Features
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Interval Pause: 4 to 20 s
After-wiping Time: 2 to 20 s
Wiper Motor's Park Switch
Wipe/Wash Mode Priority
One External Capacitor Determines All Time Sequences
Relay Driver with Z-diode
Interference Protection According to VDE 0839 or ISO/TR 7637/1
Load-dump Protected
Description
The U642B is a bi-polar integrated circuit designed for the wiper application in the
automotive market. It includes wipe, wash and internal mode.
Functional Description
As a convenience feature of the windshield wiper, intermittent and wipe/wash opera-
tion fuctions are implemented in most of the automobiles. The U642B is a
cost-effective solution for an accurate timing function control. Wipe/wash mode has
priority over interval mode. Interval pause and after-wiping time can be set to fixed val-
ues by using 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.
Figure 1.
Block Diagram
V
S
8
OUT
7
PARK
6
V
Ref
Park switch
comparator
WASH
5
V
Ref
Input
comparator
Interval- and
Wipe/Wash
Wiper Control
IC
U642B
Load-dump
comparator
V
Ref
Logic
V
Ref
Wipe/wash
comparator
Interval
comparator
A
B
C
D
E
F
1
GND
2
INT
3
C
t
4
R
t
Rev. 4774A–AUTO–11/03
ATMEL [ ATMEL CORPORATION ]
