Analog Devices Inc./Maxim Integrated MAX6138BEXR30-T

Overview

MAX6138BEXR30-T from Maxim Integrated is a precision two-terminal shunt-mode bandgap voltage reference with a fixed 3.000V reverse breakdown voltage, 0.2% initial accuracy, 25ppm/°C max temperature coefficient, and operation over –40°C to +85°C - used in high-accuracy analog signal chains for portable instrumentation and battery-powered data acquisition.

For engineers reviewing the MAX6138BEXR30-T datasheet, MAX6138BEXR30-T pinout, MAX6138BEXR30-T application, or MAX6138BEXR30-T equivalent, key selection criteria include shunt-current range (60µA–15mA), low dynamic impedance (0.3–0.8Ω), 45µVRMS wideband noise (10Hz–10kHz), SC70-3 package footprint, and capacitor-free stability with capacitive loads.

Technical Context

The MAX6138BEXR30-T implements a laser-trimmed BiCMOS bandgap core to maintain stable 3.000V output across supply and load variations. Its two-terminal architecture requires external series resistance (RS) to set shunt current, enabling flexible biasing from higher-voltage rails without dedicated reference supplies.

It operates as a precision shunt regulator: reverse current (ISHUNT) flows between pins 1 (+) and 2 (–), while pin 3 is NC (must float or tie to pin 2). Temperature compensation ensures ≤25ppm/°C drift over –40°C to +85°C, with typical drift as low as ±4ppm/°C.

Key Specifications

Pinout & Package

MAX6138BEXR30-T is housed in a 3-pin SC70-3 surface-mount package (1.8mm × 1.8mm), 50% smaller than SOT23 equivalents. Pin 3 is No Connect (NC) and must be left floating or tied to pin 2 per datasheet requirement.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar shunt voltage reference applications.

Compared with TLVH431ACDBVR and LM4040C30IDCKR, MAX6138BEXR30-T delivers 2.5× tighter initial tolerance, 4× lower temperature drift, 2× lower noise, and superior dynamic regulation - making it the sole choice for 16-bit+ data acquisition where reference error dominates total system INL.

Availability

MAX6138BEXR30-T is available at Aetrix Electronics and suitable for portable instrumentation, battery-powered medical sensors, and industrial process transmitters requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6138BEXR30-T includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and power-management ICs for demanding industrial, medical, and communications applications.

The MAX6138 family delivers high-accuracy, low-drift shunt references in ultra-compact SC70 packages - engineered specifically for space-constrained, battery-operated systems needing metrology-grade voltage stability without external capacitors.

FAQ

What is the maximum shunt current rating for MAX6138BEXR30-T?

The absolute maximum reverse current for MAX6138BEXR30-T is 20mA, but its specified operating range is 60µA to 15mA. Exceeding 15mA may cause excessive self-heating and degrade long-term stability. The device remains functional up to 20mA, though thermal derating and reliability impact must be evaluated per application. Always size RS to limit ISHUNT within 60µA–15mA across all VS and ILOAD conditions.

Can MAX6138BEXR30-T be used with capacitive loads without instability?

Yes - MAX6138BEXR30-T is explicitly designed to be stable with any output capacitance, including 0µF up to unlimited values. This eliminates the need for an external output capacitor and avoids phase-margin issues common in shunt references. The internal architecture ensures unconditional stability, verified across 100pF to 10µF loads in characterization testing per the datasheet.

What does the "B" in MAX6138BEXR30-T indicate?

The "B" denotes the initial accuracy grade: ±0.2% (max) at +25°C. Within the MAX6138 family, "A" = ±0.1%, "B" = ±0.2%, and "C" = ±0.5%. All grades share identical temperature coefficient (≤25ppm/°C), noise, dynamic impedance, and package - only the trimmed bandgap voltage tolerance differs. MAX6138BEXR30-T guarantees 2.9940V to 3.0060V at room temperature.

Is pin 3 of MAX6138BEXR30-T required to be connected?

No - pin 3 is designated N.C. (No Connect) and must either be left floating or tied directly to pin 2 (cathode). It is not internally bonded and serves no electrical function. Leaving it unconnected is acceptable; connecting it to pin 2 prevents potential noise pickup. Never connect pin 3 to any other net, including VDD or signal lines, as this violates the datasheet requirement and may compromise performance.

How does MAX6138BEXR30-T compare to LM4040 in size and performance?

MAX6138BEXR30-T is offered in the same SC70-3 package as LM4040 variants but achieves 0.2% initial accuracy and 25ppm/°C tempco - versus LM4040's typical 0.5% and 100ppm/°C. Its 45µVRMS noise is half that of LM4040C30, and its dynamic impedance (0.3–0.8Ω) is ~5× lower. These improvements stem from Maxim's laser-trimmed BiCMOS process, making MAX6138BEXR30-T a higher-precision, lower-noise, and more thermally stable replacement.