LTSpice SCR Model Problems - Page 1
Forum section: electronics / projects

author: Phazer12
author_rank: Newbie
timestamp: June 01, 2021, 10:58:24 am
content: Hello!I cannot get the STMicro BTA2X series SCR's to simulate in LTSpice. My circuit runs fine with the Littlefuse S602TS but not the STMicro. When I use the STMicro model, the simulation runs forever and never ends.The Littlefuse model seems relatively simple but the STMicro model is more complex and appears to have multiple parts that I don't understand. The spice models are in the text below.I am using an .include statement on the schematic and it successfully pulls in the Littlefuse SCR model and other models in the schematic but doesn't work with the STMicro model.I appreciate any ideas!Littlefuse model (runs ok).SUBCKT S402ES 1 2 3* TERMINALS: A G KQpnp 6 4 1 Pfor OFFQnpn 4 6 5 Nfor OFFRfor 6 4 5GRrev 1 4 5GRshort 6 5 1MEGRlat 2 6 9.09Ron 3 5 211.3mDfor 6 4 ZbrkDrev 1 4 ZbrkDgate 6 5 Zgate.MODEL Zbrk D (IS=3.2E-16 IBV=100U BV=400).MODEL Zgate D (IS=1E-16 IBV=100U BV=10 VJ=0.3).MODEL Pfor PNP(IS=5E-15 BF=1.10 CJE=10p CJC=5p TF=0.3U).MODEL Nfor NPN(IS=1E-12 ISE=1E-9 BF=10.0 RC=0.45 CJE=100p CJC=5p TF=0.3U).ENDSSTMicroelectronics model (simulation runs forever).**************************************************************************** TRIACs PSpice Models ***************************************************************************** Note :** This TRIAC model simulates:* -Igt (the same for all quadrants) MAX of the specification*note: for 4 quadrants TRIAC, IGT Q4 is taken into account for all quadrants* -Il (the same for all quadrants) Typ of the specification* -Ih (the same for both polarity) Typ of the specification* -VDRM* -VRRM* -(dI/dt)c and (dV/dt)c parameters are simulated only if those* constraints exceed very highly the specified limits.* -Power dissipation is realistic and correspond to a typical TRIAC** All these parameters are constant, and don't vary neither with* temperature nor other parameters.** The "STANDARD" parameter switch between 4 quadrants TRIACs (STANDARD = 1)* and 3 quadrants TRIACs (STANDARD = 0).* The "STANDARD" parameter maintains or suppress the triggering possibility of* the TRIAC in the fourth quadrant, and has absolutely NO EFFECT on other* parameters.** For a correct triac behavior, the "Maximum step size" must be below* or equal 20µs.****$.subckt Triac_ST A K G PARAMS:+ Vdrm=400v+ Igt=20ma+ Ih=6ma+ Rt=0.01+ Standard=1** Vdrm : Repetitive forward off-state voltage* Ih : Holding current* Igt : Gate trigger current* Rt : Dynamic on-state resistance* Standard : Differenciation between Snubberless and Standard TRIACs* (Standard=0 => Snubberless TRIACs, Standard=1 => Standard TRIACs)****************************** Power circuit ***********************************************************Switch circuit****************************** Q1 & Q2 ConductionS_S3 A Plip1 positive 0 Smain*RS_S3 positive 0 1GD_DAK1 Plip1 Plip2 DakR_Rlip Plip1 Plip2 1kV_Viak Plip2 K DC 0 AC 0** Q3 & Q4 ConductionS_S4 A Plin1 negative 0 Smain*RS_S4 negative 0 1GD_DKA1 Plin2 Plin1 DakR_Rlin Plin1 Plin2 1kV_Vika K Plin2 DC 0 AC 0*****************************Gate circuit*****************************R_Rgk G K 10GD_DGKi Pg2 G DgkD_DGKd G Pg2 DgkV_Vig Pg2 K DC 0 AC 0R_Rlig G Pg2 1k******************************Interface circuit****************************** positive pilotR_Rp Controlp positive 2.2C_Cp 0 positive 1uE_IF15OR3 Controlp 0 VALUE {IF( ( (V(CMDIG)>0.5) | (V(CMDILIH)>0.5) | (V(CMDVdrm)>0.5) ),400,0 )}** negative pilotR_Rn Controln negative 2.2C_Cn 0 negative 1uE_IF14OR3 Controln 0 VALUE {IF( ( (V(CMDIG)>0.5) | (V(CMDILIHN)>0.5) | (V(CMDVdrm)>0.5) ),400,0 )}****************************** Pilots circuit ********************************************************** Pilot Gate *****************************E_IF1IG inIG 0 VALUE {IF( ( ABS(I(V_Vig)) ) > (Igt-1u) ,1,0 )}E_MULT2MULT CMDIG 0 VALUE {V(Q4)*V(inIG)}E_IF2Quadrant4 Q4 0 VALUE {IF(((I(V_Vig)>(Igt-0.000001))&((V(A)-V(K))<0)&(Standard==0)),0,1)}****************************** Pilot IHIL ******************************E_IF10IL inIL 0 VALUE {IF( ((I(V_Viak))>(Ih/2)),1,0 )}E_IF5IH inIH 0 VALUE {IF( ((I(V_Viak))>(Ih/3)),1,0 )}** Flip_flop IHILE_IF6DIHIL SDIHIL 0 VALUE {IF((V(inIL)*V(inIH)+V(inIH)*(1-V(inIL))*(V(CMDILIH)) )>0.5,1,0)}C_CIHIL CMDILIH 0 1nR_RIHIL SDIHIL CMDILIH 1KR_RIHIL2 CMDILIH 0 100Meg****************************** Pilot IHILN ******************************E_IF11ILn inILn 0 VALUE {IF( ((I(V_Vika))>(Ih/2)),1,0 )}E_IF3IHn inIHn 0 VALUE {IF( ((I(V_Vika))>(Ih/3)),1,0 )}* Flip_flop IHILnE_IF4DIHILN SDIHILN 0 VALUE {IF((V(inILn)*V(inIHn)+V(inIHn)*(1-V(inILn))*(V(CMDILIHN)) )>0.5,1,0)}C_CIHILn CMDILIHN 0 1nR_RIHILn SDIHILN CMDILIHN 1KR_RIHILn2 CMDILIHN 0 100Meg****************************** Pilot VDRM *****************************E_IF8Vdrm inVdrm 0 VALUE {IF( (ABS(V(A)-V(K))>(Vdrm*1.3)),1,0 )}E_IF9IHVDRM inIhVdrm 0 VALUE {IF( (I(V_Viak)>(Vdrm*1.3)/1.2meg)| (I(V_Vika)>(Vdrm*1.3)/1.2meg),1,0)}* Flip_flop VDRME_IF7DVDRM SDVDRM 0 VALUE {IF((V(inVdrm)+(1-V(inVdrm))*V(inIhVdrm)*V(CMDVdrm) )>0.5,1,0)}C_CVdrm CMDVdrm 0 1nR_RVdrm SDVDRM CMDVdrm 100R_RVdrm2 CMDVdrm 0 100Meg****************************** Switch Model *****************************.MODEL Smain VSWITCH Roff=1.2meg Ron={Rt} Voff=0 Von=100***************** Diodes Model *****************.MODEL Dak D( Is=3E-12 Cjo=5pf).MODEL Dgk D( Is=1E-16 Cjo=50pf Rs=5).ends*********************************************************************** TRIACs PSpice Library ******************************************************************************************************************************************** Standard TRIACs definition ************************************************************************$.subckt T4050-6 A K GX1 A K G Triac_ST params:+ Vdrm=600v+ Igt=50ma+ Ih=85ma+ Rt=0.010+ Standard=1* 2021 / ST / Rev 0.ends*$.subckt T405-700 A K GX1 A K G Triac_ST params:+ Vdrm=700v+ Igt=5ma+ Ih=10ma+ Rt=0.120+ Standard=1* 2021 / ST / Rev 0.ends*$.subckt T435-700 A K GX1 A K G Triac_ST params:+ Vdrm=700v+ Igt=35ma+ Ih=35ma+ Rt=0.120+ Standard=1* 2021 / ST / Rev 0.ends*$.subckt T835-8G A K GX1 A K G Triac_ST params:+ Vdrm=800v+ Igt=35ma+ Ih=35ma+ Rt=0.05+ Standard=1* 2021 / ST / Rev 0.ends*$.subckt T850-8G A K GX1 A K G Triac_ST params:+ Vdrm=800v+ Igt=50ma+ Ih=75ma+ Rt=0.05+ Standard=1* 2021 / ST / Rev 0.ends*$.subckt T850-6G A K GX1 A K G Triac_ST params:+ Vdrm=600v+ Igt=50ma+ Ih=75ma+ Rt=0.05+ Standard=1* 2021 / ST / Rev 0.ends*$.subckt T1210-6G A K GX1 A K G Triac_ST params:+ Vdrm=600v+ Igt=10ma+ Ih=15ma+ Rt=0.035+ Standard=1* 2021 / ST / Rev 0.ends*$.subckt T1050-8G A K GX1 A K G Triac_ST params:+ Vdrm=800v+ Igt=50ma+ Ih=50ma+ Rt=0.040+ Standard=1* 2021 / ST / Rev 0.ends

author: T3sl4co1l
author_rank: Super Contributor
timestamp: June 01, 2021, 05:07:22 pm
content: Oh god, it's a pile of IFs. You can try different simulation settings but that model is cursed.Tim

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: June 01, 2021, 07:54:15 pm
content: Phazer12,The Littelfuse model is for an SCR.The ST model is for 8 different TRIACs.An SCR works in one quadrant, positive voltage and positive current with a positive trigger. The model is built around two transistors.The TRIAC can work with positive or negative voltages and with positive or negative trigger pulses. It is built around four transistors. It is therefore more complicated.These type of devices can be troublesome in simulation because they containing positive feedback. The positive feedback is the latching action. The positive feedback can cause convergence issues.Do you need a TRIAC or an SCR?Jay_Diddy_B

author: Phazer12
author_rank: Newbie
timestamp: June 02, 2021, 02:55:06 am
content: Thanks Jay Diddy. I don't really need a triac, and SCR will do so I'll use the Littlefuse Sxx65 series.