Application Notes
AN1003
C3
.1µF
R1
47
D1
1N4001
VDD
120VAC
(HIGH)
R2
1M
RV1
VARISTOR
D1
1N4001
D3
1N5231
C1
220µF
C2
.01µF
AC
(RETURN)
WHITE
+5V
2000 W
U1
R70
100Ω
VDD
VSS
GP0
GP1
GP2
Q1
L4X8E5
Q2
Q4025L6
GP5
GP4
GP3
R3
20M
R6
470
12C508
R4
470
DECREASE HEAT
S1
R5
470
S2
INCREASE HEAT
Figure AN1003.24 Microcontroller Heater Control
Summary
The load currents chosen for the examples in this application
note were strictly arbitrary, and the component values will be the
same regardless of load current except for the power triac or
SCR. The voltage rating of the power thyristor devices must be a
minimum of 200 V for 120 V input voltage and 400 V for 240 V
input voltage.
The use of alternistors instead of triacs may be much more
acceptable in higher current applications and may eliminate the
need for any dv/dt snubber network.
For many electrical products in the consumer market, competitive
thyristor prices and simplified circuits make automatic control a
possibility. These simple circuits give the designer a good feel for
the nature of thyristor circuits and their design. More sophistica-
tion, such as speed and temperature feedback, can be devel-
oped as the control techniques become more familiar. A
remarkable phenomenon is the degree of control obtainable with
very simple circuits using thyristors. As a result, industrial and
consumer products will greatly benefit both in usability and mar-
ketability.
©2002 Teccor Electronics
Thyristor Product Catalog
AN1003 - 9
http://www.teccor.com
+1 972-580-7777
TECCOR [ TECCOR ELECTRONICS ]
