Fixed 1.225 V shunt reference in SOT-23-3
As a shunt reference, it behaves like a precision Zener diode: it regulates the voltage across its terminals by sinking current through an external series resistor. The cathode current range is 80 µA minimum to 12 mA maximum, which sets the resistor value and the allowable load current.
The ±0.5% initial tolerance means a fresh part from the reel will output between 1.218 V and 1.232 V at 25°C. This is tight enough for a 10-bit ADC reference without external trimming, but marginal for 12-bit systems that need better than ±1 LSB accuracy. Temperature coefficient is 100 ppm/°C. If your circuit measures signals across temperature, budget this drift into the system error budget. For low-noise analog front-ends, a bypass capacitor at the reference output filters this noise further, but the capacitor adds a startup time constant that matters in power-cycled applications.
SOT-23-3 package — rework and layout notes
The SOT-23-3 package (also known as TO-236-3 or SC-59) has three leads with 0.95 mm pitch. The small body and low thermal mass make it easy to rework with a hot-air station — the part lifts cleanly at 300°C with minimal risk to the board pads. Confirm the pinout from the datasheet before layout — the SOT-23-3 orientation mark is a small dot at pin 1 corner.
The base product number is LM4041, which covers multiple voltage options and tolerance grades. The 'C' in the part number indicates the ±0.5% tolerance grade; the 'I' indicates the industrial temperature range.