5V fixed shunt reference in SOT-23-3
It operates as a shunt (two-terminal) reference, meaning it sinks current through an external resistor from a higher supply rail — no separate supply pin, just a cathode and anode.
Biasing the shunt — cathode current and output drive
The shunt reference requires a bias resistor from the supply to the cathode to set the operating current. The LM4040A50IDBZR is specified for a cathode current range from 95 µA minimum to 15 mA maximum. The 95 µA floor sets the minimum bias current to maintain regulation; below that the output voltage may drift. The 15 mA ceiling limits the total current available to both the reference and any load — if the load draws 10 mA, the bias resistor must still deliver at least 95 µA through the reference itself.
SOT-23-3 footprint and surface-mount assembly
The part ships in a SOT-23-3 package (also listed as TO-236-3 / SC-59). The three-pin footprint — cathode, anode, and no-connect — is standard across the LM4040 family.
For production BOMs, the active lifecycle means no forced redesign horizon from the manufacturer side — though it is always prudent to monitor PCNs for any future changes.