4–31
Motorola Sensor Device Data
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16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
TEST
LOW–SUPPLY
TRIP
VSS
R1
OSC
LED
FEEDBACK
SILVER
VDD
IRED
I/O
BRASS
STROBE
DETECT
C1
C2
HORN
X1
TO OTHER
MC145010(s),
ESCAPE LIGHT(S),
AUXILIARY ALARM(S),
REMOTE ALARM(S),
AND/OR AUTO–DIALER
IR
CURRENT
R13*
4.7 TO 22
Q1
2.2 M
R5
D4
VISIBLE
LED
R7
47 k
R6
100 k
SW1
+
+
MC145010
REVERSE POLARITY
PROTECTION
CIRCUIT
PUSHBUTTON
TEST
R2
10 M
0.01
μ
F
C6
C3
1500 pF
R1
100 k
R3
470
R4
100 k
9 V
B1
D1
1 TO 22
μ
F
C4**
C1
0.047
μ
F
C2*
4700 pF
R14
560
R11 250 k
D2
IR DETECTOR
R8
8.2 k
R9
5 k
R10
4.7 k
D3
IR EMITTER
R12
1 k
C5
100
μ
F
Values for R4, R5, and C6 may differ depending on type of piezoelectric horn used.
* C2 and R13 are used for coarse sensitivity adjustment. Typical values are shown.
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.
**C4 should be 22
μ
F if B1 is a carbon battery. C4 could be reduced to 1
μ
F when an alkaline battery is used.
Figure 5. Typical Battery–Powered Application
PIN DESCRIPTIONS
C1 (Pin 1)
A capacitor connected to this pin as shown in Figure 5
determines the gain of the on–chip photo amplifier during
pushbutton 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 pushbutton
test.
Av
≈
1 + (C1/10) where C1 is in pF. CAUTION: The value
of the closed–loop gain should not exceed 10,000.
C2 (Pin 2)
A capacitor connected to this pin as shown in Figure 5
determines the gain of the on–chip photo amplifier except
during pushbutton 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.
DETECT (Pin 3)
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 6.
STROBE (Pin 4)
This output provides a strobed, regulated voltage refer-
enced to VDD. The temperature coefficient of this voltage is
±
0.2%/
°
C maximum from – 10
°
to 60
°
C. The supply–voltage
coefficient (line regulation) is
±
0.2%/V maximum from 6 to
12 V. Strobe is tied to external resistor string R8, R9, and
R10.
F
Freescale Semiconductor, Inc.
n
.