Fixed 1.225 V shunt reference in a SOT-23-3
The LM4041CEM3-1.2 is a precision shunt voltage reference from Texas Instruments, delivering a fixed 1.225 V output with a ±0.5% initial tolerance. It operates as a two-terminal shunt (like a Zener), requiring only a cathode resistor to set the bias current. The SOT-23-3 package and surface-mount footprint make it a compact fit for dense PCB layouts in industrial control, automotive modules, and portable instrumentation.
Output current and cathode current — bias budget
Rated output current is 12 mA. Minimum cathode current is 68 µA.
NRND — plan a second source or successor now
New designs should select an alternative from the same LM4041 family — the base product number LM4041 covers multiple voltage options and tolerances in the same SOT-23-3 footprint.
Noise and temperature drift — signal-chain impact
Wideband noise from 10 Hz to 10 kHz is 20 µVrms, which is low enough for 12-bit ADC references without additional filtering in most industrial signal chains. The temperature coefficient is 100 ppm/°C, meaning the output voltage shifts by roughly 122 µV over a 100°C swing — a factor to budget in the system accuracy calculation.