Explanation of Maximum Ratings and Characteristics for Thyristors

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1 8 Explanaion of Maximum Raings and Characerisics for Thyrisors Inroducion Daa shees for s and riacs give vial informaion regarding maximum raings and characerisics of hyrisors. If he maximum raings of he hyrisors are surpassed, possible irreversible damage may occur. The characerisics describe various perinen device parameers which are guaraneed as eiher minimums or maximums. Some of hese characerisics relae o he raings bu are no raings in hemselves. The characerisic does no define wha he circui mus provide or be resriced o, bu defines he device characerisic. For example, a minimum value is indicaed for he dv/d because his value depics he guaraneed wors-case limi for all devices of he specific ype. This minimum dv/d value represens he maximum limi ha he circui should allow. Maximum Raings V RRM : Peak Repeiive Reverse Volage The peak repeiive reverse volage raing is he maximum peak reverse volage ha may be coninuously applied o he main erminals (anode, cahode) of an. (Figure AN18.1) An opengae condiion and gae resisance erminaion is designaed for his raing. An increased reverse leakage can resul due o a posiive gae bias during he reverse volage exposure ime of he. The repeiive peak reverse volage raing relaes o case emperaures up o he maximum raed juncion emperaure. Volage Drop (V T ) a Specified Curren (i T ) +I Laching Curren (I L ) V DRM : Peak Repeiive Forward (Off-sae) Volage The peak repeiive forward (off-sae) volage raing (Figure AN18.1) refers o he maximum peak forward volage which may be applied coninuously o he main erminals (anode, cahode) of an. This raing represens he maximum volage he should be required o block in he forward direcion. The may or may no go ino conducion a volages above he V DRM raing. This raing is specified for an open-gae condiion and gae resisance erminaion. A posiive gae bias should be avoided since i will reduce he forward-volage blocking capabiliy. The peak repeiive forward (off-sae) volage raing applies for case emperaures up o he maximum raed juncion emperaure. The peak repeiive off-sae volage raing should no be surpassed on a ypical, non-ransien, working basis. (Figure AN18.2) V DRM should no be exceeded even insananeously. This raing applies for eiher posiive or negaive bias on main erminal 2 a he raed juncion emperaure. This volage is less han he minimum breakover volage so ha breakover will no occur during operaion. Leakage curren is conrolled a his volage so ha he emperaure rise due o leakage power does no conribue significanly o he oal emperaure rise a raed curren. Volage Drop (V T ) a Specified Curren (i T ) +I Laching Curren (I L ) Reverse Leakage Curren - (I RRM ) a Specified V RRM -V Minimum Holding Curren (I H ) Off - Sae Leakage Curren - (I DRM ) a Specified V DRM +V -V Minimum Holding Curren (I H ) Off-sae Leakage Curren (I DRM ) a Specified V DRM +V Specified Minimum Reverse Blocking Volage (V RRM ) Specified Minimum Off - Sae Blocking Volage (V DRM ) Specified Minimum Off-sae Blocking Volage (V DRM ) Figure AN18.1 Reverse Breakdown Volage -I Forward Breakover Volage V-I Characerisics of Device Figure AN18.2 -I Breakover Volage V-I Characerisics of Device 22 Teccor Elecronics AN18-1 hp:// Thyrisor Produc Caalog

2 AN18 Applicaion Noes I T : Curren Raing For RMS and average currens, he resricing facor is usually confined so ha he power dissipaed during he on sae and as a resul of he juncion-o-case hermal resisance will no produce a juncion emperaure in excess of he maximum juncion emperaure raing. Power dissipaion is changed o RMS and average curren raings for a 6 Hz sine wave wih a 18 conducion angle. The average curren for conducion angles less han 18 is deraed because of he higher RMS curren conneced wih high peak currens. The DC curren raing is higher han he average value for 18 conducion since no RMS componen is presen. The dissipaion for non-sinusoidal waveshapes can be deermined in several ways. Graphically ploing insananeous dissipaion as a funcion of ime is one mehod. The oal maximum allowable power dissipaion (P D ) may be deermined using he following equaion for emperaure rise: T JMAX T P C D = R JC where T J (max) is he maximum raed juncion emperaure (a zero raed curren), T C is he acual operaing case emperaure, and R JC is he published juncion-o-case hermal resisance. Transien hermal resisance curves are required for shor inerval pulses. The limiing facor for RMS curren is deermined by muliplying power dissipaion by hermal resisance. The resuling curren value will ensure an operaing juncion emperaure wihin maximum value. For convenience, dissipaion is convered o RMS curren a a 36 conducion angle. The same RMS curren can be used a a conducion angle of less han 36. For informaion on non-sinusoidal waveshapes and a discussion of dissipaion, refer o he preceding descripion of curren raing. I TSM : Peak Surge (Non-repeiive) On-sae Curren and The peak surge curren is he maximum peak curren ha may be applied o he device for one full cycle of conducion wihou device degradaion. The maximum peak curren is usually specified as sinusoidal a 5 Hz or 6 Hz. This raing applies when he device is conducing raed curren before he surge and, hus, wih he juncion emperaure a raed values before he surge. The juncion emperaure will surpass he raed operaing emperaure during he surge, and he blocking capaciy may be decreased unil he device revers o hermal equilibrium. The surge-curren curve in Figure AN18.3 illusraes he peak curren ha may be applied as a funcion of surge duraion. This surge curve is no inended o depic an exponenial curren decay as a funcion of applied overload. Insead, he peak curren shown for a given number of cycles is he maximum peak surge permied for ha ime period. The curren mus be deraed so ha he peak juncion emperaure during he surge overload does no exceed maximum raed juncion emperaure if blocking is o be reained afer a surge. Peak Surge (Non-repeiive) On-sae Curren (I TSM ) Amps Figure AN18.3 SUPPLY FREQUENCY: 6 Hz Sinusoidal LOAD: Resisive RMS ON-STATE CURRENT [IT(RMS)]: Maximum Raed Value a Specified Case Temperaure 4 A TO A T-22 Noes: 1) Gae conrol may be los during and immediaely following surge curren inerval. 2) Overload may no be repeaed unil juncion emperaure has reurned o seady-sae raed value. 15 A TO Surge Curren Duraion Full Cycles Peak Surge Curren versus Surge Curren Duraion I TM : Peak Repeiive On-sae Curren and The I TM raing specifies he maximum peak curren ha may be applied o he device during brief pulses. When he device operaes under hese circumsances, blocking capabiliy is mainained. The minimum pulse duraion and shape are defined and conrol he applied di/d. The operaing volage, he duy facor, he case emperaure, and he gae waveform are also defined. This raing mus be followed when high repeiive peak currens are employed, such as in pulse modulaors, capaciive-discharge circuis, and oher applicaions where snubbers are required. di/d: Rae-of-change of On-sae Curren and The di/d raing specifies he maximum rae-of-rise of curren hrough a hyrisor device during urn-on. The value of principal volage prior o urn-on and he magniude and rise ime of he gae rigger waveform during urn-on are among he condiions under which he raing applies. If he rae-of-change of curren (di/d) exceeds his maximum value, or if urn-on wih high di/d during minimum gae drive occurs (such as dv/d or overvolage evens), hen localized heaing may cause device degradaion. During he firs few microseconds of iniial urn-on, he effec of di/d is more pronounced. The di/d capabiliy of he hyrisor is grealy increased as soon as he oal area of he pelle is in full conducion. The di/d effecs ha can occur as a resul of volage or ransien urn-on (non-gaed) is no relaed o his raing. The di/d raing is specified for maximum juncion emperaure. As shown in Figure AN18.4, he di/d of a surge curren can be calculaed by means of he following equaion. di ---- d I TM = As an example, surge curren of 4 A a 6 Hz has a di/d of 4/8.3 or A/ms. hp:// AN Teccor Elecronics Thyrisor Produc Caalog

3 Applicaion Noes AN18 di d = (I TM ) I TM Figure AN18.4 I 2 Raing and I di/d Relaionship of Maximum Curren Raing o The I 2 raing gives an indicaion of he energy-absorbing capabiliy of he hyrisor device during surge-overload condiions. The raing is he produc of he square of he RMS curren (I RMS ) 2 ha flows hrough he device and he ime during which he curren is presen and is expressed in A 2 s. This raing is given for fuse selecion purposes. I is imporan ha he I 2 raing of he fuse is less han ha of he hyrisor device. Wihou proper fuse or curren limi, overload or surge curren will permanenly damage he device due o excessive juncion heaing. P G : Gae Power Dissipaion and = 8.3 ms for 6 Hz 1 ms for 5 Hz Gae power dissipaion raings define boh he peak power (P GM ) forward or reverse and he average power (P G(AV) ) ha may be applied o he gae. Damage o he gae can occur if hese raings are no observed. The widh of he applied gae pulses mus be considered in calculaing he volage and curren allowed since he peak power allowed is a funcion of ime. The peak power ha resuls from a given signal source relies on he gae characerisics of he specific uni. The average power resuling from high peak powers mus no exceed he average-power raing. I DRM : Peak Repeiive Off-sae (Blocking) Curren I DRM is he maximum leakage curren permied hrough he when he device is forward biased wih raed posiive volage on he anode (DC or insananeous) a raed juncion emperaure and wih he gae open or gae resisance erminaion. A 1 resisor conneced beween gae and cahode is required on all sensiive s. Leakage curren decreases wih decreasing juncion emperaures. Effecs of he off-sae leakage currens on he load and oher circuiry mus be considered for each circui applicaion. Leakage currens can usually be ignored in applicaions ha conrol high power. The descripion of peak off-sae (blocking/leakage) curren for he riac is he same as for he excep ha i applies wih eiher posiive or negaive bias on main erminal 2. (Figure AN18.2) I RRM : Peak Repeiive Reverse Curren This characerisic is essenially he same as he peak forward off-sae (blocking/leakage) curren excep negaive volage is applied o he anode (reverse biased). V TM : Peak On-Sae Volage and The insananeous on-sae volage (forward drop) is he principal volage a a specified insananeous curren and case emperaure when he hyrisor is in he conducing sae. To preven heaing of he juncion, his characerisic is measured wih a shor curren pulse. The curren pulse should be a leas 1 µs duraion o ensure he device is in full conducion. The forward-drop characerisic deermines he on-sae dissipaion. See Figure AN18.5, and refer o IT: Curren Raing on page AN18-2. T S, T J : Temperaure Range and The maximum sorage emperaure (T S ) is greaer han he maximum operaing emperaure (acually maximum juncion emperaure). Maximum sorage emperaure is resriced by maerial limis defined no so much by he silicon bu by peripheral maerials such as solders used on he chip/die and lead aachmens as well as he encapsulaing epoxy. The forward and off-sae blocking capabiliy of he device deermines he maximum juncion (T J ) emperaure. Maximum blocking volage and leakage curren raings are esablished a elevaed emperaures near maximum juncion emperaure; herefore, operaion in excess of hese limis may resul in unreliable operaion of he hyrisor. Characerisics V BO : Insananeous Breakover Volage and Breakover volage is he volage a which a device urns on (swiches o on sae by volage breakover). (Figure AN18.1) This value applies for open-gae or gae-resisance erminaion. Posiive gae bias lowers he breakover volage. Breakover is emperaure sensiive and will occur a a higher volage if he juncion emperaure is kep below maximum T J value. If s and riacs are urned on as a resul of an excess of breakover volage, insananeous power dissipaions may be produced ha can damage he chip or die. Posiive or Negaive Insananeous On-sae Curren (i T ) Amps Figure AN TC = 25 C 4 A TO and 25 A TO Posiive or Negaive Insananeous On-sae Volage (v T ) Vols On-sae Curren versus On-sae Volage (Typical) 22 Teccor Elecronics AN18-3 hp:// Thyrisor Produc Caalog

4 AN18 Applicaion Noes I GT : DC Gae Trigger Curren I GT is he minimum DC gae curren required o cause he hyrisor o swich from he non-conducing o he conducing sae for a specified load volage and curren as well as case emperaure. The characerisic curve illusraed in Figure AN18.6 shows ha rigger curren is emperaure dependen. The hyrisor becomes less sensiive (requires more gae curren) wih decreasing juncion emperaures. The gae curren should be increased by a facor of wo o five imes he minimum hreshold DC rigger curren for bes operaion. Where fas urn-on is demanded and high di/d is presen or low emperaures are expeced, he gae pulse may be 1 imes he minimum I GT, plus i mus be fas-rising and of sufficien duraion in order o properly urn on he hyrisor. 4. V GT : DC Gae Trigger Volage V GT is he DC gae-cahode volage ha is presen jus prior o riggering when he gae curren equals he DC rigger curren. As shown in he characerisic curve in Figure AN18.8, he gae rigger volage is higher a lower emperaures. The gae-cahode volage drop can be higher han he DC rigger level if he gae is driven by a curren higher han he rigger curren. The difference in V GT for he and he riac is ha he riac can be fired in four possible modes. The hreshold rigger volage can be slighly differen, depending on which of he four operaing modes is acually used. 2. I GT I GT (T C = 25 C) V GT V GT (T C = 25 C) Raio of 1. Raio of.5 Figure AN18.6 Normalized DC Gae Trigger Curren for All Quadrans versus Case Temperaure The descripion for he applies as well o he riac wih he addiion ha he riac can be fired in four possible modes (Figure AN18.7): Quadran I (main erminal 2 posiive, gae posiive) Quadran II (main erminal 2 posiive, gae negaive) Quadran III (main erminal 2 negaive, gae negaive) Quadran IV (main erminal 2 negaive, gae posiive) Figure AN Case Temperaure (T C ) C (-) I GT - I GT (-) I GT ALL POLARITIES ARE ERENCED TO POSITIVE (Posiive Half Cycle) QII QIII + - QI QIV (+) I GT (+) I GT NEGATIVE (Negaive Half Cycle) NOTE: Alernisors will no operae in Q IV Definiion of Operaing Quadrans + I GT Figure AN18.8 I L : Laching Curren Case Temperaure (T C ) C Normalized DC Gae Trigger Volage for All Quadrans versus Case Temperaure Laching curren is he DC anode curren above which he gae signal can be wihdrawn and he device says on. I is relaed o, has he same emperaure dependence as, and is somewha greaer han he DC gae rigger curren. (Figure AN18.1 and Figure AN18.2) Laching curren is a leas equal o or much greaer han he holding curren, depending on he hyrisor ype. Laching curren is greaer for fas-rise-ime anode currens since no all of he chip/die is in conducion. I is his dynamic laching curren ha deermines wheher a device will say on when he gae signal is replaced wih very shor gae pulses. The dynamic laching curren varies wih he magniude of he gae drive curren and pulse duraion. In some circuis, he anode curren may oscillae and drop back below he holding level or may even go negaive; hence, he uni may urn off and no lach if he gae signal is removed oo quickly. The descripion of his characerisic for he riac is he same as for he, wih he addiion ha he riac can be lached on in four possible modes (quadrans). Also, he required laching is significanly differen depending on which gaing quadrans are used. Figure AN18.9 illusraes ypical laching curren requiremens for he four possible quadrans of operaion. hp:// AN Teccor Elecronics Thyrisor Produc Caalog

5 Applicaion Noes AN18 dv/d, Saic: Criical Rae-of-rise of Off-sae Volage and Saic dv/d is he minimum rae-of-rise of off-sae volage ha a device will hold off, wih gae open, wihou urning on. Figure AN18.11 illusraes he exponenial definiion. This value will be reduced by a posiive gae signal. This characerisic is emperaure-dependen and is lowes a he maximum-raed juncion emperaure. Therefore, he characerisic is deermined a raed juncion emperaure and a raed forward off-sae volage which is also a wors-case siuaion. Line or oher ransiens which migh be applied o he hyrisor in he off sae mus be reduced, so ha neiher he rae-ofrise nor he peak volage are above specificaions if false firing is o be prevened. Turn-on as resul of dv/d is non-desrucive as long as he follow curren remains wihin curren raings of he device being used. IL ma I II III IV I GT ma Criical dv/d Figure AN18.9 Typical Laching (I L ) Requiremens for Four Quadrans versus Gae Curren (I GT ) I H : Holding Curren and The holding curren is he DC principal on-sae curren below which he device will no say in regeneraion/on sae afer laching and gae signal is removed. This curren is equal o or lower in value han he laching curren (Figure AN18.1 and Figure AN18.2) and is relaed o and has he same emperaure dependence as he DC gae rigger curren shown in Figure AN18.1. Boh minimum and maximum holding curren may be imporan. If he device is o say in conducion a low-anode currens, he maximum holding curren of a device for a given circui mus be considered. The minimum holding curren of a device mus be considered if he device is expeced o urn off a a low DC anode curren. Noe ha he low DC principal curren condiion is a DC urn-off mode, and ha an iniial on-sae curren (laching curren) is required o ensure ha he hyrisor has been fully urned on prior o a holding curren measuremen. I H I H (T C = 25 C) Raio of INITIAL ON-STATE CURRENT = 4 ma dc Case Temperaure (T C ) C V D Figure AN18.11 dv V D =.63 d = RC 63% of V D Exponenial Rae-of-rise of Off-sae Volage Defining dv/d dv/d, Commuaing: Criical Rae-of-rise of Commuaion Volage Commuaing dv/d is he rae-of-rise of volage across he main erminals ha a riac can suppor (block wihou swiching back on) when commuaing from he on sae in one half cycle o he off sae in he opposie half cycle. This parameer is specified a maximum raed case emperaure (equal o T J ) since i is emperaure-dependen. I is also dependen on curren (commuaing di/d) and peak reapplied volage (line volage) and is specified a raed curren and volage. All devices are guaraneed o commuae raed curren wih a resisive load a 5 Hz o 6 Hz. Commuaion of raed curren is no guaraneed a higher frequencies, and no direc relaionship can be made wih regard o curren/ emperaure deraing for higher-frequency operaion. Wih inducive loading, when he volage is ou of phase wih he load curren, a volage sress (dv/d) occurs across he main erminals of he riac during he zero-curren crossing. (Figure AN18.12) A snubber (series RC across he riac) should be used wih inducive loads o decrease he applied dv/d o an amoun below he minimum value which he riac can be guaraneed o commuae off each half cycle. Figure AN18.1 Normalized DC Holding Curren versus Case Temperaure 22 Teccor Elecronics AN18-5 hp:// Thyrisor Produc Caalog

6 AN18 Applicaion Noes Commuaing dv/d is specified for a half sinewave curren a 6 Hz which fixes he di/d of he commuaing curren. The commuaing di/d for 5 Hz is approximaely 2% lower while I RMS raing remains he same. (Figure AN18.4) E SOURCE IG E M TIME q : Circui-commuaed Turn-off The circui-commuaed urn-off ime of he device is he ime during which he circui provides reverse bias o he device (negaive anode) o commuae i off. The urn-off ime occurs beween he ime when he anode curren goes negaive and when he anode posiive volage may be reapplied. (Figure AN18.14) Turn-off ime is a funcion of many parameers and very dependen on emperaure and gae bias during he urn-off inerval. Turn-off ime is lenghened for higher emperaure so a high juncion emperaure is specified. The gae is open during he urn-off inerval. Posiive bias on he gae will lenghen he urn-off ime; negaive bias on he gae will shoren i. di/d I TRM IT I TM di/d (di/d) C 5% I TM I D Off-Sae Leakage 5% I RM i R Reverse Curren Volage across 1% rr q V D Off-Sae Volage 63% V T dv/d Figure AN18.12 V DRM (dv/d) C Waveshapes of Commuaing dv/d and Associaed Condiions 1 g : Gae-conrolled Turn-on and The g is he ime inerval beween he applicaion of a gae pulse and he on-sae curren reaching 9% of is seady-sae value. (Figure AN18.13) As would be expeced, urn-on ime is a funcion of gae drive. Shorer urn-on imes occur for increased gae drives. This urn-on ime is acually only valid for resisive loading. For example, inducive loading would resric he rae-ofrise of anode curren. For his reason, his parameer does no indicae he ime ha mus be allowed for he device o say on if he gae signal is removed. (Refer o he descripion of IL: Laching Curren on page AN18-4.) However, if he load was resisive and equal o he raed load curren value, he device definiely would be operaing a a curren above he dynamic laching curren in he urn-on ime inerval since curren hrough he device is a 9% of is peak value during his inerval. Gae Trigger Pulse Off-sae Volage On-sae Curren 1% Delay Turn-on 9% 1% Rise 1% 9% 5% 5% Gae Pulse Widh Figure AN18.14 Waveshapes of q Raing Tes and Associaed Condiions R JC, R JA : Thermal Resisance (Juncion-o-case, Juncion-o-ambien) and The hermal-resisance characerisic defines he seady-sae emperaure difference beween wo poins a a given rae of hea-energy ransfer (dissipaion) beween he poins. The hermal-resisance sysem is an analog o an elecrical circui where hermal resisance is equivalen o elecrical resisance, emperaure difference is equivalen o volage difference, and rae of hea-energy ransfer (dissipaion) is equivalen o curren. Dissipaion is represened by a consan curren generaor since generaed hea mus flow (seady-sae) no maer wha he resisance in is pah. Juncion-o-case hermal resisance esablishes he maximum case emperaure a maximum raed seadysae curren. The case emperaure mus be held o he maximum a maximum ambien emperaure when he device is operaing a raed curren. Juncion-o-ambien hermal resisance is esablished a a lower seady-sae curren, where he device is in free air wih only he exernal hea sinking offered by he device package iself. For R JA, power dissipaion is limied by wha he device package can dissipae in free air wihou any addiional hea sink: T R JC J T = C P AV T R JA J T = A P AV Figure AN18.13 Waveshapes for Turn-on and Associaed Condiions hp:// AN Teccor Elecronics Thyrisor Produc Caalog

AN303 APPLICATION NOTE

AN303 APPLICATION NOTE LATCHING CURRENT INTRODUCTION An imporan problem concerning he uilizaion of componens such as hyrisors or riacs is he holding of he componen in he conducing sae afer he rigger curren