1.225 V shunt reference with ±0.5% tolerance — the BOM accuracy floor
Its ±0.5% initial tolerance sets the system accuracy without external trimming — adequate for 8- to 10-bit ADC bias or comparator thresholds where a 1% error budget is acceptable. As a shunt reference, it regulates by sinking current through a bias resistor from a higher supply rail. The 12 mA maximum output current and 65 µA minimum cathode current define the resistor sizing: for a 5 V supply, a 330 Ω resistor sets the shunt current near 3 mA, well within the stable operating region.
20 µVrms noise and 100 ppm/°C drift — what they mean for measurement
The noise specification of 20 µVrms over 10 Hz to 10 kHz covers the full audio band and most low-frequency measurement bandwidths. For a 1.225 V reference, this is 16 ppm RMS noise — quiet enough for a 12-bit ADC with a 2.5 V full-scale input without additional filtering. Temperature coefficient is 100 ppm/°C. The TO-92 package's larger thermal mass reduces self-heating drift compared to SOT-23 references under varying load.
TO-92 through-hole: footprint and thermal reality
The TO-226-3 / TO-92-3 package is a three-lead through-hole form factor with 0.100-inch pin spacing. It is designed for insertion into a 0.040-inch diameter plated through-hole. The bulkier body and longer leads add series inductance compared to SMD, but the thermal resistance is lower — the plastic TO-92 can dissipate 500-600 mW in still air, giving headroom for the 1.225 V × 12 mA = 14.7 mW internal dissipation.
The /NOPB suffix indicates lead-free / RoHS-compliant construction. No separate lead-free qualification step is needed for assembly lines running SAC305 solder.