a low-side type. The pull-up resistor R10 provides the off-
state. R3 is a protection resistor for the input stage.
Hazard warning can be activated independent of the igni-
tion switch position.
Pin 5, Supply voltage sense
This pin supplies the lamp outage comparator at Pin 8 and
is externally connected to the battery (Kl 30).
Pin 6 and 7, Control input relay 1 and 2
The feedback detects the bright phase and the dark phase
and enables the oscillator.
Pin 8, Lamp outage detection
The lamp current is monitored via an external shunt
resistor, RShunt and an internal comparator K1 with its
reference voltage of typ. 81 mV (VS = 12 V). The outage
of one lamp out of two lamps is detected according to the
Nominal current of 1 lamp: 21 W / (VS = 12 V):
Ilamp = 1.75 A
Nominal current of 2 lamps: 2 x 21 W / (VS = 12 V):
Ilamp = 3.5 A.
[The detection threshold is recommended to be set in the
middle of the current range: Ioutage 2.7 A
Thus the shunt resistor is calculated as:
RShunt = VT (K1) / Ioutage
RShunt = 81 mV/2.7 A = 30 mW.
Comparator K1‘s reference voltage is matched to the
characteristics of filament lamps (see “control signal
threshold” in the data part).
The combination of shunt resistor and resistance of wire
harness prevents Pin 8 from a too high voltage in the case
of shortet lamps.
Pin 9, Supply voltage
This pin supplies the oscillator, the comparators and the
logic parts of the IC.
Pin 10, GND
The integrated circuit is protected against transients
according to ISO–TR 7637–3 level 3 via resistor R2 to
ground (–31). An integrated protection circuit together
with external resistors R2, R3, R4, R6, R8 and R9 limits the
current pulses in the IC. Against reversed battery the IC
is also protected .
Pin 11 and 13, Control output relay 1 and 2
The relay control outputs are high-side driver with a low
saturation voltage and capable to drive a typical
automotive relay with a coil resistance of 60 W.
Pin 12, Supply voltage power
This pin supplies the relay drivers connected directly to
the battery (Kl 30). It is internally clamped by a 27-V
Absolute Maximum Ratings
Reference point ground (terminal 31), with external circuitry.
Supply voltage, 1 min
Pins 5, 9, 12
Storage temperature range
Ambient temperature range
–55 to +150
–40 to +100
Rev. A1, 25-Feb-97