Datasheet

9/2/04
Page 4 of 11
© 2004 Fairchild Semiconductor Corporation
6-PIN DIP RANDOM-PHASE
OPTOISOLATORS TRIAC DRIVERS
(600 VOLT PEAK)
MOC3051-M MOC3052-M
I
F
versus Temperature (normalized)
This graph (figure 3) shows the increase of the trigger current
when the device is expected to operate at an ambient tempera-
ture below 25°C. Multiply the normalized I
FT
shown this graph
with the data sheet guaranteed I
FT
.
Example:
T
A
= -40°C, I
FT
= 10 mA
I
FT
@ -40°C = 10 mA x 1.4 = 14 mA
Phase Control Considerations
LED Trigger Current versus PW (normalized)
Random Phase Triac drivers are designed to be phase control-
lable. They may be triggered at any phase angle within the AC
sine wave. Phase control may be accomplished by an AC line
zero cross detector and a variable pulse delay generator which
is synchronized to the zero cross detector. The same task can
be accomplished by a microprocessor which is synchronized
to the AC zero crossing. The phase controlled trigger current
may be a very short pulse which saves energy delivered to the
input LED. LED trigger pulse currents shorter than 100 µs must
have an increased amplitude as shown on Figure 4. This graph
shows the dependency of the trigger current I
FT
versus the
pulse width can be seen on the chart delay t(d) versus the LED
trigger current.
I
FT
in the graph I
FT
versus (PW) is normalized in respect to the
minimum specified I
FT
for static condition, which is specified in
the device characteristic. The normalized I
FT
has to be multi-
plied with the devices guaranteed static trigger current.
Example:
Guaranteed I
FT
= 10 mA, Trigger pulse width PW = 3 µs
I
FT
(pulsed) = 10 mA x 5 = 50 mA
Figure. 4 LED Current Required to Trigger vs. LED Pulse Width
Figure. 2 On-State Characteristics
ON-STATE VOLTAGE - V
TM
(V)
-3 -2 -1 0 1 2 3
ON-STATE CURRENT - I
TM
(mA)
-800
-600
-400
-200
0
200
400
600
800
PW
in
, LED TRIGGER PULSE WIDTH ( µ s)
1
25
20
15
10
5
0
251020 50 10
0
NORMALIZED TO:
PW
in
≥ 100 µ s
I
FT
, NORMALIZED LED TRIGGER CURRENT
Figure. 3 Trigger Current vs. Ambient Temperature
AMBIENT TEMPERATURE - T
A
(
o
C)
-40 -20 0 20 40 60 80 100
TRIGGER CURRENT - I
FT
(NORMALIZED)
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
Figure. 1 LED Forward Voltage vs. Forward Current
I
F
- LED FORWARD CURRENT (mA)
110100
V
F
- FORWARD VOLTAGE (V)
1.0
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
T
A
= -55
o
C
T
A
= 25
o
C
T
A
= 100
o
C
NORMALIZED TO T
A
= 25°C