The LM431AIMX from Texas Instruments is an adjustable shunt voltage reference in an 8-SOIC package. It sets a reference voltage from 2.5 V up to 36 V, sourcing up to 100 mA from the cathode. The minimum cathode current for regulation is 1 mA. The 8-SOIC footprint (3.90 mm width) is common for board-level power supply and bias circuits where a precision shunt reference is needed.
Lifecycle and compliance
The part is RoHS non-compliant per the manufacturer's current declaration. For new designs requiring RoHS compliance, a functional alternative like the TL431IDBVR (same basic die, ±2.2% tolerance, SOT-23 package) is worth evaluating.
Functional second-source fit
The closest functional peer is the TL431IDBVR, also a shunt reference from Texas Instruments. Both are adjustable from 2.5 V and source 100 mA, but the TL431IDBVR is in a smaller SOT-23 package and has a slightly looser ±2.2% tolerance. The 8-SOIC footprint of the LM431AIMX is larger than the SOT-23, so a board respin is required if swapping to the TL431IDBVR. The electrical characteristics are otherwise very close.