flc02-200d STMicroelectronics, flc02-200d Datasheet - Page 4

• Manufacturer Part Number: flc02-200d
• Description: Fire Lighter Circuit
• Manufacturer: STMicroelectronics

FLC02-200D
BASIC APPLICATION
4/7
The applications of the FLC02 using the capaci-
tance discharge topology operate in 2 modes :
- Ignition mode : Transistor T is OFF
- Blanking mode : Transistor T is ON
1) IGNITION MODE (Transistor T
PHASE 1:
The energy coming from the mains is stored into
the capacitorC. For that, the AC voltage is rectified
by the diode Ds.
PHASE 2 :
At the end of the phase 1, the voltage across the
capacitor C reaches the avalanche threshold of
the zener. Then a current flows through the gate of
the thyristor Th which fires.
The firing of the thyristor causes an alternating cur-
rent to flow through the capacitor C.
The positive parts of this current flow through C, Th
and the primary of the HV transformer.
The negativeparts of the current flow through C, D
and the primary of the HV transformer.
MAINS
AC
Rs
Sensor
OFF
D
T
s
)
Z
R
RS RESISTOR CALCULATION
The Rs resistor allows, in addition with the capaci-
tor C, to adjust the spark frequency and to limitate
the current from the mains. Its value shall allow
the thyristor Th to fire even in the worst case. In
this borderline case the system must fire with the
lower RMS mains voltage value while the break-
down voltage and current of the FLC are at the
maximum.
The maximum Rs value is equal to :
Rs max
Th
D
V
AC
min x 2
c
Ic
I
BO 1
max
V
BO
Ic
max
t