U6433B-FP TEMIC Semiconductors, U6433B-FP Datasheet - Page 2

• Manufacturer Part Number: U6433B-FP
• Description: Flasher/ 18-m Shunt/ Frequency Doubling Disabling
• Manufacturer: TEMIC Semiconductors

Pin Description
Functional Description
Pin 1, GND
The integrated circuit is protected against damage via
resistor R
An integrated protection circuit together with external
resistances R
Pin 2, Supply voltage, V
The arrangement of the supply connections to Pin 2 must
be such as ensure that, on the connection printed circuit
board (PCB), the resistance of V
that to Pin 2.
Pin 3, Relay control output (driver)
The relay control output is a high-side driver with a low
saturation voltage and capable to drive a typical
automotive relay with a minimum coil resistance of 60
Pin 4 and 5 Oscillator
Flashing frequency, f
components as follows (see figure 1):
where
In the case of a lamp outage (see Pin 7) the oscillator
frequency is switched to the lamp outage frequency f
with f
Duty cycle in normal flashing mode: 50%
Duty cycle in lamp outage mode: 40% (bright phase)
Pin 6, Supply voltage, Sense
For accurate monitoring via the shunt resistor, a mini-
mized layer resistance from point V
recommended.
U6433B
2 (5)
Pin
1
2
3
4
5
6
7
8
2
[
4
2.2 f
Symbol
to ground (–31) in the case of battery reversal.
GND
OSC
OSC
REL
LD
2
V
V
SI
f
C
R
and R
S
S
1
1
1
1
.
[

+
R
47
4
6.8 k
1
IC ground
Supply voltage
Relay driver
Oscillator
Oscillator
Supply voltage
Lamp failure detection
Start input (49a)
limits the current pulses in the IC.
1
m
, is determined by the R
S
F
W
C
- Power
1
1
to 510 k
1.5
S
Function
to Pin 6 is lower than
W
Hz
S
/ shunt to Pin 6 is
1
C
W
1
2
.
Pin 7, Lamp outage detection
Control Signal Threshold 1 ( 49-mV Comparator K1)
The detection point for lamp failure can be calculated
from the control signal threshold, typically 49 mV with
V
the frequency changeover is reached at a lamp load of
21 W + 11.4 W. The variation of the control signal
threshold supply voltage takes into account the PTC char-
acteristic of filament lamps.
Control Signal Threshold 2 ( 8-mV Comparator K4)
A voltage drop at R
resistor let the flasher work in frequency doubling mode.
If the voltage drop of V
doubling is disabled. This can be achieved either with a
switch which by passes the shunt resistor ( e.g., a special
hazard warning switch ) or with a small lamp load.
The arrangement of the supply connections to Pins 2 and
6 must ensure that, on the connection, PCB, the layer
resistance from V
Flasher operation starts with a lamp load of P
Pin 8, Start input
Start condition for flashing: the voltage at Pin 8 has to be
below K3 threshold (flasher switch closed).
Humidity and dirt may decrease the resistance between
49 a and GND. If this leakage resistance is
is still kept in its off-condition. In this case the voltage at
Pin 8 is between the thresholds of comparators K2 and
K3.
During the bright phase the voltage at Pin 8 is above the
K2 threshold, during the dark phase it is below the K3
threshold.
For proper start conditions a minimum lamp wattage of
1 W is required.
S
= 12 V. With a measuring resistance of R
GND
OSC
REL
V
S
1
2
3
4
S
to Pin 6 is lower than the one to Pin 2.
Figure 2. Pinning
3
TELEFUNKEN Semiconductors
U6433B
between 49 mV and 8 mV shunt
R3MAX
= 8 mV falls the frequency
Rev. A3, 25-Feb-97
8
6
5
7
OSC
LD
Vs
SI
u
3
L
13298
5 k
= 18 m
y
W
1 W.
the IC
W,