S2006FS221V Teccor Electronics, Inc., S2006FS221V Datasheet - Page 139

• Manufacturer Part Number: S2006FS221V
• Description: Thyristor Product Catalog
• Manufacturer: Teccor Electronics, Inc.

Application Notes
Phase Control from Logic (DC) Inputs
Triacs can also be phase-controlled from pulsed DC unidirec-
tional inputs such as those produced by a digital logic control
system. Therefore, a microprocessor can be interfaced to AC
load by using a sensitive gate triac to control a lamp's intensity or
a motor's speed.
There are two ways to interface the unidirectional logic pulse to
control a triac. Figure AN1003.19 illustrates one easy way if load
current is approximately 5 A or less. The sensitive gate triac
serves as a direct power switch controlled by HTL, TTL, CMOS,
or integrated circuit operational amplifier. A timed pulse from the
system's logic can activate the triac anywhere in the AC sine-
wave producing a phase-controlled load.
Figure AN1003.19
The key to DC pulse control is correct grounding for DC and AC
supply. As shown in Figure AN1003.19, DC ground and AC
ground/neutral must be common plus MT1 must be con-
nected to common ground. MT1 of the triac is the return for
both main terminal junctions as well as the gate junction.
Figure AN1003.20 shows an example of a unidirectional (all neg-
ative) pulse furnished from a special I.C. that is available from
LSI Computer Systems in Melville, New York. Even though the
circuit and load is shown to control a Halogen lamp, it could be
applied to a common incandescent lamp for touch-controlled
dimming.
Figure AN1003.20
©2002 Teccor Electronics
Thyristor Product Catalog
115 V ac
220 V ac
N
L
C 1 = 0.15 µF, 200 V
C 2 = 0.22 µF, 200 V
C 3 = 0.02 µF, 12 V
C 4 = 0.002 µF, 12 V
C 5 = 100 µF, 12 V
R 1 = 270, ¼ W
R 2 = 680 k, ¼ W
V DD = 15 V DC
Halogen
Lamp
16
C 1
115 V ac
8
NOTE: As a precaution,
transformer should have
thermal protection.
R 3 = 62, ¼ W
R 4 = 1 M to 5 M, ¼ W
R 5 , R 6 = 4.7 M, ¼ W
D 1 = 1N4148
Z = 5.6 V, 1 W Zener
T = Q4006LH4 Alternistor
L = 100 µH (RFI Filter)
MT1
MT2
(Selected for sensitivity)
Sensitive Gate Triac Operating in
Quadrants I and IV
Typical Touch Plate Halogen Lamp Dimmer
V DD
OV
G
L
T
R 3
D 1
R 1
Z
C 2
R 2
+
C 5
VDD MODE
8
TRIG VSS
1
C 1 = 0.15 µF, 400 V
C 2 = 0.1 µF, 400 V
C 3 = 0.02 µF, 12 V
C 4 = 0.002 µF, 12 V
C 5 = 100 µF, 12 V
R 1 = 1 k, ¼ W
R 2 = 1.5 M, ¼ W
G
LS7631 / LS7632
7
2
6
3
EXT
CAP
MT 2
MT 1
220 V ac
C 3
SENS
SYNC
Sensitive Gate
Triac
5
4
C 4
Load
R 3 = 62, ¼ W
R 4 = 1 M to 5 M, ¼ W
R 5 , R 6 = 4.7 M, ¼ W
D 1 = 1N4148
Z = 5.6 V, 1 W Zener
T = Q6006LH4 Alternistor
L = 200 µH (RFI Filter)
(Selected for sensitivity)
R 4
R 5
120 V
60 Hz
Hot
Neutral
R 6
Touch
Plate
AN1003 - 7
For a circuit to control a heavy-duty inductive load where an
alternistor is not compatible or available, two SCRs can be driven
by an inexpensive TO-92 triac to make a very high current triac or
alternistor equivalent, as shown in Figure AN1003.21. See ”Rela-
tionship of IAV, IRMS, and IPK’ in AN1009 for design calcula-
tions.
Figure AN1003.21
Figure AN1003.22 shows another way to interface a unidirec-
tional pulse signal and activate AC loads at various points in the
AC sine wave. This circuit has an electrically-isolated input which
allows load placement to be flexible with respect to AC line. In
other words, connection between DC ground and AC neutral is
not required.
Figure AN1003.22
Microcontroller Phase Control
Traditionally, microcontrollers were too large and expensive to be
used in small consumer applications such as a light dimmer.
Microchip Technology Inc. of Chandler, Arizona has developed a
line of 8-pin microcontrollers without sacrificing the functionality
of their larger counterparts. These devices do not provide high
drive outputs, but when combined with a sensitive triac can be
used in a cost-effective light dimmer.
Figure AN1003.23 illustrates a simple circuit using a transformer-
less power supply, PIC 12C508 microcontroller, and a sensitive
triac configured to provide a light dimmer control. R
to the hot lead of the AC power line and to pin GP
tection diodes of the input structure allow this connection without
damage. When the voltage on the AC power line is positive, the
protection diode form the input to V
input buffer will see approximately V
read this pin as high. When the voltage on the line is negative,
the protection diode from V
and the input buffer sees approximately V
will read the pin as low. By polling GP
software can detect zero crossing.
Timed
Input
Pulse
Triac
R in
G
MT 2
MT 1
1
2
Triac Driving Two Inverse Parallel Non-Sensitive
Gate SCRs
Opto-isolator Driving a Triac or Alternistor
G
A
K
6
4
SS
to the input pin is forward biased,
K
100
0.1 F
250 V
A
DD
G
Load could be here
instead of upper location
DD
4
is forward biased, and the
+ 0.7 V. The software will
for a change in state, the
C 1
Non-sensitive
SS
Neutral
100
Load
Gate SCRs
G
OR
- 0.7 V. The software
http://www.teccor.com
MT 2
MT 1
[phone]
Hot
4
. The ESD pro-
Load
3
Gate Pulse
is connected
Input
Alternistor
120 V
60 Hz
Triac or
Neutral
AN1003
Hot