Freescale Semiconductor
Technical Data
MC145011
Rev 4, 05/2005
Photoelectric Smoke Detector IC
with I/O For Line-Powered
Applications
The CMOS MC145011 is an advanced smoke detector component containing
sophisticated very-low-power analog and digital circuitry. The IC is used with an
infrared photoelectric chamber. Detection is accomplished by sensing scattered
light from minute smoke particles or other aerosols. When detection occurs, a
pulsating alarm is sounded via on-chip push-pull drivers and an external piezo-
electric transducer.
The variable-gain photo amplifier allows direct interface to IR detectors (pho-
to-diodes). Two external capacitors C1 and C2, C1 being the larger, determine
the gain settings. Low gain is selected by the IC during most of the standby state.
Medium gain is selected during a local-smoke condition. High gain is used during
pushbutton test. During standby, the special monitor circuit which periodically
checks for degraded chamber sensitivity uses high gain, also.
The I/O pin, in combination with V
SS
, can be used to interconnect up to 40
units for common signaling. An on-chip current sink provides noise immunity
when the I/O is an input. A local-smoke condition activates the short-circuit-pro-
tected I/O driver, thereby signaling remote smoke to the interconnected units.
Additionally, the I/O pin can be used to activate escape lights, enable auxiliary or
remote alarms, and/or initiate auto-dialers.
While in standby, the low-supply detection circuitry conducts periodic checks
using a load current from the LED pin. The trip point is set using two external re-
sistors. The supply for the MC145011 must be a dc power source capable of sup-
plying 35 mA continuously and 45 mA peak. When the MC145011 is in standby,
an external LED is continuously illuminated to indicate that the device is receiving
power.
An extinguished LED accompanied by a pulsating audible alarm indicates a
local-smoke condition. A pulsating audible alarm with the LED illuminated indi-
cates a remote-smoke condition. A beep or chirp indicates a low-supply condition
or degraded chamber sensitivity. A low-supply condition does not affect the
smoke detection capability if V
DD
≥
6 V. Therefore, the low-supply condition and
degraded chamber sensitivity can be distinguished by performing a pushbutton
(chamber) test. This circuit is designed to operate in smoke detector systems
that comply with UL217 and UL268 specifications.
Features
•
•
•
•
•
•
Operating Voltage Range: 6 to 12 V
Operating Temperature Range: -10 to 60°C
Average Standby Supply Current (Visible LED Illuminated): 20 mA
Power-On Reset Places IC in Standby Mode (Non-Alarm State)
Electrostatic Discharge (ESD) and Latch Up Protection Circuitry on All Pins
Chip Complexity: 2000 FETs, 12 NPNs, 16 Resistors, and 10 Capacitors
ORDERING INFORMATION
Device
MC145011P
MC145011DW
Package
Plastic Dip
Soic Package
MC145011
PHOTOELECTRIC SMOKE
DETECTOR IC WITH I/O FOR
LINE-POWERED APPLICATIONS
P SUFFIX
PLASTIC DIP
CASE 648-08
DW SUFFIX
PLASTIC SOIC
CASE 751G-04
C1 1
C2 2
Detect 3
Strobe 4
V
DD
5
IRED 6
I/O 7
Brass 8
16 Test
Low-Supply
15
Trip
14 V
SS
13 R1
12 Osc
11 LED
10 Feedback
9 Silver
Figure 1. Pin Connections
© Freescale Semiconductor, Inc., 2005. All rights reserved.
C1 C2
1 2
Detect
3
AMP
V
DD
- 3.5 V
REF
GAIN
GATE
ON/OFF
-
COMP
+
Smoke
7
Alarm
Logic
LOW SUPPLY
I/O
ZERO
OSC
R1
Test
12 OSC
13
16
Horn Modulator
And Driver
8
9
10
6
11
Timing
Logic
Brass
Silver
Feedback
IRED
LED
Gate
On/Off
V
DD
- 5 V
REF
-
COMP
+
Strobe
Low-supply
Trip
4
15
PIN 5 = V
DD
PIN 14 = V
SS
Figure 2. Block Diagram
Table 1. Maximum Ratings
(1)
(Voltages referenced to V
SS
)
Parameter
DC Supply Voltage
DC Input Voltage
C1, C2, Detect
Osc, Low-Supply Trip
I/O
Feedback
Test
Symbol
V
DD
V
in
Value
-0.5
to +12
-0.25
to V
DD
+0.25
-0.25
to V
DD
+0.25
-0.25
to V
DD
+10
-15
to +25
-1.0
to V
DD
+0.25
±10
±25
+25 / -150
1200
(2)
350
(3)
-55
to +125
260
Unit
V
V
DC Input Current, per Pin
DC Output Current, per Pin
DC Supply Current, V
DD
and V
SS
Pins
Power Dissipation in Still Air
Storage Temperature
Lead Temperature, 1 mm from Case for 10 Seconds
5 Seconds
Continuous
I
in
I
out
I
DD
P
D
T
stg
T
L
mA
mA
mA
mW
°C
°C
1. Maximum Ratings are those values beyond which damage to the device may occur. Functional operation should be restricted to the limits
in the Electrical Characteristics tables.
2. Derating: -12 mW/°C from 25° to 60°C.
3.
Derating: - 3.5 mW/°C from 25° to 60°C.
This device contains protection circuitry to guard against damage due to high static voltages or electric fields. However, precautions must
be taken to avoid applications of any voltage higher than maximum rated voltages to this high-impedance circuit. For proper operation, V
in
and V
out
should be constrained to the range V
SS
≤
(V
in
or V
out
)
≤
V
DD
except for the I/O, which can exceed V
DD
, and the Test input, which
can go below V
SS
.
Unused inputs must always be tied to an appropriate logic voltage level (e.g., either V
SS
or V
DD
). Unused outputs and/or an unused I/O
must be left open.
MC145011
2
Sensors
Freescale Semiconductor
Table 2. Electrical Characteristics
(T
A
= -10 to 60°C Unless Otherwise Indicated, Voltages Referenced to V
SS
)
Characteristic
Power Supply Voltage Range
Supply Threshold Voltage, Low-Supply Alarm
Average Operating Supply Current,
Excluding the Visible LED Current
(per Package)
Peak Supply Current,
Excluding the Visible LED Current
(per Package)
Symbol
V
DD
V
TH
I
DD
Low-Supply Trip: V
in
= V
DD
/3
Standby
Configured per
Figure 8
During Strobe On, IRED Off
Configured per
Figure 8
During Strobe On, IRED On
Configured per
Figure 8
I/O
Feedback
Test
I/O
Feedback
Test
Osc, Detect
Low-Supply Trip
Feedback
Test
Test
I/O
LED
Silver, Brass
Silver, Brass
Strobe
V
IL
Test Condition
V
DD
/V
DC
—
—
12.0
Min
6.0
6.5
—
Max
12
7.8
12
Unit
V
V
µA
i
DD
12.0
12.0
9.0
9.0
9.0
9.0
9.0
9.0
—
—
—
—
—
3.2
6.3
8.5
—
—
—
—
0.5
25
—
—
—
5.5
V
DD
- 0.1
V
DD
- 4.4
—
2.25
(1)
-4
—
—
V
DD
- 4
V
DD
-
3.08
2.0
3.0
1.5
2.7
7.0
—
—
—
±100
±100
±
00
-1
10
100
140
0.6
1.0
—
—
V
DD
- 5.6
0.1
3.75
(1)
—
-16
±1
V
DD
- 2
V
DD
- 3.92
mA
Low-Level Input Voltage
V
High-Level Input Voltage
V
IH
V
Input Current
I
in
V
in
= V
SS
or V
DD
V
in
= V
SS
or V
DD
V
in
= V
SS
or V
DD
V
in
= V
SS
V
in
= V
DD
No Local Smoke, V
in
= V
DD
No Local Smoke, V
in
= 17 V
I
out
= 10 mA
I
out
= 16 mA
I
out
= -16 mA
Inactive, I
out
= -1
µA
Active, I
out
= 100
µA
to 500
µA
(Load Regulation)
Inactive, I
out
= 1
µA
Active, I
out
= 6 mA
(Load Regulation)
12.0
12.0
12.0
12.0
9.0
9.0
12.0
6.5
6.5
6.5
—
9.0
—
9.0
6.5
12.0
12.0
—
—
nA
Low-Level Input Current
Pull-Down Current
I
IL
I
IH
µA
µA
Low-Level Output Voltage
High-Level Output Voltage
Output Voltage
(For Line Regulation, see
Pin Descriptions)
V
OL
V
OH
V
out
V
V
V
IRED
High-Level Output Current
I/O
I
OH
Local Smoke, V
out
= 4.5 V
Local Smoke, V
out
= V
SS
(Short Circuit Current)
mA
Off-State Output Leakage Current
Common Mode
Voltage Range
Smoke Comparator
Reference Voltage
1. T
A
= 25°C only.
LED
I
OZ
V
IC
V
ref
V
out
= V
SS
or V
DD
Local Smoke, Pushbutton Test, or
Chamber Sensitivity Test
Local Smoke, Pushbutton Test, or
Chamber Sensitivity Test
µA
V
V
C1, C2, Detect
Internal
MC145011
Sensors
Freescale Semiconductor
3
Table 3. AC Electrical Characteristics
(Reference Timing Diagram
Figure 6
and
Figure 7)
(T
A
= 25°C, V
DD
= 9.0 V, Component Values from
Figure 8:
R1 = 100.0 KΩ,
C3 = 1500.0 pF, R2 = 10.0 MΩ)
No.
1
2
3
4
5
6
7
8
9
10
IRED Pulse Width
IRED Rise Time
IRED Fall Time
11
11, 12
13
14
15
16
17
18
19
Silver and Brass Modulation Period
Silver and Brass Duty Cycle
Silver and Brass Chirp Pulse Period
Silver and Brass Chirp Pulse Width
Rising Edge on I/O to Smoke Alarm Response Time
Strobe Pulse Period
t
w(IRED)
t
r
t
f
t
mod
t
on
/t
mod
t
CH
t
w(CH)
t
RR
t
stb
Local or Remote Smoke
Local or Remote Smoke
Low Supply or Degraded
Chamber Sensitivity
Low Supply or Degraded
Chamber Sensitivity
Remote Smoke,
No Local Smoke
Smoke Test
Chamber Sensitivity Test,
without Local Smoke
Low Supply Test,
without Local Smoke
Pushbutton Test
Strobe Pulse Width
IRED Pulse Period
t
w(stb)
t
IRED
Smoke Test
Chamber Sensitivity Test,
without Local Smoke
Pushbutton Test
Oscillator Period
(1)
LED Status
Characteristic
Symbol
1/f
osc
t
LED
Test Condition
Free-Running Sawtooth
Measured at Pin 12
No Local Smoke, and
No Remote Smoke
Remote Smoke, but
No Local Smoke
Local Smoke or
Pushbutton Test
Min
9.5
Max
11.5
Unit
ms
Illuminated
Illuminated
Extinguished
9.5
9.67
38.9
0.302
94
—
—
297
73
38.9
9.5
—
9.67
38.9
38.9
0.302
11.5
11.83
47.1
0.370
116
30
200
363
77
47.1
11.5
800
11.83
47.1
47.1
0.370
ms
%
s
ms
ms
s
µs
µs
ms
s
1. Oscillator period T (= T
r
+ T
f
) is determined by the external components R1, R2, and C3 where T
r
= (0.6931) R2 C3 and
T
f
= (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.
1
Pin Name
C1
Description
A capacitor connected to this pin as shown in
Figure 8.
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.
A
v
≈
1 + (C1/10) where C1 is in pF. CAUTION: The value of the closed-loop gain should not exceed 10,000.
A capacitor connected to this pin as shown in
Figure 8.
determines the gain of the on-chip photo amplifier except during
pushbutton or chamber sensitivity tests.
A
v
≈
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.
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, V
DD
, and V
SS
. Lead length and/or foil traces to this pin
must be minimized, also. See
Figure 9.
2
C2
3
DETECT
MC145011
4
Sensors
Freescale Semiconductor
Table 4. Pin Description
Pin No.
4
Pin Name
STROBE
(Continued)
Description
This output provides a strobed, regulated voltage referenced to V
DD
. 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.
This pin is connected to the positive supply potential and may range from + 6 to + 12 V with respect to V
SS
.
This output provides pulsed base current for external NPN transistor Q1 used as the infrared emitter driver. Q1 must
have
β ≥
100. At 10 mA, the temperature coefficient of the output voltage is typically + 0.5%/°C from - 10° to 60°C. The
supply-voltage coefficient (line regulation) is
±
0.2%/V maximum from 6 to 12 V. The IRED pulse width (active-high) is
determined by external components R1 and C3. With a 100 kΩ/1500 pF combination, the nominal width is 105
µs.
To minimize noise impact, IRED is not active when the visible LED and horn outputs are active. IRED is active near the
end of Strobe pulses for Smoke Tests, Chamber Sensitivity Test, and Pushbutton Test.
This pin can be used to connect up to 40 units together in a wired-OR configuration for common signaling. V
SS
is used
as the return. An on-chip current sink minimizes noise pick up during non-smoke conditions and eliminates the need for
an external pull-down resistor to complete the wired-OR. Remote units at lower supply voltages do not draw excessive
current from a sending unit at a higher supply voltage.
I/O can also be used to activate escape lights, auxiliary alarms, remote alarms, and/or auto-dialers.
As an input, this pin feeds a positive-edge-triggered flip-flop whose output is sampled nominally every 625 ms during
standby (using the recommended component values). A local-smoke condition or the pushbutton-test mode forces this
current-limited output to source current. All input signals are ignored when I/O is sourcing current.
If unused, I/O must be left unconnected.
This half of the push-pull driver output is connected to the metal support electrode of a piezoelectric audio transducer
and to the horn-starting resistor. A continuous modulated tone from the transducer is a smoke alarm indicating either
local or remote smoke. A short beep or chirp is a trouble alarm indicating a low supply or degraded chamber sensitivity.
This half of the push-pull driver output is connected to the ceramic electrode of a piezoelectric transducer and to the
horn-starting capacitor.
5
6
VDD
IRED
7
I/O
8
BRASS
9
10
11
SILVER
FEEDBACK This input is connected to both the feedback electrode of a self-resonating piezoelectric transducer and the horn-starting
resistor and capacitor through current-limiting resistor R4. If unused, this pin must be tied to V
SS
or V
DD
.
LED
This active-low open-drain output directly drives an external visible LED.
The load for the low-supply test is applied by this output. This low-supply test is non-coincident with the smoke tests,
chamber sensitivity test, pushbutton test, or any alarm signals.
The LED also provides a visual indication of the detector status as follows, assuming the component values shown in
Figure 8:
Standby (includes low-supply and chamber sensitivity tests) - constantly illuminated
Local Smoke - constantly extinguished
Remote Smoke - constantly illuminated
Pushbutton Test - constantly extinguished (system OK); constantly illuminated (system problem)
This pin is used in conjunction with external resistor R2 (10 MΩ) to V
DD
and external capacitor C3 (1500 pF) to V
DD
to
form an oscillator with a nominal period of 10.5 ms.
This pin is used in conjunction with resistor R1 (100 kΩ) to pin 12 and C3 (1500 pF, see pin 12 description) to determine
the IRED pulse width. With this RC combination, the nominal pulse width is 105
µs.
This pin is the negative supply potential and the return for the I/O pin. Pin 14 is usually tied to ground.
This pin is connected to an external voltage which determines the low-supply alarm threshold. The trip voltage is
obtained through a resistor divider connected between the V
DD
and LED pins. The low-supply alarm threshold voltage
(in volts)
≈
(5R7/R6) + 5 where R6 and R7 are in the same units.
This input has an on-chip pull-down device and is used to manually invoke a test mode.
The
Pushbutton Test
mode is initiated by a high level at pin 16 (usually depression of a S.P.S.T. normally-open
pushbutton switch to V
DD
). After one oscillator cycle, IRED pulses approximately every 336 ms, regardless of the
presence of smoke. Additionally, the amplifier gain is increased by automatic selection of C1. Therefore, the background
reflections in the smoke chamber may be interpreted as smoke, generating a simulated-smoke condition. After the
second IRED pulse, a successful test activates the horn-driver and I/O circuits. The active I/O allows remote signaling
for system testing. When the Pushbutton Test switch is released, the Test input returns to V
SS
due to the on-chip pull-
down device. After one oscillator cycle, the amplifier gain returns to normal, thereby removing the simulated-smoke
condition. After two additional IRED pulses, less than a second, the IC exits the alarm mode and returns to standby
timing.
12
13
14
15
OSC
R1
VSS
LOW-
SUPPLY
TRIP
TEST
16
MC145011
Sensors
Freescale Semiconductor
5
WindowsCE
