MC145012P Ver la hoja de datos (PDF) - Freescale Semiconductor
Número de pieza
componentes Descripción
Fabricante
MC145012P
Freescale Semiconductor
MC145012P Datasheet PDF : 14 Pages
| |||
C1
0.047 µF
C2(10)
4700 pF
1 TO 22 µF +
C4(12)
R8
8.2 k
R9(11)
5k
R10
4.7 k
1
C1
R14
560 Ω
2
C2
R11 250 k
3
DETECT
D2
IR Detector
4 STROBE
Reverse
9V
B1
D1
Polarity
Protection
Circuit
16
TEST
LOW-SUPPLY 15
TRIP
MC145012
14
VSS
13
R1
R12
1k
C5 +
100 µF
D3
5
VDD
IR Emitter
Q1
IR R13(10)
Current 4.7 TO 22
6
IRED
7
I/O
12
OSC
11
LED
10
FEEDBACK
To Other
MC145012(s),
Escape Light(S),
Auxiliary Alarm(S),
Remote Alarm(S),
And/or Auto-dialer
8
BRASS
9
SILVER
SW1
Pushbutton
Test
R6
100 k
R7
47 k
R1
100 k
C3
1500 pF
R2
7.5 M
R3
470
D4
Visible
LED
0.01 µF
C6 (9)
R4 (9)
100 k
Horn
X1
2.2 M
R5(9)
9. Values for R4, R5, and C6 may differ depending on type of piezoelectric horn used.
10.C2 and R13 are used for coarse sensitivity adjustment. Typical values are shown.
11.R9 is for fine sensitivity adjustment (optional). If fixed resistors are used, R8 = 12 k, R10 is 5.6 k to 10 k, and R9 is eliminated.
When R9 is used, noise pickup is increased due to antenna effects. Shielding may be required.
12.C4 should be 22 µF if B1 is a carbon battery. C4 could be reduced to 1 µF when an alkaline battery is used.
Figure 8. Typical Battery-Powered Application
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.
Sensors
Freescale Semiconductor
MC145012
9
Share Link: