The Texas Instruments LM4051CIM3X-1.2/NOPB is a precision shunt voltage reference that delivers a fixed 1.225 V output with a ±0.5% initial tolerance. It is designed for applications requiring a stable voltage rail for ADC references, comparator thresholds, or bias supplies in industrial control, data acquisition, and power management circuits.
±0.5% tolerance and 50 ppm/°C drift — the accuracy floor
The ±0.5% initial accuracy is the untrimmed error at 25°C. For a 1.225 V output, that is roughly ±6 mV. A system with a 10-bit ADC at a 2.5 V reference sees about 1 LSB of error from the reference alone — acceptable for most industrial sensing loops without a calibration step. In a slow-sampling ADC (below 100 SPS), this noise aliases into the DC reading; a simple RC filter at the reference output knocks it below the ADC's quantization noise floor.
12 mA cathode current — how many loads it can drive
As a shunt reference, the LM4051CIM3X-1.2/NOPB sinks current through the cathode to regulate the output voltage. The maximum continuous cathode current is 12 mA. The minimum operating current is 65 µA (the cathode current at no load). For a typical ADC reference input drawing 100 µA, the series resistor must be sized so the total current through the device stays between 65 µA and 12 mA across the input supply range. Exceeding 12 mA forces the output out of regulation.
SOT-23-3 package — board integration notes
The surface-mount footprint mates with standard SOT-23 land patterns. The base product number is LM4051, and the suffix CIM3X-1.2/NOPB indicates the ±0.5% grade, 1.225 V output, SOT-23-3 package, and lead-free (NOPB) finish.
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