AN 5950 Understanding i2 Phase Control Thyristor Datasheets Application Note AN5950-1 Sept 2009 LN26885 Authors: Dinesh Chamund, Colin Rout INTRODUCTION This note will guide you through the Dynex i2 Phase Control Thyristor data sheet format and explain its contents. For the purpose of discussion and illustration, Dynex datasheet for the DCR3030V42 has been chosen and its contents explained in sequence starting from the first page. The i2 Phase Control Thyristor datasheet includes tables and graphs of data regarding device ratings and characteristics. In order to use the datasheet properly it is important that the user has a good understanding of the information presented in the datasheet. Also when benchmarking with similar product from a different supplier, allowance should be made for any difference in the way the parameters are defined, specified and measured. Hopefully this will promote an efficient and reliable use of the device and also help the user to make a correct choice of device for the intended application. The datasheet is organised in the following sections: PART NUMBER FEATURES APPLICATIONS TABLE OF VOLTAGE RATINGS ORDERING INFORMATION KEY PARAMETERS/PACKAGE OUTLINE TABLES OF RATINGS o CURRENT RATINGS o SURGE RATINGS o THERMAL AND MECHANICAL RATINGS TABLES OF CHARACTERISTICS o DYNAMIC CHARACTERISTICS o GATE CHARACTERISTICS CURVES PACKAGE DETAILS PART NUMBER DCR3030V42 The part numbering scheme for the Dynex i2 Phase Control Thyristor is as follows: DCR = Dynex Control Rectifier 3030 = Headline average current rating (A) V = Package code 42 = Maximum repetitive voltage rating (V)/100 A Dynex datasheet is a controlled document with a specific document number, issue number, and date. This information appears below the device type in the header on the right hand side of the first page . Dynex reserves the right to change the data without notice and so the users are advised to refer to the latest version by visiting Dynex web site: http://www.dynexsemi.com KEY PARAMETERS/PACKAGE OUTLINE This is a summary of main parameters unique to the part number. The full description of these parameters is found with appropriate test conditions in the main body of the Page 1 of 23 AN 5950 datasheet. It is important that when comparing the key parameters with other similar product a full description of the parameters should be considered as manufacturers often specify different test conditions. TABLE OF VOLTAGE RATINGS This table provides the repetitive peak voltage ratings of the device given under specified conditions. Fig.1 gives the package outline and its code (V). Fig. 1 Package outline FEATURES The features section provides a list of specific key attributes of the device design and technologies. APPLICATIONS A few examples of possible application are indicated here. It should be noted that inclusion in this section does not imply that Dynex has fully tested the device under all application conditions. The suitability of a device for a given application rests solely with the user. Page 2 of 23 VDRM, VRRM are the peak repetitive voltages in the (direct) forward and reverse directions. The rating is for 50Hz half sine waves of voltage and assumes that the device is maintained at the maximum rated junction temperature of 125°C by suitable heatsinking, if required. VDRM & VRRM are the voltages that the device reaches when the leakage currents IRDM &IRRM reach their test limits as given in the datasheet, or the maximum rated voltage whichever is reached first. The device may well be capable of reaching a higher voltage but excessively large leakage currents will make temperature control difficult and failure through thermal run-away may occur for all but the shortest pulses. As the temperature of the device is reduced, the natural avalanche voltage of the silicon wafer reduces. In some cases, at very low temperatures and at the lower limit of the tolerance on the silicon specification the full voltage rating of the device may not be achieved. Where this is the case, this is annotated on the datasheet. Because of transient voltage spikes generated by switching devices on the supply, thyristors are usually operated at nominal peak line voltages of VDRM divided by a safety factor of 1.5 to 2.5, depending on the transient voltages. A low safety factor is used when the AN 5950 transients are largely determined, usually in the case of self commutated converters with large energy storage elements. If the transients on the mains supply are unknown then a safety factor of 2 to 2.5 should be used. VDSM & VRSM are the peak non-repetitive voltages in the forward and reverse directions and are the voltages that can be applied occasionally and non-repetitively and should not be exceeded under any circumstances. ORDERING INFORMATION This specifies the correct part number for ordering the device, for example: DCR3030V42 (4200V part) Other voltage grades can be selected as given in the table of voltage ratings. TABLES OF RATINGS CURRENT RATINGS IT(AV) – Mean on-state current IT(AV) is the average value of a half sine wave current flowing in a thyristor such that the peak junction temperature is limited to the rated temperature of 125°C with the case temperature specified. The average current rating of the device is related to the thermal rating of the device package and thus by equating the power generated within the device to the power dissipated in the package, the average current rating can be calculated. A more thorough analysis of the current rating derivation is given in the Appendix 1. There is no industry standard definition for IT(AV), manufacturers quote IT(AV) with case temperatures of 60°C, 65°C, 70°C and 85°C . Others quote with respect to a heatsink temperature of 55°C (see Fig.17 Appendix 1). Thus direct comparison of headline ratings is very difficult. Even if all manufacturers quoted at the same case temperature this would still not resolve the problem because, in reality, what is really important in the application is how the device performs on the heatsink. Some manufacturers quote low values of thermal resistance junction to case with correspondingly higher values for thermal resistance case to heatsink but with similar thermals junction to heatsink. Therefore their headline IT(AV) at a given case temperature may be quoted as being higher than competitors’ devices but when rated on the same heatsink there is no appreciable difference in performance. Dynex quotes a headline IT(AV) at 60°C case temperature but gives full de-rating curves for both half sine and rectangular waves to enable the user to make direct and meaningful comparisons. IT(RMS) – RMS current rating For today’s capsule devices IT(RMS) = π. IT(AV) /2. Historically IT(RMS) could have been different because, for single sided devices with a flexible lead for the load current terminal, the current carrying capability of the connections could be less than the capability of the silicon. For capsule (puk) devices, the cross sectional area of the electrodes is the same as the silicon so no allowance needs to be made. The limitation is now the equipment busbars. IT – Continuous (direct) on-state current IT is the maximum continuous current that the thyristor can conduct while maintaining the junction temperature to its maximum rated value of 125°C. Note that, like IT(AV) , this figure depends upon the stated reference case temperature. Page 3 of 23 AN 5950 SURGE RATING ITSM – Surge (non-repetitive) on-state current ITSM is the maximum 10ms half sine wave of current, following maximum load current ( i.e. the thyristor junction temperature is at Tj max) that the thyristor can conduct without the device experiencing thermal run-away and the silicon melting. ITSM is determined by the manufacturer by viewing the forward voltage characteristic of the thyristor at high currents and observing the onset of thermal run-away. Exceeding this limit will damage the device and the rating should only be used for the selection of fuses. Because the device is so hot following the surge current pulse it loses its ability to block voltage, this rating is for zero reverse re-applied voltage. Also the temperature excursion is so high that the device will fail due to temperature cycling wear out if this level of current is repeated several times in the life of the device. In practice, Dynex derates the surge current limit of its i2 thyristors by 10% which means that Page 4 of 23 the device can survive about 100 occurrences of the stated current in its life. I2t – for fusing I2t for fusing is ∫i dt and is calculated for a 2 half sine wave as I2TSM.base width/2 As well as the single 10 ms half sine wave rating, Dynex gives a graph showing the ratings for shorter and longer pulses of current with the corresponding I2t values; figure 11 of the datasheet. These are derived by calculating the current that gives the same peak temperature as the 10ms half sine wave derived from the physical rating of the device. Again 100 occurrences in the life of the device are permissible. AN 5950 THERMAL AND MECHANICAL RATINGS Rth(j-c) – Thermal resistance – junction to case The thermal resistance enables the calculation of the temperature rise of the silicon in the device above the external case temperature. It has the dimensions of °C/W or K/W. In other words, if the device is generating DC power losses P, then the temperature rise of the junction above the case temperature is P x R th(j-c). Values of the thermal resistance are given for double side cooling and cooling via either the anode or cathode electrode. Rth(c-h) – Thermal resistance – case to heatsink Of course the reference point for temperature rise for the user is the ultimate cooling medium air, water, oil etc. The total thermal resistance will include the thermal resistance of the heat sink (fin) to ambient, which is the user’s design choice and the contact thermal resistance between the device contact surface and the heat sink (Fig. 17 Appendix 1). This resistance depends upon the quality of the interface and the value quoted is with the inclusion of a good quality thermally and electrically conductive compound and with the joint clamped to the median recommended force. Tvj – Virtual junction temperature The device junction temperature cannot be directly measured but is usually calculated from a measured reference temperature e.g. case or heat sink using the product of thermal resistance value and the power dissipation. Hence it is referred to as the virtual junction temperature. The maximum value of Tvj is limited by the blocking capability of the device. This is set at 125°C. If this limit is exceeded then the subsequent reliability of the device operation cannot be guaranteed. Tstg – Storage temperature range During the storage of the device there are no application stresses applied (blocking stress, power losses etc) and hence the storage temperature range is determined purely by the withstand capability of the materials used Page 5 of 23 AN 5950 in the construction of the device. The storage temperature range is conservatively set at 55°C to 125°C. Fm – Clamping force Correct clamping of the device is necessary to assure the electrical and thermal contact to the active part of the device. The recommended maximum and minimum force is stated for each device type (see Appendix 3 and Application note AN4839). DYNAMIC CHARACTERISTICS IRRM/IDRM – Peak reverse and off-state current IRRM and IDRM are the maximum blocking currents when VRRM and VDRM are applied to the device respectively. These currents are temperature dependant and specified at Tcase = 125°C and tp= 10ms. Note that for high voltage devices the blocking current can contribute substantially to the power losses. dV/dt – Maximum Linear rate of rise of offstate voltage This is the maximum value for the linear rate of rise of forward voltage (from 0V to 67%VDRM) that can be applied without initiating turn-on in the thyristor with the gate open circuit. It is not advisable to exceed this value as it will cause uncontrolled turn-on in the device and may cause damage. It is usual practice to protect the device against excessive values of dV/dt by use of an additional snubber circuit (RC or RCD snubber circuit). The dV/dt capability of a thyristor reduces with increasing temperature. This is because triggering of the thyristor is initiated by the sum of the junction leakage current, the Cdv/dt displacement current and the gate current. dV/dt is specified at Tcase = 125°C which should be the worst case. Page 6 of 23 dI/dt – Rate of rise of on-state current This is the maximum rate of rise of on-state current (load current) for which two values are specified; repetitive @50Hz and nonrepetitive. These values are specified under the conditions of forward blocking voltage of 67%VDRM, peak forward current of twice the rated average current (2xIT(AV)), Tj = 125°C and the gate conditions for each device type (gate source voltage, gate resistance and the gate current rise time). When a thyristor is triggered on the initial conduction area is small and hence the current carrying capacity is limited. If the dI/dt rating is exceeded then damage to the thyristor may occur. It is advisable to control the dI/dt of the load current by use of turn-on snubber circuit (usually a clamped reactor). Note that the dI/dt snubber discharge current should be included in dI/dt considerations. VT(TO) – Threshold voltage For a simple calculation of conduction losses of a thyristor, the on state IV characteristic is approximated to a straight line and an intercept on the voltage - axis. The intercept is called the threshold voltage. Two values of VT(TO) are given on the datasheets to give more accurate approximations by splitting the IV curve into a low level current range and a high level current range. rT – On-state slope resistance The straight line in the above approximation is also defined by a slope (dIT/dVT) = 1/rT where rT is called the slope resistance (dVT/dIT). Once again rT is specified for low and high level current range respectively. A full explanation of how VT(TO) and rT are derived is given in the Appendix 2. AN 5950 tgd – Delay time This is the gate controlled delay time defined as the time interval during turn-on between 10% of the peak gate current IGT and 90% of the anode voltage VD (see Fig.22 in Appendix 4). The value is specified under the conditions of VD = 67%VDRM, Tj = 125°C, and gate conditions for the given thyristor (gate source = 30V, 10Ω and tr = 0.5µs). tq – Turn-off time The turn-off time tq is defined as the time interval between the anode current reaching zero value after the conduction period and when the thyristor can withstand reapplied positive anode voltage (see Fig. 23 Appendix 5). Assuming the dI/dt is slow then tq is a function of Tvj, dI/dt, and dV/dt (see Figures 26, 27 and 28 in Appendix 6). tq is specified under the conditions of Tj = 125°C, VR = 200V, dI/dt = 1A/µs, and dVDR/dt = 20V/µs linear. QS – Stored charge This is defined as the time integral of the reverse recovery current which flows when a thyristor is reverse biased after forward conduction (see Fig. 23 Appendix 5). The value of QS is specified at Tj=125°C, the falling rate of current (- dI/dt), reverse peak voltage VRpk, and the reverse blocking voltage VRM. The measurement is done with a suitable RC snubber circuit to limit the peak voltage to the specified limit. For practical reason the integral is taken over the first 150µs of recovery. Note that QS has the same meaning as Qrr (reverse recovery charge) used elsewhere. Qs is a function of dI/dt (Fig.12) and Tvj (Fig. 24 in Appendix 6) assuming dI/dt is slow. IL – Latching current The latching current is the minimum anode current required to maintain the thyristor in forward conduction state after turn-on has been initiated and the gate signal is then removed. Therefore the gate trigger current should be maintained or repeated until the anode current reaches this value under all conditions. IH – Holding current The holding current is the minimum anode current required to sustain the thyristor in conduction after latching. The thyristor will turn-off suddenly if the current through the thyristor drops below the holding current. For this reason care should be taken to eliminate oscillations at low value of anode current. GATE TRIGGER CHARACTERISTICS AND RATINGS VGT – Gate trigger voltage This defines the minimum gate voltage required to trigger the thyristor. The VGT is specified at VDRM = 5V and Tcase = 25°C when the thyristor is most immune to triggering. VGD – Gate non-trigger voltage The gate non-trigger voltage is defined as the maximum gate voltage which will not trigger the thyristor. It is specified at VDRM and Tcase = 125°C when the thyristor is most sensitive to triggering. IGT – Gate trigger current This defines the minimum gate current required to trigger the thyristor. IGT is a function of anode to cathode voltage and junction temperature. In the datasheet IGT is specified at VDRM = 5V and Tcase = 25°C. IGD – Gate non-trigger current The gate non-trigger current is the maximum gate current which will not trigger the Page 7 of 23 AN 5950 thyristor and is specified at VDRM and Tcase = 125°C. Note that both VGD and IGD ratings are important when operating a thyristor in a Page 8 of 23 “noisy” environment where it is possible to trigger the thyristor spuriously. Any uncontrolled triggering of the thyristor can lead to malfunction of the circuit operation and possible damage to the device. AN 5950 CURVES Maximum and characteristics: minimum on-state On-state power dissipation 7000 min 125°C max 125°C 25°C max 25°C 6000 Instantaneous on-state current IT - (A) note that in contrast to the linear model using VTO and rT this model gives an accurate estimation of conduction losses over the entire quoted current range. Fig.3 and Fig.6 show maximum on-state power dissipation as a function of mean onstate current IT(AV) for sinusoidal and rectangular waves respectively. These are based on the maximum on-state characteristics at 125°C in Fig.2. A family of curves is given for conduction angles ranging from 30° to 180° and DC. The power loss curves do not include any switching losses (turn-on and turn-off losses). 5000 4000 3000 2000 1000 0 0.0 0.5 1.0 1.5 2.0 2.5 Instantaneous on-state voltage VT - (V) Fig.2 Maximum & minimum on-state characteristics Fig. 2 shows the graph of maximum and minimum on-state characteristics of the thyristor when it is in full conduction. The instantaneous on-state currents and voltages are plotted against each other at temperature of 25°C and 125°C. These characteristics are used for calculation of on-state power losses. To facilitate the use of a computer for these calculations, an analytical model equation is also given for the voltage drop as a function of current for a specified temperature. The model is valid for a given range of thyristor current and Tj = 125°C (isothermal operation). The voltage drop model used here is: = + × ln + × + × √ where A, B, C and D are the constants of the curve fit of the equation to the measured values. Note that in the model VTM is a function of IT alone because isothermal operation (no self heating due to device loss) is assumed for the given current range. Also Maximum permissible case temperature Fig. 4 and Fig. 7 depict maximum permissible case temperature for double side cooled arrangement as a function of average current for sine and rectangular waves respectively and for conduction angles ranging from 30° to 180° and DC. These curves have been derived for the maximum junction temperature of 125°C using the junction to case thermal resistances for the appropriate waveforms (see Table 9). Maximum permissible heatsink temperature Fig. 5 and Fig. 8 show the maximum permissible heatsink temperature for double side cooling, for sine and rectangular waves with conduction angles ranging from 30° to 180° and DC. These curves are calculated for the maximum junction temperature of 125°C and using the junction to heatsink thermal resistances for the given waveforms. Thus from the curves of maximum power dissipation and maximum permissible case temperature, it is possible to calculate the required heatsink thermal resistance for a given ambient temperature. Page 9 of 23 AN 5950 Maximum (limit) transient thermal impedance – junction to case (°C/kW) Fig. 9 gives the maximum transient thermal impedance curve, junction to case, for double side, anode side and cathode side cooling arrangements. Note that the unit is in °C/kW. The transient thermal impedance curve (Zth(jc)) gives the temperature response to a unit power step (1 kW). If the time interval is sufficiently long then the curve reaches the steady state DC value given in the table of Thermal and Mechanical Ratings. The Zth(j-c) curve is obtained by thermal modelling of the device using finite element (FE) method and is verified by measurements. An analytical equation of the curve is also given represented by the sum of four exponential terms: =4 ℎ − () = 1 − − =1 The curve fit parameters Ri and τi are given in the table of Fig. 9. Zth(j-c)(t) is used to calculate the device junction temperature for time dependant power dissipation. The two simplest and most common waveforms are the half sine and rectangular wave. With these repetitive wave shapes the peak junction temperature reached is slightly above that calculated using the average power dissipation and increases with decreasing conduction angle. To allow for this, incremental values ΔZth dependent upon wave shape are given in a table within Fig. 9. These values should be added to the values of appropriate Z th(j-c) (t) curve. Please note that ΔZth values are given in °C/W. Multi-cycle surge current Fig. 10 shows the surge current, ITSM, as a function of the number of 10ms half sine wave pulses (50Hz) at Tcase = 125°C and with Page 10 of 23 no reverse voltage applied (VR = 0 V). This curve is derived by calculating the value of the repetitive 50Hz current pulses that gives the same peak temperature as the rated single cycle surge current. Single-cycle surge current Fig. 11 shows the single-cycle, half-sine wave surge current capability, ITSM, for varying pulse width. Also on the same graph the corresponding I2t values are given. These variations are derived by calculating the current that gives the same peak junction temperature as the 10ms half-sine wave derived from the physical rating of the device. The test conditions are; Tcase = 125°C and VR = 0 V. Note that the device rating has been derated by 10% so that about 100 pulses can be tolerated over the life of the device. Stored Charge Fig. 12 gives the variation of stored charge (same as recovered charge) as a function of the rate of decay of on-state current (dI/dt). The measurement conditions are Tj = 125°C, VR(peak) = ~ 60% VDRM and VR = ~ 40% VDRM with appropriate snubber to control the reverse voltage. The maximum and the minimum curves with model equations are given. Reverse Recovery Current In Fig. 13 the reverse recovery current associated with the stored charge of Fig. 12 is given. IRR is also a function of junction temperature (see Fig. 26 in Appendix 6). Gate Characteristics Fig. 14 and Fig. 15 depict the gate characteristics. These are the graphs of gate voltage VGT v the gate current IGT with upper and lower limit curves. In Fig. 14 the regions of uncertain triggering for -40°C, 25°C and 125°C are shown at the AN 5950 left of the area defined by the upper and lower gate characteristic curves. Any areas on the right of the dividing lines are the preferred area of operation for each respective temperature. The upper limit curve gives the maximum values of VGT and IGT as appear in the table of Gate Characteristics and Ratings (e.g. VGT = 1.5V and IGT = 0.25A at Tj = 25°C for DCR3030V42). The embedded table in the Fig.14 gives the maximum permitted peak gate power dissipation PGM (Watts) for various pulse widths and repetition rates. For dynamic triggering, much higher peak gate current is recommended and Fig. 15 gives extended gate characteristics to include higher current and voltage range. Also on the graph are lines of constant peak power. These lines are the power limits corresponding to the values in the table embedded in the Fig. 14. For further details on thyristor gate triggering and characteristics please refer to Application Note AN4840. PACKAGE DETAILS The outline drawing of the package is given in the Fig. 16. Note that the same package type is used for devices with different voltage ratings. The particular device is highlighted in the table provided, which gives the maximum and minimum thickness appropriate to the device type. Page 11 of 23 AN 5950 130 16 180 120 90 60 30 Mean power dissipation - (kW) 12 110 Maximum case temperature, T case ( o C ) 14 180 120 90 60 30 120 10 8 6 4 2 100 90 80 70 60 50 40 30 20 10 0 0 0 1000 2000 3000 4000 5000 0 Mean on-state current, IT(AV) - (A) 1000 2000 3000 4000 5000 Mean on-state current, IT(AV) - (A) Fig.3 On-state power dissipation – sine wave Fig.4 Maximum permissible case temperature, double side cooled – sine wave 12 180 120 90 60 30 100 10 Mean power dissipation - (kW) Maximum heatsink temperature, T Heatsink - ( ° C) 125 75 50 25 8 6 d.c. 180 120 90 60 30 4 2 0 0 0 1000 2000 3000 4000 Mean on-state current, IT(AV) - (A) Fig.5 Maximum permissible heatsink temperature, double side cooled – sine wave Page 12 of 23 0 1000 2000 3000 4000 5000 6000 Mean on-state current, IT(AV) - (A) Fig.6 On-state power dissipation – rectangular wave AN 5950 125 d.c. 180 120 90 60 30 120 110 100 Maximum heatsink temperature Theatsink -( o C) Maximum permissible case temperature , Tcase -(° C) 130 90 80 70 60 50 40 30 20 100 75 50 25 10 0 0 0 2000 4000 6000 Mean on-state current, IT(AV) - (A) 0 8000 1000 2000 3000 4000 5000 6000 Mean on-state current, IT(AV ) - (A) Fig.7 Maximum permissible case temperature, Fig.8 Maximum permissible heatsink temperature, double side cooled – rectangular wave double side cooled – rectangular wave Double side cooled 20 18 16 Anode side cooled Ri (°C/kW) Ti (s) Cathode side cooled Ri (°C/kW) Cathode Sided Cooling Ti (s) 14 1 0.9206 2 1.8299 3 3.4022 4 1.3044 0.00768 0.05795 0.40786 1.2085 0.9032 1.6719 3.0101 7.4269 0.00759 0.05365 0.31445 5.624 0.9478 2.0661 1.6884 13.0847 0.00784 0.06455 0.38944 4.1447 i 4 Z th [ Ri (1 exp(T / Ti )] 12 i 1 DRth(j-c) Conduction 10 Tables show the increments of thermal resistance Rth(j-c) when the device operates at conduction angles other than d.c. 8 6 4 2 0 0.001 Ri (°C/kW) Ti (s) Double Side Cooling Anode Side Cooling Thermal Impedance ( °C/kW) d.c. 180 120 90 60 30 0.01 0.1 1 10 Double side cooling DZth (z)°C/W q° sine. rect. 180 1.34 0.88 120 1.57 1.30 90 1.83 1.54 60 2.08 1.81 30 2.27 2.11 15 2.36 2.28 Anode Side Cooling DZth (z)°C/w q° sine. rect. 180 1.34 0.88 120 1.57 1.30 90 1.84 1.54 60 2.08 1.81 30 2.28 2.11 15 2.37 2.28 Cathode Sided Cooling DZth (z)°C/W q° sine. rect. 180 1.33 0.88 120 1.57 1.29 90 1.83 1.53 60 2.07 1.80 30 2.26 2.10 15 2.35 2.26 Time ( s ) Fig.9 Maximum (limit) transient thermal impedance – junction to case (°C/kW) Page 13 of 23 AN 5950 100 25 Conditions: Tcase= 125 C VR = 0 half-sine wave 90 Conditions: Tcase = 125 C VR =0 Pulse width = 10ms Surge current, ITSM- (kA) Surge current, ITSM - (kA) 80 20 70 I2t ITSM 60 15 50 40 10 I2t (MA2s) 100 30 20 5 10 0 10 1 10 Number of cycles 0 1 100 Fig.10 Multi-cycle surge current 10 Pulse width, tP - (ms) 100 Fig.11 Single-cycle surge current 600 18000 QSmax = 3397.4*(di/dt) 0.5061 16000 IRRmax = 48.236*(di/dt) 0.7553 500 Reverse recovery current, IRR - (A) 14000 Stored Charge, Q S - (uC) 12000 10000 8000 QSmin = 1357.3*(di/dt) 0.6271 6000 Conditions: Tj = 125oC VRpeak ~ 2500V VRM ~ 1700V snubber as appropriate to control reverse voltages. 4000 2000 10 20 300 IRRmin = 29.853*(di/dt) 0.8222 200 Conditions: Tj=125oC VRpeak ~ 2500V VRM ~ 1700V snubber as approriate to control reverse voltages 100 0 0 400 30 Rate of decay of on -state current, di/dt - (A/us) 0 0 10 20 Rate of decay of on-state current, di/dt - (A/us) Fig. 12 Stored Charge Page 14 of 23 Fig. 13 Reverse Recovery Current 30 AN 5950 10 9 8 Gate trigger voltage, VGT - (V) 7 Upper Limit 6 5 Preferred gate drive area 4 3 2 Tj = -40oC Tj = 25oC 1 Lower Limit Tj = 125o C 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Gate trigger current IGT, - (A) Fig14 Gate Characteristics 30 Lower Limit Upper Limit 5W 25 10W 20W 50W Gate trigger voltage, VGT - (V) 20 100W 150W -40C 15 10 5 0 0 1 2 3 4 5 6 7 8 9 Gate trigger current, IGT - (A) Fig. 15 Gate characteristics Page 15 of 23 10 AN 5950 PACKAGE DETAILS For further package information, please contact Customer Services. All dimensions in mm, unless stated otherwise. DO NOT SCALE. 3rd ANGLE PROJECTION DO NOT SCALE IF IN DOUBT ASK HOLE Ø3.60 X 2.00 DEEP (IN BOTH ELECTRODES) 20° OFFSET (NOM.) TO GATE TUBE Ø110.0 MAX. Ø73.0 NOM. Ø1.5 CATHODE Device DCR1474SV18 DCR1475SV28 DCR1476SV42 DCR1478SV48 DCR1574SV28 DCR1575SV42 DCR1576SV52 DCR4060V22 DCR3780V28 DCR3030V42 DCR2720V52 DCR2290V65 DCR1910V85 GATE ANODE Ø73.0 NOM. FOR PACKAGE HEIGHT SEE TABLE NOMINAL WEIGHT 1160g Lead length: 420mm Lead terminal connector: M4 ring Package outline type code: V Fig.16Package outline Page 16 of 23 Maximum Minimum Thickness Thickness (mm) (mm) 27.265 26.515 27.34 26.59 27.57 26.82 27.69 26.94 27.34 26.59 27.57 26.82 27.69 26.94 27.265 26.515 27.34 26.59 27.57 26.82 27.69 26.94 27.95 27.2 28.31 27.56 AN 5950 APPENDIX 1: () = The Derivation of Average Current v Case Temperature Curves using the linear approximation to the Forward Volt Drop curve. The Forward voltage drop curve of a thyristor can be approximated by the simple equation = () + × (1) −( ) + ( ) 2 −4 2 . .( − ) ℎ ( −) 2 2 . Note that this is the average current rating ignoring any reverse recovery losses or turnon losses that might need to be considered at higher frequencies or high di/dt at turn-on or turn-off. Also average current rating is referenced to the case temperature. Sometime the heatsink temperature (Fig. 17) is used for the reference temperature and in this case Rth(j-hs) is used in the calculations. where VT(TO) is the threshold voltage and rT is the slope resistance (see Appendix 2). 2 = () × () + × (2) 2 = () × () + 2 × () × (3) where k is the form factor of the waveform, IT(AV) is the average current and IRMS is the RMS current. The rise in junction temperature Tj above the case temperature Tcase is given by − = × ℎ( −) Junction Temperature (Tj) Heat The Power dissipated in the thyristor is given by : (7) Rthj-c) Case Temperature (Tc) Rth(j-hs) Rth(c-hs) Heatsink Temperature (Ths) Rth(hs-a) Ambient Temperature Ta (4) Fig.17 Thermal Circuit where Rth(j-c) is the thermal resistance from junction to case corresponding to the form factor k. Re-arranging this give = − (5) ℎ ( −) Substituting this in equation (3) and rearranging 2 ( 2 × ) × () + () × () − − ℎ ( −) =0 (6) Therefore, solving the quadratic equation (6) for IT(AV) we have Page 17 of 23 AN 5950 APPENDIX 2: Linear model characteristics: of Thyristor on-state IT ΔIT rT = ΔVT/ΔIT ΔVT IT(AV) VT 3. A variation of Fig. 19 which uses two straight lines instead of one to approximate to the true curve. In this version the lines pass through 1/6IT(AV) and IT(AV) and also IT(AV)and 20 x IT(AV). 4. As Fig 20. A tangential point constructed such that the value of IT(AV) calculated from IT(AV) = (-VT(TO) (VT(TO)2 + 4*k2*rT*P))/2*k2*rT is the same as that calculated by more exacting methods. This method is a variation of method 1). It has been used to retrospectively calculate meaningful values of VT0 and rT where more accurate current rating data already exists. IT VT(TO) ΔIT Fig.18 VT(TO) and rT @ tangent to IT(AV) ΔVT The linear approximation of the on-state characteristics of a thyristor is modelled by a straight line (piece-wise linear model) defined by an intercept on the x-axis VT(TO) (called the threshold voltage) and an inverse slope of the line rT (called the slope resistance) as shown in the Fig. 18. The construction of the straight line leads to different definitions. Here are the four variations: 1. As illustrated in Fig. 18 where the line is tangent to the IV curve at the average current. 2. As shown in Fig. 19 where a chord is drawn through IT(AV) and 3xIT(AV). The definition is commonly used for thyristors. For rectifier diodes a chord through 3IT(AV) and 5xIT(AV) sometimes gives a better result. Page 18 of 23 rT = ΔVT/ΔIT 3xIT(AV ) IT(AV) VT VT(TO) Fig. 19 VT(TO) and rT represented by a chord Dynex uses a variant of (3) with two straight lines; the first is a best fit straight line to the actual high current part of the forward voltage drop curve. A second line is then calculated for the best fit to the remaining low current part of the curve. AN 5950 IT APPENDIX 3: ΔIT ΔVT Clamping force requirements: rT = ΔVT/ΔIT IT(AV) VT VT(TO) Fig. 20 Variation of tangent method Fig. 21 shows the dependence of the thermal resistance Rth(j-c) as a function of clamping force for a pressure contact thyristor. The minimum and the maximum values are chosen to be on the relatively flat portion of the curve. It is recommended to clamp the device using the value of the force between the minimum and maximum values quoted on the datasheets. Low value of clamping force results in increase in the thermal resistance and hence decreases in the device current carrying capability. Too high clamping force may reduce the device of thermal cycling capability and hence the product life. Limitations of VT(TO) and rT model curve, ie where the straight line meets the true curve. It can be seen that depending on where a point is taken on the curve the answers will be optimistic or pessimistic. Definitions 1, 2 and 4 give adequate accuracy up to 3 x IT(AV). The Dynex method gives reasonable accuracy at low currents and very good at the high current part of the curve and lesser accuracy in the intermediate region. For improved accuracy a mathematical model is needed which approximates better to the true curve. This is the four coefficient curve for the equation given in the datasheet. Rth(j-c) Using any one of the first four models gives the correct value of the conduction losses at one or at most two points on the VTM vs IT Fmin Fmax Clamping force Fm Fig. 21 Dependence of Rth(j-c) on clamping force Fm Please also refer to Application Note AN4839 for further details on clamping of power semiconductor devices. Page 19 of 23 AN 5950 APPENDIX 4: APPENDIX 5: Thyristor turn-on Characteristics Thyristor turn-off characteristics IT dIT/dt VD 90% IT(t) VD(t) t tgd IG dIG/dt IG(t) 90% IGM 10% t tr Fig. 22 Thyrisror turn-on waveforms Fig. 23 Thyristor turn-off waveforms The turn-on process in a thyristor from its blocking state begins with the application of a gate signal. The thyristor current cannot flow instantaneously. A physical process called conductivity modulation takes place before the current is established in the thyristor. The time taken to undergo this process is called the turn-on delay time (td). This delay time is a function of gate signal (gate current amplitude IGM, rise time of the gate current pulse tr and the pulse-width of the gate current), the junction temperature Tj and offstate voltage Vd. For measurement purpose it is defined as the time interval between the gate current reaching 10% of its peak value and when the anode voltage drops to 90% of the applied forward blocking voltage VD (see Fig. 22). On the datasheets it is called the gate controlled delay time tgd. Fig. 23 shows the schematic presentation of the turn-off waveforms for a thyristor and defines the dynamic parameters tq and QS specified in the datasheets. Page 20 of 23 The turn-off process in a thyristor begins when the anode current falls below the holding current. However the thyristor cannot revert to the blocking state instantaneously because of the charge storage phenomenon. The stored charge in the thyristor has to be removed by carrier recombination and the reverse recovery process before a thyristor can resume the blocking state. The time taken to revert back to the blocking state is called the turn-off time (tq). For measurement purpose it is defined as shown in Fig. 23. For a given switching application the off time should be longer than the tq for a proper circuit function. Recovery charge QS AN 5950 contributes towards the switching loss per pulse (see Application Note AN5951). 26 to 28 show the typical, normalised dependence of tq on these conditions. APPENDIX 6: 1.2 Dependence of Tq, Qs, and Irr on temperature and commutation conditions For most Phase Control Thyristor applications, the turn-off di/dt can be classed as “slow”, therefore the Stored Charge is independent of the initial current. Curves of the variation of Stored Charge and Reverse Recovery Current on di/dt are given in the data sheet at a Tvj of 125°C. Figure 24 shows the typical normalised dependence of Stored Charge on Tvj, while figure 25 is the corresponding curve for the Reverse Recovery Current. Similarly (2) it can be shown that the time needed for the thyristor to regain the ability to block forward current ( tq) is dependent upon temperature, di/dt and dV/dt. . Figures Normalised Stored Charge Value During conduction, current flow is achieved through the injection of excess carriers (charge) from the electrodes. As the forward current decreases towards extinction, a number of the excess carriers recombine at a rate governed by the carrier lifetime. It can be shown (1) that for fast rates of fall of the forward current (di/dt) the Stored Charge is dependent on the value of the forward current and independent of the di/dt and conversely, at slow values of di/dt the Stored Charge is independent of the forward current and dependent on the di/dt. The terms “fast” and “slow” are relative and are determined by the length of the current fall time relative to the carrier lifetime. 0.8 0.6 0.4 0.2 0 0 20 40 60 80 100 120 140 Virtual Junction Temperature, Tvj - (oC) Fig. 24 Variation of stored charge with temperature 1.2 1.1 Normalised Reverse recovery current The turn-off process in a thyristor begins when the anode current falls below the holding current. However the thyristor cannot revert to the blocking state instantaneously because of the stored charge phenomenon. 1 1 0.9 0.8 0.7 0.6 0 50 100 150 200 Junction temperature, Tvj - (oC) Fig.25 Dependence of reverse recovery current on junction temperature Page 21 of 23 AN 5950 1.6 2.5 y = 0.2791e0.0102x R² = 1 1.4 1.2 Normalised turn-off time Normalised turn-off time 2 1.5 1 1 0.8 0.6 0.4 0.5 0.2 0 y = 0.178ln(x) + 0.4721 R² = 0.9976 0 0 50 100 150 200 Junction temperature TVJ (oC) 0 100 200 300 400 Rate of change of re-applied forward voltagedv/dt (V/us) Fig. 26 Variation of tq with temperature Fig. 28 Variation of tq with dV/dt References: (1) P.D.Taylor (1987) ‘Thyristor Design and Realization’,Wiley, England. P. 67 (2) Fukui, H., Naito, M., and Terasawa, Y. (1980). ‘One dimensional analysis of reverse receovery and dV/dt triggering characteristics of a thyristor’. IEEE Trans. Elelctron. Devices,ED-27, 596-602 1.6 Normalised Turn-off time 1.5 1.4 1.3 1.2 1.1 y = 0.119ln(x) + 1 R² = 1 1 0 20 40 60 80 100 Rate of decay of on-state current di/dt (A/us) Fig. 27 Variation of tq with dI/dt Page 22 of 23 AN 5950 HEADQUARTERS OPERATIONS CUSTOMER SERVICE DYNEX SEMICONDUCTOR LIMITED Phone: +(0) 1522 502753 / 502901 Doddington Road, Lincoln, Lincolnshire, LN6 3LF Fax: +(0) 1522 500020 United Kingdom. e-mail: [email protected] Phone: +44 (0) 1522 500500 © Dynex Semiconductor 2003 TECHNICAL DOCUMENTATION-NOT FOR RESALE. Fax: +44 (0) 1522 500550 PRODUCED IN UNITED KINGDOM Web: http://www.dynexsemi.com This publication is issued to provide information only which (unless agreed by the Company in writing) may not be used, applied or reproduced for any purpose nor form part of any order or contract nor to be regarded as a representation relating to the products or services concerned. No warranty or guarantee express or implied is made regarding the capability, performance or suitability of any product or service. The Company reserves the right to alter without prior notice the specification, design or price of any product or service. Information concerning possible methods of use is provided as a guide only and does not constitute any guarantee that such methods of use will be satisfactory in a specific piece of equipment. It is the user’s responsibility to fully determine the performance and suitability of any equipment using such information and to ensure that any publication or data used is up to date and has not been superseded. These products are not suitable for use in any medical products whose failure to perform may result in significant injury or death to the user. All products and materials are sold and services provided subject to the Company’s conditions of sale, which are available on request. All brand names and product names used in this publication are trademarks, registered trademarks or trade names of their respective owners. Page 23 of 23

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