MC145012 Datasheet, PDF (1/12 Pages) Freescale Semiconductor, Inc – Photoelectric Smoke Detector IC with I/O and Temporal Pattern Horn Driver

MOTOROLA
SEMICONDUCTOR TECHNICAL DATA
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 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–
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 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 V.
Therefore, the low–supply condition and degraded chamber sensitivity can be
further distinguished by performing a pushbutton (chamber) test.
• 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 Supply Current: 8 µA
• 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
Order this document
by MC145012/D
MC145012
16
1
P SUFFIX
PLASTIC DIP
CASE 648–08
16
1
DW SUFFIX
SOIC PACKAGE
CASE 751G–03
ORDERING INFORMATION
MC145012P PLASTIC DIP
MC145012DW SOIC PACKAGE
PIN ASSIGNMENT
C1 1
C2 ²
Detect 3
Strobe 4
V_DD 5
IRED ⁶
I/O ⁷
Brass 8
16 Test
15
Low–Supply
Trip
14 V_SS
13 _R1
12 _Osc
11 _LED
10 _Feedback
9 Silver
REV 4
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