U840B

www.DataSheet4U.com U840B Digital / Wipe-Wash Control for Rear or Front Wiper Description The circuits U840B (DIP8) and U840B-FP (SO8) are designed as interval wipe/ wash timer for automotive applications. The interval pause t3 can be set in a range from 0.8 s to 22 s by an external 30 kW potentiometer. All other time periods are determined by the basic frequency f0 of the oscillator. The wipe/ wash (WIWA) mode has priority over the interval mode. The program Pin PP controls, whether the wiper immediatly starts to wipe, or with a delay time t4 of 0.8 s. The inputs CP and INT are digital debounced, the turn-on as well as the turn-off. The integrated relay driver is protected against short circuits and is switched to conductive condition in the case of a load-dump. The circuit is protected with the recommended external circuitry against load-dump and RF interference, refer to ISO 7637–1/3 (DIN 40839). Features D Interval-switch A and B to GND D Wipe/ wash push button to VBatt D Output driver protected against short circuit digital debounced: t6 = 10 ms D All time periods digital determined by RC-oscillator D Turn-on time of relay t2 = 375 ms D Adjustable interval pause, t3 = 0.8 to 22 s D Dry wiping time t5 = 3.7 s D Program Pin PP determines turn-on delay t4 during wipe-wash mode PP to GND: t4 = 0.8 s PP to VS: t4 = 0 s Interval mode: t4 = 0 s D Inputs CP and INT digital debounced, t1 = 100 ms D All inputs with integrated RF protection D Load-dump protected and interference ...