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Электронный компонент: U2044B

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1
Features
Temperature and Supply Voltage Compensated Flashing Frequency
Frequency Doubling Indicates Lamp Outage
Two Relay Driver Outputs with High Current-carrying Capacity and Low Saturation
Voltage
Minimum Lamp Load for Flasher Operation:
1 W
Very Low Susceptibility to EMI
Protection According to ISO/TR7637/1 Level 4
Extremly Low Current Consumption < 10 A (with Switches Open)
Reverse Polarity Protection
Three Control Inputs: Left, Right and Hazard Warning
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 direc-
tion 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 indicated by frequency doubling during direction mode. Thanks to
extreme low current consumption the U2044B can be directly connected to the
battery.
Dual Output
Flasher
U2044B
Rev. 4721AAUTO05/03
2
U2044B
4721AAUTO05/03
Figure 1. Block Diagram
+
-
+
-
+
-
-
+
-
+
27.5 V
+
-
V
Ref2
V
Ref1
V
S
-81 mV
6
7
8
5
9
GND
10
13
11
3
2
4
47 k
12
V
S
/2
R
9
47 k
R
8
R
Shunt
Contact
1
2
14
1
V
S
-6 V
4.7 F
82 k
R
1
C
1
220
R
2
Hazard warning
4.7 k
R
3
4.7 k
R
6
R
4
1.2 k
R
10
right
left
1.2 k
R
7
1.2 k
R
5
1
2
Relay
30
30
30
15
31
12700
30 m
4.7 k
K1
W
W
W
W
W
W
W
W
W
W
W
3
U2044B
4721AAUTO05/03
Pin Configuration
Figure 2. Pinning DIP14/SO14
1
2
3
4
14
13
12
11
OSC
SIR
SIHW
OSC
OR2
OR1
SIL
5
6
7
10
9
8
VS
CR1
CR2
GND
LD
U2044B
VS
VS
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
V
S
6
CR1
Control input relay 1
7
CR2
Control input relay 2
8
LD
Lamp failure detection
9
VS
V
S
10
GND
IC ground
11
OR1
Output relay 1
12
VS
V
S
13
OR2
Output relay 2
14
OSC
Oscillator
4
U2044B
4721AAUTO05/03
Functional Description
Oscillator (Pin 1 and 14)
Flashing frequency, f
1
, is determined by the R
1
C
1
components as follows (see Figure 1):
where
C
1
47 F
R
1
= 6.8 k
W
to 180 k
W
In the case of a lamp outage, the oscillator frequency is switched to the lamp outage fre-
quency f
2
with f
2
2.2
f
1
.
Duty cycle in normal flashing mode:
50%
Duty cycle in lamp outage mode:
40% (bright phase)
Start Input Right and Left
(Pin 2 and 3)
Flashing is disabled as long as the input comparator is tied to GND (pull-down resistor
R
7
or R
5
). The high-side flasher switch left or right changes the comparator status and
enables the output stage at pin 11 or Pin 13. R
6
and R
4
are protection resistors for the
input stage.
With an open flasher switch the current consumption is only I < 10 A. The IC is 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 the ON-position as
shown in Figure 1.
Start Input Hazard
Warning (Pin 4)
In contrast to the direction switches, the hazard input is a low-side type. The pull-up
resistor R
10
provides the off-state. R
3
is a protection resistor for the input stage. Hazard
warning can be activated independent of the ignition switch position.
Supply Voltage Sense
(Pin 5)
This pin supplies the lamp outage comparator at pin 8 and is externally connected to the
battery (Kl 30).
Control Input Relay 1
and 2 (Pin 6 and 7)
The feedback detects the bright phase and the dark phase and enables the oscillator.
Lamp Outage Detection
(Pin 8)
The lamp current is monitored via an external shunt resistor, R
Shunt
and an internal com-
parator, K1, with its reference voltage of typically 81 mV (V
S
=
12 V). The outage of one
lamp out of two lamps is detected according to the following calculation:
Nominal current of 1 lamp: 21 W/(V
S
= 12 V):
I
lamp
= 1.75 A
Nominal current of 2 lamps: 2
21 W / (V
S
= 12 V):
I
lamp
= 3.5 A
We recommend setting the detection threshhold in the middle of the current range:
I
outage
2.7 A
Thus the shunt resistor is calculated as:
R
Shunt
= V
T
(K1)/I
outage
R
Shunt
= 81 mV/2.7 A = 30 m
W
Comparator K1's reference voltage is matched to the characteristics of filament lamps
(see section "Control Signal Threshold").
f
1
1
R
1
C
1
1.5
-----------------------------------
Hz
5
U2044B
4721AAUTO05/03
The combination of the shunt resistor and the resistance of the wire harness prevents
pin 8 from a too high voltage in the case of shorted lamps.
Supply Voltage (Pin 9)
This pin supplies the oscillator, the comparators and the logic parts of the IC.
GND (Pin 10)
The integrated circuit is protected against transients according to ISO-TR 7637-3 level 3
via resistor R
2
to ground (-31). An integrated protection circuit together with external
resistors R
2,
R
3,
R
4,
R
6,
R
8
and R
9
limits the current pulses in the IC. The IC is also pro-
tected against reversed battery.
Control Output Relay 1
and 2 (Pin 11 and 13)
The relay control outputs are high-side drivers with a low saturation voltage and capable
of driving a typical automotive relay with a coil resistance of 60
W.
Supply Voltage Power
(Pin 12)
This pin supplies the relay drivers connected directly to the battery (Kl 30). It is internally
clamped by a 27-V Z-diode.
Absolute Maximum Ratings
Reference point pin 1
Parameters
Symbol
Value
Unit
Supply voltage, 1 min, pins 5, 9 and 12
V
S
24
V
Junction temperature
T
j
150
C
Ambient temperature range
T
amb
-40 to +100
C
Storage temperature range
T
stg
-55 to +150
C
Thermal Resistance
Parameters
Symbol
Value
Unit
Junction ambient, DIP14
Junction ambient, SO14
R
thJA
R
thJA
90
120
K/W
K/W
Electrical Characteristics
Typical values under normal operation in application circuit Figure 1, V
S
(+30) = 12 V.
Reference point ground (-31), T
amb
= 25
C, unless otherwise specified
Parameters
Test Conditions
Symbol
Min.
Typ.
Max.
Unit
Supply voltage range
Pins 5, 9, 12
V
S
8
18
V
Supply current, switches open
Pins 5, 9, 12
I
S
10
A
Output current for relay driver
Pins 11, 13
I
O
300
mA
Saturation voltage
R
L
= 82
W
V
S
= 8 V
V
S
= 12 V
V
O
1.0
1.2
V
V
Relay output reverse current
Pin 11, 13
I
O
0.1
mA
Relay coil resistance
R
L
60
W
Start delay
First bright phase
t
on
10
ms