Freescale Semiconductor
Technical Data
Document Number: MC145012
Rev 9.0, 11/2006
Photoelectric Smoke Detector IC with
I/O and Temporal Pattern Horn Driver
The CMOS MC145012 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
(photodiodes). 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
push-button 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-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 pulsed load current from the LED pin. The trip point is set using two external
resistors. The supply for the MC145012 can be a 9.0 V battery.
A visible LED flash accompanying a pulsating audible alarm indicates a local-
smoke condition. A pulsating audible alarm with no LED flash indicates a remote-
smoke condition. A beep or chirp occurring virtually simultaneously with an LED
flash indicates a low-supply condition. A beep or chirp occurring halfway between
LED flashes indicates degraded chamber sensitivity. A low-supply condition does
not affect the smoke detection capability if V
DD
≥
6.0 V. Therefore, the low-supply
condition and degraded chamber sensitivity can be further distinguished by
performing a push-button (chamber) test.
Features
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Circuit is designed to operate in smoke detector systems that comply with
UL217 and UL268 Specifications
Operating Voltage Range: 6.0 V to 12 V, Average Supply Current: 8
µA
Operating Temperature Range: -10 to 60°C
I/O Pin Allows Units to be Interconnected for Common Signalling
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
Supports NFPA 72, ANSI S3.41, and ISO 8201 Audible Emergency Evacuation
Signals
Ideal for battery-powered applications
Pb-Free Packaging Designated by Suffix Codes ED and EG
ORDERING INFORMATION
Device
MC145012P
648-08
MC145012ED
-55 to +125°C
MC145012DW
751G-04
MCZ145012EG/R2
16 SOICW (Pb-Free)
16 Lead SOICW
16 PDIP (Pb-Free)
Temp. Range
Case No.
Package
16 Lead Plastic Dip
MC145012
PHOTOELECTRIC SMOKE
DETECTOR IC WITH I/O AND
TEMPORAL PATTERN
HORN DRIVER
P SUFFIX
ED SUFFIX (PB-FREE)
PLASTIC DIP
CASE 648-08
DW SUFFIX
EG SUFFIX (PB-FREE)
SOIC PACKAGE
CASE 751G-04
C1
1
16
15
14
13
12
11
10
9
C2 2
DETECT 3
STROBE 4
VDD 5
IRED 6
I/O 7
BRASS 8
TEST
LOW-SUPPLY
TRIP
VSS
R1
OSC
LED
FEEDBACK
SILVER
Figure 1. Pin Connections
© Freescale Semiconductor, Inc., 2006. All rights reserved.
FREESCALE [ FREESCALE SEMICONDUCTOR, INC ]
