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ACST8-8C
January 2002 - Ed: 4B
OVER VOLTAGE PROTECTED
AC POWER SWITCH
s
V
DRM
/ V
RRM
= +/- 800V
s
Avalanche controlled device
s
I
T(RMS)
= 8A with T
CASE
= 90 C
s
High noise immunity: static dV/dt > 750 V/s
s
Gate triggering current : I
GT
< 30 mA
s
Snubberless turn off commutation:
(dI/dt)c > 4.5A/ms
s
TO-220FPAB package
FEATURES
The ACST8-8C belongs to the AC power switch
family built around the ASD technology. This high
performance device is adapted to home appliances
or industrial systems and drives an induction motor
up to 8A.
This ACST switch embeds a triac structure with a
high voltage clamping device to absorb the inductive
turn off energy and withstand line transients such as
those described in the IEC61000-4-5 standards.
DESCRIPTION
s
Enables equipment to meet EN61000-4-5
standard
s
High off-state reliability with planar technology
s
Need no external overvoltage protection
s
Reduces the power component count
BENEFITS
G
COM
OUT
FUNCTIONAL DIAGRAM:
s
AC static switching in appliance & industrial
control systems
s
Washing machine with bi-rotational induction
motor drive
s
Induction motor drive for:
- refrigerator / freezer compressor
- air conditioning compressor
MAIN APPLICATIONS
ASDTM
AC Switch Family
COM
G
OUT
TO-220FPAB
ACST8-8C
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Symbol
Parameter
Value
Unit
V
DRM /
V
RRM
Repetitive peak off-state voltage
800
V
I
T(RMS)
RMS on-state current full cycle sine wave 50 to 60 Hz
Tcase = 90C
8
A
I
TSM
Non repetitive surge peak on-state current
Tj initial = 25C, full cycle sine wave
tp = 20ms
80
A
tp = 16.7ms
85
A
I
2
t
Thermal constraint for fuse selection
tp = 10ms
35
A
2
s
dI/dt
Non repetitive on-state current critical rate of rise
I
G
= 10mA (tr < 100ns)
Rate period > 1mn
100
A/
s
V
PP
Non repetitive line peak pulse voltage
note 1
2
kV
Tstg
Storage temperature range
- 40 to + 150
C
Tj
Operating junction temperature range
- 40 to + 125
C
Tl
Maximum lead soldering temperature during 10s
260
C
Note 1: according to test described by IEC61000-4-5 standard & Figure A.
ABSOLUTE RATINGS (limiting values)
Symbol
Parameter
Value
Unit
P
G (AV)
Average gate power dissipation
0.1
W
P
GM
Peak gate power dissipation (tp = 20s)
10
W
I
GM
Peak gate current (tp = 20s)
1
A
GATE CHARACTERISTICS (maximum values)
Symbol
Parameter
Value
Unit
Rth (j-a)
Junction to ambient
60
C/W
Rth (j-c)
Junction to case for full cycle sine wave conduction
3.5
C/W
THERMAL RESISTANCE
Parameter Symbol
Parameter description
I
GT
Gate triggering current
V
GT
Gate triggering voltage
V
GD
Non triggering voltage
I
H
Holding current
I
L
Latching current
V
TM
On state voltage
V
TO
On state characteristic threshold voltage
R
D
On state characteristic dynamic resistance
I
DRM
/ I
RRM
Forward or reverse leakage current
dV/dt
Static pin OUT voltage rise
(dI/dt)c
Turn off current rate of decay
V
CL
Avalanche voltage at turn off
PARAMETER DESCRIPTION
ACST8-8C
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Symbol
Test conditions
Values
Unit
I
GT
V
OUT
= 12V (DC)
R
L
= 33
Tj = 25C
MAX.
30
mA
V
GT
V
OUT
= 12V (DC)
R
L
= 33
Tj = 25C
MAX.
1.5
V
V
GD
V
OUT
= V
DRM
R
L
= 3.3k
Tj =125C
MIN.
0.2
V
I
H
I
OUT
= 100mA Gate open
Tj = 25C
MAX.
40
mA
I
L
I
G
= 20mA
Tj = 25C
MAX.
70
mA
V
TM
I
OUT
= 11A
tp = 380s
Tj = 25C
MAX.
1.5
V
V
TO
Tj = 125C
MAX.
0.95
V
R
D
Tj = 125C
MAX.
50
m
I
DRM
I
RRM
V
OUT
= V
DRM
V
OUT
= V
RRM
Tj = 25C
MAX.
10
A
Tj = 125C
MAX.
1
mA
dV/dt
V
OUT
= 550V
gate open
Tj = 125C
MIN.
750
V/
s
(dI/dt)c
Without snubber
Tj = 125C
MIN.
4.5
A/ms
V
CL
I
CL
= 1mA
tp = 1ms
Tj = 25C
TYP.
1200
V
ELECTRICAL CHARACTERISTICS PER SWITCH
For either positive or negative polary of pin OUT voltage respect to pin COM voltage
The ACST8-8C device is especially designed to drive medium power induction motors in washing ma-
chines, refrigerators, dish washers, and tumble dryers.
Pin COM
: Common drive reference, to be connected to the power line neutral
Pin G
: Switch Gate input to be connected to the controller
Pin OUT
: Switch Output to be connected to the load
When driven from a low voltage controller, the ACST switch is triggered with a negative gate current flow-
ing out of the gate pin G. It can be driven by the controller through a resistor as shown on the typical appli-
cation diagram. In appliance systems, the ACST8-8C switch intends to drive medium power load in ON /
OFF full cycle or phase angle control mode.
Thanks to its thermal and turn-off commutation characteristics, the ACST8-8C switch is able to drive
an inductive load up to 8A without a turn-off aid snubber circuit.
In washing machine or drier appliances, the tumble rotates in both directions. When using bidirectional
phase shift induction motor, two switches are connected on each side of the phase shift capacitor: in
steady-state operation, one switch only conducts energising the coils and defining the tumble direction.
AC LINE SWITCH BASIC APPLICATION
ACST8-8C
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CONTROL
UNIT
COM
OUT
G
TYPICAL APPLICATION DIAGRAM
ROBUSTNESS AGAINST FAST CAPACITOR DISCHARGE
When parasitic transients or controller mis-operation occur, the blocked switch may turn on by spurious
switch firing. Since the phase shift capacitor is charged, its energy is instantaneously dissipated through
the two ACSTs which can be destroyed. To prevent such a failure, a resistive inductive circuit R-L is added
in series with the phase shift capacitor.
The dI/dt depends on the maximal voltage V
max
of the phase shift capacitor (700V on 240V mains applica-
tions), and on the inductance L:
dI
dt
V
L
=
max
The total switch turn on di/dt is the sum of the di/dt created by any RC noise suppressor discharge and the
dI/dt created by the motor capacitor discharge.
Since the maximal di/dt capability at turn-on of the ACST8 is 100A/s, the motor capacitor di/dt is assumed
to be less than 50A/s; therefore, the inductance should be 14H.
The resistor R limits the surge current through the ACST8 during the capacitor discharge according to the
specified curve I
TSM
= f (tp) as shown in Figure 6
(to be issued), and 1.2
is low enough to limit the resistor
dissipation (usually less than 1 W).
Finally both the 14H inductance and the 1.2
resistance provide a safety margin of two on the surge cur-
rent I
TSM
described in Figure 6.
C
L
V
AC
T1
T2
ON
R
700V
M
Fast capacitor discharge when
one ACST switch turns on (T2)
and the motor runs (T1 ON).
ACST8-8C
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The ACST8-8C switch is able to safely withstand the AC line transient voltages either by clamping the low
energy spikes or by breaking over under high energy shocks.
The test circuit in Figure A is representative of the ACST application and is used to test the ACST switch
according to the IEC61000-4-5 standard conditions. Thanks to the load impedance, the ACST switch with-
stands voltage spikes up to 2 kV above the peak line voltage by breaking over safely. Such non repetitive
testing can be done 10 times on each AC line voltage polarity.
AC LINE TRANSIENT VOLTAGE RUGGEDNESS
L
R
V
AC
+ V
PP
SURGE VOLTAGE
AC LINE & GENERATOR
G
COM
OUT
Fig. A: Overvoltage ruggedness test circuit for resistive and inductive loads
according to IEC61000-4-5 standard R = 47
, L = 10H & V
PP
= 2kV
0
1
2
3
4
5
6
7
8
9
10
11
0
1
2
3
4
5
6
7
8
IT(RMS)(A)
=180
P(W)
180
Fig. 1: Maximum power dissipation versus RMS
on-state current.
0
1
2
3
4
5
6
7
8
9
0
25
50
75
100
125
Tc(C)
=180
IT(RMS)(A)
Fig. 2-1: RMS on-state current versus case
temperature.
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