The RE46C121 is low power CMOS ionization type smoke detector IC. With few external components this circuit will provide all the required features for an ionization type smoke detector. An internal oscillator strobes power to the smoke detection circuitry for 10.5mS every 1.66 seconds to keep standby current to a minimum. A check for a low battery condition is performed every 40 seconds when in standby. The temporal horn pattern supports the NFPA 72 emergency evacuation signal. An interconnect pin allows multiple detectors to be connected such that when one unit alarms all units will sound. Although this device was designed for smoke detection utilizing an ionization chamber it can be used in a variety of security applications. The RE46C121 was designed for use in smoke detectors that comply with Underwriters Laboratory Specification UL217 and UL268.

   Guard Outputs for Ion Detector Input

   +/-0.75pA Detect Input Current

   Internal Reverse Battery Protection

   Internal Low Battery Detection

   Low Quiescent Current Consumption (

   Available in 16L PDIP or 16L N SOIC

   ESD Protection on all Pins

   Interconnect up to 40 Detectors

   Compatible with MC145018

   Available in Standard Packaging or RoHS Complaint Pb Free Packaging