S2006FS221V Teccor Electronics, Inc., S2006FS221V Datasheet - Page 123

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

Application Notes
Sidac
Basic Operation
The sidac is a multi-layer silicon semiconductor switch. Figure
AN1001.7 illustrates its equivalent block construction using two
Shockley diodes connected inverse parallel. Figure AN1001.7
also shows the schematic symbol for the sidac.
Figure AN1001.7
The sidac operates as a bidirectional switch activated by voltage.
In the off state, the sidac exhibits leakage currents (I
than 5 µA. As applied voltage exceeds the sidac V
begins to enter a negative resistance switching mode with char-
acteristics similar to an avalanche diode. When supplied with
enough current (I
high current to flow. When it switches to on state, the voltage
across the device drops to less than 5 V, depending on magni-
tude of the current flow. When the sidac switches on and drops
into regeneration, it remains on as long as holding current is less
than maximum value (150 mA, typical value of 30 mA to 65 mA).
The switching current (I
value. When the sidac switches, currents of 10 A to 100 A are
easily developed by discharging small capacitor into primary or
small, very high-voltage transformers for 10 µs to 20 µs.
The main application for sidacs is ignition circuits or inexpensive
high voltage power supplies.
Geometric Construction
Figure AN1001.8
©2002 Teccor Electronics
Thyristor Product Catalog
Equivalent Diode Relationship
N
N
P
P
S
3
5
2
4
), the sidac switches to an on state, allowing
Sidac Block Construction
Cross-sectional View of a Bidirectional Sidac Chip
with Multi-layer Construction
MT2
MT1
S
) is very near the holding current (I
P
N
P
N
N
1
3
P
2
4
2
5
MT1
P
MT2
3
Schematic Symbol
P
N
1
4
MT2
MT1
BO
DRM
, the device
) less
H
)
AN1001 - 3
Diac
Basic Operation
The construction of a diac is similar to an open base NPN tran-
sistor. Figure AN1001.9 shows a simple block construction of a
diac and its schematic symbol.
Figure AN1001.9
The bidirectional transistor-like structure exhibits a high-imped-
ance blocking state up to a voltage breakover point (V
which the device enters a negative-resistance region. These
basic diac characteristics produce a bidirectional pulsing oscilla-
tor in a resistor-capacitor AC circuit. Since the diac is a bidirec-
tional device, it makes a good economical trigger for firing triacs
in phase control circuits such as light dimmers and motor speed
controls. Figure AN1001.10 shows a simplified AC circuit using a
diac and a triac in a phase control application.
Figure AN1001.10
Geometric Construction
Figure AN1001.11
MT1
Block Construction
Cross-section of Chip
N
P
Diac Block Construction
AC Phase Control Circuit
Cross-sectional View of Diac Chip
MT2
MT1
Load
P
N
N
N
MT2
MT1
Equivalent Diode
Relationship
Schematic Symbol
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MT1
MT2
[phone]
BO
) above
MT2
AN1001