2.49V shunt reference — the fixed output that defines this part
The LM336DT is a precision shunt voltage reference from STMicroelectronics with a fixed 2.49V output. This is the exact voltage a designer gets — no adjustable tap, no external divider to set it. The ±4.02% tolerance means the output can sit anywhere from about 2.39V to 2.59V across the full operating range, which is a wider window than the ±1% or ±2% grades in the same family. For an 8-bit ADC reference, that 200 mV spread eats into the LSB budget; for a comparator threshold or a bias rail, it may be perfectly acceptable.
Obsolete — PCN reality and sourcing posture
STMicroelectronics lists the LM336DT as Obsolete. Sourcing now runs through independent distribution, where available stock is remnant inventory from the last production runs. Date-code provenance matters: stock surfacing years after the last-time-buy may be genuine NOS or could be pulled from a secondary market. Read the PCN before you buy, and confirm the date codes match your acceptance window.
8-SOIC footprint and rework considerations
The 8-SOIC package matches the industry SOIC-8 land pattern. Tape & Reel (TR) is the standard shipping medium.