Precision reference, not a regulator — the ±0.04% tolerance tells you where it fits
The MAX6167AESA+ is a series voltage reference from Analog Devices, delivering a fixed 4.5 V output with an initial tolerance of ±0.04%. That level of accuracy — 1.8 mV at 4.5 V — is what you spec when the ADC's least-significant bit budget has no room for a sloppy rail. It is a series reference, meaning the load current comes through the pass transistor, not a resistor divider, so the output stays within spec down to 5 mA output without the dropout penalty of a shunt reference.
Noise and drift — the two specs that decide the ADC reference fit
For a 16-bit ADC with a 4.5 V reference, 55 µVp-p represents roughly 0.8 LSB of peak-to-peak noise at the reference input — clean enough that the converter's own noise floor, not the reference, limits the SNR. The temperature coefficient is 5 ppm/°C, which translates to 22.5 µV/°C drift at the output.
Supply headroom and quiescent draw
Input voltage ranges from 4.7 V to 12.6 V, so the reference needs at least 200 mV of headroom above the 4.5 V output to regulate. Quiescent supply current is 120 µA, making it suitable for battery-powered instruments where the reference stays on continuously, but not for sub-µA sleep-mode systems — the reference itself draws more than a typical MCU in deep sleep.
Package and board-fit
The tube delivery means it ships in the standard anti-static tube, not tape-and-reel — factor that into pick-and-place setup if you are feeding from a tray.