118 lines
2.4 KiB
Plaintext
118 lines
2.4 KiB
Plaintext
SOA test for generic diode, including self-heating
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* forward direction
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* ngspice-35
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*.temp 200
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vtamb tamb 0 27
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v1 1 0 0.7
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R1 1 0 100 ; just a parallel resistor
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D1 1 0 tj dmod thermal
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Rtj tj tamb 100 ; the thermal resistance junction to ambient
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* diode model parameters include all SOA parameters
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.model dmod d (rs=200m bv=21 rth0=1e6 tnom=25 fv_max=1.5 bv_max=20 id_max=1.5 pd_max=1 te_max=175)
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.option warn=1 maxwarns=2
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.control
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save @d1[id] all
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*dc v1 3 -22.5 -0.5
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dc v1 0.02 2 0.02
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*display
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set xbrushwidth=3
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* get data from diode model
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let pdmax = @dmod[pd_max]
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let idmax = @dmod[id_max]
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let vmax = @dmod[fv_max]
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let tmax = @dmod[te_max]
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let tnom = @dmod[tnom]
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let iid = @d1[id]
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let ilen = length(iid)
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let soa = unitvec(ilen) * idmax
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* the current power dissipation in the diode
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let pd=@d1[id]*v(1) + 1p ; 1p for log scale, avoid 0
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* plot the static SOA diagram
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* no self heating
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let i = 0
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while i < ilen
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* power limit
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let pp = soa[i] * v(1)[i]
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if pp > pdmax
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let soa[i] = soa[i] * pdmax / pp
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end
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* voltage limit
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if v(1)[i] > vmax
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let soa[i] = 1p
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end
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* temperature limit
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let tcur = pp * @Rtj[r] + v(tamb)
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if tcur[i] > tmax
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let soa[i] = 1p
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end
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let i = i + 1
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end
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settype current iid soa
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plot iid soa loglog ylimit 10m 10 xlimit 0.1 1 title 'Diode SOA (safe operating area, no self-heating)' ylabel 'Diode current' xlabel 'Diode forward voltage'
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unlet pdmax
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let pdmax = @dmod[pd_max] - (v(tj) - tnom) / @Rtj[r]
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let tdio = v(tj)
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echo
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*echo pdmax $&pdmax
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*echo temp $&tdio
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*echo tnom $&tnom
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echo
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let plen = length(pdmax)
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let i = 0
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while i < plen
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if pdmax[i] < 0
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let pdmax[i] = 1p
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end
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let i = i + 1
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end
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* plot the static SOA diagram
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* now with self heating
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let i = 0
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while i < ilen
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* power limit
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let pp = soa[i] * v(1)[i]
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if pp > pdmax[i]
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let soa[i] = soa[i] * pdmax[i] / pp
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end
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* voltage limit
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if v(1)[i] > vmax
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let soa[i] = 1p
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end
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* temperature limit
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let tcur = pp * @Rtj[r] + v(tamb)
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if tcur[i] > tmax
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let soa[i] = 1p
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end
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let i = i + 1
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end
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settype current iid soa
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plot iid soa loglog ylimit 10m 10 xlimit 0.1 1 title 'Diode SOA (safe operating area, including self-heating)' ylabel 'Diode current' xlabel 'Diode forward voltage'
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*settype power pd pdmax
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*plot pd pdmax loglog ylimit 1m 10 xlimit 0.1 1
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*settype temperature tj
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*plot tj
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*plot pd vs tj pdmax vs tj
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.endc
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.end
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