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®
Application Specific Discretes
A.S.D.™
TN22
STARTLIGHT
FEATURES
High clamping voltage structure (1200 - 1500V)
n
Low gate triggering current for direct drive from
n
2, TAB
1
3
line (< 1.5mA)
High holding current (> 175mA), ensuring high
n
TAB
striking energy.
DESCRIPTION
The TN22 has been specifically developed for use
1
2
3
1
2
3
in electronic starter circuits. Use in conjunction
with a sensitive SCR and a resistor, it provides
high energy striking characteristics with low trig-
DPAK
(TN22-B)
IPAK
(TN22-H)
geringpower.Thankstoitselectronicconcept, this
TN22based starter offers high reliabilitylevels and
extended life time of the fluorescent tubelamps.
ABSOLUTE RATINGS (limiting values)
Symbol Parameter Value Unit
V
DRM
I
T(RMS)
Repetitive peak off-state voltage
RMS on-state current
= 110°C 400 V
T
j
Tc= 95°C 2 A
Full sine ware (180° conduction angle)
TAB
I
T(AV)
Mean on-state current
Full sine ware (180° conduction angle)
I
TSM
Non repetitive surge peak on-state current
(T
2
t
I
dI/dt
2
I
t Value for fusing
Critical rate of rise of on-state current
IG=5mA dIG/dt = 70 mA/µs.
T
stg
T
j
Tl
Storage and operating junction temperature range
Maximum lead temperature for soldering during 10s at
4.5mm from case
October 2000 - Ed:1
initial = 25°C)
j
Tc= 95°C 1.8 A
tp = 8.3ms 22 A
tp = 10ms 20
tp = 10ms 2 A
50 A/µs
-40to+150
°C
-40to+110
260 °C
2
s
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TN22
THERMAL RESISTANCES
Symbol Parameters Value Unit
Rth(j-a)
Rth(j-c)
Junction to ambient
Junction to case
100 °C/W
3 °C/W
GATE CHARACTERISTICS (maximum values)
P
= 300 mW PGM=2W(tp=20µs) I
G (AV)
=1A(tp=20µs) V
FGM
RGM
=6V
ELECTRICAL CHARACTERISTICS
Symbol Test conditions Type Value Unit
I
GT
V
GT
I
H
V
TM
I
DRM
dV/dt
VD=12V (DC) RL=33Ω
VD=12V (DC) RL=33Ω
=1KΩ
R
GK
VGK=0V
ITM= 2A tp= 380µs
V
Rated
DRM
Linear slope up to
=67%V
V
D
DRMVGK
=0V
Tj= 25°C MAX 1.5 mA
Tj= 25°C MAX 3 V
Tj= 25°C MIN 175 mA
Tj= 25°C MAX 3.1 V
Tj= 25°C MAX 0.1 mA
Tj= 110°C MIN 500 V/µs
Symbol Test conditions Type
V
BR
ID= 5mA VGK= 0V Tj = 25°C
MIN 1200 V
MAX 1500 V
Value
TN22-1500
Unit
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TN22
This thyristor has been designed for use as a fluorescent tube starter switch.
An electronic starter circuit provides :
BASIC APPLICATION DIAGRAM
INDUCTANCE
BALLAST
AC
VOLT AGE
FLUORESCENT
TUBE
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.
STARTER CIRCUIT
R
TN22
S
CONTROLLER
(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 rectified current flows through the resistor R and the
TN22 gate : at every half-cycle when this current
reaches the gate triggering current (I
) the thyris-
GT
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 :
Ifthe current through the devices is higher than the
holding current (I
the current falls below I
) the thyristor remains on until
H
. Then the thyristor turns
H
off.
If the current is equal or lower than the holding current the thyristor turns off instantaneously.
When the thyristor turns off the current flowing
through the ballast choke generates a high voltage
pulse. This overvoltage is clamped by the thyristor
avalanche characteristic (V
BR
).
Ifthe lamp isnot struck afterthe first pulse,the system 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 triggering current and the peak line voltage.
Switch S : This function can be realized with a gate
sensitive SCR type : P0130AA 1EA3
This component is a low voltage device (< 50V)
and the maximum current sunk 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 series in the thyristor cathode.
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