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MOC3051SR2M View Datasheet(PDF) - Fairchild Semiconductor

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MOC3051SR2M Datasheet PDF : 11 Pages
1 2 3 4 5 6 7 8 9 10
6-PIN DIP RANDOM-PHASE
OPTOISOLATORS TRIAC DRIVERS
(600 VOLT PEAK)
MOC3051-M
MOC3052-M
AC SINE
0ϒ
180°
LED PW
LED CURRENT
LED TURN OFF MIN 200 µs
Figure 5. Minimum Time for LED Turn–Off to Zero
Cross of AC Trailing Edge
Figure. 6 Holding Current, I H vs. Temperature
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
- 40 - 30 - 20 -10 0 10 20 30 40 50 60 70 80
TA , AMBIENT TEMPERATURE (oC)
Figure. 8 LED Trigger Current, I FT vs. dv/dt
1.5
1.4
1.3
1.2
1.1
1
0.9
0.8
0.7
0.6
0.5
0.001 0.01
0.1
NORMALIZED TO:
IFT at 3 V
1
10 100 1000 10000
dv/dt (V/ µs)
Minimum LED Off Time in Phase Control
Applications
In Phase control applications one intends to be able to control
each AC sine half wave from 0 to 180 degrees. Turn on at zero
degrees means full power and turn on at 180 degree means
zero power. This is not quite possible in reality because triac
driver and triac have a fixed turn on time when activated at
zero degrees. At a phase control angle close to 180 degrees
the driver’s turn on pulse at the trailing edge of the AC sine
wave must be limited to end 200 ms before AC zero cross as
shown in Figure 5. This assures that the triac driver has time
to switch off. Shorter times may cause loss of control at the
following half cycle.
10000
Figure. 7 Leakage Current, I DRM vs. Temperature
1000
100
10
1
0.1
-40
-20
0
20
40
60
80
100
TA , AMBIENT TEMPERATURE (oC)
IFT versus dv/dt
Triac drivers with good noise immunity (dv/dt static) have inter-
nal noise rejection circuits which prevent false triggering of the
device in the event of fast raising line voltage transients. Induc-
tive loads generate a commutating dv/dt that may activate the
triac drivers noise suppression circuits. This prevents the
device from turning on at its specified trigger current. It will in
this case go into the mode of “half waving” of the load. Half
waving of the load may destroy the power triac and the load.
Figure 8 shows the dependency of the triac drivers IFT versus
the reapplied voltage rise with a Vp of 400 V. This dv/dt condi-
tion simulates a worst case commutating dv/dt amplitude.
It can be seen that the IFT does not change until a commutat-
ing dv/dt reaches 1000 V/ms. The data sheet specified IFT is
therefore applicable for all practical inductive loads and load
factors.
© 2004 Fairchild Semiconductor Corporation
Page 5 of 11
9/2/04
 

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