mc33187d Freescale Semiconductor, Inc, mc33187d Datasheet - Page 3

• Manufacturer Part Number: mc33187d
• Description: Long Duration Automotive Timer
• Manufacturer: Freescale Semiconductor, Inc

Pin 1 : RC
frequency of the clock oscillator. The period of oscillation is
nominally given by t = RtCt with the overall time period given
by T = 4096 RtCt. However, the following formula is believed
to give a more accurate forecast of the overall time interval
provided by the circuit for values of Rt between 200K and 2M
and values of Ct between 1nF and 1uF.
Formula : T = 4.1 10e-3 (RT * (RT/150)*2.7) *CT.
Pin 2 : GND
Pin 3 : RELAY
transistor rated. Icmax = 400mA and Vmax = 18V. The relay
driver output is on (low) during the time period.
minimum of extra components.
similar), illuminated by a lamp in parallel with the rear window
defogger. Rin protects the toggle input from supply line
transients with a nominal of Rin = 10KΩ. The relay is intended
to be a standard automotive relay (Rnom = 60Ω) with contacts
rated appropriately for the defogger controlled. Dz with a
nominal value of 16V +-5% is included to provide protection of
MC33187
Oscillator frequency control. Rt and Ct control the
Ground : Most negative supply terminal.
Relay output driver. Open collector drive from a Darlington
This is the standard operation of this circuit requiring the
The ON/OFF switch is a non-latching push button (or
Defogger
Resistor
Rear
Freescale Semiconductor, Inc.
Batt
For More Information On This Product,
Ct
Figure 1.
Dz
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DEVICE DESCRIPTION
Rt
Rin
.Defogger Timer Operation
MOTOROLA
APPLICATION
MC33187
RC
GND
Relay
Toggle
Pin 4 : TOGGLE
input toggles the timer between the On and Off state. If the
timer is On and timing, it may be turned off by a positive going
signal on the toggle pin before the time delay has elapsed.
Pin 5 : VCC
voltage of 5 to 18V applied to Vcc through Rs. An internal 7V
zener limits the Vcc terminal voltage. Cs is included to provide
supply rail decoupling.
vehicle system are Rs = 1KOhm and Cs = 100nF.
the relay drive output transistor against relay turn-off and
supply lines transients.
protection required. An MZD16 will provide adequate
protection for all relay turn-off and low energy supply
transients, while a P6KE16A will provide full protection against
all known transients. If the relay output is to be connected in
any other way or to a non-standard relay, the maximum ratings
quoted under the General Description above should be noted.
On/Off Control. A positive going voltage transition on this
Positive supply terminal. The timer requires a supply
Recommended values of Rs and Cs on a standard 12V
S1
The type of zener used is dependent of the level of
N / C
N / C
Vcc
TS
Batt
Cs
Rs
Batt
3