Features
• Temperature and Supply Voltage Compensated Flashing Frequency
• Frequency Doubling Indicates Lamp Outage
• Relay Driver Output with High Current Carrying Capacity and Low Saturation Voltage
• Minimum Lamp Load for Flasher Operation: ³ 1 W
• Very Low Susceptibility to EMI
• Protection According to ISO/TR 7637/1 Level 4
Flasher IC with
Description
The bipolar integrated circuit U6043B is used in relay-controlled automotive flashers
18-mW Shunt
where a high level EMC is required.
Lamp outage is indicated by frequency doubling during hazard warning as well as
direction mode. U6043B
4726A–AUTO–06/03
1
Block Diagram
Figure 1. Car Flasher Application Circuit
+ VS
+ 49
6 2
C1 R3
Measuring comparator 18 mW
Shunt
V 6 - 49 mV
4 20 kW 5 kW
K1 7
K2
Pulse 3
R1
generator
49 a-Comparator K 2 Relay
20 kW
49 a-Comparator K 8 R2
3
49 a
K3 1.5...2.2 kW
5 23 V
20 kW 5 kW
IC Ground
1
R4
470 W 5 W 21 W 21 W 21 W 21 W 5 W
Indicator lamps
GND
- 31
2 U6043B
4726A–AUTO–06/03
U6043B
Pin Configuration
Figure 2. Pinning
GND 1 8 SI
VS 2 7 LD
U6043B
REL 3 6 VS
OSC 4 5 OSC
Pin Description
Pin Symbol Function
1 GND IC ground
2 VS Supply voltage
3 REL Relay driver
4 OSC Oscillator
5 OSC Oscillator
6 VS Supply voltage, Sense
7 LD Lamp outage detection
8 SI Start input (49a)
3
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Functional Description
Pin 1, GND The U6043B is protected against damage in case of battery reversal via resistor R4 to
ground (-31). An integrated protection circuit together with external resistances R2 and
R4 limits the current pulses in the IC.
Pin 2, Supply Voltage, The arrangement of the supply connections to Pin 2 (and 6) must be so as to ensure
VS power that on the connection printed circuit board (PCB), the resistance of VS to Pin 6 is lower
than that to Pin 2.
Pin 3, Relay Control The relay control output is a high-side driver with a low saturation voltage. It is capable
Output (Driver) of driving a typical automotive relay with a minimum coil resistance of 60 W.
Pin 4 and 5, Oscillator The flashing frequency, f1, is determined by the R1C1 components as given by the fol-
lowing formula below (see Figure 1):
1
f 1 » ----------------------------------- Hz
R 1 ´ C 1 ´ 1.5
where C1 £ 47 µF, R1 = 6.8 kW to 510 kW
In case of a lamp outage (see Pin 7) the oscillator frequency is switched to the lamp out-
age frequency f2 with f2 » 2.2 ´ f1.
Duty cycle in normal flashing mode: 50%
Duty cycle in lamp outage mode: 40% (bright phase)
Pin 6, Supply Voltage, For accurate monitoring via the shunt resistor, a minimized layer resistance from point
Sense VS/shunt to Pin 6 is recommended.
Pin 7, Lamp Outage The lamp current is monitored via an external shunt resistor Rsh and an internal compar-
Detection ator K1 with its reference voltage of typ. 49 mV (VS = 12 V). The outage of one lamp is
detected according to the following calculation:
Nominal current of 1 lamp: 21 W/(VS = 12 V): Ilamp = 1.75 A
Nominal current of 2 lamps: 2 ´ 21 W/(VS = 12 V): Ilamp = 3.5 A
We recommend setting the detection threshold in the middle of the current range:
Ioutage » 2.7 A
Thus, the shunt resistor is calculated as:
Rsh = VT (K1)/Ioutage
Rsh = 49 mV/2.7 A = 18 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 7 from a
too high voltage in case of shorted lamps.
4 U6043B
4726A–AUTO–06/03
U6043B
Pin 8, Start Input Start condition for flashing: the voltage at Pin 8 has to be below the K3 threshold (flasher
switch closed).
Humidity and dirt may decrease the resistance between 49 a and GND. If this leakage
resistance is > 5 kW, the IC is still kept in the 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.
Absolute Maximum Ratings
Reference point Pin 1
Parameters Symbol Value Unit
Supply voltage Pin 2 and 6 VS 16.5 V
Surge Forward Current
tP = 0.1 ms Pin 2 and 6 IFSM 1.5 A
tP = 300 ms Pin 2 and 6 IFSM 1.0 A
tP = 300 ms Pin 8 IFSM 50 mA
Output current Pin 3 IO 0.3 A
Power Dissipation
Tamb = 95°C DIP 8 Ptot 420 mW
SO8 Ptot 340 mW
Tamb = 60°C DIP 8 Ptot 690 mW
SO8 Ptot 560 mW
Junction temperature TJ 150 °C
Ambient temperature range Tamb -40 to +95 °C
Storage temperature range Tstg -55 to +150 °C
Thermal Resistance
Parameters Symbol Value Unit
DIP8 RthJA 110 K/W
Junction ambient
SO8 RthJA 160 K/W
5
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Electrical Characteristics
Typical values under normal operation in application circuit (see Figure 1), VS (+49, Pin 2 and 6) = 12 V.
Reference point ground (-31), Tamb = 25°C, unless otherwise specified.
Parameters Test Conditions Symbol Min. Typ. Max. Unit
Supply voltage range Pin 2 and 6 VS 9 15 V
Dark phase, Pin 2 and 6 IS 4.5 8 mA
Supply current
Bright phase, Pin 2 and 6 IS 7.0 11 mA
Relay control output: Pin 3
Saturation voltage IO = 150 mA, VS= 9 V VO 1.0 V
Reverse current IO 0.1 mA
Start delay (Delay time) First bright phase ton 10 ms
Frequency tolerance Normal flashing Df1 -5 +5 %
Basic frequency f1 Df1 47 53 %
Bright period
Control frequency f2 Df2 37 45 %
Frequency increase Lamp outage f2 2.15 ´ f1 2.3 ´ f1 Hz
VS = 15 V, Pin 7 VRs 50 53 57 mV
Control signal threshold VS = 9 V, Pin 7 VRs 43 45 47 mV
VS = 12 V, Pin 7 VRs 47 49 51 mV
Leakage resistance 49a to GND RP 4 5 kW
Lamp load PL 1 W
6 U6043B
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U6043B
Ordering Information
Extended Type Number Package Remarks
U6043B DIP8 –
U6043B-FP SO8 –
Package Information
DIP8
7
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SO8
Package SO8 5.2
Dimensions in mm 4.8
5.00
4.85 3.7
1.4
0.25 0.2
0.4 3.8
0.10
1.27 6.15
3.81 5.85
8 5
technical drawings
according to DIN
specifications
1 4
8 U6043B
4726A–AUTO–06/03
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4726A–AUTO–06/03 xM
