MC33197A Datasheet, PDF (5/8 Pages) Motorola, Inc – Automotive Wash Wiper Timer

Freescale SMeC3m31ic97oAnductor, Inc.
Overvoltage Protection
In reference to the Block Diagram and Typical Application,
all of the foregoing operational cases require:
R1 ≥ 100 Ω, C1 ≥ 47 µF
R3 ≥ 1.0 kΩ, R4 ≥ 4.7 kΩ, R5 ≥ 4.7 kΩ
The circuit will not operate during the transient conditions.
By using the above component values, the circuit will be able
to sustain the following overvoltages on Vbb without
permanent damage:
1. +28 V for 5 minutes
2. –15 V for 5 minutes
3. –16 V cycled off for 1.0 minute
4. +80 V pulse decaying exponentially to 8.0 V in 400 ms
repeated 3 times at 1.0 minute intervals.
5. ± 300 V pulse decaying exponentially to 30 V in 300 ms
with a maximum energy of 1.0 Joule.
6. ±100 V pulse decaying exponentially to 10 V in 2 ms.
Recommended External Component Values
Below are the recommended component values to ensure
the device will operate properly, and that all specified
parameters will stay within their tolerances.
R1 should be greater than 100 Ω; recommended value of
220 Ω. R1 can be up to 500 Ω, but in this case the tb2v
parameter could be out of it’s specified value (see Electrical
Characteristics and Note 1). Also, the minimum operating
voltage range should be greater than 8.0 V. The following
values should be adhered to:
10 kΩ ≤ R2 ≤ 68 kΩ
1.5 kΩ ≤ R3 ≤ 47 kΩ
R4 ≥ 4.7 kΩ
R5 ≥ 4.7 kΩ
C1 ≥ 47 uF
47 nF ≤ C2 ≤ 470 nF
Application Information
The following is an example of timing calculations using
the following external components values:
R2 = 22 kΩ, R3 = 2.2 kΩ, C2 = 100 nF (Referring to Block
Diagram and Typical Application).
Oscillator Time Base Calculation:
tb1 duration = tb1 x 4 x R2 x C2 = 1 x 4 x 27e3 x 100e–9 =
10.8 ms
tb2 duration_g (INT to Gnd) = tb2g x R3 x C2 = 15.5 x 2.2e3
x 100e–9 = 3.41 ms
tb2 duration_v (INT to Vbb) = tb2v x R3 x C2 = 12.1 x 2.2e3
x 100e–9 = 2.66 ms
Intermittent timing calculation:
T3 = 16 x 4 x tb1 duration = 16 x 4 x 10.8 ms = 691 ms
T4 = 144 x 4 x tb2 duration_g = 144 x 4 x 3.41 ms = 1.96 s
(INT connected to Gnd)
T4 = 144 x 4 x tb2 duration_v = 144 x 4 x 2.66 ms = 1.53 s
(INT connected to Vbb)
Wash wipe timing calculation:
T2 = 96 x 4 x tb1 = 96 x 4 x 10.8 ms = 4.15 s
T1 Debounce Time Calculation (see T1 Debounce Timing)
When oscillator is oscillating at tb1:
T1 minimum = 4 x tb1 = 4 x 10.8 ms = 43.2 ms
T1 maximum = 2 x 4 x tb1 = 2 x 4 x 10.8 ms = 86.4 ms
When oscillator is oscillating at tb2:
T1 minimum (INT connected to Gnd, tb2g) = 4 x tb2 = 4 x
3.41 ms = 13.6 ms
T1 maximum (INT connected to Gnd, tb2g) = 2 x 4 x tb2 =
2 x 4 x 3.41 ms = 27.3 ms
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