At the moment of current feeding at terminal VCC, the IC generates the supply voltage via backup capacitor
externally connected. As soon as an internal switching threshold of 7 V is reached, trigger pulses are
delivered at the output TR with a repetition instalment of 960 µs. After successful triggering of the oscillator
circuit, an oscillation detector guarantees blocking of further trigger pulses. It identifies a stable oscillating
process, after a minimum of oscillations is detected per timing.
As soon as a switching threshold of 8 V is reached, all logic units are reset and the timer output S is activated
as well. The IC starts a counter, which interrups the control after one second.
Furthermore, the IC monitors the temperature and the oscillation circuit from a supply voltage of 8 V.
The comparator input EI is useful for error detection. Voltage > 3.75 V, applied at EI, are evaluated as error
signals. The error signal is enqired and registered within a cycle repeating every 960 µs. After registration of
the error signal, a counter starts to generate a delay of one second. After this delay time, the voltage at EI is
evaluated again. The error storage is set only after a second error, appearing within a directly following
evaluation cycle. This error storage is resettable by a short-time power supply disconnection, or with input
LW connected via a change of lamp.
The error storing causes the cutting further triggers and the control of the turn-off transistor as well, which
turns the output TR to ground. Therefore, the turn-off transistor prevents the control of the oscillator circuit,
attenuating it extremly quickly.
Thereby, the current consumption increases by the control of the turn-off transistor. This current amounts
more than 5 mA, that the supply voltage across the backup capacitor at pin VCC breaks down (because
feed is less 5 mA). With a switching threshold of 6 V, the control current of the turn-off transistor is
switched off, that enables the supply voltage to rise up to the limiting voltage. Because the trigger pulse gate,
blocked by the error memory, the oscillation can’t start again.
With error storing and attenuation of the oscillation by overtemperature it can be defined via selection of the
temperature mode, whether the oscillation is automatically triggered after cooling-down of the assembly, or
only after mains disconnection.
Absolute Maximum Ratings
peak current for t< 100 µs
input voltage error indicator
input voltage lamp
voltage difference between
VLW - VCC
VLW and VCC for
divider factor 16 via LW
input current at pin TM
negative current load
for t<1µs with max. repeat
frequency = 200kHz
switching output current