AT404 EZYTRIGGER
April 2002
Data subject to change without notice
Page 1 of 2
The AT404 EasyTrigger in combination with a fibre optic
cable replaces pulse transformers including all associated
circuitry in phase controlled thyristor equipment. It is
intended for applications where high insulation voltages or
long transmitting distances are important. Because of the
small control current, the unit serves as an ideal link
between the control intelligence and the thyristor. Each unit
triggers a single thyristor and is intended for 115 -
690Vrms supplies.
The operation of the AT404 is based on a controlled
current source connected between anode and gate of the
thyristor to be triggered. The large gate current is initiated
by the output current from a fibre optic receiver diode. With
a suitable transmitter, small and large thyristors can be
triggered directly from standard logic circuits without the
need of a gate drive power supply. The receiver diode is
not part of the unit.
Among the many possible applications, it is specifically
useful in electrostatic precipitators.
ABSOLUTE MAXIMUM RATINGS
Parameter
Symbol
AT404-22
AT404-24
Unit
Peak voltage - positive and negative
Vp
2200
2400
V
Nominal mains voltage
Vm
690
690
Vrms
Continuous DC voltage
V=
690
690
Vdc
Turn-on delay for gate current = 1A
tdg
5
5
s
Transient immunity
(dv/dt)d
2000
2000
V/ s
Ambient temperature
Ta
-25 to +85
ºC
External gate cathode short circuit during operation can be destructive
TECHNICAL DATA at 25°C
Parameter
Symbol
AT404-22
AT404-24
Unit
200mA Gate current threshold
Vgtl
16
16
V
1.2A gate current threshold
Vgtm
36
36
V
100V
1.2
1.2
200V
2
2
400V
2.5
2.5
800V
3
3
Gate current rise time at anode
voltage of
1200V
(di/dt)g
4
4
A/ s
Peak gate current (typical)
Ip
1.3
1.3
A
Anode - cathode current at Vp
In
5.1
5.8
mA
Maximum off state gate current
Io
2
2
A
Minimum output current of receiver diode
Icm
15
15
A
Minimum voltage rating of receiver diode
Vcm
30
30
V
Turn-on delay with receiver current = 30uA
tdi
35
35
s
APPLICATION INFORMATION
The sensitivity of the fibre optic system is important if it is desirable to drive the AT404 directly from the
control logic. For a receiver diode output above 30
µA the turn-on delay is approximately inversely
proportional to the current and therefore pulse shaping can reduce the turn-on delay down to a
AT404
Actual Size
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