MC33197A

3

MOTOROLA ANALOG IC DEVICE DATA

Figure 1. Intermittent Wash Wiper Typical Application

INT

Out

Gnd

V

C2

R2

R3

R1

C1

M

M

W/W

R4

Osc2

Osc1

+ Battery Line

Water

Pump

Wiper Motor

Wash Wipe

Switch

Low Speed

High Speed

MC33197A

Low Speed

High Speed

Intermittent

Washer

This application shows the MC33197A with the external wirings and two speed

wiper motor. This application has the Intermittent and Wash Wiper functions.

V

bb

CC

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:

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com