MC33197A Datasheet, PDF (3/8 Pages) Motorola, Inc – Automotive Wash Wiper Timer

Freescale SMeC3m31ic97oAnductor, Inc.
+ Battery Line
Figure 1. Intermittent Wash Wiper Typical Application
Vbb
Washer
Intermittent
Low Speed
High Speed
M
C1
R1
R3
VCC
INT
MC33197A
R4
Out
W/W
Osc2 Osc1 Gnd
C2
R2
Wiper Motor
Low Speed
Wash Wipe
Switch
Water
M
Pump
High Speed
This application shows the MC33197A with the external wirings and two speed
wiper motor. This application has the Intermittent and Wash Wiper functions.
INTRODUCTION
The MC33197A is a wiper timer control device designed
for use in harsh automotive applications. The device can
perform the intermittent, after wash, and continuous wiper
timer functions.
The MC33197A is designed to directly drive a wiper motor
relay. The MC33197A is suitable for both front and rear wiper
applications. The MC33197A connects directly to the
vehicle’s battery voltage (Vbat) through a 220 Ω resistor used
with a 47 µF de–coupling filter capacitor. The device has an
internal oscillator controlled by one of two external resistors
(R2 and R3) in addition to one external capacitor (C2),
dependent on the application function required. The values of
C2 and R2 determine the tb1 time base. Tb1 is used to
generate the relay wiper activation during the INT function
(T3) and the after wash timing (T2) during the wash wipe
mode. The values C2 and R3 determine the tb2 time base.
The tb2 time base is used to generate the pause or
intermittent time (T4).
The intermittent wiper function can generate intermittent
timing (T4) from less than 500 ms to more than 30 seconds.
The intermittent function of the device can be activated by the
INT input connected to either ground or Vbat. The intermittent
timing is externally adjustable by changing the value of
resistor R3.
The wash wiper timer function detects the water pump
motor’s operation. When the pump motor activation is
detected, the MC33197A turns the wiper on for the entire
duration of the pump motor’s activation. When the motor is
turned off, it generates an after wash timing (T2) to maintain
the wiping action. The W/W pin is connected to the water
pump motor through a protection resistor (R4).
The MC33197A also has a continuous function, which
activates the wiper relay whenever the CONT input is
activated. The CONT input is connected to a switch through
a protection resistor (R5). The CONT input comparator has
an input threshold of Vbb/2 with hysteresis.
The device has internal debounce circuitry, based on the
oscillator period. This provides filtering of the intermittent
(INT) and wash wipe (W/W) input signals (see T1 Debounce
Timing paragraph that follows). The device directly drives the
wiper motor relay. It internally incorporates a 20 V free
wheeling zener diode to protect the device against
overvoltage spikes produced when relay is switched off.
Intermittent Operation
Conditions:
• W/W not connected or connected to ground.
• CONT not connected or connected to ground.
• INT connected to Vbb or to ground.
MOTOROLA ANALOG IC DEVICE_FD_oA_rT_MA _{ore Information On This Product,}
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