4–34
Motorola Sensor Device Data
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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
piezoelectric transducer.
The variable–gain photo amplifier allows direct interface to IR detectors
(photo–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 VSS, 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–protected 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
resistors. The supply for the MC145011 must be a dc power source capable of
supplying 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
indicates 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 VDD
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.
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
SEMICONDUCTOR TECHNICAL DATA
P SUFFIX
PLASTIC DIP
CASE 648–08
PIN ASSIGNMENT
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
C1
C2
Detect
Strobe
VDD
IRED
I/O
Brass
Test
Low–Supply
Trip
VSS
R1
Osc
LED
Feedback
Silver
ORDERING INFORMATION
MC145011P
MC145011DW
PLASTIC DIP
SOIC PACKAGE
1
16
DW SUFFIX
PLASTIC SOIC
CASE 751G–03
1
16
REV 3
F
Freescale Semiconductor, Inc.
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