MC33187D View Datasheet(PDF) - Motorola => Freescale
Part Name
Description
Manufacturer
MC33187D Datasheet PDF : 7 Pages
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Freescale SMeCm33i1c8o7 nductor, Inc.
The circuit shown demonstrates the use of the timer to
As soon as the last switch is opened, the energy stored in
provide a delay in turning the courtesy light off after the the relay coil causes the common connection of the switches
vehicle doors are closed. The components are the same as to rise to the voltage permitted by the clamp consisting of Dz
the defogger timer and Rt, Ct, Rs and Cs are as described in (approximately 16V).
the general description above, while Dz and Rin are
This provides a toggle input via Rin, causing the relay
described in the description of the defogger timer. S1 to Sn output of the integrated circuit to go low, thus keeping the
represent the doors switches which can be basically the relay energised for the period preset, with the direct
same as for a conventional system, except that only the relay connection to Rin ensuring that any switch bounce or noise
coil current and not the full lamp current passes through during this period cannot cause toggle input to be detected.
them.
Retriggering at the end of the timing period is prevented by
The operation of the circuit is as follows :
the built in the debounce timer.
While one of the door switches is closed, the courtesy
light is on with the relay current flowing through the switch.
Figure 2. Courtesy Light Timer Operation
Ct
Rt
Cs
Batt
RC
TS
GND
N/C
Relay
N/C
Batt
Rin
Rs
S1
Sn
Toggle
Vcc
Dz
MC33187
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