1.225V fixed shunt — the reference that doesn't need a separate supply rail
The LM4041CIM7X-1.2 is a shunt voltage reference from Texas Instruments that delivers a fixed 1.225V output with ±0.5% initial tolerance. Unlike a series reference, it sinks current through a cathode to the negative rail — the same topology as a Zener diode — so it operates from whatever supply is available, as long as the cathode current stays above 65 µA and below 12 mA. The 20 µVrms noise spec (10 Hz to 10 kHz) and 100 ppm/°C temperature coefficient make it suitable for precision analog chains — ADC references, comparator thresholds, or DAC bias — where a 1.225V rail is needed without a dedicated low-noise LDO.
SC-70-5 — small footprint, but the cathode current sets the bias resistor
The SC-70-5 package (also known as SOT-353) is a 5-lead surface-mount package about 2.0 mm × 2.1 mm — a tight fit for space-constrained boards. The shunt topology means the designer must size the series resistor from the supply to the cathode so that the cathode current stays between 65 µA (minimum to maintain regulation) and 12 mA (absolute maximum) across all load and supply conditions.
Inventory that exists on the independent market is factory-original sealed reels or cut tape from genuine production runs — date-code spread varies by lot. For a pin-compatible replacement, the buyer should evaluate the broader LM4041 family (base product number LM4041) in the same SC-70-5 package and 1.225V fixed output with ±0.5% tolerance — the LM4041CIM7-1.2 or LM4041AIM7-1.2 may be available as active alternatives, though the exact tolerance and temperature range must be verified against the BOM requirement.