Detector IC with I/O
The CMOS MC145010 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
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 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 pulsed load current from the LED pin. The trip point is set using two external
resistors. The supply for the MC145010 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 occurring half-way between LED
flashes indicates 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 further distinguished by
performing a push button (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: 12 µA
• 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
• Ideal for battery powered applications.
-55 to +125°C
16 Lead Plastic Dip
16 Lead SOICW
Rev 7.0, 05/2006
DETECTOR IC WITH I/O
ED SUFFIX (PB-FREE)
EG SUFFIX (PB-FREE)
Figure 1. Pin Connections
© Freescale Semiconductor, Inc., 2006. All rights reserved.