Revise the SOA and add new parameters:

pd_max id_max idr_max te_max rth_ext derating
rth_ext is currently not used

src/spicelib/devices/vdmos/vdmos.c

@@ -140,8 +140,10 @@ IFparm VDMOSmPTable[] = { /* model parameters */
  IOP("vgdr_max", VDMOS_MOD_VGDR_MAX, IF_REAL, "maximum voltage G-D branch"),
  IOP("pd_max", VDMOS_MOD_PD_MAX, IF_REAL, "maximum device power dissipation"),
  IOP("id_max", VDMOS_MOD_ID_MAX, IF_REAL, "maximum drain/source current"),
- IOP("idr_max", VDMOS_MOD_IB_MAX, IF_REAL, "maximum drain/source reverse current"),
+ IOP("idr_max", VDMOS_MOD_IDR_MAX, IF_REAL, "maximum drain/source reverse current"),
  IOP("te_max", VDMOS_MOD_TE_MAX, IF_REAL, "maximum temperature"),
+ IOP("rth_ext", VDMOS_MOD_RTH_EXT, IF_REAL, "thermal resistance case to ambient, incl. heat sink"),
+ IOP("derating", VDMOS_MOD_DERATING, IF_REAL, "thermal derating for power"),
 };
 
 char *VDMOSnames[] = {

src/spicelib/devices/vdmos/vdmosdefs.h

@@ -39,7 +39,7 @@ typedef struct sVDMOSinstance {
 #define VDMOSname gen.GENname
 #define VDMOSstates gen.GENstate
 
-    const int VDMOSdNode;  /* number of the gate node of the mosfet */
+    const int VDMOSdNode;  /* number of the drain node of the mosfet */
     const int VDMOSgNode;  /* number of the gate node of the mosfet */
     const int VDMOSsNode;  /* number of the source node of the mosfet */
     int VDMOStempNode;  /* number of the temperature node of the mosfet */
@@ -361,6 +361,12 @@ typedef struct sVDMOSmodel {       /* model structure for a resistor */
     double VDMOSvdsMax;
     double VDMOSvgsrMax;
     double VDMOSvgdrMax;
+    double VDMOSid_max;
+    double VDMOSidr_max;
+    double VDMOSpd_max;
+    double VDMOSrth_ext;
+    double VDMOSte_max;
+    double VDMOSderating;
 
     unsigned VDMOStypeGiven  :1;
     unsigned VDMOSdrainResistanceGiven   :1;
@@ -424,6 +430,12 @@ typedef struct sVDMOSmodel {       /* model structure for a resistor */
     unsigned VDMOSvdsMaxGiven  :1;
     unsigned VDMOSvgsrMaxGiven  :1;
     unsigned VDMOSvgdrMaxGiven  :1;
+    unsigned VDMOSrth_extGiven  :1;
+    unsigned VDMOSpd_maxGiven  :1;
+    unsigned VDMOSte_maxGiven  :1;
+    unsigned VDMOSid_maxGiven  :1;
+    unsigned VDMOSidr_maxGiven  :1;
+    unsigned VDMOSderatingGiven  :1;
 } VDMOSmodel;
 
 #ifndef NMOS
@@ -510,8 +522,10 @@ enum {
     VDMOS_MOD_VGDR_MAX,
     VDMOS_MOD_PD_MAX,
     VDMOS_MOD_ID_MAX,
-    VDMOS_MOD_IB_MAX,
+    VDMOS_MOD_IDR_MAX,
     VDMOS_MOD_TE_MAX,
+    VDMOS_MOD_RTH_EXT,
+    VDMOS_MOD_DERATING,
 };
 
 /* device questions */

src/spicelib/devices/vdmos/vdmosmask.c

@@ -182,6 +182,7 @@ VDMOSmAsk(CKTcircuit *ckt, GENmodel *inst, int which, IFvalue *value)
         case VDMOS_MOD_TKSUBTHRES2:
             value->rValue = model->VDMOStksubthres2; 
             return(OK);
+        /* SOA */
         case VDMOS_MOD_VGS_MAX:
             value->rValue = model->VDMOSvgsMax;
             return(OK);
@@ -197,6 +198,25 @@ VDMOSmAsk(CKTcircuit *ckt, GENmodel *inst, int which, IFvalue *value)
         case VDMOS_MOD_VGDR_MAX:
             value->rValue = model->VDMOSvgdrMax;
             return(OK);
+        case VDMOS_MOD_PD_MAX:
+            value->rValue = model->VDMOSpd_max;
+            return(OK);
+        case VDMOS_MOD_ID_MAX:
+            value->rValue = model->VDMOSid_max;
+            return(OK);
+        case VDMOS_MOD_IDR_MAX:
+            value->rValue = model->VDMOSidr_max;
+            return(OK);
+        case VDMOS_MOD_TE_MAX:
+            value->rValue = model->VDMOSte_max;
+            return(OK);
+        case VDMOS_MOD_RTH_EXT:
+            value->rValue = model->VDMOSrth_ext;
+            return(OK);
+        case VDMOS_MOD_DERATING:
+            value->rValue = model->VDMOSderating;
+            return(OK);
+
         default:
             return(E_BADPARM);
     }

src/spicelib/devices/vdmos/vdmosmpar.c

@@ -262,6 +262,30 @@ VDMOSmParam(int param, IFvalue *value, GENmodel *inModel)
             model->VDMOSvgdrMax = value->rValue;
             model->VDMOSvgdrMaxGiven = TRUE;
             break;
+        case VDMOS_MOD_PD_MAX:
+            model->VDMOSpd_max = value->rValue;
+            model->VDMOSpd_maxGiven = TRUE;
+            break;
+        case VDMOS_MOD_ID_MAX:
+            model->VDMOSid_max = value->rValue;
+            model->VDMOSid_maxGiven = TRUE;
+            break;
+        case VDMOS_MOD_IDR_MAX:
+            model->VDMOSidr_max = value->rValue;
+            model->VDMOSidr_maxGiven = TRUE;
+            break;
+        case VDMOS_MOD_TE_MAX:
+            model->VDMOSte_max = value->rValue;
+            model->VDMOSte_maxGiven = TRUE;
+            break;
+        case VDMOS_MOD_RTH_EXT:
+            model->VDMOSrth_ext = value->rValue;
+            model->VDMOSrth_extGiven = TRUE;
+            break;
+        case VDMOS_MOD_DERATING:
+            model->VDMOSderating = value->rValue;
+            model->VDMOSderatingGiven = TRUE;
+            break;
         default:
             return(E_BADPARM);
     }

src/spicelib/devices/vdmos/vdmosset.c

@@ -190,6 +190,24 @@ VDMOSsetup(SMPmatrix *matrix, GENmodel *inModel, CKTcircuit *ckt,
         if (!model->VDMOSvgdrMaxGiven)
             model->VDMOSvgdrMax = 1e99;
 
+        if (!model->VDMOSpd_maxGiven)
+            model->VDMOSpd_max = 1e99;
+
+        if (!model->VDMOSid_maxGiven)
+            model->VDMOSpd_max = 1e99;
+
+        if (!model->VDMOSidr_maxGiven)
+            model->VDMOSidr_max = 1e99;
+
+        if (!model->VDMOSte_maxGiven)
+            model->VDMOSte_max = 1e99;
+
+        if (!model->VDMOSderatingGiven)
+            model->VDMOSderating = 0;
+
+        if (!model->VDMOSrth_extGiven)
+            model->VDMOSrth_ext = model->VDMOSrthca;
+
         if (!model->VDMOSqsResistanceGiven)
             model->VDMOSqsResistance = 0.0;
 

src/spicelib/devices/vdmos/vdmossoachk.c

@@ -19,12 +19,21 @@ VDMOSsoaCheck(CKTcircuit *ckt, GENmodel *inModel)
     VDMOSinstance *here;
     double vgs, vgd, vds;    /* actual mos voltages */
     int maxwarns;
-    static int warns_vgs = 0, warns_vgd = 0, warns_vds = 0;
+    static int warns_vgs = 0, warns_vgd = 0, warns_vds = 0, warns_id = 0, warns_idr = 0, warns_pd = 0, warns_te = 0;
+    double id;  /* current VDMOS current */
+    double idr;  /* current reverse diode current */
+    double pd;  /* current VDMOS power dissipation */
+    double pd_max;  /* maximum VDMOS power */
+    double te;  /* current VDMOS temperature */
 
     if (!ckt) {
         warns_vgs = 0;
         warns_vgd = 0;
         warns_vds = 0;
+        warns_id = 0;
+        warns_idr = 0;
+        warns_pd = 0;
+        warns_te = 0;
         return OK;
     }
 
@@ -35,13 +44,13 @@ VDMOSsoaCheck(CKTcircuit *ckt, GENmodel *inModel)
         for (here = VDMOSinstances(model); here; here = VDMOSnextInstance(here)) {
 
             vgs = ckt->CKTrhsOld [here->VDMOSgNode] -
-                  ckt->CKTrhsOld [here->VDMOSsNodePrime];
+                  ckt->CKTrhsOld [here->VDMOSsNode];
 
             vgd = ckt->CKTrhsOld [here->VDMOSgNode] -
-                  ckt->CKTrhsOld [here->VDMOSdNodePrime];
+                  ckt->CKTrhsOld [here->VDMOSdNode];
 
-            vds = ckt->CKTrhsOld [here->VDMOSdNodePrime] -
-                  ckt->CKTrhsOld [here->VDMOSsNodePrime];
+            vds = ckt->CKTrhsOld [here->VDMOSdNode] -
+                  ckt->CKTrhsOld [here->VDMOSsNode];
 
             if (!model->VDMOSvgsrMaxGiven) {
                 if (fabs(vgs) > model->VDMOSvgsMax)
@@ -135,6 +144,92 @@ VDMOSsoaCheck(CKTcircuit *ckt, GENmodel *inModel)
                     warns_vds++;
                 }
 
+            /* max. drain current */
+            id = fabs(here->VDMOScd);
+            if (model->VDMOSid_maxGiven && id > fabs(model->VDMOSid_max))
+                if (warns_id < maxwarns) {
+                    soa_printf(ckt, (GENinstance*)here,
+                        "Id=%.4g A at Vd=%.4g V has exceeded Id_max=%.4g A\n",
+                        id, vds, model->VDMOSid_max);
+                    warns_id++;
+                }
+
+            /* max. reverse current */
+            idr = fabs(*(ckt->CKTstate0 + here->VDIOcurrent) * -1. + here->VDMOScd);
+            if (model->VDMOSidr_maxGiven && idr > fabs(model->VDMOSidr_max))
+                if (warns_idr < maxwarns) {
+                    soa_printf(ckt, (GENinstance*)here,
+                        "Idr=%.4g A at Vd=%.4g V has exceeded Idr_max=%.4g A\n",
+                        fabs(idr), vds, model->VDMOSidr_max);
+                    warns_idr++;
+                }
+
+            pd = fabs((id + idr) * vds);
+            pd += fabs(*(ckt->CKTstate0 + here->VDMOScqgd) *
+                (*(ckt->CKTrhsOld + here->VDMOSgNode) -
+                    *(ckt->CKTrhsOld + here->VDMOSdNode)));
+            pd += fabs(*(ckt->CKTstate0 + here->VDMOScqgs) *
+                (*(ckt->CKTrhsOld + here->VDMOSgNode) -
+                    *(ckt->CKTrhsOld + here->VDMOSsNode)));
+
+            /* Calculate max power including derating:
+               up to tnom the derating is zero,
+               at maximum temp allowed the derating is 100%.
+               Device temperature by self-heating or given externally. */
+            if (here->VDMOSthermal && model->VDMOSderatingGiven && model->VDMOSpd_maxGiven
+                && model->VDMOSte_maxGiven && model->VDMOStnomGiven) {
+                te = ckt->CKTrhsOld[here->VDMOStcaseNode];
+                if (te < model->VDMOStnom - CONSTCtoK)
+                    pd_max = model->VDMOSpd_max;
+                else {
+                    pd_max = model->VDMOSpd_max - (te - model->VDMOStnom + CONSTCtoK) * model->VDMOSderating;
+                    pd_max = (pd_max > 0) ? pd_max : 0.;
+                }
+                if (pd > pd_max)
+                    if (warns_pd < maxwarns) {
+                        soa_printf(ckt, (GENinstance*)here,
+                            "Pd=%.4g W at Vd=%.4g V and Te=%.4g C has exceeded Pd_max=%.4g W\n",
+                            pd, vds, te, pd_max);
+                        warns_pd++;
+                    }
+                if (te > model->VDMOSte_max)
+                    if (warns_te < maxwarns) {
+                        soa_printf(ckt, (GENinstance*)here,
+                            "Te=%.4g C at Vd=%.4g V has exceeded te_max=%.4g C\n",
+                            te, vds, model->VDMOSte_max);
+                        warns_te++;
+                    }
+
+            }
+            /* Derating of max allowed power dissipation, without self-heating,
+            external temp given by .temp (global) or instance parameter 'temp',
+            therefore no temperature limits are calculated */
+            else if (!here->VDMOSthermal && model->VDMOSderatingGiven && model->VDMOSpd_maxGiven && model->VDMOStnomGiven) {
+                if (here->VDMOStemp < model->VDMOStnom)
+                    pd_max = model->VDMOSpd_max;
+                else {
+                    pd_max = model->VDMOSpd_max - (here->VDMOStemp - model->VDMOStnom) * model->VDMOSderating;
+                    pd_max = (pd_max > 0) ? pd_max : 0.;
+                }
+                if (pd > pd_max)
+                    if (warns_pd < maxwarns) {
+                        soa_printf(ckt, (GENinstance*)here,
+                            "Pd=%.4g W at Vd=%.4g V and Te=%.4g C has exceeded Pd_max=%.4g W\n",
+                            pd, vds, here->VDMOStemp - CONSTCtoK, pd_max);
+                        warns_pd++;
+                    }
+            }
+            /* No derating, max power is fixed by model parameter pd_max */
+            else {
+                pd_max = model->VDMOSpd_max;
+                if (pd > pd_max)
+                    if (warns_pd < maxwarns) {
+                        soa_printf(ckt, (GENinstance*)here,
+                            "Pd=%.4g W at Vd=%.4g V has exceeded Pd_max=%.4g W\n",
+                            pd, vds, pd_max);
+                        warns_pd++;
+                    }
+            }
         }
     }