The MICS-5914 is a compact MOS gas sensor designed for robust ammonia detection and multi-gas sensing applications including gas leak detection and indoor/outdoor air quality monitoring. The sensor features a micro-machined silicon diaphragm with an embedded heating resistor and sensing layer, operating at a nominal heating voltage of 2.2 V with a heating power of 66 mW (60–73 mW range) and heating current of 30 mA. It detects ammonia (1–500 ppm), ethanol (10–500 ppm), hydrogen (1–1000 ppm), propane (>1000 ppm), and iso-butane (>1000 ppm), with a sensing resistance in air (R0) ranging from 10 to 1500 kO and a sensitivity factor (SR) between 1.5 and 15. The sensor operates across an ambient temperature range of -30 °C to +85 °C, relative humidity of 5–95% RH, and is housed in an extremely compact 5 × 7 × 1.55 mm footprint suitable for SMD assembly. Its robust MEMS construction, low-cost high-volume manufacturability, and minimal form factor make it ideal for portable air quality monitors, industrial safety systems, and IoT environmental sensing applications.