1.225 V shunt reference — the BOM anchor for precision rails
The STMicroelectronics LM4041AELT-1.2 is a precision shunt voltage reference that delivers a fixed 1.225 V output with ±0.1% initial tolerance. It operates as a two-terminal shunt regulator, meaning it sinks current from the supply through an external resistor — no load capacitor needed, and the output voltage stays stable across the full cathode current range of 50 µA to 12 mA. The SOT-23-3 package makes it a drop-in fit for tight layouts where a reference sits next to an ADC or comparator input.
Output noise is specified at 60 µVrms over a 10 Hz to 10 kHz bandwidth. For a 12-bit ADC with a 2.5 V reference, that noise contribution is under 0.1 LSB — clean enough for most industrial sensor interfaces. If your design needs better than 0.5% total accuracy across temperature, this part holds the line without external trimming.