MC145018 View Datasheet(PDF) - Freescale Semiconductor
Part Name
Description
Manufacturer
MC145018
Freescale Semiconductor
MC145018 Datasheet PDF : 8 Pages
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Table 4. Timing Parameters
(C = 0.1 µF, Rbias = 8.2 MΩ, VDD = 9.0 V, TA = 25°C, See Figure 7)
Characteristics
Oscillator Period
No Smoke
Smoke
Oscillator Rise Time
Horn Output
(During Smoke)
On Time
Off Time
LED Output
Between Pulses
On Time
Horn Output
(During Low Battery)
On Time
Between Pulses
Symbol
tCI
tr
PWon
PWoff
tLED
PWon
ton
toff
Min
1.46
37.5
10.1
450
450
35.0
10.1
10.1
35.0
100.0
VDD = 9.0 VDC
10.0
TA = 25°C
10.0
VDD = 7.2 VDC
1.0
VDD = 9.0 VDC or 7.2 VDC
Max
1.85
45.8
12.3
550
550
44.5
12.3
12.3
44.5
Units
s
ms
ms
ms
ms
s
ms
ms
s
TA = 25°C
1.0
0.1
0 1 2 3 4 5 6 7 8 9 10
VDS, Drain To Source Voltage (VDC)
Figure 3. Typical LED Output I-V Characteristic
0.1
P-CH Source
and N-CH
Sink Current
0.01
0 1 2 3 4 5 6 7 8 9 10
VDS, Drain To Source Voltage (VDC)
Figure 4. Typical Comparator Output I-V Characteristic
1000.0
100.0
VDD = 9.0 Vdc
TA = 25°C
1000.0
100.0
VDD = 9.0 Vdc
TA = 25°C
10.0
VDD = 7.2 Vdc
VDD = 7.2 Vdc
10.0
P-CH Source Current
N-CH SInk Current
1.0
1.0
0 1 2 3 4 5 6 7 8 9 10
0 1 2 3 4 5 6 7 8 9 10
VDS, Drain To Source Voltage (Vdc)
VDS, Drain To Source Voltage (Vdc)
Figure 5. Typical P Horn Driver Output I-V Characteristic
DEVICE OPERATION
Timing
The internal oscillator of the MC145018 operates with a
period of 1.65 seconds during no-smoke conditions. Each
1.65 seconds, internal power is applied to the entire IC and a
check is made for smoke, except during LED pulse, Low
Battery Alarm Chirp, or Horn Modulation (in smoke). Every 24
clock cycles a check is made for low battery by comparing
VDD to an internal zener voltage. Since very small currents
are used in the oscillator, the oscillator capacitor should be of
a low leakage type.
Detect Circuitry
If smoke is detected, the oscillator period becomes
41.67 ms and the piezoelectric horn oscillator circuit is
MC145018
4
Sensors
Freescale Semiconductor
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