MC145011P 查看數據表（PDF） - Freescale Semiconductor
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MC145011P
Freescale Semiconductor
MC145011P Datasheet PDF : 12 Pages
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Table 3. AC Electrical Characteristics
(Reference Timing Diagram Figure 6 and Figure 7) (TA = 25°C, VDD = 9.0 V, Component Values from Figure 8: R1 = 100.0 KΩ,
C3 = 1500.0 pF, R2 = 10.0 MΩ)
No.
Characteristic
1 Oscillator Period(1)
Symbol
Test Condition
Min
Max
Unit
1/fOSC Free-Running Sawtooth
9.5
11.5
ms
Measured at Pin 12
2 LED Status
tLED No Local Smoke, and
No Remote Smoke
Illuminated
3
Remote Smoke, but
Illuminated
No Local Smoke
4
Local Smoke or Push
Extinguished
button Test
5 STROBE Pulse Width
6 IRED Pulse Period
7
tW(STB)
9.5
11.5
ms
tIRED Smoke Test
9.67
11.83
s
Chamber Sensitivity Test, 38.9
47.1
without Local Smoke
8
Push button Test
0.302
0.370
9 IRED Pulse Width
10 IRED Rise Time
IRED Fall Time
11 SILVER and BRASS Modulation Period
11, 12 SILVER and BRASS Duty Cycle
13 SILVER and BRASS Chirp Pulse Period
tw(IRED)
94
116
µs
tR
—
30
µs
tF
—
200
tMOD Local or Remote Smoke
297
363
ms
tON/tMOD Local or Remote Smoke
73
77
%
tCH Low Supply or Degraded
38.9
47.1
s
Chamber Sensitivity
14 SILVER and BRASS Chirp Pulse Width
tW(CH) Low Supply or Degraded
9.5
11.5
ms
Chamber Sensitivity
15 Rising Edge on I/O to Smoke Alarm Response Time
16 Strobe Pulse Period
tRR
Remote Smoke,
No Local Smoke
tSTB Smoke Test
—
800
ms
9.67
11.83
s
17
Chamber Sensitivity Test, 38.9
47.1
without Local Smoke
18
Low Supply Test,
38.9
47.1
without Local Smoke
19
Push button Test
0.302
0.370
1. Oscillator period T (= TR + TF) is determined by the external components R1, R2, and C3 where TR = (0.6931) R2 C3 and
TF = (0.6931) R1 C3. The other timing characteristics are some multiple of the oscillator timing as shown in the table.
Table 4. Pin Description
Pin No. Pin Name
Description
1
C1
A capacitor connected to this pin as shown in Figure 8. determines the gain of the on-chip photo amplifier during push
button test and chamber sensitivity test (high gain). The capacitor value is chosen such that the alarm is tripped from
background reflections in the chamber during push button test.
Av ≈ 1 + (C1/10) where C1 is in pF. CAUTION: The value of the closed-loop gain should not exceed 10,000.
2
C2
A capacitor connected to this pin as shown in Figure 8. determines the gain of the on-chip photo amplifier except during
push button or chamber sensitivity tests.
Av ≈ 1 + (C2/10) where C2 is in pF. This gain increases about 10% during the IRED pulse, after two consecutive local
smoke detections.
Resistor R14 must be installed in series with C2. R14 ≈ [1/(12√C2)] - 680 where R14 is in ohms and C2 is in farads.
3
DETECT This input to the high-gain pulse amplifier is tied to the cathode of an external photodiode. The photodiode should have
low capacitance and low dark leakage current. The diode must be shunted by a load resistor and is operated at zero
bias.
The Detect input must be ac/dc decoupled from all other signals, VDD, and VSS. Lead length and/or foil traces to this
pin must be minimized, also. See Figure 9.
MC145011
4
Sensors
Freescale Semiconductor
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