APPLICATION NOTE MicroNote™ 132 AIRCRAFT LIGHTNING PROTECTION A Shortcut to Selecting Transient Voltage Suppressors for RTCA/DO-160E Threats Using Microsemi's New DIRECTselect™ Method by Mel Clark Table of Contents Background 3 Abnormal Voltage Characteristics 4 Definitions for Graphs 1-14 5 Using DIRECTselect 6 Clamping Voltage Significance 7 Selecting Lightning Protection for Waveform 5A 8 Protecting Across Power Distribution Lines 10 Multiple Surge Events 12 Summary and Conclusions 12 Acknowledgments and References 12 Index of DIRECTselect Graphs 13 DIRECTselect Graphs and Data Tables 2 Microsemi - Scottsdale Division 8700 East Thomas Road, Scottsdale, AZ 85252 Ph: (480) 941-6300 14-27 Fax: (480) 947-1503 © 2006 MicroNote 132 Aircraft Lightning Protection BACKGROUND Within the thin metal and composite shell of every jetliner, tens of thousands of sensitive semiconductor components are performing critical functions from navigation to engine control. Since aircraft are struck by lightning twice a year, on average, protection of sensitive electronic devices providing a myriad of functions is essential to ensuring the safety of both passengers and crew. Although aircraft lightning threats are well defined in RTCA/DO-160E, there are very few off-the-shelf transient voltage suppressors (TVSs) that are direct "plug-ins" rated for operating voltage and surge protection from the three waveforms and five levels of lightning threats defined in this document. Microsemi offers its RT65KP and RT130KP series TVS components for protection across 28V dc and 115V ac power distribution lines respectively. These are in production and readily available. Data sheets for these parts can be found on our web site at www.microsemi.com . Normally, lengthy calculations must be made to convert surge ratings from standard 10/1000 µs, off-the-shelf TVS components, to their equivalent values for specified aircraft lightning threats. In addition, matching a device with the threat can be cumbersome. Our MicroNotes 126, 127 and 130 thoroughly illustrate these computations, providing a path from defined surge requirements per aircraft specs, to the parameters of available TVS products suitable for a given application. Now there's a better way using Microsemi's DIRECTselect™ to quickly guide the designer to a suitable solution. DIRECTselect Method Here is how it works: Define your surge requirements as specified in DO-160E in Section 22, Induced Transient Susceptibility per waveform, 3, 4, or 5A and Threat Levels 1 through 5 as specified in Table 22-2. Herein are the defined threat levels for Pin Injection, the most severe threats to your circuit. Most requirements combine Waveforms 3 and 4. Since Waveform 4 (6.4/69 µs) is more severe, by a factor of 3.8 [1], we have included only Waveform 4 on our charts for simplicity. Values of Waveform 3 only, when required, are easily calculated using the guidance in MicroNote 127 [2]. For reference, Waveforms 3, 4, and 5A are illustrated in figures 1, 2 and 3 respectively Table 22-2. Defines the matrix of Threat Levels 1 through 5 from DO-160E Section 22. © 2006 Microsemi - Scottsdale Division 8700 East Thomas Road, Scottsdale, AZ 85252 Ph: (480) 941-6300 Fax: (480) 947-1503 3 This table defines the peak open circuit voltage, Voc, and peak short circuit current, Isc, for each of the waveforms listed. In making your TVS selection, maximum working voltage (VWM) values are required along with peak pulse current (IP) threat, since the graphs shown on pages 14 thru 27 are plotted with IP vertically and Vwm horizontally. The working voltage as displayed on the graph must exceed the curve depicting the current limit of the Threat Level. Examples will lead you through the selection process. Individual graphs exist for each product family and are arranged in ascending order of power level / surge current, from 500 W up through 30,000 W. An extensive but condensed form of this information is also shown in MicroNote 130 [3]. Graphs 1 through 7 are associated with Waveform 4 and Graphs 8 through 14 are associated with Waveform 5A. Each graph is accompanied by a supplemental table containing multiple data points from which each curve was derived, plus a list of the applicable Microsemi products for use with these specific surge current threat levels. This presentation provides direction for TVS selection for a broad distribution, from low voltage, low level lightning threats to data lines up through high levels for power distribution lines. ABNORMAL VOLTAGE CHARACTERISTICS Other critical voltage parameters include Surge Limits associated with abnormal voltage. These are maximum excursions above the nominal operating voltage. Surges differ from transient voltage in that they are long term Abnormal Voltage Characteristics with high-line voltages extending for durations of tens, up to hundreds of milliseconds which can destroy TVSs. These voltage anomalies are caused by normal generator functions and must be considered in TVS selection. An example of the ac abnormal ac surge voltage curve, displaying voltage vs time is shown in Figure 16-5 in DO-160E, Section 16 and illustrated below: Figure 16-5. Envelope of ac Abnormal Voltage Surges per RTCA/DO-160E The normal operating voltage values in this graph are for 115 V rms. For 230 V lines, double the values shown on the graph [4]. The rms values must be converted to peak ac values for comparing with TVS parameters since the TVSs are characterized for peak, not rms values. A TVS will not withstand the long surge durations of abnormal voltage surge. They must be selected so that the maximum Peak Working Voltage, VWM, is equal to or greater than the peak abnormal voltage. For exceptions, contact the factory. 4 Microsemi - Scottsdale Division 8700 East Thomas Road, Scottsdale, AZ 85252 Ph: (480) 941-6300 Fax: (480) 947-1503 © 2006 MicroNote 132 Aircraft Lightning Protection DC power lines are also plagued with the same anomaly, abnormal dc voltage surge, resulting from voltage excursions produced by the generators. For dc power, there are three categories of surge voltage as shown in DO-160E, Section 16, Figure 16-6, as shown below. Figure 16-6. Typical Abnormal dc Voltage Surges per RTCA/DO-160E Note that there are 3 categories of abnormal voltages for 28 V nominal and with 100 ms worst case surge, similar to the ac power lines. Three levels of abnormal voltages are listed; Category A, B and C with the most common requirement being Category B. For 14 V dc requirements, divide these upper voltage limits by 2 [5]. As with the envelope for the ac voltages, the VWM of the TVS must be equal to or greater than the voltage limit. For exceptions, consult the factory. DEFINITIONS FOR GRAPHS 1 THROUGH 14 The green, blue and yellow curves represent the ratings of the TVS device in terms of rated Peak Pulse Current (IP) at ambient temperatures. IP is shown in the vertical axis while Working Voltage (VWM) is in the horizontal axis. The green curve on each graph depicts the peak surge current rating vs working voltage at 25oC along with additional curves for derating to 70oC (blue curve) and 100oC (yellow curve). The red curves, which are nearly horizontal, represent the Pin Injection current threat levels as defined by DO-160E and are labeled accordingly. If the curve for the applicable ambient operating temperature is above the red curve designating the maximum threat level, theTVS device will perform at that threat level. Only those levels that are applicable for the associated device families are included on the graph. The fourteen individual graphs in this document cover the entire DO-160E threat range. Seven of these graphs display surge threats and surge capability of the TVSs for Waveform 4 (6.4/69 µs) and seven display this same information for Waveform 5A (40/120 µs). Values shown on the graph include the +20% high side tolerance. Based on requests from the aerospace industry, Microsemi devices meet the vast majority of needs. If no part exists for a given voltage and surge current rating, custom components can be designed. Consult the factory for this option. GRAPH OVERVIEW Each graph is derived from the peak pulse current (Ipp) levels at 10/1000 µs ratings of the product data sheet. For the shorter aircraft transients, the power levels are higher, 3.33x for the 6.4/69 µs waveform and 2.33x for the 40/120 µs waveform with the multiplication factors including the +20% tolerance of the threat duration [6]. For Waveform 4, the graph numbers with associated TVS power levels with part types are listed on the following page: © 2006 Microsemi - Scottsdale Division 8700 East Thomas Road, Scottsdale, AZ 85252 Ph: (480) 941-6300 Fax: (480) 947-1503 5 Graph Number TVS Power Level Product Series (more details on graphs) 1 2 3 4 5 6 7 500 W 600 W 1500 W 3000 W 5000 W 15,000 W 30,000 W P5KE, SMA, HSMBJSAC P6KE, SMB 1.5KE, SMC, SMCJLCE SML 5KP, PLAD5KP 15KP, PLAD15KP 30KP, PLAD30KP A more complete listing of each product series is shown on its associated graph. A second series of graphs, 8 through 14, is included for Waveform 5A and contains the equivalent information on the product series for the associated graph as waveform 4 above but with threat levels increased to the magnitude of waveform 5A. USING DIRECTselect - EXAMPLES FOR WAVEFORM 4 For our first example, let's consider a low level transient voltage threat to an ARINC - 429, +/- 5 V data line. For this illustration, the lightning threat requires protection from Waveform 4, (6.9/69 µs) Level 3 (300Voc/60Isc). Applications with voltages going in both positive and negative directions require bidirectional TVS devices. We know the selection will be within the first few of the seven graphs because of the relatively low current rating requirement. Since the lowest voltage devices have the highest current ratings, the device would most likely be found on the first one or two graphs. In reviewing Graph 1, we see that the 500 W TVS at 5 V peak working voltage (VWM) have a peak current rating of 180 A. This is well above the necessary requirement of 60 A for Level 3 with margin for temperature derating up to 100oC. In the supplementary table, data points for these graphs are provided which include the major parameters: Peak Pulse Current (IPP), Clamping Voltage (VC), and VWM. Exact values not shown can be extrapolated from this data. Device selection for the ARINC - 429, Slow Data rate signals, 10-11 kHz, would be the SMBJ5.0C or SMBJ5.0CA. For the Fast Data rate signals at 100 kHz, the selection would be the HSMBJSAC5.0, which has a low capacitance of 25 pf or less. Two of these devices are required in anti-parallel. Refer to the data sheet on Microsemi's web site for complete information on installing this part. The selection shown is a surface mount device; however these parts are also available in axial lead configurations. In our second example, a TVS is required for performance to Waveform 4 (6.4/69 µs), Level 3 (Voc300V/Isc60A) for +/-48 V ac. This application also requires a bidirectional device and must have a higher power rating than in the previous example because its operating voltage is significantly greater. Since silicon TVSs are constant power rated, the current rating will be about one-tenth the value for a 48 V TVS compared to a 5.0V device in the same series. However, the peak power requirement is greater (the product of the IPP x VC), so we continue our search among the graphs for a higher power device. In Graph 3, for the 1,500 W series, we find that the peak current capability of a 48 V device is 62 A @ 25oC on the green curve while the requirement is 45 A at 48 V on the red curve for Level 3. It is interesting to note that the specified requirement of 60 A per Table 22-2 is reduced significantly by the clamping voltage, subtracting from the driving voltage [7], thus proportionally reducing the surge current. This is reflected in the downward slope of the Level 3 Curve. The SMCJ48CA, (CA suffix denoting bidirectional performance for ac) or equivalent will meet the surge requirements at 25oC and 70oC but is marginal at 100oC. The next level up, the 3000 W series is recommended for 100oC performance if required (see graph 4). Why are the driving currents of Levels 1 through 5 reduced with increasing voltage? Because the clamping voltage effects subtract from the driving voltage, thus lowering the driving current as illustrated in the following equation: 6 Microsemi - Scottsdale Division 8700 East Thomas Road, Scottsdale, AZ 85252 Ph: (480) 941-6300 Fax: (480) 947-1503 © 2006 MicroNote 132 Aircraft Lightning Protection Is = (Voc - Vc) / Zs = (300 V - 77.4 V) / 5 ohm = 44.5 A Where: Is Voc Vc Zs (Eq. 1.) = peak driving current of surge through the TVS = open circuit voltage - 300 V = Max clamping voltage of SMCJ48CA = Source impedance of driving voltage - Voc / Isc In this equation we see the Voc driving voltage of 300 V is reduced to 222.6V, with a corresponding reduction of the short circuit current to 44.5 A, Isc, about 25% below the value of 60 A specified for Level 3. CLAMPING VOLTAGE SIGNIFICANCE We are making a detour from the normal presentation to discuss the clamping voltage and its significance. The purpose of the TVS is to clamp the voltage spike to a level below the failure threshold of the components it is protecting. The failure threshold voltage is not the operating voltage of the protected device. All components have a margin between rated value and failure threshold which is usually not specified by the manufacturer. Maximum operating voltage levels specified on data sheets for ICs and power transistors are for steady state conditions while most components can tolerate short term voltage spikes of less than 150 µs up to 50% greater values than the operating voltages. Normally the higher the voltage of the protected device, the more narrow themargin between maximum operating voltage level and voltage spike failure level. For example, a 400V rated switching transistor can usually tolerate a clamping level of 420 V or more, which is about 5% greater than its steady state operating level. A 5 V to 15 V UART (universal asynchronous receiver transmitter) can normally withstand a 50% or greater voltage clamp above its maximum operating level. Manufacturers are reluctant to provide any other than the maximum operating voltage. The above failure threshold values are based on the writer's experience, including test measurements. Our third example of protection is for a 48V signal line monitoring status of voltage across a relay. The threat is Waveform 4, Level 4 (750Voc/150Isc). This takes us to a higher power level device requirement which we find is the 5000 W rated TVS shown in Graph 5. The peak current protection is more than twice that for our second example so we look for a TVS with higher power that will withstand this higher peak current surge. Observing the 48V level in graph 5, for 5000 W devices, we see that the maximum peak current rating for this voltage level is approximately 210A @ 25oC. The derating graphs indicate that this part will operate safely at 70oC but marginal at 100oC. For 100oC performance, the higher power 15KP48A in graph 6 is recommended. A unipolar device was selected because this is a dc application. Clamping of the negative transients is through the diode in the forward direction which can withstand higher surge currents than in the avalanche mode. A fourth example of protection continues when ascending to a higher threat level, protecting from a transient surge per Waveform 4, Level 5 (1600Voc/320Isc). Operating conditions are on a 28 V dc power distribution line which must withstand an Abnormal Voltage condition of 60 V maximum, Category B (reference figure 16.6 page 6). Continue working your way further into the pages noting that in Graph 6 the 15,000 W TVS series will withstand surge currents of greater than 320 A at a VWM selection level of 60 V for Abnormal Voltage conditions. For somewhat higher VWM selections, a TVS will not conduct during the Abnormal Voltage but will withstand a surge > 320 A for the Level 5 transient threat. A good selection for this application, referencing Graph 6, would be a 15KP64A. Verify that the clamping voltage is compatible with the maximum failure threshold voltage of the protected circuit / component . This device is rated for approximately 500 A @ 64 V 25oC and well above 320 A @ 100oC. It has a clamping voltage of 104 V at its rated peak pulse current (Ipp), the protection level at maximum rated surge current capability as shown on the graph. However, at 25oC, this device has an excess margin of about 60% of its surge rating. Note that it can be derated to 100oC with a close margin of safety. © 2006 Microsemi - Scottsdale Division 8700 East Thomas Road, Scottsdale, AZ 85252 Ph: (480) 941-6300 Fax: (480) 947-1503 7 The 15,000 W devices are made using stacked chips. This has been found to be the most economical method of achieving size reduction for the higher power surge suppressors. The forthcoming PLAD15KP series is made up of a single chip in a surface mount package and as of the first quarter 2007, is in its late stages of development. Our fifth example is one in which a 125 V dc status monitoring signal line must be protected from conditions of Waveform 4, Level 5 (1600Voc/300Isc) in a 70oC ambient. Continue on to Graph 7 and locate the coordinates for the required performance. At 130V, the 30KP130A device has a 6.4/69 µs rating of 500 A at 25oC and 400 A at 70oC; and 330A for 100oC. This selection should perform well for the application. SELECTING LIGHTNING PROTECTION FOR WAVEFORM 5A Waveform 5A is defined as having a waveform, of 40/120 µs +/- 20%. Calculations in the following examples are based on the +20% worst case, increasing the pulse duration from 120 µs to 144 µs maximum. Graphs 8 through 14 depict curves for Waveform 5A. These protection levels are developed in the same manner as those for Waveform 4 but with lower Ipp ratings attributed to the longer Waveform 5A. The increase in surge current / power for Waveform 5A is 2.33 times the peak current value for a given device found on Microsemi's data sheets as stated earlier. Referring to Table 22-2 and the column for Waveform 5A, note that the voltage spike amplitudes are identical to those for Waveform 4. However, the current is higher by a factor of 5 because of the lower source impedance of only 1 ohm compared to 5 ohms for Waveform 4. The more severe conditions of Waveform 5A are attributed to closer proximity of the lightning source including those conductors close the skin of the aircraft, areas containing a higher density of composite materials, long power distribution lines, and long signal line runs within the airframe plus a myriad of others. From the writer's experience, ac and dc power distribution systems may be located in areas requiring protection from Waveform 5A surges, depending on the airframe structure. With the large amounts of composite materials used in construction of the Boeing 787, both power and data lines are subjected to more severe lightning threats. Note: frequency is 1 MHz TABLE 22-2 from Sec 22. RTCA/DO-160E, the matrix defining the threat Level for each Waveform per RTCA/DO-160E, Section 22, is repeated above for ease of reference rather than refer back to page 3. Most threats presented by Waveform 5A appear to be Level 4 (750Voc/750Isc) based on the writers experience. The increase in surge current of Waveform 5A above Waveform 4 is a factor of 5. This results from a source impedance (Zs) reduction to 1 ohm for Waveform 5A, down from a Zs of 5 ohms for Waveform 4. Another component of the increased threat for Waveform 5A is its 74% longer duration compared to Waveform 4. 8 Microsemi - Scottsdale Division 8700 East Thomas Road, Scottsdale, AZ 85252 Ph: (480) 941-6300 Fax: (480) 947-1503 © 2006 MicroNote 132 Aircraft Lightning Protection Typical 5A Level 4 threats require the higher power, 30 kW, device family for protection. Multiple 30 kW devices are often wired in series or parallel to provide the surge current withstand capability for Level 4, Waveform 5A threats. Although there have been no requests, TVS devices for Level 5 threats can be designed to meet these requirements. Example 1 of protecting from Waveform 5A threats is that of a 125 V dc status signal line subjected to Level 2 (125Voc/125Isc). This is an easy one to solve since the operating voltage and threat are at the same level. There will be zero voltage impressed on the line because it is of the same value as the threat, hence no current is driven into the 125 V signal line and no protection is required (see EQ.1). For this same threat at lower operating voltages, protection will be required as shown in the following example. Example 2 of protection from Waveform 5A is one in which a low speed 32 V bidirectional signal line is exposed to a Level 2 (125Voc/125Isc) threat. ARINC-429 and most other signals are run through shielded wiring that provides significant lightning protection, also the line impedances are quite high, further reducing lightning threats. This issue was discussed earlier in the section on protecting from Waveform 4 threats. For this requirement, the solution is found on Graph 11 for the 3000 W device. The closest fit is the SMLJ33CA (33V VRWM) which can be derated for 100oC performance. This is a compact surface mount device available in the DO-214AB (J bend tabs) or DO215AB (gull wing tabs). The SMLJ series is a frequent choice for signal line protection from harsh lightning conditions. Example 3, for a Waveform 5 threat from Level 3 (300Voc/300Isc) lightning exposure, is for a 12 V power supply. The 3000 W device in Graph 11 will protect up to 70oC as observed on the coordinates; however, for protection at 100oC ambient levels, the 5000 W device depicted in Graph 12 is required. As of this issue, the 5KP12A axial leaded device is recommended for this application. In development is our surface mount PLAD5KP5.0 series which is targeted to be available during the second quarter of 2007. Example 4 is more challenging, protecting a 48 V off-line switching power supply having a 100 V rated transistor from threat Level 4 (750Voc/750Isc). Ambient operating temperature is 100oC and the power is Category B with a maximum voltage surge of 60V for 100 ms. Since a TVS will not withstand the power delivered by a 100 ms surge, 60 V becomes our defacto operating voltage. From Graph 14 for the 30,000 W TVS, our highest powered device for this voltage (30KP60A) will withstand a peak current of 708 A at 40/120 µs, (with VC of 97.3V) only 55 A above the threat level of 655A at 25oC (seeEq.1). This is a close margin, but more than adequate to meet this requirement. A level of creativity is required to meet higher temperature requirements. . One option to increase surge current capability is to use two devices of the same voltage type matched in parallel, providing twice the current capability of a single device to meet the often required 100oC ambient. They must be matched under surge conditions to ensure near equal voltage for sharing the current evenly. Two each of a 30KP60A matched in parallel will provide the necessary protection up to 100oC with an approximate 50% safety margin. As of the writing of this text, at least two aircraft system manufacturers are using parallel matched 30KP type TVS devices to increase the current capability sufficient for protecting from Waveform 5A, Level 4. Another approach would be to series two 30KP33CA devices for this requirement. There are no 30KP30A devices available, making this part the only option. This TVS is rated at almost twice the current, (1276A) as the 30KP60A (708A) and would provide more than adequate surge current rating for 100oC ambient performance. As a result, the clamping voltage for the two devices in series is conservatively estimated to be 100 V maximum, the same value as the maximum rated operating voltage of the protected device [8]. Using identical TVSs where the series voltage adds up to the Vwm value is recommended where possible when surge currents are beyond the capability of a single TVS. Multiple devices can be used as long as they are of the same type or of higher current rating when an equally divisible required number is not available. © 2006 Microsemi - Scottsdale Division 8700 East Thomas Road, Scottsdale, AZ 85252 Ph: (480) 941-6300 Fax: (480) 947-1503 9 PROTECTING ACROSS POWER DISTRIBUTION LINES For protection across high voltage ac power distribution lines, there is the option of stacking lower voltage, higher current rated devices in series to compensate for the inherently lower surge current ratings of high voltage TVSs. For high Vwm applications, high surge current protection across ac distribution lines requiring survival from a Level 4 (750Voc/750Isc) threat, multiple TVSs in series are often required. Consider an application across a 115V ac distribution line having an abnormal high voltage of 255 V peak for 180 V rms (ref Figure 16-5 on page 5) feeding a switching power supply. At least 420 V clamping is required for protection of the 400 V rated transistor within the supply. A few well chosen parts can be stacked in series which have a clamping voltage of 420 V maximum and still meet the surge current and a working voltage level equal to or slightly above the 255 V, 100 ms abnormal high voltage condition. When reviewing the selection of available 30KPxx series and comparing the listed Ipp, remember that the current rating in the data sheet is for a 10/1000 µs waveform and Waveform 5A is 40/120 µs. Per the section on page 13, Graph Overview, the 10/1000 µs surge current rating is multiplied by 2.33x to obtain its higher value for the shorter 40/120 µs pulse width. For example, we first calculate the true surge current (Is) of the Level 4 threat to the power supply using 400 V switching transistors. Is = (Voc - Vc) / Zs = (750V - 420V) / 1 ohm = 330A (Eq. 2) From this simple calculation we find that the true threat @ 25oC is 330 A, 40/120 µs. Next, we review the devices available from the 30KPxx data sheet to select TVSs that provide the desired electrical parameters with surge capability of 330 A plus derating for high temperature performance. Remember to multiply the data sheet Ipp values by 2.33 to derive the Ip value for a 40/120 µs, Waveform, 5A. Our target working voltage is 255 V peak, the worse case abnormal high voltage condition, or slightly higher, but still meeting conditions of maximum surge current and clamp voltage. For a trial fit we divide the working voltage by two, with a resulting value of 127.5V which is closely rounded up to 130V providing a 30KP130CA option. Total clamping voltage of both parts in series is 2 x Vc, (Vc is 209 V) which is 418V, very close to our required 420 V Vc maximum. The peak pulse current of the 30KP130CA for the 40/120 µs Waveform 5A is: Ip at 4/120 µs = 2.33 x Ipp at 10/1000 µs = 2.33 x 142 A = 331 A max Ipp (Eq. 3) Just a reminder that Ip is used to denote peak current rating at a waveform other than 10/1000 µs while Ipp denotes the 10/1000 µs data sheet rated peak pulse current. This limit of 331 A for the TVS is approximately equal to that calculated for this surge event, 330 A, and is only suitable for 25oC ambient temperatures, with no margin for derating to higher temperatures. Three devices in series will provide a greater surge protection level. Dividing 255 V by three, provides a perfect 30KP85A option. Total clamp voltage for the three parts in series is the additive values of each part, 137 V x 3 yielding a 411 V, Vc which is slightly conservative for the 420 V minimum requirement. The peak surge current (Ip) rating for the device rated for a 4/120 µs, Waveform 5A is derived in the same manner as in the previous example yielding 508 A Ip which provides a 54% increased margin and can be conservatively derated to 100oC. In this example, the stacked devices were all the same voltage without fractional values remaining. If this is not the case, use a lower voltage device which matches closest when added together but is still above the system operating voltage. 10 Microsemi - Scottsdale Division 8700 East Thomas Road, Scottsdale, AZ 85252 Ph: (480) 941-6300 Fax: (480) 947-1503 © 2006 MicroNote 132 Aircraft Lightning Protection Protection across 230 V ac lines requires performance at an abnormal voltage surges up to 360 V ac, 509V peak for 100 ms that is twice the value in figure 16-5, shown on page 4. TVS protection voltage levels are double the values previously illustrated for 115V. The same techniques are used for selecting lightning protection devices. In some applications where narrow margins exist between operating voltage and clamping voltage, the designer is encouraged to consult the factory for assistance. A list of technical personnel is found on the last page of this document. For protection across 28 V, Category B dc bus lines from threat level 4, the net surge current is higher resulting from the lower clamp voltage as shown with a 30KP60A selected for protection. This 66.7 V minimum breakdown device will adequately meet the 60V for 100 ms, Abnormal Voltage condition. Is = (Voc-Vc) / Zs = (750V-97.3V) / 1 ohm = 652 A (Eq. 4) The Level 4 surge current threat for a 28 V dc line is almost double that for the 115 V ac requirement previously shown. The reason being the lower clamping voltage of 97.3 V reducing the driving voltage far less than the 420V clamping voltage across the ac power line. For higher voltage ac applications the driving voltage is reduced to 330 V by the 420 V clamping voltage with a net surge of 330 A while the reduction of the driving voltage across the dc line is only 97.3 V with a resulting 652 A IS. The Ip of the 30KP60A for a 40/120 µs pulse is 304 A x 2.33 = 708 A, [9] providing a margin of 8.6% above the Ip requirement of 652A for a 25oC ambient. Since the abnormal surge voltage does not exceed 60 V, using a device with a breakdown voltage equal to this value has been acceptable for most applications. However, many applications require the lowest clamping voltage which can be attained as described in subsequent paragraphs. Lower voltage TVSs providing lower clamping voltage than the 30KP60A described above include the 30KP58CA and 30KP54A. Minimum breakdown voltages are 64.4 V and 60.0 V respectively with minimum clamping voltages of 94.0 V and 87.5 V respectively. Maximum IP for the 30KP54A is 797 A at 40/120 µs. Let's compare the difference when using the 30KP54A for protection. Is =(Voc-Vc) / Zs = (750V-87.5V) / 1 ohm = 662.5 A (Eq. 5) The 30KP54A affords 89 A of additional current protection and a lower clamping voltage by 9.8 V for protecting more sensitive components. Although the lower end of the breakdown voltage (VBR), 60.0 V, is identical to the o maximum Abnormal Voltage, the TVS will draw current when the temperature drops to -25 C for example, since TVSs have a positive temperature coefficient of voltage. However, the current drawn by the TVS will be minimum, only sufficient to maintain a breakkdown voltage equal to the maximum Abnormal Voltage during this brief time period of 100 ms. For a power line, this small amount of extra current drawn for heating the TVS should present no problem. For higher ambient temperatures, the normal practice for increasing surge current capability for this requirement is with matched parallel devices because there is no device of one half of the voltage of the 30KP54A to provide two components in series. Voltage matching is performed under surge conditions to ensure a very close match, typically within the range of +/- 0.5%, for even load sharing between devices. Matching under surge assures that the device is well into bulk conduction. This is normally performed by the manufacturer. Parallel matched TVSs for aircraft lightning protection and general heavy duty surge protection have been in use for several decades and have a record of proven performance. This method has been thoroughly tested in battle performance in military ships and aircraft. For higher current applications, using single components, beyond the limitations of Microsemi's 30,000 watt devices, there is the RT130KP275CV thru 295CV or CA series, which is rated at 40,000 W for 10/1000 µs. They are characterized for Waveform 4, 6.4/69 µs and available in voltages intended for protection across 115 ac lines including abnormal high voltage conditions. Using the conversion equations reviewed in MicroNote No. 127, they may be applicable for other protection requirements confronted by the designer. Copies of the RT130KP275CV thru 295CV or CA series data sheets can be downloaded from our web site at www.microsemi.com . © 2006 Microsemi - Scottsdale Division 8700 East Thomas Road, Scottsdale, AZ 85252 Ph: (480) 941-6300 Fax: (480) 947-1503 11 MULTIPLE SURGE EVENTS More recently, inquiries have been made for devices to withstand multiple surge events as defined by RTCA/DO-160E and Boeing Spec. No. D6-160E. The profile of the surge consists of the maximum value followed by multiple strokes. Microsemi is developing a program to evaluate the performance of their TVS series for Ipp ratings of this multiple surge threat. This information will be added to a future revision. SUMMARY / CONCLUSIONS This document is the fourth in our series of MicroNotes providing selection guidance specifically for the avionics design engineer (the others include MicroNotes Nos. 126. 127 and 130). It translates the data sheet peak pulse current ratings of the 10/1000 µs waveform into the surge rating equivalents to meet the Waveform 3, 4 and Waveform 5A threats described in RTCA/DO-160. A matrix of curves for each device family from 500 W peak pulse power up through 30,000 W has been derived for surge ratings of each device family at 25oC, 70oC, and 100oC for each of the above threats. Each curve is supported with a chart listing the data sheet electrical parameters for the individual components listed along with calculated data points for the curves. Using the examples and guidelines in the text, the designer is able to select directly from the curve, a device to fit his requirement with minimal calculating and guesswork. We expect those using this document to save valuable design time by more rapidly selecting a TVS correctly rated for a given application. Since this is our first effort at presenting this information in graph selection format, we expect to make revisions to keep up with the emerging technologies and updates of RTCA/DO-160E. We also recognize that there is room for modifications to make this document more user friendly. To help achieve this goal, constructive comments to the writer from the user are welcome. It is Microsemi's desire to provide the design engineer with the most up to date design information to assist in achieving his/her goal more efficiently. ACKNOWLEDGEMENTS The author wishes to express his appreciation to Kent Walters for his excellent contribution in thoroughly editing this document and Joe Leindecker for his valuable contribution with development and layout of the graphs and supporting tables. CONTACTS FOR ADDITIONAL TECHNICAL INFORMATION Mel Clark ([email protected]) at 480-941-6433 Kent Walters ([email protected]) at 480-941-6524 Ken Dierberger ([email protected]) at 480-941-6547 REFERENCES [1] [2] [3] [4] [5] [6] [7] [8] 12 Clark, O. M., MicroNote™ No. 127, Microsemi Corp., 2004, p. 6 Clark, O. M., MicroNote No. 127, Microsemi Corp., 2004, p. 6 Walters, K., MicroNote No. 130, Microsemi Corp., 2005 RTCA/DO-160E, Section 16, Figure 16-5, 2004, p. 16-37 RTCA/DO-160E, Section 16, Figure 16-6, 2004, p. 16-38 Clark, O. M., MicroNote No. 127, Microsemi Corp., 2004 p. 10 Clark, O. M., MicroNote No. 127, Microsemi Corp., 2004, p. 17 Clark, O. M. and Walters, K. MicroNote No. 112, Microsemi Corp. 2004 Microsemi - Scottsdale Division 8700 East Thomas Road, Scottsdale, AZ 85252 Ph: (480) 941-6300 Fax: (480) 947-1503 © 2006 MicroNote 132 Aircraft Lightning Protection Index to DIRECTselect Graphs and Datapoints © 2006 Graph # Waveform Rating Graph Graph Graph Graph Graph Graph Graph 1 2 3 4 5 6 7 Waveform Waveform Waveform Waveform Waveform Waveform Waveform 4 4 4 4 4 4 4 500 W 600W 1,500W 3,000W 5,000W 15,000W 30,000W 14 15 16 17 18 19 20 Graph Graph Graph Graph Graph Graph Graph 8 9 10 11 12 13 14 Waveform Waveform Waveform Waveform Waveform Waveform Waveform 5A 5A 5A 5A 5A 5A 5A 500W 600W 1,500W 3,000W 5,000W 15,000W 30,000W 21 22 23 24 25 26 27 Microsemi - Scottsdale Division 8700 East Thomas Road, Scottsdale, AZ 85252 Ph: (480) 941-6300 Pg # Fax: (480) 947-1503 13 Waveform 4 RTCA/DO-160E using 500 W TVS Diodes Data Points for Curves in Graph 1 14 VC Peak Surge Currents for the Red Curves* IS Threat for Levels shown on graph Threat Levels 1-4 IP 25 oC 6.4/69 µs A IP 70 oC 6.4/69 µs A IP 100 oC 6.4/69 µs A 1 50V/10A A 2 125V/25A A 3 300V/60A A 4 750V/150A A 148.2 147.9 V V IPP 500 W 10/1000 µs A 5 6 7 9.2 10.3 12.0 54.3 48.5 41.7 179 160 138 146 131 113 125 112 96.6 8.2 7.9 7.6 23.1 22.9 22.6 58.2 57.9 57.6 8 9 10 13.6 15.4 17.0 36.7 32.5 29.4 121 107 97 99 88 79.5 84.7 74.9 67.9 7.2 7.0 6.6 22.8 21.9 21.6 57.2 56.9 56.6 12 15 18 19.9 24.4 29.2 25.1 20.6 17.2 83 68 57 68.0 55.8 46.7 58.1 47.6 39.9 6.0 5.1 4.0 21.0 20.1 19.2 56.0 55.1 54.2 20 28 30 32.4 45.4 48.4 15.4 11.0 10.3 51 36 34 41.8 29.5 27.9 35.7 25.2 23.8 3.5 0.9 18.5 15.9 15.3 53.5 50.9 50.3 36 40 48 58.1 64.5 77.4 8.6 7.8 6.5 29 26 22 23.7 21.3 18.0 20.3 18.2 15.4 50 60 70 80 96.8 113 6.0 5.2 4.4 20 17.3 14.5 16.4 14.2 11.9 14.0 12.1 10.2 80 90 100 126 146 162 4.0 3.4 3.1 13.3 11.3 10.2 10.9 9.3 8.4 9.3 7.9 7.1 13.4 12.1 9.5 Microsemi TVs Part Numbers compliant to RTCA/DO-160E Standard Capacitance • Axial Lead P5KE5.0A-170A, CA 1N6103A-6137A 1N6461-6468 • Surface Mount SMAJ5.0A-170A, CA Low capacitance • Axial Lead SAC5.0-50 • Surface Mount HSMBJSAC5.0-50 Over limit 25 oC VWM Conversion to 6.4/69 µs IP Values Over limit 25 oC 500 W TVS @10/1000 µs * Surge currents are reduced by clamping voltage (see Eq. 1). In the table above, the first three columns, VWM, VC, and IPP 500 W are taken from the data sheet while the subsequent 0 0 three columns of 6.4/69 µs data were derived as illustrated earlier in this document and also MicroNoteTM 127. The 70 C and 100 C curves were added for simplifying selection since many TVS devices require derating for higher temperatures. © 2006 Microsemi Corporation Waveform 4 RTCA/DO-160E using 600 W TVS Diodes Data Points for Curves in Graph 2 600 W TVS @10/1000 µs IP 25 oC 6.4/69 µs A IP 70 oC 6.4/69 µs A IP 100 oC 6.4/69 µs A 1 50V/10A A 2 125V/25A A 3 300V/60A A 4 750V/150A A V V IPP 600 W 10/1000 µs A 5 6 7 9.2 10.3 12.0 65.2 58.3 50.0 217 194 166 178 159 136 152 136 116 8.2 7.9 7.6 23.1 22.9 22.6 58.2 57.9 57.6 148.2 147.9 147.6 8 9 10 13.6 15.4 17.0 44.1 39.0 35.3 147 130 118 120 107 96.7 103 91.0 82.6 7.2 7.0 6.6 22.2 21.9 21.6 57.2 56.9 56.6 147.2 12 15 18 19.9 24.4 29.2 30.2 24.0 20.5 101 80.0 68.2 82.8 65.6 55.9 77.7 56.0 47.7 6.0 5.2 4.0 21.0 20.1 19.2 56.0 55.1 54.2 20 28 30 32.4 45.4 48.4 18.5 13.2 12.4 61.3 43.9 41.3 50.2 35.9 33.9 42.9 30.7 28.9 3.5 0.9 0.3 18.5 15.9 15.3 53.5 50.9 36 40 48 58.1 64.5 77.4 10.3 9.3 7.7 34.3 31.0 25.6 28.1 25.4 20.9 24.0 21.7 17.9 0 13.4 12.1 9.5 50 60 70 80.0 96.8 113 7.1 5.6 5.3 23.6 20.6 17.6 19.3 16.9 14.4 16.5 14.4 12.3 80 90 100 126 146 162 4.7 4.1 3.7 15.6 13.6 12.3 12.8 11.2 10.1 10.9 9.52 8.61 Microsemi TVs Part Numbers compliant to RTCA/DO-160E Standard Capacitance • Axial Lead P6KE6.8A-200A, CA • Surface Mount SMBJ(G)5.0A-170A, CA Over limit 25 oC VC Peak Surge Currents for the Red Curves* IS Threat for Levels shown on graph Threat Levels 1-4 Over limit 25 oC VWM Conversion to 6.4/69 µs IP Values 9.0 5.6 2.4 * Surge currents are reduced by clamping voltage (see Eq.1). In the table above, the first three columns, VWM, VC, and IPP 600 W are taken from the data sheet while the subsequent 0 0 three columns of 6.4/69 µs data were derived as illustrated earlier in this document and also MicroNoteTM 127. The 70 C and 100 C curves were added for simplifying selection since many TVS devices require derating for higher temperatures. © 2006 Microsemi Corporation 15 Data Points for Curves in Graph 3 1500 W TVS @10/1000 µs 16 Waveform 4 RTCA/DO-160E using 1500 W TVS Diodes Conversion to 6.4/69 µs IP Values Peak Surge Currents for the Red Curves* IS Threat for Levels shown on graph Threat Levels 2-5 IP 25 oC 6.4/69 µs A IP 70 oC 6.4/69 µs A IP 100 oC 6.4/69 µs A 2 125V/10A A V V IPP 1500 W 10/1000 µs A 3 4 5 300V/60A 750V/150A 1600V/320A A A A 5 6 7 9.2 10.3 12.0 163 146 125 543 486 416 445 398 341 380 340 291 23.1 22.9 22.6 58.2 57.9 57.6 148.2 147.9 147.6 318.2 317.9 317.6 8 9 10 13.6 15.4 17.0 110 97.4 88.2 366 324 294 300 266 241 256 227 206 22.8 21.9 21.6 57.2 56.9 56.6 147.2 146.9 146.6 317.3 316.9 316.6 12 15 18 19.9 24.4 29.2 75.3 61.5 51.4 251 205 171 206 168 140 176 144 120 21.0 20.1 19.2 56.0 55.1 54.2 146.0 145.1 144.2 316.0 20 28 30 32.4 45.4 48.4 46.3 33.0 31.0 154 110 103 126 90.2 84.5 108 77.0 72.1 18.5 15.9 15.3 53.5 50.9 50.3 143.5 140.9 33 40 48 53.3 64.5 77.4 28.1 23.2 19.4 93.6 77.2 64.6 76.7 63.3 52.0 65.5 54.0 45.2 14.3 12.1 9.5 49.3 47.1 44.5 50 60 70 80.0 96.8 113 18.2 15.5 13.3 60.6 51.6 44.2 49.6 42.3 36.2 42.4 36.1 30.9 9.0 5.6 2.4 44.0 40.6 37.4 80 90 100 126 146 162 11.4 10.3 9.3 38.0 34.7 31.0 31.2 28.1 25.4 26.6 24.0 21.7 0 34.8 30.8 27.6 Over limit 25 oC VC Over limit 25 oC VWM Microsemi TVs Part Numbers compliant to RTCA/DO-160E Standard Capacitance • Axial Lead 1.5KE6.8A-400A 1N5629A-1N5665A 1N5907, 1N5908 1N6036A-1N6072A 1N6138A-1N6073A 1N6027A-1N60303A 1N6469-1N6476 • Surface Mount SMCJ(G)5.0A-170A, CA Low capacitance • Axial Lead LC6.5-170A LCE6.5-170A • Surface Mount SMCJ(G)LCE6.5-170A * Surge currents are reduced by clamping voltage (see Eq.1). In the table above, the first three columns, VWM, VC, and IPP 1500 W are taken from the data sheet while the subsequent 0 0 three columns of 6.4/69 µs data were derived as illustrated earlier in this document and also MicroNoteTM 127. The 70 C and 100 C curves were added for simplifying selection since many TVS devices require derating for higher temperatures. © 2006 Microsemi Corporation Data Points for Curves in Graph 4 Conversion to 6.4/69 µs IP Values Peak Surge Currents for the Red Curves* IS Threat for Levels shown on graph Threat Levels 2-5 IP 25 oC 6.4/69 µs A IP 70 oC 6.4/69 µs A IP 100 oC 6.4/69 µs A 2 125V/10A A VC V V IPP 3000 W 10/1000 µs A 3 4 5 300V/60A 750V/150A 1600V/320A A A A 5 6 7 9.2 10.3 12.0 326 291 250 1085 969 832 889 794 682 759 678 582 23.2 22.9 22.6 58.1 57.9 57.6 148.2 147.9 147.6 318.1 317.9 317.6 8 9 10 13.6 15.4 17.0 221 195 176 736 649 586 603 532 480 515 454 410 22.8 21.9 21.6 57.2 56.9 56.6 147.2 146.9 146.6 317.3 317.0 316.6 12 15 18 19.9 24.4 29.2 151 123 103 502 409 343 412 335 281 351 286 240 21.0 20.1 19.2 56.0 55.1 54.2 146.0 145.1 144.1 316.0 315.1 314.1 20 28 30 32.4 45.4 48.4 92.6 66.0 62.0 308 220 206 252 180 169 215 154 144 18.5 15.9 15.3 53.5 50.3 50.3 143.5 140.9 140.3 313.5 310.9 310.3 33 40 48 53.3 64.5 77.4 56.2 46.4 38.8 187 154 129 153 126 105 130 107 90.3 14.3 12.1 9.5 49.3 47.1 44.5 139.3 137.1 138.5 50 60 70 82.4 96.8 113 36.4 31.0 26.6 120 103 88.6 98.4 84.5 72.6 84.0 72.1 62.0 8.5 5.6 2.4 43.5 40.6 37.4 134.2 80 90 100 126 146 162 22.8 20.6 18.6 75.9 68.6 61.9 62.2 56.2 50.7 53.1 48.0 43.3 0 34.8 30.8 27.6 Over limit 25 oC VWM Over limit 25 oC 3000 W TVS @10/1000 µs Waveform 4 RTCA/DO-160E using 3,000 W TVS Diodes Microsemi TVs Part Numbers compliant to RTCA/DO-160E Standard Capacitance • Surface Mount SMLJ(G)5.0A-170A, CA * Surge currents are reduced by clamping voltage (see Eq.1). In the table above, the first three columns, VWM, VC, and IPP 3000 W are taken from the data sheet while the subsequent 0 0 three columns of 6.4/69 µs data were derived as illustrated earlier in this document and also MicroNoteTM 127. The 70 C and 100 C curves were added for simplifying selection since many TVS devices require derating for higher temperatures. © 2006 Microsemi Corporation 17 Data Points for Curves in Graph 5 18 Conversion to 6.4/69 µs IP Values Peak Surge Currents for the Red Curves* IS Threat for Levels shown on graph Threat Levels 3-5 V IPP 5000 W 10/1000 µs A IP 25 oC 6.4/69 µs A IP 70 oC 6.4/69 µs A IP 100 oC 6.4/69 µs A 3 300V/60A A 4 750V/150A A 5 1600V/320A A 5 6 7 9.2 10.3 12.0 543 485 417 1808 1615 1389 1482 1316 1138 1266 1124 972 58.2 57.9 57.6 148.2 147.9 147.6 318.2 317.9 317.6 8 9 10 13.6 15.4 17.0 367 325 294 1222 1082 979 1002 889 803 855 757 685 57.2 56.9 56.6 147.2 146.9 146.6 317.3 317.0 316.6 12 15 18 19.9 24.4 29.2 251 206 172 835 686 572 684 562 469 584 480 400 56.0 55.1 54.2 146.0 145.1 144.2 316.0 315.1 314.0 20 28 30 32.4 45.4 48.4 154 110 103 512 366 342 420 300 280 358 256 239 53.5 50.9 50.3 143.5 140.9 140.3 313.5 310.9 310.3 36 40 50 58.1 64.5 80.0 86 78 60 286 260 200 234 213 164 200 182 140 48.3 47.1 44.0 138.4 137.1 134 308.3 307.1 304.0 60 70 80 96.8 113 126 52 44 40 173 146 133 142 119 109 121 102 93.1 40.6 37.4 34.8 131 127 124 90 100 110 146 162 177 113 31 28 34 103 93.2 92.7 84.5 76.4 79.1 72.1 65.2 30.8 27.6 24.6 121 118 115 Over limit 25 oC 5000 W TVS @10/1000 µs Waveform 4 RTCA/DO-160E using 5000 W TVS Diodes VWM VC V Microsemi TVs Part Numbers compliant to RTCA/DO-160E Standard Capacitance • Axial Lead 5KP5.0A - 110, CA • Surface Mount PLAD5KP5.0A - 110A, CA (In development) * Surge currents are reduced by clamping voltage (see Eq.1). In the table above, the first three columns, VWM, VC, and IPP 5000 W are taken from the data sheet while the subsequent 0 0 three columns of 6.4/69 µs data were derived as illustrated earlier in this document and also MicroNoteTM 127. The 70 C and 100 C curves were added for simplifying selection since many TVS devices require derating for higher temperatures. © 2006 Microsemi Corporation Data Points for Curves in Graph 6 15,000 W TVS @10/1000 µs Peak Surge Currents for the Red Curves* IS Threat for Levels shown on graph Threat Levels 4-5 IP 25 oC 6.4/69 µs A IP 70 oC 6.4/69 µs A IP 100 oC 6.4/69 µs A 4 750V/150A A 5 1600V/320A A IPP 15,000 W 10/1000 µs A 20 28 30 32.4 47.5 48.4 396 316 296 1319 1052 986 1082 863 807 923 736 690 143.0 140.3 140.0 313.0 310.5 310.0 36 40 50 59.7 64.5 80.0 251 228 180 836 759 599 685 622 491 585 531 419 138.0 137.0 134.0 308.0 307.0 304.0 60 70 80 97.3 113 126 154 132 117 513 439 390 421 360 321 359 307 273 131.0 127.0 125.0 301.0 297.0 294.0 90 100 150 146 162 243 103 93 62 343 310 206 281 254 169 240 217 144 120.0 118.0 101.0 291.0 288.0 271.0 200 280 322 452 47 33 156 110 128 90 109 77 86 60 250 VV VC Conversion to 6.4/69 µs IP Values Microsemi TVs Part Numbers compliant to RTCA/DO-160E Standard Capacitance • Axial Lead 15KP33A-280A, CA • Surface Mount PLAD15KP33A-280A, CA (In development) Over limit 25 oC VWM Waveform 4 RTCA/DO-160E using 15,000 W TVS Diodes * Surge currents are reduced by clamping voltage (see Eq.1). In the table above, the first three columns, VWM, VC, and IPP 15,000 W are taken from the data sheet while the subsequent 0 0 three columns of 6.4/69 µs data were derived as illustrated earlier in this document and also MicroNoteTM 127. The 70 C and 100 C curves were added for simplifying selection since many TVS devices require derating for higher temperatures. 19 © 2006 Microsemi Corporation Data Points for Curves in Graph 7 30,000 W TVS @10/1000 µs Waveform 4 RTCA/DO-160E using 30,000 W TVS Diodes Conversion to 6.4/69 µs IP Values Peak Surge Currents for the Red Curves* IS Threat for Levels shown on graph Threat Levels 4-5 V IPP 30,000 W 10/1000 µs A IP 25 oC 6.4/69 µs A IP 70 oC 6.4/69 µs A IP 100 oC 6.4/69 µs A 4 750V/150A A 5 1600V/320A A 33 36 40 58.6 61.8 68.6 548 502 456 1825 1672 1518 1496 1371 1245 1278 1170 1062 138 137 136 308 307 306 48 50 60 77.7 80.0 97.3 386 368 304 1285 1225 1012 1054 1004 829 899 857 708 135 134 131 304 302 300 70 80 90 114 126 146 264 232 206 879 772 686 721 633 562 615 540 480 127 124 121 297 295 290 100 150 200 162 243 322 186 124 94 619 413 313 507 339 257 433 289 219 118 101 86 287 271 255 250 275 300 403 443 483 74 68 62 246 226 206 201 185 169 172 158 144 66 61 53 239 231 223 400 644 40 133 109 93 21 191 VWM VC V Microsemi TVs Part Numbers compliant to RTCA/DO-160E Standard Capacitance • Axial Lead 30KP33A-400A, CA • Surface Mount PLAD30KP30A-400A, CA (In Develoment) * Surge currents are reduced by clamping voltage (see Eq.1). In the table above, the first three columns, VWM, VC, and IPP 30,000 W are taken from the data sheet while the subsequent 0 0 three columns of 6.4/69 µs data were derived as illustrated earlier in this document and also MicroNoteTM 127. The 70 C and 100 C curves were added for simplifying selection since many TVS devices require derating for higher temperatures. 20 © 2006 Microsemi Corporation Data Points for Curves in Graph 8 500 W TVS @10/1000 µs VC Conversion to 40/120 µs IP Values Peak Surge Currents for the Red Curves* IS Threat for Levels shown on graph Threat Levels 1-2 IP 25 oC 40/120 µs A IP 70 oC 40/120 µs A IP 100 oC 40/120 µs A 1 50V/50A A 2 125V/125A A V V IPP 500 W 10/1000 µs A 5 6 7 9.2 10.3 12.0 54.3 48.5 41.7 126 113 97.2 103 92.7 79.7 88.2 79.1 68.3 40.8 39.7 38.0 116 114 113 8 9 10 13.6 15.4 17.0 36.7 32.5 29.4 85.5 75.7 68.5 70.1 62.1 56.1 59.8 53.0 47.9 36.4 34.6 33.0 112 110 108 12 15 18 19.9 24.4 29.2 25.1 20.6 17.2 58.5 48.0 40.1 48.0 39.3 32.9 41.0 33.6 28.1 30.1 25.6 20.8 105 101 96.8 20 28 30 32.4 45.4 48.4 15.4 11.0 10.3 35.9 25.6 24.0 29.4 21.0 19.7 25.1 17.9 16.8 17.1 4.6 1.6 91.6 79.0 76.6 36 40 48 53.3 64.5 77.4 8.6 7.8 6.5 20.0 18.1 15.1 16.4 14.8 12.4 14.0 12.7 10.6 71.7 60.5 47.6 50 60 70 82.4 96.8 113 6.0 5.2 4.4 14.0 12.1 10.2 11.5 9.9 8.4 9.8 8.4 7.1 42.6 28.2 12.0 80 90 100 126 146 162 4.0 3.4 3.1 9.3 7.9 7.2 7.6 6.5 5.9 6.5 5.5 5.0 Devices > 78 VWM within limits Microsemi TVs Part Numbers compliant to RTCA/DO-160E Standard Capacitance • Axial Lead P5KE5.0A-170A, CA 1N6103A-6137A 1N6461-6468 • Surface Mount SMAJ5.0A-170A, CA Low capacitance Over limit 25 oC VWM Waveform 5A RTCA/DO-160E using 500 W TVS Diodes • Axial Lead SAC5.0-50 • Surface Mount HSMBJSAC5.0-50 * Surge currents are reduced by clamping voltage (see Eq.1). In the table above, the first three columns, VWM, VC, and IPP 500 W are taken from the data sheet while the subsequent 0 0 three columns of 40/120 µs data were derived as illustrated earlier in this document and also MicroNoteTM 127. The 70 C and 100 C curves were added for simplifying selection since many TVS devices require derating for higher temperatures. © 2006 Microsemi Corporation 21 Data Points for Curves in Graph 9 600 W TVS @10/1000 µs 22 Waveform 5A RTCA/DO-160E using 600 W TVS Diodes Conversion to 40/120 µs IP Values Peak Surge Currents for the Red Curves* IS Threat for Levels shown on graph Threat Levels 1-2 V IPP 600 W 10/1000 µs A IP 25 oC 40/120 µs A IP 70 oC 40/120 µs A IP 100 oC 40/120 µs A 1 50V/50A A 2 125V/125A A 5 6 7 9.2 10.3 12.0 62.2 58.3 50.0 151 136 116 124 112 95.1 106 95.2 81.2 40.8 39.7 38.0 116 114 113 8 9 10 13.6 15.4 17.0 44.1 39.0 35.3 103 90.8 82.2 84.5 74.4 67.4 72.1 63.6 57.5 36.4 34.6 33.0 111 109 108 12 15 18 19.9 24.4 29.2 30.2 24.0 20.5 70.4 55.9 47.8 57.7 45.8 39.2 49.3 39.1 33.4 30.1 25.6 20.8 105 101 95.8 20 28 30 32.4 45.4 48.4 18.5 13.2 12.4 43.1 30.7 28.9 35.3 25.2 23.7 30.2 21.5 20.2 17.1 4.6 1.6 92.6 79.6 76.6 36 40 48 58.1 64.5 77.4 10.3 9.3 7.7 24.0 21.7 17.9 19.7 17.8 14.7 16.8 15.2 12.5 66.9 60.5 47.6 50 60 70 82.4 96.8 113 7.1 6.2 5.3 16.5 14.4 12.3 13.5 11.8 10.1 11.6 10.1 8.6 42.6 28.2 12.0 80 90 100 126 146 162 4.7 4.1 3.7 10.9 9.6 8.6 8.9 7.9 7.0 7.6 6.7 6.0 Devices > 75 VWM within limits VC V Standard Capacitance • Axial Lead P6KE6.8A-200A, CA • Surface Mount SMBJ(G)5.0A-170A, CA Over limit 25 oC VWM Microsemi TVs Part Numbers compliant to RTCA/DO-160E * Surge currents are reduced by clamping voltage (see Eq.1). In the table above, the first three columns, VWM, VC, and IPP 600 W are taken from the data sheet while the subsequent 0 0 three columns of 40/120 µs data were derived as illustrated earlier in this document and also MicroNoteTM 127. The 70 C and 100 C curves were added for simplifying selection since many TVS devices require derating for higher temperatures. © 2006 Microsemi Corporation Data Points for Curves in Graph 10 1500 W TVS @10/1000 µs Waveform 5A RTCA/DO-160E using 1500 W TVS Diodes Conversion to 40/120 µs IP Values Peak Surge Currents for the Red Curves* IS Threat for Levels shown on graph Threat Levels 1-3 IP 25 oC 40/120 µs A IP 70 oC 40/120 µs A IP 100 oC 40/120 µs A 1 50V/50A A 2 125V/125A A 3 300/300 A 5 6 7 9.2 10.3 12.0 163 146 125 380 340 291 312 279 239 266 238 203 40.8 39.7 38.0 116 114 113 291 290 288 8 9 10 13.6 15.4 17.0 110 97.4 88.2 256 227 206 210 186 169 179 159 144 36.4 34.6 33.0 111 110 108 286 12 15 18 19.9 24.4 29.2 75.3 61.5 51.4 175 143 120 144 117 98.4 122 100 84.0 30.1 25.6 20.8 105 101 95.8 20 28 30 32.4 45.4 48.4 46.3 33.0 31.0 108 76.9 72.2 88.6 63.0 59.2 75.6 53.8 50.5 17.1 4.6 1.6 92.6 79.6 76.6 36 40 48 58.1 64.5 77.4 28.1 23.2 19.4 65.5 54.0 45.2 53.7 44.3 37.1 45.8 37.8 31.6 66.9 60.5 47.6 50 60 70 82.4 96.8 113 18.2 15.5 13.3 42.4 36.1 31.0 34.8 29.6 25.4 29.7 25.2 21.7 80 90 100 126 146 162 11.4 10.3 9.3 26.6 24.0 21.7 21.8 19.7 17.8 18.6 16.8 15.2 42.6 28.2 12.0 Devices >60 VWM within limits V Standard Capacitance • Axial Lead 1.5KE6.8A-400A 1N5629A-1N5665A 1N5907, 1N5908 1N6036A-1N6072A 1N6138A-1N6073A 1N6027A-1N60303A 1N6469-1N6476 • Surface Mount SMCJ(G)5.0A-170A, CA Low capacitance Over limit 25 oC VC Over limit 25 oC V IPP 1500 W 10/1000 µs A VWM Microsemi TVs Part Numbers compliant to RTCA/DO-160E • Axial Lead LC6.5-170A LCE6.5-170A • Surface Mount SMCJ(G)LCE6.5-170A * Surge currents are reduced by clamping voltage (see Eq.1). In the table above, the first three columns, VWM, VC, and IPP 1500 W are taken from the data sheet while the subsequent 0 0 three columns of 40/120 µs data were derived as illustrated earlier in this document and also MicroNoteTM 127. The 70 C and 100 C curves were added for simplifying selection since many TVS devices require derating for higher temperatures. © 2006 Microsemi Corporation 23 Data Points for Curves in Graph 11 3000 W TVS @10/1000 µs 24 Waveform 5A RTCA/DO-160E using 3000 W TVS Diodes Conversion to 40/120 µs IP Values Peak Surge Currents for the Red Curves* IS Threat for Levels shown on graph Threat Levels 1-3 IP 25 oC 40/120 µs A IP 70 oC 40/120 µs A IP 100 oC 40/120 µs A 1 50V/50A A 2 125V/125A A 3 300V/300A A 5 6 7 9.2 10.3 12.0 326 291 250 759 678 582 622 556 477 531 475 408 40.8 39.7 38.0 116 114 113 290.8 289.7 288 8 9 10 13.6 15.4 17.0 221 195 176 515 454 410 422 372 336 361 318 287 36.4 34.6 33.0 111 110 108 286.4 285 283 12 15 18 19.9 24.4 29.2 151 123 103 352 287 240 289 235 197 246 201 168 30.1 25.6 20.8 105 101 95.8 280 275 270 20 28 30 32.4 45.4 48.4 92.6 66.0 62.0 216 154 144 177 126 118 151 108 101 17.1 4.6 1.6 92.6 79.6 76.6 267 36 40 48 58.1 64.5 77.4 51.6 46.4 38.8 120 108 90.4 98.4 88.6 74.1 84.0 75.6 63.3 0 66.9 60.5 47.6 50 60 70 82.4 96.8 113 35.9 31.0 26.6 83.6 72.2 61.9 68.5 59.2 50.7 58.5 50.5 43.3 45.0 28.2 12.0 80 90 100 126 146 162 22.8 20.6 18.6 53.1 48.0 43.3 43.5 39.4 35.5 37.2 33.6 30.3 0 VC V Standard Capacitance • Surface Mount SMLJ(G)5.0A-170A, CA Over limit 25 oC V IPP 3000 W 10/1000 µs A VWM Microsemi TVs Part Numbers compliant to RTCA/DO-160E * Surge currents are reduced by clamping voltage (see Eq.1). In the table above, the first three columns, VWM, VC, and IPP 3000 W are taken from the data sheet while the subsequent 0 0 three columns of 40/120 µs data were derived as illustrated earlier in this document and also MicroNoteTM 127. The 70 C and 100 C curves were added for simplifying selection since many TVS devices require derating for higher temperatures. © 2006 Microsemi Corporation Data Points for Curves in Graph 12 5000 W TVS @10/1000 µs VWM VC Waveform 5A RTCA/DO-160E using 5000 W TVS Diodes Conversion to 40/120 µs IP Values Peak Surge Currents for the Red Curves* IS Threat for Levels shown on graph Threat Levels 2-4 IP 25 oC 40/120 µs A IP 70 oC 40/120 µs A IP 100 oC 40/120 µs A 2 125V/125A A 3 300V/300A A 4 750V/750A A V V IPP 5000 W 10/1000 µs A 5 6 7 9.2 10.3 12.0 543 485 417 1265 1130 972 1037 927 797 886 791 681 116 114 113 291 290 288 741 740 738 8 9 10 13.6 15.4 17.0 367 325 294 855 757 685 701 621 562 599 530 480 111 110 108 286 285 283 736 734 732 12 15 18 19.9 24.4 29.2 251 206 172 585 480 401 480 394 329 410 336 281 105 101 95.8 280 275 270 Over limit 25 oC 20 28 30 32.4 45.4 48.4 154 110 103 359 256 240 294 210 197 251 179 168 92.6 79.6 76.6 267 254 251 36 40 48 58.1 64.5 77.4 86 78.0 65.0 200 182 151 164 149 124 140 127 106 66.9 60.5 47.6 50 60 70 82.4 96.8 113 60.0 47.0 44.0 140 109 102 115 89.4 83.6 98.0 76.3 71.4 45.0 28.2 12.0 80 90 100 126 146 162 49.0 34.0 31.0 95.5 79.2 72.2 78.3 64.9 59.2 66.9 55.4 50.6 0 Microsemi TVs Part Numbers compliant to RTCA/DO-160E Standard Capacitance • Axial Lead 5KP5.0A - 110A, CA • Surface Mount PLAD5KP5.0A - 110A, CA (In development) Over limit 25 oC * Surge currents are reduced by clamping voltage (see Eq.1). In the table above, the first three columns, VWM, VC, and IPP 5000 W are taken from the data sheet while the subsequent 0 0 three columns of 40/120 µs data were derived as illustrated earlier in this document and also MicroNoteTM 127. The 70 C and 100 C curves were added for simplifying selection since many TVS devices require derating for higher temperatures. © 2006 Microsemi Corporation 25 Data Points for Curves in Graph 13 15,000 W TVS @10/1000 µs Waveform 5A RTCA/DO-160E using 15,000 W TVS Diodes Conversion to 40/120 µs IP Values Peak Surge Currents for the Red Curves* IS Threat for Levels shown on graph Threat Levels 2-4 V IPP 15,000 W 10/1000 µs A IP 25 oC 40/120 µs A IP 70 oC 40/120 µs A IP 100 oC 40/120 µs A 2 125V/125A A 3 300V/300A A 4 750V/750A A 20 30 40 34.3 50.7 65.8 396 296 228 923 690 531 757 565 436 646 483 372 92.6 76.9 60.5 267 251 236 50 60 70 81 97.3 114 178 154 132 413 359 308 339 294 252 289 251 215 45.0 28.2 12.0 220 203 187 717 701 686 Over limit 25 oC 80 90 100 126 146 162 119 103 93 277 240 217 227 197 178 194 168 152 0 174 154 138 150 200 280 243 322 452 62 47 33 144 109 76.9 118 89.8 63.0 101 76.7 53.8 VWM VC V Microsemi TVs Part Numbers compliant to RTCA/DO-160E Standard Capacitance • Axial Lead 15KP33A-280A, CA • Surface Mount PLAD15KP33A-280A, CA (In development) 57 0 * Surge currents are reduced by clamping voltage (see Eq.1). In the table above, the first three columns, VWM, VC, and IPP 15,000 W are taken from the data sheet while the subsequent 0 0 three columns of 40/120 µs data were derived as illustrated earlier in this document and also MicroNoteTM 127. The 70 C and 100 C curves were added for simplifying selection since many TVS devices require derating for higher temperatures. 26 © 2006 Microsemi Corporation 30,000 W TVS @10/1000 µs VWM VC Waveform 5A RTCA/DO-160E using 30,000 W TVS Diodes Conversion to 40/120 µs IP Values Peak Surge Currents for the Red Curves* IS Threat for Levels shown on graph Threat Levels 3 - 5 IP 25 oC 40/120 µs A IP 70 oC 40/120 µs A IP 100 oC 40/120 µs A 3 300V/300A A V V IPP 30,000 W 10/1000 µs A 4 5 750V/750A 1600V/1600A A A 33 40 50 58.6 68.6 89.6 548 456 354 1277 1062 826 1047 871 678 894 744 579 241 231 220 691 681 670 60 70 80 97.3 114 126 304 264 232 708 615 540 581 504 442 496 431 378 203 186 174 653 636 624 90 100 150 146 162 243 206 186 124 480 433 289 394 355 237 336 303 202 154 138 57 200 250 275 322 403 443 94 74 68 219 172 158 179 141 130 153 121 111 0 300 400 483 644 62 40 144 93.2 118 76.4 101 65.2 Over limit 25 oC Data Points for Curves in Graph 14 Microsemi TVs Part Numbers compliant to RTCA/DO-160E Standard Capacitance • Axial Lead 30KP33A-400A, CA • Surface Mount PLAD30KP30A-400A, CA (In Develoment) Over limit 25 oC * Surge currents are reduced by clamping voltage (see Eq.1). In the table above, the first three columns, VWM, VC, and IPP 30,000 W are taken from the data sheet while the subsequent 0 0 three columns of 40/120 µs data were derived as illustrated earlier in this document and also MicroNoteTM 127. The 70 C and 100 C curves were added for simplifying selection since many TVS devices require derating for higher temperatures. 27 © 2006 Microsemi Corporation Micronote 132 Aircraft Lightning Protection For additional technical information, please contact one of our technical personnel listed below: Mel Clark ([email protected]) at 480-941-6433 Kent Walters ([email protected]) at 480-941-6524 Ken Dierberger ([email protected]) at 480-941-6547 © 2006 Microsemi - Scottsdale Division 8700 East Thomas Road, Scottsdale, AZ 85252 Ph: (480) 941-6300 Fax: (480) 947-1503