The MAX6001-MAX6005 family from Maxim Integrated (now part of Analog Devices) is a set of low-cost series voltage references in the tiny SOT23-3 package. The key word is series: a conventional shunt (two-terminal) reference must waste current through a ballast resistor, but these devices behave like a precision three-terminal regulator and draw only what the load needs - so the power-supply current is virtually independent of the input voltage. The MAX6004 is the 4.096 V grade (the family runs 1.250 V, 2.500 V, 3.000 V, 4.096 V and 5.000 V). MAX6004EUR+T is the RoHS ("+"), tape-and-reel ("T") option.

For a low-power reference the numbers are what matter. Quiescent current is a 45 µA maximum, and supply-current variation with input is just 0.8 µA/V - so the part sits almost unnoticed on a battery rail. Initial accuracy is 1%, the temperature coefficient is 100 ppm/°C maximum, and the device both sources and sinks 45 µA, so it can reference a node that pulls either way. Dropout is low: it regulates 4.096 V with only 100 mV of headroom at a 400 µA load, so it works from a supply close to the output.

It is also easy to apply. The reference is stable with any capacitive load from 0 to 2.2 nF - it neither requires an output capacitor nor is upset by one in that range - which removes the compensation guesswork that trips up many references. Load regulation is 0.12 µV/µA and wideband noise is 8 µV/√Hz. The MAX6004 operates over the extended -40 °C to +85 °C range from an input of roughly 4.3 V (V_OUT + 200 mV) up to 12.6 V.

Note: Values are taken from the Maxim MAX6001-MAX6005 datasheet. Confirm every parameter against the latest official documentation before committing a design.

MAX6004EUR+T ships in the SOT23-3 (3-pin small-outline transistor package, outline 21-0051) - the tiny three-lead body that makes a board-level voltage reference take almost no space, ideal for the portable and battery products it targets. With only three pins (IN, OUT, GND) the layout is simple: keep the OUT trace short to the circuit it references, bypass IN, and place any 0-2.2 nF output capacitor close to the pin. The dimensional drawing below gives the full mechanical detail.

The SOT23-3 has three pins - input, output and ground (per the MAX6001-MAX6005 datasheet):

• Pin 1 - IN: Supply input; ~4.3 V to 12.6 V. Bypass to GND.
• Pin 2 - OUT: Reference output, 4.096 V; sources and sinks 45 µA. Stable with 0-2.2 nF.
• Pin 3 - GND: Ground.

The closest options are the voltage grades in the same family - identical except for output voltage - and Maxim's other SOT23 series references. Match the output voltage to your ADC/DAC full scale before substituting.

Selection Tips: Stay with the MAX6004 for a 4.096 V series reference; step within the family to the MAX6001 (1.25 V), MAX6002 (2.5 V), MAX6003 (3.0 V) or MAX6005 (5.0 V) for a different output - they are pin- and behavior-identical. Choose the MAX6025 series when a tighter initial accuracy than 1% is needed.

Maxim Integrated, now part of Analog Devices, Inc. (ADI), built the MAX6001-MAX6005 to bring series-reference efficiency to cost- and space-sensitive portable designs - a precision reference that wastes no shunt current and fits a SOT23-3.

ADI maintains the datasheet, the accuracy and tempco grades, and the stability and bypass guidance for the family - the documentation that turns a three-pin SOT23 into a dependable system voltage reference.