to your specific requirements. In general, the parts can be rapidly designed using computer based CAD tools to meet any input or output voltage requirements within the ranges of Recom standard products (i.e. up to 48V at either input or output). Prototype samples can also be produced in short timescales. Custom parts can be designed to your specification, or where the part fits within a standard series, the generic series specification can be used. All custom parts re-ceive the same stringent testing, inspection and quality procedures, as standard products. However there is a minimum order quantity as the additional documentation and administrative tasks must be covered in terms of costs. A general figure for this MOQ can be around 3000pcs of low wattage converters (0,25pcs ~ 2W), 1000pcs medium sized wattage (2W~15W) and 500pcs for higher wattages (> 20W).Recom custom parts are used in many applications, which are very specific to the individual customer, however, some typical examples are: ● ● ● ● ● ● ● hingly small (the only actual recorded failures due to tin whiskers were in exceptional environments such as deep space or as a contributary factor to corona discharge flashover in a UHV transformer), we have undertaken tin whisker mitigation procedures as recommended by Jedec in their 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 hot dipped in Sn-Ag-Cu solder just before injection molding. Hot dipping with SnAg4 or SnAgCu is generally an effective mitigation practice and considered whisker free. ECL Logic driver Multiple cell battery configurations Telecommunications line equipment Marine apparatus Automotive electronics LCD display power circuitry Board level instrumentation systems Vapour Phase Reflow Soldering Vapour phase soldering is a still upcoming soldering practice; therefore there are no standard temperature profiles available. Principally, the Lead-free Soldering Profile recommended by RECOM can be used for vapour phase soldering. RECOM has tested large quantities of 8-pin and 10-pin SMD converters and recommends as an absolute maximum condition 240°C for 90s dwell time. In standard applications with small sized components 244 To discuss your custom DC-DC converter requirements, please contact Recom technical support desk or your local distributor. Tin Whisker Mitigation The use of pure tin coating has caused considerable customer concern about the possibility of tin whisker formation. Although it is the opinion of Recom that the risks of converter failure due to tin whisker formation are vanis- 2008 www.recom-electronic.com Notes www.recom-international.com 2008 245 Innoline Application Notes Contents Innoline Application Notes R-78xx-0.5 Series R-78HBxx-xx Series ● EMC Considerations R-78Axx-0.5SMD Series R-62xxP_D Series ● Soft Start Circuit R-78xx-1.0 Series Pos-to-Neg Circuit Ideas ● Positive-to-Negative Converters R-78Axx-1.0SMD Series Introduction R-78Bxx-1.0 Series EMC Considerations Although all Innoline converters are switching regulators, and contain internal high frequency oscillators, they have been designed to minimise radiated and conducted emissions. If the end-application is particularly sensitive to conducted interference, the following input filter can be used for all R-78, R-5xxx, R-6xxx and R-7xxx converters. Soft Start Innoline converters with Vadj pins (R-78Axx-xxSMD, R-5xxx, R-6xxx and R-7xxx families) can be fitted with an external circuit to create a soft start output. Any general purpose PNP transistor and diode can be used for TR1 and D1 and typical values for R1 = 100K and C1 = 10µF. 246 2008 www.recom-electronic.com Innoline Application Notes Positive to Negative Converters Features ● Innoline Switching Regulators ● Rev.1 ● ● Innoline Switching Regulators can also be used to convert a positive voltage into a negative voltage The standard parts can be used - only two extra capacitors are required Fixed and variable output voltages are available. Input voltage range can be lower than the output voltage for higher output voltages Positive-to-Negative Switching Regulators Selection Guide Series R-78xx-0.5 R-78Axx-0.5SMD R-78xx-1.0 R-78Axx-1.0SMD R-78Bxx-1.0 R-78Bxx-1.5 R-78HBxx-0.5 Maximum Output Current -0.4A -0.2A -0.4A -0.2A Input Voltages (VDC) min. max. 4.75 – 28, 5.0 – 26, 8.0 – 18 4.75 – 28, 5.0 – 26, 8.0 – 18 Output Voltages (VDC) No. of Outputs Case Adjustable Vout? -1.5, -1.8, -2.5, -3.3, -5.0, -6.5, -9.0, -12, -15 -1.5, -1.8, -2.5, -3.3, -5.0, -6.5, -9.0, -12, -15 S SIP3 No Max Cap. Load 220µF S SMD Yes 220µF No 220µF No 100µF -1A/-0-8A/-0.6A 9 - 28, 9-26 -1.8, -2.5, -3.3, -5, -9, -12 S SIP12 Yes Not recommended to be used in this mode due to the reduced efficiency and higher Ripple & Noise figures. 470µF Not recommended to be used in this mode due to the reduced input and output voltage range Not recommended to be used in this mode due to the reduced input and output voltage range -0.6A 4.75 – 28, -1.5, -1.8, -2.5, -3.3, -5.0, S SIP3 -0.4A 8.0 – 28, 8.0 – 26 -6.5, -9.0, -0.3A 8.0 – 18 -12, -15 Not recommended to be used in this mode due to the reduced input and output voltage range -0.4A/-0.35A 15 – 65, -3.3, -5.0,-6.5 S SIP3 -0.3A/-0.25/-0.2A 15 – 62, 15 – 59, 15 – 56, -9.0, -12, -15 -0.2A 20 – 48 -24 R-5xxxP/DA Not recommended to be used in this mode due to the reduced input and output voltage range R-61xxP/D Not recommended to be used in this mode as R-78B series offer a lower cost alternative R-62xxP/D R-7xxxP/D Circuit Ideas www.recom-international.com 2008 247 INNOLINE Positive to Negative Converter DC/DC-Converter R-78xx-0.5 Series Positive to Negative Converter C1 and C2 are required and should be fitted close to the converter pins. Maximum capacitive load including C2 is 220µF Pin Connections Pin # Negative Output 1 +Vin 2 -Vout 3 GND Positive Output +Vin GND +Vout Selection Guide Part Number SIP3 Input Range (1) (V) Output Voltage (V) Output Current (A) Efficiency Min. Vin Max. Vin (%) (%) External Capacitors C1 C2* R-781.5-0.5 4.75 – 28 -1.5 -0.4 68 67 10µF/35V 22µF/6.3V R-781.8-0.5 4.75 – 28 -1.8 -0.4 71 70 10µF/50V 22µF/6.3V R-782.5-0.5 4.75 – 28 -2.5 -0.4 75 76 10µF/50V 22µF/6.3V R-783.3-0.5 4.75 – 28 -3.3 -0.4 77 80 10µF/50V 22µF/6.3V R-785.0-0.5 6.5 – 28 -5.0 -0.4 79 84 10µF/50V 22µF/10V R-786.5-0.5 5.0 – 26 -6.5 -0.3 81 86 10µF/50V 10µF/10V R-789.0-0.5 8.0 –18 -9.0 -0.2 87 89 10µF/50V 10µF/16V R-7812-0.5 8.0 – 18 -12 -0.2 87 90 10µF/50V 10µF/25V R-7815-0.5 8.0 – 18 -15 -0.2 87 91 10µF/50V 10µF/25V * Maximum capacitive load including C2 is 220µF Application Example (see also Circuit Ideas at end of section) Derating-Graph (Ambient Temperature) Maximum capacitive load ±220µF 248 2008 www.recom-electronic.com INNOLINE Positive to Negative Converter DC/DC-Converter R-78Axx0.5 SMD Positive to Negative Converter C1 and C2 are required and should be fitted close to the converter pins. Maximum capacitive load including C2 is 220µF Pin Connections Pin # Negative Output 1,2 +Vin 3,7,8,9 -Vout 4,5 GND 6 -Vout Adj. 10 On/Off Positive Output +Vin GND +Vout +Vout Adj. On/Off Selection Guide Part Number SIP3 Input Range (1) (V) Output Voltage (V) Output Current (A) Efficiency Min. Vin Max. Vin (%) (%) External Capacitors C1 C2 R-78A1.5-0.5SMD 4.75 – 28 -1.5 -0.4 68 67 10µF/35V 22µF/6.3V R-78A1.8-0.5SMD 4.75 – 28 -1.8 -0.4 71 70 10µF/50V 22µF/6.3V R-78A2.5-0.5SMD 4.75 – 28 -2.5 -0.4 75 76 10µF/50V 22µF/6.3V R-78A3.3-0.5SMD 4.75 – 28 -3.3 -0.4 77 80 10µF/50V 22µF/6.3V R-78A5.0-0.5SMD 4.75 – 28 -5.0 -0.4 79 84 10µF/50V 22µF/10V R-78A6.5-0.5SMD 5.0 – 26 -6.5 -0.3 81 86 10µF/50V 10µF/10V R-78A9.0-0.5SMD 8.0 – 18 -9.0 -0.2 87 89 10µF/50V 10µF/16V R-78A12-0.5SMD 8.0 – 18 -12 -0.2 87 90 10µF/50V 10µF/25V R-78A15-0.5SMD 8.0 – 18 -15 -0.2 87 91 10µF/50V 10µF/25V * Maximum capacitive load including C2 is 220µF Application Example (see also Circuit Ideas at end of section) Derating-Graph Maximum capacitive load ±220µF www.recom-international.com 2008 (Ambient Temperature) 249 R-78Axx-0.5 SMD Positive to Negative INNOLINE DC/DC-Converter Table 1: Adjustment Resistor Values 0.5Adc Vout (nom.) R-78A1.8 -0.5SMD 1.8Vdc Vout (adj) R1 -1.5 (V) 3KΩ R2 R-78A2.5 -0.5SMD 2.5Vdc R1 R2 R-78A3.3 -0.5SMD 3.3Vdc R1 R2 R-78A5.0 -0.5SMD 5.0Vdc R1 R2 R-78A6.5 -0.5SMD 6.5Vdc R1 R2 R-78A9.0 -0.5SMD 9.0Vdc R1 R2 R-78A12 -0.5SMD 12.0Vdc R1 R2 200Ω -1.8 (V) 12KΩ -2.5 (V) 11.8KΩ -3.0 (V) 4.64KΩ 44.2KΩ 88.4KΩ 17KΩ -3.3 (V) 27KΩ 6.7KΩ -3.6 (V) 60.4KΩ 42KΩ 14KΩ -3.9 (V) 28KΩ 58KΩ 23KΩ -4.5 (V) 11.3kΩ 180KΩ 49KΩ 26KΩ 17KΩ -4.9 (V) 7.15kΩ 850KΩ 77kΩ 36KΩ 24KΩ -5.0 (V) 6.34kΩ 86kΩ 39KΩ 26KΩ -5.1 (V) 5.9kΩ 231kΩ 97KΩ 42KΩ 28KΩ -5.5 (V) 3.9kΩ 56.2kΩ 160KΩ 56KΩ 36KΩ 112KΩ 63KΩ 24.6KΩ 400KΩ 125KΩ -6.5 (V) 14kΩ -8.0 (V) 2.32kΩ -9.0 (V) 10.7KΩ 200KΩ -10 (V) 4.75KΩ 54.9KΩ 345KΩ -11 (V) 1.65KΩ 16.5KΩ 740KΩ -12 (V) 3.6KΩ -12.6 (V) 0Ω 180KΩ Typical Application 250 2008 www.recom-electronic.com INNOLINE Positive to Negative Converter DC/DC-Converter R-78Bxx1.0 Series Positive to Negative Converter C1 and C2 are required and should be fitted close to the converter pins. Maximum capacitive load including C2 is 220µF Pin Connections Pin # Negative Output 1 +Vin 2 -Vout 3 GND Positive Output +Vin GND +Vout Selection Guide Part Number SIP3 Input Range (1) (V) Output Voltage (V) Output Current (A) Efficiency Min. Vin Max. Vin (%) (%) External Capacitors C1 C2* R-78B1.5-1.0 4.75 – 28 -1.5 -0.6 70 68 10µF/50V 22µF/6.3V R-78B1.8-1.0 4.75 – 28 -1.8 -0.6 72 72 10µF/50V 22µF/6.3V R-78B2.5-1.0 4.75 – 28 -2.5 -0.6 75 77 10µF/50V 22µF/6.3V R-78B3.3-1.0 4.75 – 28 -3.3 -0.6 77 80 10µF/50V 22µF/6.3V R-78B5.0-1.0 6.5 – 28 -5.0 -0.6 83 85 10µF/50V 22µF/10V R-78B6.5-1.0 8.0 – 26 -6.5 -0.4 84 87 10µF/50V 10µF/10V R-78B9.0-1.0 8.0 – 18 -9.0 -0.4 88 89 10µF/25V 10µF/25V R-78B12-1.0 8.0 – 18 -12 -0.3 89 90 10µF/25V 10µF/25V R-78B15-1.0 8.0 – 18 -15 -0.3 89 91 10µF/25V 10µF/25V * Maximum capacitive load including C2 is 220µF Application Example (see also Circuit Ideas at end of section) Derating-Graph Maximum capacitive (Ambient Temperature) load ±220µF www.recom-international.com 2008 251 INNOLINE Positive to Negative Converter DC/DC-Converter R-78HBxx0.5 Series Positive to Negative Converter C1 and C2 are required and should be fitted close to the converter pins. Maximum capacitive load including C2 is 100µF Pin Connections Pin # Negative Output 1 +Vin 2 -Vout 3 GND Positive Output +Vin GND +Vout Selection Guide Part Number SIP3 Input Range (1) (V) Output Voltage (V) Output Current (A) Efficiency Min. Vin Max. Vin (%) (%) External Capacitors C1 C2* R-78HB3.3-0.5 15 – 65 -3.3 -0.4 78 75 1µF/100V 22µF/6.3V R-78HB5.0-0.5 15 – 65 -5.0 -0.4 82 80 1µF/100V 22µF/10V R-78HB6.5-0.5 15 – 65 -6.5 -0.35 84 82 1µF/100V 22µF/10V R-78HB9.0-0.5 15 – 62 -9.0 -0.3 87 85 1µF/100V 10µF/16V R-78HB12-0.5 15 – 59 -12 -0.25 88 86 1µF/100V 10µF/25V R-78HB15-0.5 15 – 56 -15 -0.2 89 87 1µF/100V 10µF/25V R-78HB15-0.5 15 – 48 -24 -0.2 89 87 1µF/100V 10µF/35V * Maximum capacitive load including C2 is 100µF Application Example (see also Circuit Ideas) Derating-Graph Maximum capacitive (Ambient Temperature) load ±100µF 252 2008 www.recom-electronic.com INNOLINE Positive to Negative Converter DC/DC-Converter R-62xxP/D SIP12 Positive to Negative Converter C1 and C2 are required and should be fitted close to the converter pins. Maximum capacitive load including C2 is 220µF Pin Connections Pin # Negative Output 2,3,4 +Vin 5,6,7,8 -Vout 9,10,11 GND 12 -Vout Adj. 1 On/Off Positive Output +Vin GND +Vout +Vout Adj. On/Off Selection Guide Part Number SIP3 Input Range (1) (V) Output Voltage (V) Output Current (A) Efficiency Min. Vin Max. Vin (%) (%) External Capacitors C1 C2* R-621.8P/D 9 – 28 -1.8 (-1.5~-3.6) -1.0 72 65 10µF/50V 100µF/6.3V R-622.5P/D 9 – 28 -2.5 (-1.5~-4.5) -1.0 76 72 10µF/50V 100µF/6.3V R-623.3P/D 9 – 28 -3.3 (-1.8~-6V) -1.0 79 76 10µF/50V 100µF/10V R-625.0P/D 9 – 28 -5.0 (-1.8~-9V) -1.0 81 80 10µF/50V 100µF/10V R-629.0P/D 9 – 26 -9.0 (-3.3~-15V) -0.8 84 85 10µF/50V 100µF/25V R-62512P/D 9 – 26 -12 (-3.3~-15V) -0.6 86 88 10µF/50V 100µF/25V * Maximum capacitive load including C2 is 470µF Derating Max output current calculation: Internal power dissipation (1W) = Io x Vo x (1-Efficiency) Io = 1(W) / Vo x (1-Efficiency) Example : R-625.0P at Vin = +9VDC, Vout=-5.0V Efficiency = 80% (see ”Selection Guide” table) Io = 1W / 5V x (1-0.8) = -1000mA at Vin = +9VDC, Vout=-8.0V (with trim) Efficiency = 80% (see ”Selection Guide” table) Io = 1W / 8V x (1-0.8) = -625mA www.recom-international.com 2008 253 R-62xxP_D Positive to Negative INNOLINE DC/DC-Converter Remote On/Off Control Application Example Maximum capacitive load ±220µF Table 1: Adjustment Resistor Values -1Adc Vout (nominal) R-621.8P/D R-622.5P/D R-623.3P/D 1.8VDC 2.5VDC 3.3VDC Vout (adj) R1 1.5 13.6KΩ R2 R2 R1 R2 5VDC R1 R2 3.3KΩ 1.8 254 R1 R-625.0P/D 8.2KΩ 3.1KΩ 820Ω 15KΩ 5.1KΩ 1.5KΩ 13KΩ 3.6KΩ 51KΩ 7.0KΩ 2.0 10KΩ 2.5 5.1KΩ 3.0 2.5KΩ 10KΩ 3.3 1.7KΩ 5.9KΩ 3.6 1.2KΩ 3.9KΩ 18KΩ 14KΩ 3.9 2.8KΩ 9.1KΩ 20KΩ 4.5 1.6KΩ 3.9KΩ 60KΩ 9.7KΩ 5.0 2.4KΩ 5.1 2.2KΩ 60KΩ 5.5 1.6KΩ 15KΩ 6.0 1.1KΩ 7.2KΩ 7.0 2.8KΩ 8.0 1.5KΩ 2008 www.recom-electronic.com INNOLINE DC/DC-Converter Positive to Negative Circuit Ideas Application Examples Negative Voltage Doubler 12V Battery Stabilisor Negative Rail Generator for Asymmetric Rails www.recom-international.com 2008 255 Powerline DC-DC Application Notes Contents Powerline Application Notes Switching Frequency ● Common Mode Chokes for EMC Output Ripple and Noise ● Powerline Definitions and Testing Transient Recovery Time Introduction Current Limiting Input Voltage Range Fold Back Current Limiting Pi Filter Isolation Heat Sink Dimensions Output Voltage Accuracy Break Down Voltage -HC Variants Voltage Balance Temperature Coefficient Line Regulation Ambient Temperature Load Regulation Operating Temperature Range Efficiency Storage Temperature Range ● Undervoltage Lockout UVL Tables ● Output Voltage Trimming Trim Tables ● Powerline Heat Sinks Common Mode Chokes for EMC Recom offers a range of Common Mode Chokes useful for EMI Filtering to meet the requirements of EN-55022, Class B. The component values given are suggested values and may need to be optimised to suit the application. The effectiveness of any filter network is heavily dependent on using quality capacitors, the layout of the board and having a low impedance path to ground. See section on filtering elsewhere in the Application Notes for more details. EMC Filter Suggestion 256 2008 www.recom-electronic.com Powerline DC-DC Application Notes Component Values All capacitors MLCC (Multi Layer Ceramic Capacitor). RP08-A Vin = 12VDC nom., C1=4.7µF/50V, C2=Not Required, C3,C4=1nF/3kV, CMC-06 Vin = 24VDC nom., C1=6.8µF/50V, C2=Not Required, C3,C4=1nF/3kV, CMC-06 Vin = 48VDC nom., C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=1nF/3kV, CMC-06 RP08-AW Vin = 9~36VDC, C1=4.7µF/50V, C2=Not Required, C3,C4=1nF/3kV, CMC-06 Vin = 18~75VDC, C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=1nF/3kV, CMC-06 RP10-E RP12-A Vin = 12VDC nom., C1=3.3µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-06 Vin = 24VDC nom., C1=4.7µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-06 Vin = 48VDC nom., C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=1nF/2kV, CMC-06 RP10-EW RP12-AW Vin = 9~36VDC, C1=3.3µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-06 Vin = 18~75VDC, C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=1nF/2kV, CMC-07 RP15-A Vin = 12VDC nom., C1=10µF/25V, C2=10µF/25V, C3,C4=470pF/2kV, CMC-07 Vin = 24VDC nom., C1=6.8µF/50V, C2=6.8µF/50V, C3,C4=470pF/2kV, CMC-06 Vin = 48VDC nom., C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=470pF/2kV, CMC-01 RP15-AW Vin = 9~36VDC, C1=6.8µF/50V, C2=6.8µF/50V, C3,C4=470pF/2kV, CMC-05 Vin = 18~75VDC, C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=470pF/2kV, CMC-06 RP15-F Vin = 12VDC nom., C1=4.7µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-06 Vin = 24VDC nom., C1=3.3µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-06 Vin = 48VDC nom., C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=1nF/2kV, CMC-06 RP15-FW Vin = 9~36VDC, C1=2.2µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-05 Vin = 18~75VDC, C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=1nF/2kV, CMC-06 RP20-F Vin = 12/24VDC nom., C1=4.7µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-05 Vin = 48VDC nom., C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=1nF/2kV, CMC-05 RP20-FW Vin = 9~36VDC, C1=4.7µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-05 Vin = 18~75VDC, C1=2.2µF/100V, C2=2.2µF/100V, C3,C4=1nF/2kV, CMC-06 RP30-E Vin = 24VDC nom., C1=4.7µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-05 Vin = 24VDC nom., C1=6.8µF/50V, C2=6.8µF/50V, C3,C4=1nF/2kV, CMC-05 Vin = 48VDC nom., C1=2.2µFII2.2µF/100V, C2=2.2µFII2.2µF/100V, C3,C4=1nF/2kV, CMC-05 RP30-EW Vin = 9~36VDC, C1=6.8µF/50V, C2=6.8µF/50V, C3,C4=1nF/2kV, CMC-05 Vin = 18~75VDC, C1=2.2µF II 2.2µF/100V, C2=2.2µF II 2.2µF/100V, C3,C4=1nF/2kV, CMC-05 Continued on next page www.recom-international.com 2008 257 Powerline DC-DC Application Notes RP40-G Vin = 12VDC nom., C1=4.7µF/50V, C2=Not Required, C3,C4=1nF/2kV, CMC-05 Vin = 24VDC nom., C1=6.8µF/50V, C2=6.8µF/50V, C3,C4=1nF/2kV, CMC-05 Vin = 48VDC nom., C1=2.2µF II 2.2µF/100V, C2=2.2µF II 2.2µF/100V, C3,C4=1nF/2kV, CMC-08 RP40-GW Vin = 9~36VDC, C1=4.7µF/50V, C2=4.7µF/50V, C3,C4=1nF/2kV, CMC-05 Vin = 18~75VDC, C1=2.2µF II 2.2µF/100V, C2=2.2µF II 2.2µF/100V, C3,C4=1nF/2kV, CMC-08 RP60-G Vin = 24VDC nom., C1=4.7µF/50V, C2=4.7µF/50V, C3,C4=1nF/2kV, CMC-05 Vin = 48VDC nom., C1=2.2µF II 2.2µF/100V, C2=2.2µF II 2.2µF/100V, C3,C4=1nF/2kV,CMC-08 Recommended PCB Layout 258 2008 www.recom-electronic.com Powerline DC-DC Application Notes Recommended Footprint Details CMC-01 Component CMC-01 CMC-05 Component CMC-05 CMC-06 Inductance Rating DCR 450µHx2 5.2A 25mOhm Component CMC-06 CMC-07 Component CMC-7 Inductance Rating DCR 620µHx2 1.7A 80mOhm Inductance Rating DCR 325µHx2 3.3A 35mOhm CMC-08 Inductance Rating DCR 145µHx2 5.2A 20mOhm www.recom-international.com Component CMC-8 2008 Inductance Rating DCR 830µHx2 5.2A 31mOhm 259 Powerline DC-DC Application Notes Powerline – Definitions and Testing General Test Set-Up Figure 1-3: General DC/DC converter test set-up Note: If the converter is under test with remote sense pins, connect these pins to their respective output pins. All tests are made in ”Local sensing“ mode. Input Voltage Range The minimum and maximum input voltage limits within which a converter will operate to specifications. PI Filter An input filter, consisting of two capacitors, connected before and after a series inductor to reduce input reflected ripple current. The effective filter is C1/L + L/C2, so the inductor filter element is doubly effective. Figure 2: PI Filter With nominal input voltage and rated output load from the test set-up, the DC output voltage is measured with an accurate, calibrated DC voltmeter. Output voltage accuracy is the difference between the measured output voltage and specified nominal value as a percentage. Output accuracy (as a %) is then derived by the formula: Vnom is the nominal, output specified in the converter data sheet. Voltage Balance For a multiple output power converter, the percentage difference in the voltage level of two outputs with opposite polarrities and equal nominal values. Line Regulations Make and record the following measurements with rated output load at +25°C: ● Output voltage at nominal line (input) voltage. Vout N ● Output voltage at high line (input) voltage. Vout H ● Output voltage at low line (input) voltage. Vout L The line regulation is Vout M (the maximum of the two deviations of output) for the value at nominal input in percentage. Output Voltage Accuracy 260 2008 Vout – Vnom X100 Vnom N Vout M – Vout N Vout N X100 www.recom-electronic.com Powerline – Definitions and Testing Make and record the following measurements with rated output load at +25°C: ● Output voltage with rated load connected to the output. (Vout FL) ● Output voltage with no load or the minimum specified load for the DC-DC converter. (Vout ML) Load regulation is the difference between the two measured output voltages as a percentage of output voltage at rated load. Efficiency The ratio of output load power consumption to input power consumption expressed as a percentage. Normally measured at full rated output power and nominal line conditions. Switching Frequency The rate at which the DC voltage is switched in a DC-DC converter or switching power supply. The ripple frequency is double the switching frequency in pushpull designs. Output Ripple and Noise Because of the high frequency content of the ripple, special measurement techniques must be employed so that correct measurements are obtained. A 20MHz bandwidth oscilloscope is used, so that all significant harmonics of the ripple spike are included. This noise pickup is eliminated as shown in Figure 3, by using a scope probe with an external connection ground or ring and pressing this directly against the output common terminal of the power converter, while the tip contacts the voltage output terminal. This provides the shortest possible connection across the output terminals. Load Regulation Vout ML – Vout FL Vout FL X100 Figure 3: www.recom-international.com 2008 261 Powerline – Definitions and Testing Output Ripple and Noise (continued) Transient Recovery Time Figure 4 shows a complex ripple voltage waveform that may be present on the output of a switching power supply. There are three components in the waveform, first is a charging component that originates from the output rectifier and filter, then there is the discharging component due to the load discharging the output capacitor between cycles, and finally there are small high frequency switching spikes imposed on the low frequency ripple. Figure 4: Amplitude The time required for the power supply output voltage to return to within a specified percentage of rated value, following a step change in load current. Figure: 5 Transient Recovery Time Current Limiting output current is limited to prevent damage of the converter at overload situations. If the output is shorted, the Fold Back Current Limiting A method of protecting a power supply from damage in an overload condition, reducing the output current as the load approaches short circuit. output voltage is regulated down so the current from the outputs cannot be excessive. Figure 6: Fold Back Current LimitingTime 262 2008 www.recom-electronic.com Powerline – Definitions and Testing Isolation The electrical separation between the input and output of a converter, (consisting of resistive and capacitive isola- Break-Down Voltage The maximum continuous DC voltage, which may be applied between the input and output terminal of a power supply without causing damage. Typical break-down voltage for DC-DC converters is 1600VDC because the equivalent DC isolation for 230VAC continuous rated working voltage is 1500VDC. tion) normally determined by transformer characteristics and circuit spacing. Figure 7: Temperature Coefficient With the power converter in a temperature test chamber at full rated output load, make the following measurements: ● Output voltage at +25°C ambient temperature. ● Set the chamber for maximum operating ambient temperature and allow the power converter to stabilize for 15 to 30 minutes. Measure the output voltage. ● Set the chamber to minimum operating ambient temperature and allow the power converter to stabilize for 15 to 30 minutes. ● Ambient Temperature The temperature of the still-air immediately surrouding an operating power supply. Care should be taken when comparing manufacturer’s data- sheets that still-air ambient temperature and not case temperature is quoted. Operating Temperature Range The range of ambient or case temperature within a power supply at which it operates safely and meets its specifications. Storage Temperature Range The range of ambient temperatures within a power supply at non-opera- ting condition, with no degradation in its subsequent operation. www.recom-international.com 2008 Divide each percentage voltage deviation from the +25°C ambient value by the corresponding temperature change from +25°C ambient. The temperature coefficient is the higher one of the two values calculated above, expressed as percent per change centigrade. 263 Powerline – Definitions and Testing Some converters from our Powerline offer the feature of trimming the output voltage in a certain range around the nominal value by using external trim resistors. Because different series use different circuits for trimming, no general equation can be given for calculating the trim resistors. Output Voltage Trimming: The following trimtables give values for chosing these trimming resistors. If voltages between the given trim points are required, extrapolate between the two nearest given values to work out the resistor required or use a variable resistor to set the voltage. Single Output Voltage Trim Tables RP15-, RP20-, RP30-, RP40-, RP60- xx3.3S (For RP15-SA/SAW see other table) Trim up Vout = RU = 1 3,333 57.93 2 3,366 26.16 3 3,399 15.58 4 3,432 10.28 5 3,465 7.11 6 3,498 4.99 7 3,531 3.48 8 3,564 2.34 9 3,597 1.46 10 3,63 0.75 % Volts KOhms Trim down Vout = RD = 1 3,267 69.47 2 3,234 31.23 3 3,201 18.49 4 3,168 12.12 5 3,135 8.29 6 3,102 5.74 7 3,069 3.92 8 3,036 2.56 9 3,003 1.50 10 2,97 0.65 % Volts KOhms RP15-, RP20-, RP30-, RP40-, RP60- xx05S (For RP15-SA/SAW see other table) Trim up Vout = RU = 1 5,05 36.57 2 5,1 16.58 3 5,15 9.92 4 5,2 6.58 5 5,25 4.59 6 5,3 3.25 7 5,35 2.30 8 5,4 1.59 9 5,45 1.03 10 5,5 0.59 % Volts KOhms Trim down Vout = RD = 1 4,95 45.53 2 4,9 20.61 3 4,85 12.31 4 4,8 8.15 5 4,75 5.66 6 4,7 4.00 7 4,65 2.81 8 4,6 1.92 9 4,55 1.23 10 4,5 0.68 % Volts KOhms RP15-, RP20-, RP30-, RP40- ,RP60-xx12S (For RP15-SA/SAW see other table) Trim up Vout = RU = 1 12,12 367.91 2 12,24 165.95 3 12,36 98.64 4 12,48 64.98 5 12,6 44.78 6 12,72 31.32 7 12,84 21.70 8 12,96 14.49 9 13,08 8.88 10 13,2 4.39 % Volts KOhms Trim down Vout = RD = 1 11,88 460.99 2 11,76 207.95 3 11,64 123.60 4 11,52 81.42 5 11,4 56.12 6 11,28 39.25 7 11,16 27.20 8 11,04 18.16 9 10,92 11.13 10 10,8 5.51 % Volts KOhms RP15-, RP20-, RP30-, RP40-, RP60- xx15S (For RP15-SA/SAW see other table) Trim up Vout = RU = 1 15,15 404.18 2 15,3 180.59 3 15,45 106.06 4 15,6 68.80 5 15,75 46.44 6 15,9 31.53 7 16,05 20.88 8 16,2 12.90 9 16,35 6.69 10 16,5 1.72 % Volts KOhms Trim down Vout = RD = 1 14,85 499.82 2 14,7 223.41 3 14,55 131.27 4 14,4 85.20 5 14,25 57.56 6 14,1 39.14 7 13,95 25.97 8 13,8 16.10 9 13,65 8.42 10 13,5 2.282 % Volts KOhms 264 2008 www.recom-electronic.com Powerline – Definitions and Testing RP15-S_DA, RP15 S:DAW Output Voltage Trim Tables RP15-xx3.3SA, RP15-xx3.3SAW Trim up Vout = RU = 1 3,333 385.07 2 3,366 191.51 3 3,399 126.99 4 3,432 94.73 5 3,465 75.37 6 3,498 62.47 7 3,531 53.25 8 3,564 46.34 9 3,597 40.96 10 3,63 36.66 % Volts KOhms Trim down Vout = RD = 1 3,267 116.72 2 3,234 54.78 3 3,201 34.13 4 3,168 23.81 5 3,135 17.62 6 3,102 13.49 7 3,069 10.54 8 3,036 8.32 9 3,003 6.60 10 2,97 5.23 % Volts KOhms RP15-xx05SA, RP15-xx05SAW Trim up Vout = RU = 1 5,05 253.45 2 5,1 125.70 3 5,15 83.12 4 5,2 61.82 5 5,25 49.05 6 5,3 40.53 7 5,35 34.45 8 5,4 29.89 9 5,45 26.34 10 5,5 23.50 % Volts KOhms Trim down Vout = RD = 1 4,95 248.34 2 4,9 120.59 3 4,85 78.01 4 4,8 56.71 5 4,75 43.94 6 4,7 35.42 7 4,65 29.34 8 4,6 24.78 9 4,55 21.23 10 4,5 18.39 % Volts KOhms RP15-xx12SA, RP15-xx12SAW Trim up Vout = RU = 1 12,12 203.22 2 12,24 99.06 3 12,36 64.33 4 12,48 46.97 5 12,6 36.56 6 12,72 29.61 7 12,84 24.65 8 12,96 20.93 9 13,08 18.04 10 13,2 15.72 % Volts KOhms Trim down Vout = RD = 1 11,88 776.56 2 11,76 380.72 3 11,64 248.78 4 11,52 182.81 5 11,4 143.22 6 11,28 116.83 7 11,16 97.98 8 11,04 83.85 9 10,92 72.85 10 10,8 64.06 % Volts KOhms RP15-xx15SA, RP15-xx15SAW Trim up Vout = RU = 1 15,15 161.56 2 15,3 78.22 3 15,45 50.45 4 15,6 36.56 5 15,75 28.22 6 15,9 22.67 7 16,05 18.70 8 16,2 15.72 9 16,35 13.41 10 16,5 11.56 % Volts KOhms Trim down Vout = RD = 1 14,85 818.22 2 14,7 401.56 3 14,55 262.67 4 14,4 193.22 5 14,25 151.56 6 14,1 123.78 7 13,95 103.94 8 13,8 89.06 9 13,65 77.48 10 13,5 68.22 % Volts KOhms www.recom-international.com 2008 265 Powerline – Definitions and Testing Dual Output Voltage Trim Tables RP15-, RP20- xx05D Trim up Vout = RU = 1 10,1 90.30 2 10,2 40.60 3 10,3 24.03 4 10,4 15.75 5 10,5 10.78 6 10,6 7.47 7 10,7 5.1 8 10,8 3.32 9 10,9 1.94 10 11 0.84 % Volts KOhms Trim down Vout = RD = 1 9,9 109.3 2 9,8 49.00 3 9,7 28.90 4 9,6 18.85 5 9,5 12.82 6 9,4 8.80 7 9,3 5.93 8 9,2 3.77 9 9,1 2.10 10 9 0.76 % Volts KOhms RP15-, RP20, RP30- xx12D Trim up Vout = RU = 1 24,24 218.21 2 24,48 98.10 3 24,72 58.07 4 24,96 38.05 5 25,2 26.04 6 25,44 18.03 7 25,68 12.32 8 25,92 8.03 9 26,16 4.69 10 26,4 2.02 % Volts KOhms Trim down Vout = RD = 1 23,76 273.44 2 23,52 123.02 3 23,28 72.87 4 23,04 47.80 5 22,8 32.76 6 22,56 22.73 7 22,32 15.57 8 22,08 10.20 9 21,84 6.02 10 21,6 2.67 % Volts KOhms RP15-, RP20-, RP30-- xx15D Trim up Vout = RU = 1 30,3 268.29 2 30,6 120.64 3 30,9 71.43 4 31,2 46.82 5 31,5 32.06 6 31,8 22.21 7 32,1 15.1 8 32,4 9.91 9 32,7 5.81 10 33 2.53 % Volts KOhms Trim down Vout = RD = 1 29,7 337.71 2 29,4 152.02 3 29,1 90.13 4 28,8 59.18 5 28,5 40.61 6 28,2 28.23 7 27,9 19.39 8 27,6 12.76 9 27,3 7.60 10 27 3.47 % Volts KOhms 266 2008 www.recom-electronic.com Powerline – Definitions and Testing Undervoltage Lockout At low input voltages, the input currents can exceed the rating of the converter. Therefore, converters featuring under- voltage lockout will automitically shut down if the input voltage is too low. As the input voltage rises, they will restart. Undervoltage Lockout Tables Converter Series Nominal Input Voltage Switch ON input voltage Switch OFF input voltage RP08-S_DAW 24V (9~36VDC) 48V (18~75VDC) 9VDC 18VDC 8VDC 16VDC RP12-S_DA 12V (9~18VDC) 24V (18~36VDC) 48V (36~75VDC) 9VDC 18VDC 36VDC 8VDC 16VDC 33VDC RP12-S_DAW 24V (9~36VDC) 48V (18~75VDC) 9VDC 18VDC 8VDC 16VDC RP15-S_DA 12V (9~18VDC) 24V (18~36VDC) 48V (36~75VDC) 9VDC 17VDC 33VDC 8VDC 14.5VDC 30.5VDC RP15-S_DAW 24V (9~36VDC) 48V (18~75VDC) 9VDC 18VDC 8VDC 16VDC RP15-S_DFW 24V (9~36VDC) 48V (18~75VDC) 9VDC 18VDC 7.5VDC 15VDC RP20-S_DFW 24V (9~36VDC) 48V (18~75VDC) 9VDC 18VDC 7.5VDC 15VDC RP30-S_DE 12V (9~18VDC) 24V (18~36VDC) 48V (36~75VDC) 9VDC 17.8VDC 36VDC 8VDC 16VDC 33VDC RP30-S_DEW 24V (10~40VDC) 48V (18~75VDC) 10VDC 18VDC 8VDC 16VDC RP40-S_D_TG 12V (9~18VDC) 24V (18~36VDC) 48V (36~75VDC) 9VDC 17.8VDC 36VDC 8VDC 16VDC 34VDC RP30-S_DGW 24V (9~36VDC) 48V (18~75VDC) 9VDC 18VDC 8VDC 16VDC RP60-SG 24V (18~36VDC) 48V (36~75VDC) 17VDC 34VDC 15VDC 32VDC www.recom-international.com 2008 267 Powerline DC-DC Application Notes Powerline – Heat Sinks 7G-0047-F (12°C/W) 7G-0020A (9.5°C/W) 268 2008 www.recom-electronic.com Powerline – Heat Sinks 7G-0011A (8.24°C/W) 7G-0026A (7.8°C/W) www.recom-international.com 2008 269 Powerline –HC Versions 2” x 1” 2” x 1.6” 270 2008 www.recom-electronic.com Powerline –HC Versions 2” x 2” www.recom-international.com 2008 271 Block diagrams Unregulated Single Output RM, RL, RQS, RO, RE, ROM, RSS, RB-xxxxS, RA-xxxxS, RBM-xxxxS, RK, RP-xxxxS, RxxPxxS, RxxP2xxS, RN,RTS, RI, REZ, RKZ-xxxxS, RV-xxxxS, RAA-xxxxS, RGZ Unregulated Dual Output RQD, RSD, RB-xxxxD, RA-xxxxD, RBM-xxxxD, RH, RP-xxxxD, RxxPxxD, RxxP2xxD, RTD, RC-xxxxD, RD-xxxxD, RKZ-xxxxD, RV-xxxxD, RAA-xxxxD, RJZ Unregulated Dual Isolated Output RU, RUZ Post-Regulated Single Output RZ, RSZ (P), RY-xxxxS, RX-xxxxS, RY-SCP, REC1.5-xxxxSR/H1, REC1.8-xxxxSR/H1, REC2.2-xxxxSR/H1, REC3-xxxxSR/H1 Post-Regulated Dual Output RY-xxxxS, RX-xxxxS, RY-DCP, REC2.2-xxxxDR/H1, REC3-xxxxDR/H1 272 2008 www.recom-electronic.com Block diagrams Regulated Single Output RSO, RS, REC2.2-xxxxSRW, RW-xxxxS, REC3-xxxxSRW(Z)/H*, REC5-xxxxSRW(Z)/H*, REC7.5-xxxxSRW/AM/H*, RP08-xxxxSA, RP08-xxxxSAW, RP10-xxxxSE, RP10-xxxxSEW, RP12-xxxxSA, RP12-xxxxSAW, RP15-xxxxSA, RP15-xxxxSAW, RP15-xxxxSF, RP15-xxxxSFW, RP20-xxxxSF, RP20-xxxxSFW Regulated Dual Output RSO-xxxxD, RS-xxxxD, REC2.2-xxxxDRW, RW-xxxxD, REC3-xxxxDRW(Z)/H*, REC5-xxxxDRW(Z)/H*, REC7.5-xxxxDRW/AM/H*, RP08-xxxxDA, RP08-xxxxDAW, RP10-xxxxDE, RP10-xxxxDEW, RP12-xxxxDA, RP12-xxxxDAW, RP15-xxxxDF, RP15-xxxxDFW, RP15-xxxxDA, RP15-xxxxDAW, RP20-xxxxDF, RP20-xxxxDFW, RP30-xxxxDE, RP30-xxxxDEW, RP40-xxxxDG, RP40-xxxxDGW Regulated Dual Isolated Output REC3-DRWI www.recom-international.com 2008 273 Block diagrams Regulated Dual Output RP40-05xxTG Regulated Single Output, Synchronous Rectification RP20-xxxxSF, RP30-xxxxSE, RP30-xxxxSEW, RP40-xxxxSG, RP40-xxxxSGW, RP60-xxxxSG 274 2008 www.recom-electronic.com Block diagrams-AC/DC RAC05-xxSA, RAC10-xxSA, RAC15-xxSA, RAC20-xxSA, RAC30-xxSA, RAC60-xxSB RAC05-xxSB, RAC10-xxSB, RAC15-xxSB, RAC30-xxSB, RAC40-xxSA www.recom-international.com 2008 275 Block diagrams-AC/DC RAC05-xxDA, RAC10-xxDA, RAC15-xxDA, RAC20-xxDA, RAC30-xxDA RAC15-xxDB, RAC30-xxDB, RAC40-xxSA 276 2008 www.recom-electronic.com Block diagrams-AC/DC RAC15-05xxTA, RAC20-05xxTA RAC15-05xxTB, RAC30-05xxTA, RAC40-05xxTA www.recom-international.com 2008 277 Transport Tubes No. Types 1. RO, RM, RE, ROM, RB, RBM, RK, RH, RP, RU, RI, RD, RKZ, RUZ, RY, RY-SCP, RY-DCP, R-78xx-0.5, R-78xx-1.0 RS, RSO, RS3, RxxTR RJZ, RGZ, RW2(B) RSS, RSD, RZ RTD, RTS, RSZ, R-78Axx-xx SMD RV, RW-S, RxxPxx, RxxP2xx, RW2(A)-SMD R5-xxxxPA, R6xxxxP, R7xxxxP, RW-D, Rxx-xxxA, REC3-, REC5-, REC7.5RP08, RP12, RCD-24-xxx RP15-A, RP15-AW RP08-SMD, REC2.2-SMD, REC3-SMD, REC5-SMD, REC7.5-SMD RP10, RP15, RP20, RP30, RP40 R-78Bxx-xx, R-78HBxx-xx R-78Bxx-xxL, R-78HBxx-xxL R5-xxxxDA, R6xxxxD, R7xxxxD 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 1. 2. TUBE LENGTH = 520±2.0 278 3. TUBE LENGTH = 520±2.0 2008 TUBE LENGTH = 520±2.0 www.recom-electronic.com Tubes 4. 5. TUBE LENGTH = 520±2.0 6. TUBE LENGTH = 520±2.0 7. TUBE LENGTH =520±2.0 8. TUBE LENGTH = 520±2.0 TUBE LENGTH = 520±2.0 9. 10. TUBE LENGTH = 520±2.0 www.recom-international.com TUBE LENGTH =520±2.0 2008 279 Tubes 11. 12. 13 14. 280 2008 www.recom-electronic.com Tapes www.recom-international.com 2008 281 Tubes 282 2008 www.recom-electronic.com Tapes www.recom-international.com 2008 283