MC33197A Datasheet, PDF (4/8 Pages) Motorola, Inc – Automotive Wash Wiper Timer

Freescale SMeC3m31ic97oAnductor, Inc.
In this configuration, the circuit will respond to the
switching of INT to either Vbb or ground after a time T1 (see
T1 Debounce Timing). If INT is disconnected before the end
of T1; no action will be taken. After a time T1, the output will
be switched on for a duration, T3 = 16 x 4 x tb1 and then
switched off for a duration, T4 = 144 x 4 x tb2. This sequence
will continue to repeat so long as INT is disconnected from
Vbb or ground for a time duration greater than T1. If INT is
disconnected during the time T3; the output will remain on for
the remainder of T3. This is illustrated in the diagram on
Figure 2.
Figure 2. Switching Waveform INT Timing
INT
Wash Wiper and Intermittent Operation
If W/W is activated during the time INT is also activated,
the circuit will respond to W/W after a time T1 (see T1
Debounce Timing). The output will turn on after T1, and stay
on for a time T2 + T3 after W/W is deactivated. Following this,
normal operation of INT will occur. This is shown on Figure 4.
Figure 4. Switching Waveform W/W and INT Active
INT
W/W
Out
Out
T1
T3
T4
Wash Wipe Operation
Conditions:
• INT disconnected.
• CONT disconnected or connected to ground.
In this condition, the circuit will respond to the switching of
W/W to Vbb after a time T1 (see T1 Debounce Timing). If
W/W is disconnected or connected to ground before the end
of T1; no action will be taken. After a time T1; the circuit will
perform as shown on Figure 3. The output will turn on and
remain on for the duration of W/W. When W/W becomes
inactive, the output will remain on for T2 = 96 x 4 x tb1.
Figure 3. Switching Waveform W/W Timing
W/W
Out
T1
T4
T3
T3
T2
T1 Debounce Timing
The criteria for an input signal to be detected is that it
should be active at two successive negative internal clock
edges. The inputs are sampled on the negative edge of the
internal clock. If two consecutive samples are the same, the
input is detected as being in that state. Hence the time T1 from
a signal becoming active to the time that the circuit responds
can be anytime from 4 x tb1 to 2 x 4 x tb1 (due to synchronizing
the input to the oscillator period) when the oscillator is
oscillating with a time base of tb1 and 4 x tb2 to 2 x 4 x tb2, when
the oscillator is oscillating with a time base of tb2.
The following table summarizes all T1 debounce timings:
Condition
INT Active
INT Inactive
W/W Active When INT Inactive
W/W Active When INT Active During T3
W/W Active When INT Active During T4
Debounce Time
4 x tb1 to 2 x 4 x tb1
4 x tb1 to 2 x 4 x tb1
4 x tb1 to 2 x 4 x tb1
4 x tb1 to 2 x 4 x tb1
4 x tb2 to 2 x 4 x tb2
T1
T2
Continuous Operation
In this condition, the circuit responds to the switching of
CONT to Vbb. If CONT is connected to Vbb, the output will
turn on regardless of the state of any other input and remain
on so long as CONT is active. This command operates
directly on the relay output and does not interfere with any
other timing. Therefore, the circuit will not be reset to a
defined state.
Two MC33197A Devices Using One Decoupling
Resistor and Capacitor
Two devices may be connected to the power source using
a common R1 resistor for protection against overvoltages. If
this is done it should be noted that the current flowing
through R1 is increased and hence the voltage drop across
R1 is increased.
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MOTOROLA ANALOG IC DEVICE DATA
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