The MAX6070/MAX6071 from Maxim Integrated (now part of Analog Devices) are the high-end of the SOT23 reference range: low-noise, high-precision series references that bring instrument-grade performance to a 6-pin package. The headline is noise - a very low 4.8 µV_p-p 1/f voltage in the 0.1-10 Hz band (at 2.5 V) - paired with a low temperature drift. The MAX6071 is the version without the noise-reduction filter pin (the MAX6070 adds a FILTER pin); the BAUT33 ordering code is the B grade (0.08% initial accuracy), 3.3 V output, in 6-pin SOT23.

What sets these apart from a 3-pin reference is the Kelvin force/sense pinout. The output appears on two pins - OUTF (force) carries the load current, and OUTS (sense) is a high-impedance feedback tap - and the ground is likewise split into GNDF (force) and GNDS (sense). By sensing the voltage at the load rather than at the package, the reference cancels the IR drop in the PCB traces, so the precision arrives where it is used, not just at the pin. An EN pin shuts the part down to a low standby current.

The rest is built for accuracy. Initial accuracy is 0.08% (B grade; the A grade reaches 0.04%), and the part holds a low temperature coefficient, 85 dB ripple rejection at 60 Hz, and 1000-hour long-term stability. It sources and sinks ±10 mA, has a low 200 mV dropout, and draws 150 µA. The supply runs 2.8 V to 5.5 V, and the AEC-Q100-qualified part operates over the full -40 °C to +125 °C range in 6-pin SOT23.

Note: Values are taken from the Maxim MAX6070/MAX6071 datasheet. Confirm every parameter against the latest official documentation before committing a design.

MAX6071BAUT33+T ships in the 6-pin SOT23 (package outline 21-0088) - a small surface-mount body whose six leads carry the Kelvin force/sense pairs that a 3-pin reference cannot. The extra pins are the point: route OUTF and GNDF to the load, and OUTS and GNDS as the sense returns, so the layout preserves the reference's accuracy at the load. Bypass IN and OUTF per the datasheet, and keep the sense traces away from current-carrying paths. The package image is shown below.

The 6-pin SOT23 carries the Kelvin force/sense pairs plus supply and enable (per the MAX6071 datasheet; the MAX6070 differs at pin 1):

• Pin 1 - GNDF: Ground Force - the main ground-return connection (carries current).
• Pin 2 - GNDS: Ground Sense - Kelvin-connect to the load ground for accurate sensing.
• Pin 3 - EN: Enable; high enables the device, low puts it in low-current shutdown.
• Pin 4 - IN: Supply input, 2.8 V to 5.5 V; bypass with 0.1 µF to ground.
• Pin 5 - OUTS: Reference Output Sense - high-impedance Kelvin feedback from the load.
• Pin 6 - OUTF: Reference Output Force - the driven 3.3 V output; bypass 0.1-10 µF to ground.

The MAX6071 is the low-noise, Kelvin-connected, automotive-grade top of Maxim's SOT23 reference range. The parts below are other SOT23 series references at related voltages - choose by noise, accuracy and connection scheme.

Selection Tips: Choose the MAX6071 when low noise (4.8 µV_p-p), Kelvin force/sense accuracy and the -40 to +125 °C / AEC-Q100 grade matter - a 16-bit ADC reference or an automotive precision rail. The MAX6070 adds a FILTER pin for even lower noise. For simpler 3-pin needs the MAX6063 (3 V high-output), MAX6025 (2.5 V precision) or MAX6003/6004/6005 cover other voltages.

Maxim Integrated, now part of Analog Devices, Inc. (ADI), built the MAX6070/MAX6071 for designs that need a SOT23 reference without compromise - low noise, Kelvin-connected accuracy, and an automotive temperature range - where a 3-pin reference would limit the system.

ADI maintains the datasheet, the Kelvin-connection and bypass guidance, the accuracy and noise grades, and the AEC-Q100 documentation for the family - the basis for using the part as a high-resolution or automotive precision reference.