TEMIC U642B Datasheet
U642B
TELEFUNKEN Semiconductors
Rev . A1, 13-Feb-97
1 (6)
Automotive Wipe/Wash or Interval Switch
Description
As a convenience feature of the windshield wiper intermittent and wipe/wash operation are implemented in
most of the automobiles. The U642B controls all timing
functions accurately at a reasonable price level. Interval
pause and afterwiping time can be set to fixed values with
the help of resistors in a broad time range. Added value
can be provided with an individual, continuous adjustment of the interval pause by a potentiometer which may
be built into the stalk. For proper operation it is mandatory
to feed the signal of the wiper motor‘s park switch into
U642B.
Features
D
Interval pause: 4 to 20 s
D
Afterwiping time: 2 to 20 s
D
Wiper motor’s park switch
D
Wipe/wash mode priority
D
One external capacitor, determines all time sequences
D
Relay driver with Z-diode
D
Interference protection according to VDE 0839 or
ISO/TR 7637/1
D
Load-dump protected
Ordering Information
Extended Type Number Package Remarks
U642B DIP8
U642B–FP SO8
Block Diagram
Wipe / wash
comparator
Interval
comparator
Load-dump
comparator
V
Ref
V
Ref
V
Ref
Input
comparator
Park switch
comparator
V
Ref
8
7
6
5
4
1
23
ABC DEF
Logic
V
S
Relay control
S
1
WI WA
Timing (R)
GND Interval switch
Timing (C2)
94 8950
Figure 1. Block diagram
U642B
TELEFUNKEN Semiconductors
Rev . A1, 13-Feb-97
2 (6)
Pin Configuration
Pin Symbol Function
1 GND Ground
2 Input 1 Interval switch
3 t
c
Timing capacitor C
2
4 R
4
Afterwiping time resistance
5 WIWA Wipe/Wash switch
6 S
1
Park switch for wiper motor
7 RELAY Relay control output
8 +V
Batt
Supply voltage KI. 15
+V
Batt
RELAY
WIWA
GND
Input 1
R
4
t
c
1
2
3
4
8
7
6
5
U642B
93 7691
S
1
Figure 2. Pinning
Circuit Description
Interval Function, Pin 2
By closing the internal switch, S2, to supply voltage,
+V
Batt
, the motor is activated. The internal current source
(Pin 3) which holds the capacitor C
2
in charged state is
switched-OFF. As soon as there is a positive potential at
the park switch (S
1
), current source F (see figure 1)
charges the capacitor C
2
very fast. After the wiper
operation is finished, S
1
is again at ground potential, the
relay is in OFF position – interval pause begins – the
capacitor C
2
is discharged through the current source C,
till the voltage at Pin 3 is below the threshold of 2 V.
Interval pause can be adjusted between 4 s to 20 s with the
help of potentiometer R
3
. Now the relay switches ON and
the next interval cycle begins. Opening switch S
2
causes
current source A to discharge C
2
immediately and current
sources C and F are switched-OFF.
Wipe/Wash (WIWA) Operation, Pin 5
By closing the WIWA-switch, S3, to supply voltage,
+V
Batt
, water pump starts spraying the water on the windscreen, the current source A is switched-OFF which keeps
the capacitor C
2
in discharged state. Now the capacitor is
charged through the current sources D and F , and when after a time interval of approximately 100 ms, the voltage
at the capacitor is greater than 6.5 V, the relay is turned
on as long as the switch ”WIWA” is closed.
The after-wipe-time begins after the switch is open
whereas the sources D and F are switched OFF and the
source E is activated. Source E discharges the capacitor
till the voltage is less than 2.2 V. The relay is OFF and the
wiper-motor is switched OFF. The after-wipe-time is
determined by the current source E which can be
regulated with the external resistor R
Time
. Afterwards the
source A discharges the capacitor. Relay switch OFF is
independent of the park switch S
1
.
Interval and WIWA Functions
The interval function is interrupted immediately when the
switch S
2
is activated. The current source A discharges
the capacitor to a value of 2 V, afterwards the normal S
2
function starts.
Interval wiping starts immediately when the after-wipe-
time is over. The switching delays are slightly shorter,
because the capacitor is already charged to a value of 2 V.
The Wipe/Wash function is not interrupted when interval
switch S
2
is activated. Interval function begins after the
WIWA function is over.
Loading...