Thyristor (SCR)

A silicon-controlled rectifier (SCR) or thyristor is a four-layer, three-terminal semiconductor device that acts as a latching switch. Once triggered by a gate current, it conducts from anode to cathode and remains on until the current drops below the holding current.

Terminals

anode - Positive terminal
gate - Control terminal
cathode - Negative terminal

Parameters

Parameter	Type	Default	Description
`name`	String	required	Component identifier
`Igt`	Real	50e-6	Gate trigger current (A)
`Vbo`	Real	30	Breakover voltage (V)
`Cj0`	Real	1e-11	Zero-bias junction capacitance (F)
`Is`	Real	1e-10	Saturation current (A)
`N`	Real	2	Emission coefficient
`Ri`	Real	10	Intrinsic region resistance (Ω)
`Rg`	Real	5	Gate resistance (Ω)
`Temp`	Real	26.85	Temperature (°C)

Aliases

SCR is available as an alias for Thyristor.

Example

using CircuitSim

circ = Circuit()

scr = Thyristor("scr1", Igt=50e-6, Vbo=30)
vak = DCVoltageSource("vak", voltage=20.0)
vg = DCVoltageSource("vg", voltage=0.15)
rg = Resistor("rg", resistance=1000.0)
gnd = Ground("gnd")

add_component!(circ, scr)
add_component!(circ, vak)
add_component!(circ, vg)
add_component!(circ, rg)
add_component!(circ, gnd)

@connect circ vak.nplus scr.anode
@connect circ scr.cathode gnd.n
@connect circ vg.nplus rg.n1
@connect circ rg.n2 scr.gate
@connect circ vg.nminus gnd.n
@connect circ vak.nminus gnd.n

println(netlist_qucs(circ))

# Qucs netlist generated by CircuitSim.jl
SCR:scr1 _net3 _net2 gnd Igt="5.0e-5" Vbo="30"
Vdc:vak _net3 gnd U="20.0"
Vdc:vg _net1 gnd U="0.15"
R:rg _net1 _net2 R="1000.0"

The thyristor conducts when the gate current exceeds Igt, clamping the anode-cathode voltage to a low value determined by the device's on-state characteristics.