The RE46C122 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.
Datasheets by Manufacturer
RE46C127 — R - E International — CMOS Ionization Smoke Detector ASIC
RE46C128 — R - E International — CMOS Ionization Smoke Detector ASIC
RE46C121 — R - E International — CMOS Ionization Smoke Detector ASIC