Sensors
Freescale Semiconductor 9
MC145010
Figure 8. Typical Battery-Powered Application
CALIBRATION
To facilitate checking the sensitivity and calibrating smoke
detectors, the MC145010 can be placed in a calibration
mode. In this mode, certain device pins are controlled/
reconfigured as shown in Table 5. To place the part in the
calibration mode, pin 16 (Test) must be pulled below the V
SS
pin with 100 µA continuously drawn out of the pin for at least
one cycle on the OSC pin. To exit this mode, the Test pin is
floated for at least one OSC cycle.
In the calibration mode, the IRED pulse happens at every
clock cycle and strobe is always on (active low). Also, Low
Battery and supervisory tests are disabled in this mode.
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
Test
Low-supply
Trip
V
SS
R1
OSC
LED
Feedback
Silver
V
DD
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 µF
C6
!
C3
1500 pF
R1
100 k
R3
470
R4
!
100 k
9.0 V
B1
D1
1 TO 22 µF
C4**
C1
0.047 µF
C2*
4700 pF
R14
560 Ω
R11 250 k
D2
IR Detector
R8
8.2 k
R9
†
5.0 k
R10
4.7 k
D3
IR EMITTER
R12
1.0 k
C5
100 µF
!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 µF if B1 is a carbon battery. C4 could be reduced to 1 µF when an alkaline battery is used.
