It is a three-terminal shunt regulator — like a Zener but with tighter tolerance and lower temperature drift — commonly used in power supplies, data converters, and measurement circuits where a stable voltage reference is needed. The ±2% initial tolerance covers most general-purpose reference applications without trimming.
The LM336BLPR-2-5 can sink up to 10 mA of output current, which is the current available to the load. The minimum cathode current is 400 µA — below that the reference may not regulate. In practice, you set the bias resistor from the supply to the cathode so that the total current (load plus reference) stays between 400 µA and 10 mA. For a 5 V rail and a 1 mA load, a 2.2 kΩ resistor is a typical starting point.
It is not specified for automotive under-hood or outdoor telecom cabinets where extended temperature is required.
Through-hole TO-92-3 — rework-friendly package
The TO-92-3 (TO-226AA) package with formed leads is a through-hole part — easy to hand-solder, easy to replace. The leads are on 0.100-inch pitch, compatible with standard prototyping boards. No hot-air station needed; a soldering iron and solder sucker will lift this part without lifting the pad.