Precision 1.225V shunt reference in SOT-23-3
The Texas Instruments LM4051BEM3X-1.2/NOPB is a precision shunt voltage reference delivering a fixed 1.225V output with a tight ±0.2% initial tolerance and a low 50ppm/°C temperature coefficient. It is designed for precision analog circuits where a stable, accurate voltage reference is required over a wide operating range.
Current budget and bias resistor sizing
As a shunt reference, the LM4051BEM3X-1.2/NOPB requires an external series resistor to set the bias current. The device can sink up to 12 mA of output current while its own cathode current is just 65 µA, so the total current through the bias resistor is the sum of the load current and the cathode current. This means the bias resistor value must be chosen to supply at least 65 µA to the reference under all load conditions, plus whatever current the load draws, while keeping the total below the 12 mA maximum. The low cathode current makes it efficient for battery-powered or low-power designs.