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OM5428
PW
XOUT
DIFFEN
QC+
IC+
IC-
QC-
SDIS
AMPIN
TRIG
VEE
VCC
RMNS
SAW
FLY
XDIS
LOAD
230
Vac
Rz
500K
Ω
VR25
Rs
100K
Ω
VR37
T1
Triac
Rg
250
Ω
Active
Neutral
C1
220
µF
16V
R3
750K
Ω
C2
100
µF
16V
R2
168K
Ω
R1
1M
Ω
θ
R4
1M
Ω
VR1
50K
Ω
lin
NTC
100K
Ω
Fig.4 Typical application of the OM5428 as a time proportional temperature controller. The arrangement gives triggering around the zero
crossings of the mains voltage as long as the voltage produced by the temperature bridge connected to IC+ (pin 5) is higher than the voltage on
IC
− (pin 6). The voltage on IC− is a sawtooth with a repetition time of approximately 30 s; this time is determined by the RC network formed by
R3 and C2. The values shown for Rs, Rg, Rz and C1 give a gate current IGT = 50 mA typical at VGT = 1.5 V and a trigger pulse duration
tw = 100 µs typical.