Adjustable shunt reference — 1.24 V to 5.3 V, ±1%
The LM385BM/NOPB from Texas Instruments is an adjustable shunt voltage reference that sets its output anywhere from 1.24 V up to 5.3 V, using two external resistors.
The 20 mA output current rating tells you how much DC load the shunt can sink while staying in regulation. If your downstream circuit draws more than that, the reference voltage drifts — so budget the total load current (including the programming resistor string) to stay under that ceiling. The 55 µA minimum cathode current is the floor: run the shunt below that and it drops out of regulation entirely. In a low-power design you size the bias resistor to hold the cathode current between 55 µA and 20 mA, which gives you a wide operating window but demands a resistor calculation at the minimum supply voltage.
Noise and drift — 50 µVrms, 150 ppm/°C
The 50 µVrms noise (10 Hz to 10 kHz) is low enough for a 12-bit ADC reference without additional filtering in most cases; for 14-bit or above you may want a post-filter cap across the output. The 150 ppm/°C temperature coefficient means the output shifts about 0.8 mV over the full 0°C to 70°C range at a 5 V set point — acceptable for general-purpose regulation but not for a metrology-grade standard.