The LM4040C50IDBZTG4 is a fixed 5V shunt voltage reference from Texas Instruments' LM4040 family, trimmed to ±0.5% initial tolerance. The shunt architecture means it behaves like a Zener diode — it sinks current from a supply through a series resistor to regulate the output. For a 5V rail, the 15 mA output current ceiling sets the load the reference can drive directly; anything beyond that needs a buffer. The 95 µA cathode current is the minimum operating current — below that the reference drops out of regulation.
Temperature drift and noise — the hidden specs that decide fit
The 100 ppm/°C temperature coefficient means the output voltage shifts by up to 0.5 mV per 10°C change. In a -40°C to 85°C swing, that adds up to 12.5 mV of drift — fine for an 8-bit ADC reference, marginal for a 12-bit system without calibration. The 80 µVrms noise over 10 Hz to 10 kHz is low enough for most precision analog front-ends; if the application has a switching regulator nearby, a 0.1 µF bypass at the reference output knocks down the high-frequency hash.
TI lists the LM4040C50IDBZTG4 as Active.