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TEMIC Semiconductors |
Dual Output Flasher
U2044B
Description
The integrated circuit U2044B is used in relay controlled
automotive flashers. With two output stages each side of
the vehicle is controlled separately. A left and a right
direction indicator input with only a small control current
makes switch contacts for small loads possible.
The separate hazard warning input simplifies the
construction of the hazard switch. Lamp outage is indi-
cated by frequency doubling during direction mode.
Thanks to the extreme low current consumption U2044B
can be connected to the battery directly.
Features
D Temperature and supply voltage compensated
flashing frequency
D Frequency doubling indicates lamp outage
D Two relay driver outputs with high current-carrying
capacity and low saturation voltage
wD Minimum lamp load for flasher operation: 1 W
D Very low susceptibility to EMI
D Protection according to ISO/TR7637/1 level 4
D Extremly low current consumption < 10 mA
(@switches open)
D Reverse polarity protection
D Three control inputs: left, right and hazard warning
Ordering Information
Extended Type Number
U2044B
U2044B-FP
Package
DIP14
SO14
Remarks
Pin Description
Pin Symbol
Function
1 OSC Oscillator
2 SIL Start input left
3 SIR Start input right
4 SIHW Start input hazard warning
5 VS VS
6 CR1 Control input relay 1
7 CR2 Control input relay 2
8 LD Lamp failure detection
9 VS VS
10 GND IC ground
11 OR1 Output relay 1
12 VS VS
13 OR2 Output relay 2
14 OSC Oscillator
OSC 1
SIL 2
SIR 3
14 OSC
13 OR2
12 Vs
SIHW 4 U2044B 11 OR1
VS 5
10 GND
CR1 6
CR2 7
9 VS
8 LD
12750
Figure 1. Pinning
TELEFUNKEN Semiconductors
Rev. A1, 25-Feb-97
1 (6)
U2044B
Block Diagram
mC1
4.7 F
14
R1
82 kW
1
+
–
+
–
K1
VS–81 mV
9
5
8
VRef1
6
+
–
7
+
–
–
+ VRef2
VS /2
WRShunt
30 m
Contact
12
R9
47 kW
R8
47 kW
30
30
VS–6 V
27.5 V
–
+
11 13 GND 10
324
WR2
220
Hazard warning
WR3
4.7 k
12
WR10
1.2 k
30
Relay
12
WR4
4.7 k
WR6
4.7 k
right
15
R5
1.2 kW
R7
1.2 kW
left
31
12700
Figure 2. Application circuit
R2 for protection against continous reversed polarity: 1 Watt
Functional Description
Pin 1 and Pin 14, Oscillator
Flashing frequency, f1, is determined by the R1C1
components as follows (see figure 2):
[f1 R1
where
1
C1
1.5 Hz
C1
+R1
467.8mkFW to 510 kW
In the case of a lamp outage the oscillator frequency is
[switched to the lamp outage frequency f2 with
f2 2.2 f1.
Duty cycle in normal flashing mode: 50%
Duty cycle in lamp outage mode (bright phase): 40%
Pin 2 and Pin 3, Start input right and left
Flashing is disabled as long as the input comparator is tied
zu GND (pull-down resistor R7 or R5). The high side
flasher switch ”left” or ”right” changes the comparator
status and enables the output stage at Pin 11 or Pin 13. R6
and R4 are protection resistors for the input stage.
With an open flasher switch the current consumption is
t monly I 10 A. The IC kept in stand-by mode until there
[is a voltage drop of V 6.9 V at the pull-down resistor.
Direction mode can only be activated when the ignition
switch is in ON-position as shown in figure 2.
Pin 4, Start input hazard warnig
In contrast to the direction switches, the hazard input is
2 (6) TELEFUNKEN Semiconductors
Rev. A1, 25-Feb-97
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