RE46C145 CMOS Photoelectric Smoke Detector ASIC with Interconnect and Timer Mode Features: General Description: Internal Power On Reset The RE46C145 is a low-power, CMOS photoelec- tric-type smoke detector IC. With minimal external Low Quiescent Current Consumption components, this circuit will provide all the required fea- ESD Protection on all Pins tures for a photoelectric-type smoke detector. Interconnect up to 40 Detectors The design incorporates a gain-selectable photo 10 Minute Timer for Sensitivity Control amplifier for use with an infrared emitter/detector pair. Temporal Horn Pattern An internal oscillator strobes power to the smoke Internal Low Battery and Chamber Test detection circuitry for 100 s every 10 seconds to keep Compatible with Allegro A5366 standby current to a minimum. If smoke is sensed, the Alternate Diagnostic Mode detection rate is increased to verify an Alarm condition. UL Recognized per File S24036 A High Gain mode is available for push button chamber testing. In diagnostic mode, the photo amplifier output is avail- able on pin 15 for production calibration of the photo chamber. When in Standby, a check for a low battery condition and chamber integrity is performed every 43 seconds. The temporal horn pattern supports the NFPA72 emergency evacuation signal. An interconnect pin allows multiple detectors to be con- nected such that when one units alarms, all units will sound. An internal 10 minute timer can be used for a reduced sensitivity mode. The RE46C145 is recognized by Underwriters Laboratories for use in smoke detectors that comply with specification UL217 and UL268. Package Types RE46C145 PDIP, SOIC, SOICN C1 1 16 TEST C2 2 15 VSEN DETECT 3 14 V SS STROBE ROSC 4 13 V 5 12 COSC DD 6 11 IRED LED 7 10 IO FEED HORNB 8 9 HORNS 2009-2012 Microchip Technology Inc. DS22181C-page 1RE46C145 Functional Block Diagram VDD (5) Low Battery IO (7) + - FEED (10) Horn Driver HS (9) + - Logic and VSEN (15) Smoke Comparator Timing HB (8) LED (11) V -3.5V DD PHOTOAMP Bias and DETECT (3) + Power Reset - IRED (6) C1 (1) C2 (2) ROSC (13) Oscillator COSC (12) V -5V DD STROBE (4) TEST (16) VSS (14) Typical Application C3 9V 1F Battery R3 R 8.2k Push-to-Test ADJ1 C1 .047 F R2 1 16 C2 5k 4700 pF R4 D3 R12 2 15 10M 560 R ADJ2 D6 C5 R1 3 14 1.5nF R5 4.7k R9 250k 4 13 100k R13 330 5 12 Q3 D5 R6 6 11 1k C4 R7 Smoke Chamber 100 F 7 10 22 R11 C6 220k 1.0nF 89 To Other Units R8 R10 1.5M 100 Note 1: C3 should be located as close as possible to the device power pins. 2: C3 is typical for an alkaline battery. This capacitance should be increased to 4.7 F or greater for a carbon battery. 3: R10, R11 and C6 are typical values and may be adjusted to maximize sound pressure. DS22181C-page 2 2009-2012 Microchip Technology Inc.