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TEMIC Semiconductors
TEMIC Semiconductors

U243B-FP Datasheet Preview

U243B-FP Datasheet

Warning or Car-Direction Indicator

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U243B-FP pdf
Warning or Car-Direction Indicator
Technology: Bipolar
U243B
Features
D Can be protected against damage or interference with
a minimum of external circuitry
D Temperature- and voltage-compensated frequency
D Warning indication of lamp failure by means of
frequency doubling
D Voltage dependence of the car indicator lamps also
compensated for lamp failure
D Relay output with high-current carrying capacity and
low saturation voltage
Figure 1. Application circuit as a car flasher
(Resistor R1, R2 and Rt: 1/4 Watt
R1 for protection against continuous reversed polarity: 2 Watt)
Order Information
Extended Type Number
U243B
U243B-FP
Package
8 pin dual-inline plastic
8 pin SO plastic
Remarks
TELEFUNKEN Semiconductors
Rev. A1, 05-Sep-96
Preliminary Information
1 (6)



TEMIC Semiconductors
TEMIC Semiconductors

U243B-FP Datasheet Preview

U243B-FP Datasheet

Warning or Car-Direction Indicator

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U243B-FP pdf
U243B
Circuit Description
The application circuit shows the operation of the U243B
as a car-direction indicator signal generator. The flashing
frequency is determined by the components Rt and Ct, and
the frequency can be calculated from
1
f1
(Hz)
Rt Ct 1.5
where f1 is the frequency in normal flashing operation
(basic frequency). The control frequency f2 is typically
2.2 times the value of f1 and is the frequency in the case
of lamp failure. The bright periods for f1 and f2 are inter-
nally set in the IC and are 50% for f1 and 40% for f2.
The resistors R1 and R2 are needed to protect the circuit
against possible damage. An integrated Z-diode in addi-
tion to these external resistors limits the impulse current
in the integrated circuit to 1.5 A. Connecting the circuit
with the wrong polarity leads to current limitation by R1,
R2 and the resistance of the coil of the relay. A current of
about 150 mA would then flow over R1, so that for unlim-
ited protection against continuous reversal of the polarity
of the supply, a 2-W resistor would be necessary. A short
circuit between the indicator lamp (49a) and ground (31)
can give rise to a voltage drop of about 4 V across the
measuring resistance, R3. The circuit is not damaged by
such a short circuit.
The use of this application circuit ensures damage and
interference protection accordance to VDE 0839. The
recognition point for lamp failure can be calculated from
the control signal threshold, typically 81 mV with
VS = 12 V.
WWith 81 mV and a measuring resistance of R3 = 30 m ,
it corresponds to a lamp current of 2.7 A, i.e., the
frequency change-over with a lamp load of 21 W
+ 11.4 W. The variation of the control-signal threshold
with the supply voltage takes into account the PTC char-
Wacteristic of the filament lamps. A resistance Rp 5 k
between the lamp indicator (49a) and ground (31) ensures
that in case the direction indicator switch is open, the
flashing generator is in stand-by mode.
With a control lamp of max. 4 W between 49 and 49a the
IC still starts with the bright phase.
The arrangement of the supply connections to Pins 2 and
6 must be such as to ensure that, on the connection PCB,
the resistance of VS to Pin 6 is lower than that to Pin 2.
Defined operation is ensured with a lamp load of
PL 10 W or more. Defined operation with lamp loads
2 W require an additional external resistance as
described in “Applications”. With considerably reduced
external circuitry, the integrated circuit U243B can be
used as an instable multivibrator in the frequency range
f = 0.05 to 10 Hz.
Absolute Maximum Ratings
Reference point Pin 1
Parameters
Supply voltage
Surge forward current
tp = 0.1 ms
tp = 2 ms
tp = 2 ms
Output current
Power dissipation
Tamb = 95°C
DIP8
SO8
Tamb = 60°C
DIP8
SO8
Junction temperature
Ambient temperature range
Storage temperature range
Pins 2 and 6
Pins 2 and 6
Pins 2 and 6
Pin 8
Pin 3
Symbol
VS
IFSM
IFSM
IFSM
Io
Ptot
Ptot
Ptot
Ptot
Tj
Tamb
Tstg
Value
16.5
1.5
1.0
50
0.3
420
340
690
560
150
–40 to +95
–55 to +125
Unit
V
A
A
mA
A
mW
mW
mW
mW
°C
°C
°C
2 (6) TELEFUNKEN Semiconductors
Preliminary Information
Rev. A1, 05-Sep-96


Part Number U243B-FP
Description Warning or Car-Direction Indicator
Maker TEMIC Semiconductors
Total Page 6 Pages
PDF Download
U243B-FP pdf
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