®
TN22
STARTLIGHT
FEATURES
V
BR
: 1200 - 1500V and 1000 - 1600V versions
I
H
> 175 mA
I
GT
< 1.5 mA
SOT 194
(Plastic)
DESCRIPTION
The TN22 is an high performance asymetrical
SCR in high voltage PNPN diffused planar tech-
nology.
Package either in TO220AB, SOT 82 or SOT 194,
these parts are intended for use in electronic
ABSOLUTE RATINGS
(limiting values)
Symbol
V
DRM
I
T(RMS)
I
T(AV)
I
TSM
Parameter
Repetitive peak off-state voltage
RMS on-state current
Full sine ware (180° conductionangle)
Mean on-state current
Full sine ware (180° conductionangle)
Non repetitive surge peak on-state current
(T
j
initial = 25°C)
I
2
t Value for fusing
Critical rate of rise of on-state current
I
G
= 5 mA
dI
G
/dt = 70 mA/µs.
Storage and operating junction temperature range
Maximum lead temperature for soldering during 10s at
4.5mm from case
T
j
= 110°C
Tc= 95°C
Tc= 95°C
tp = 8.3ms
tp = 10ms
I
2
t
dI/dt
T
stg
T
j
Tl
tp = 10ms
Value
400
2
1.8
22
20
2
50
- 40 to + 150
- 40 to + 110
260
A
2
s
A/µs
°C
°C
Unit
V
A
A
A
K
AG
TO220AB
(Plastic)
SOT 82
(Plastic)
April 1995
1/7
TN22
This thyristor has been designed for use as a fluo-
rescent tube starter switch.
Au electronic starter circuit provides :
BASIC APPLICATION DIAGRAM
A pre-heating period during which a heating
current is applied to the cathode heaters.
One or several high voltage striking pulses
across the lamp.
INDUCTANCE
BALLAST
START ER CIRCUIT
220 V
AV
VOLTAG E
FLUORESCENT
TUBE
R
TN22
S
CONTROLER
(TIMER)
PRINCIPLE OF OPERATION
1/ Pre-heating
At rest the switch S is opened and when the mains
voltage is applied across the circuit a full wave rec-
tified current flows through the resistor R and the
TN22 gate : At every half-cycle when this current
reaches the gate triggering current (I
GT
) the thyris-
tor turns on.
When the device is turned-on the heating current,
limited by the ballast choke, flows through the tube
heaters.
The pre-heating time is typically 2 or 3 seconds.
2/ Pulsing
At the end of the pre-heating phase the switch S is
turned on. At this moment :
If the current through the devices is higher than the
holding current (I
H
) the thyristor remains on until
the current falls (below I
H
). Then the thyristor turns
off.
If the current is equal or lower than the holding cur-
rent the thyristor turns off the instantaneously.
When the thyristor turns off the current flowing
through the ballas choke generates a high voltage
pulse. This overvoltage is clamped by the thyristor
avalanche characteristic (V
BR
).
If the lamp is not struck after the first pulse, the sys-
tem starts a new ignition sequence again.
3/ Steady state
When the lamp is on the running voltage is about
150V and the starter switch is in the off-state.
IMPLEMENTATION
The resistor R must be chosen to ensure a proper
triggering in the worst case (minimum operating
temperature) according to the specified gate trig-
gering current and the peak line voltage.
Switch S : This function can be realized with a gate
sensitive SCR type : P0130AA...
This component is a low voltage device (< 50V)
and the maximum current sink through this switch
can reach the level of the thyristor holding current.
The pre-heating period can be determined by the
time constant of a capacitor-resistor circuit
charged by the voltage drop of diodes used in se-
ries in the thyristor cathode.
3/7
®
TN22
Fig.1 :
Maximum average power dissipation ver-
sus average on-state current (rectified full sine
wave).
Fig.2 :
Correlation between maximum average
power dissipation and maximum allowable tem-
perature (Tamb and Tcase) for different thermal
resistances heatsink + contact.
PT(av) (W)
Rth=8
o
C/W
Rth=4
o
C/W
Rth=0
o
C/W
6
5
4
3
2
1
0
P T(av) (W)
= 180
= 120
= 90
o
o
6
5
o
Rth=12
o
C/W
4
3
2
= 180
o
= 60
= 30
o
o
I T(av) (A)
1
1.4
1.6 1.8
2
0
0.2
0.4
0.6
0.8
1
1.2
0
Tcase ( C)
o
0
10
20
30
40
50
60
70
80
90 100 110
Fig.3 :
Average on-state current versus case tem-
perature (rectified full sine wave).
Fig.4 :
Thermal transient impedance junction to
ambient versus pulse duration.
I T(av) (A)
Zth(j-a)(o C/W)
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
0.0
Tcas e ( C)
o
1 .0E + 02
o
= 180
1.0E + 01
1 .0E + 00
10
20
30 40
50 60
70 80
90
100 110
1.0E-01
1.0E-02
tp(S)
1.0E-01
1.0E +0 0 1.0E +01 1 .0E +02 1 .0E + 03
Fig.5 :
Relative variation of gate trigger current and
holding current versus junction temperature.
Igt[Tj]
o
Igt[Tj=25 C]
Ih[Tj]
o
Ih[Tj=25 C]
Fig.6 :
Non repetitive surge peak on-state current
versus number of cycles.
ITSM(A)
20
18
16
14
3.0
2.5
2.0
1.5
Ih
Igt
Tj initial = 25
o
C
F = 50Hz
12
10
8
6
4
1.0
0.5
Tj(
o
C)
2
0
Number of cycles
1
10
100
1000
0.0
-40
-20
0
20
40
60
80
100
120 140
4/7
®
TN22
Fig.7 :
Non repetitive surge peak on-state current
for a sinusoidal pulse with width : tp
≤
10ms, and
corresponding value of I
2
t.
I TSM (A). I
2
t (A
2
s)
100
Tj initial = 25
o
C
8
7
6
5
10
4
3
I
2
t
2
1
1
1
I TM (A)
10
0
0.1
1
10
20
Tj=25
o
C
Tj=11 0
o
C
Vto =2.50V
Rt =0.235
Tj=110
o
C
Fig.8 :
On-state characteristics (maximum values).
VTM (V)
I TSM
tp(ms)
Fig.9 :
Relative variation of holding current versus
gate-cathode resistance (typical values).
Fig.10 :
Maximum allowable RMS current versus
time conduction and initial case temperature
(Package : SOT 82).
Note : Calculation made fot Tj max = 135°C (the
failure mode will be short circuit)
IT(rms) (A)
Tc initial = 25
o
C
500
IH (mA)
Tj=25
o
C
11
10
9
100
8
7
6
Tc initial = 45
o
C
10
5
4
3
Rgk( )
2
1000
Tc initial = 65
o
C
tp(s)
1
10
100
1
1
10
100
1
0.1
5/7
®
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