NPN BJT Driving LED

Components used

SPICE netlist

* **************************************************
* Generated from CircuitSim Schematic
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X_D1 N7 N2 LED_VIRTUAL_b2f33485 IS=1e-14 N=1 RS=0 CJO=0 M=0.5 VJ=1 BV=1e30 IBV=100p OnCurrent=5m
X_Q1 N1 N3 0 NPN3T_d3c2f74f IS=1e-16 BF=100 NF=1 VAF=1e30 IKF=1e30 ISE=0 NE=1.5 BR=1 NR=1 VAR=1e30 IKR=1e30 ISC=0 NC=2 RB=0 IRB=1e30 RBM=0 RE=0 RC=0 CJE=0 VJE=0.75 MJE=0.33 TF=0 XTF=0 VTF=1e30 ITF=0 PTF=0 CJC=0 VJC=0.75 MJC=0.33 XCJC=1 TR=0 CJS=0 VJS=0.75 MJS=0 XTB=0 EG=1.11 XTI=3 KF=0 AF=1 FC=0.5 TNOM=27 AREA=1 TEMP=27
R_R1 N2 N1 500
R_R2 N3 N4 1K
V_U1 N4 0 PULSE(0 5 0 1n 1n {50*0.01/50} {1/50})
V_V1 N6 0 dc 12 ac 0 0 distof1 0 0 distof2 0 0
E_VP1 VP1 0 N4 0 1
E_VP2 VP2 0 N2 0 1
V_IP1 N6 N7 0

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* Models and supporting definitions follow
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* LED source-variant replacement with current-sense brightness node
.subckt LED_VIRTUAL_b2f33485 T0 T1 IS=1e-14 N=1 RS=0 CJO=0 M=0.5 VJ=1 BV=1e30 IBV=100p OnCurrent=5m
    DLED T0 SENSE LED_VIRTUAL_b2f33485_DIODE
    .model LED_VIRTUAL_b2f33485_DIODE D(IS={IS} N={N} RS={RS} CJO={CJO} M={M} VJ={VJ} BV={BV} IBV={IBV})
    VSENSE SENSE T1 DC 0
    BLIT lit 0 V = { (i(VSENSE) > {OnCurrent}) ? 1 : ((i(VSENSE) < 0) ? 0 : (i(VSENSE) / {OnCurrent})) }
.ends LED_VIRTUAL_b2f33485
.subckt NPN3T_d3c2f74f C B E params: AREA=1 TEMP=27 IS=1e-16 BF=100 NF=1 VAF=1e30 IKF=1e30 ISE=0 NE=1.5 BR=1 NR=1 VAR=1e30 IKR=1e30 ISC=0 NC=2 RB=0 IRB=1e30 RBM=0 RE=0 RC=0 CJE=0 VJE=0.75 MJE=0.33 TF=0 XTF=0 VTF=1e30 ITF=0 PTF=0 CJC=0 VJC=0.75 MJC=0.33 XCJC=1 TR=0 CJS=0 VJS=0.75 MJS=0 XTB=0 EG=1.11 XTI=3 KF=0 AF=1 FC=0.5 TNOM=27
    .model NPN3T_d3c2f74f_CORE NPN(Level=1 IS={IS} BF={BF} NF={NF} VAF={VAF} IKF={IKF} ISE={ISE} NE={NE} BR={BR} NR={NR} VAR={VAR} IKR={IKR} ISC={ISC} NC={NC} RB={RB} IRB={IRB} RBM={RBM} RE={RE} RC={RC} CJE={CJE} VJE={VJE} MJE={MJE} TF={TF} XTF={XTF} VTF={VTF} ITF={ITF} PTF={PTF} CJC={CJC} VJC={VJC} MJC={MJC} XCJC={XCJC} TR={TR} CJS={CJS} VJS={VJS} MJS={MJS} XTB={XTB} EG={EG} XTI={XTI} KF={KF} AF={AF} FC={FC} TNOM={TNOM})
    Q_CORE C B E NPN3T_d3c2f74f_CORE AREA={AREA} TEMP={TEMP}
.ends NPN3T_d3c2f74f
.model Resistor_1d9c8cf9a r(tc1=0 tc2=0 tnom=27)

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* Simulation settings
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.tran 400u 1e12 0 400u
.save V(VP1) V(VP2) I(V_IP1) V(X_D1.lit)
.end