Fixed 5 V shunt reference with ±0.1% initial accuracy
The Texas Instruments LM4040AIZ-5.0/NOPB is a precision shunt voltage reference that delivers a fixed 5 V output with a ±0.1% initial tolerance.
Drift and noise — the precision budget
The temperature coefficient is 100 ppm/°C, which means the output voltage can shift up to 5 mV over a 100°C swing — a figure that matters for 12-bit-plus systems where the reference drift directly eats into the ADC's error budget. This is the noise floor the system designer must budget for; a downstream 12-bit ADC with a 5 V reference has an LSB of 1.22 mV, so the 80 µVrms noise contributes about 6.5% of one LSB — acceptable for most industrial control loops but worth derating for 16-bit precision applications.
Output current and cathode current limits
The shunt can sink up to 15 mA while maintaining regulation. The minimum cathode current is 80 µA. These two figures define the resistor value that biases the reference from the supply rail: the resistor must supply the load current plus the 80 µA minimum, and the total must not exceed 15 mA at the maximum supply voltage.
Through-hole TO-92-3 package — board fit
The LM4040AIZ-5.0/NOPB is supplied in a TO-226-3 / TO-92-3 through-hole package (supplier device package TO-92-3). This is a legacy three-lead footprint that suits breadboard prototyping, point-to-point wiring, and designs where board space is not the primary constraint. The through-hole body also handles manual rework and field replacement without hot-air equipment.