Analog Devices Inc./Maxim Integrated MAX6138AEXR25+T

Overview

MAX6138AEXR25+T from Maxim Integrated is a precision two-terminal shunt-mode bandgap voltage reference with a fixed reverse breakdown voltage of 2.5000 V, ±0.1% initial accuracy, 25 ppm/°C max temperature coefficient over –40°C to +85°C, 60 µA to 15 mA shunt-current range, and ultra-low 35 µV_RMS wideband noise (10 Hz to 10 kHz). It serves as a stable voltage reference in high-accuracy ADC/DAC biasing and portable power management circuits.

For engineers reviewing the MAX6138AEXR25+T datasheet, MAX6138AEXR25+T pinout, MAX6138AEXR25+T application, or MAX6138AEXR25+T equivalent, key selection criteria include guaranteed 0.1% initial tolerance at 2.5 V, SC70-3 package compatibility with space-constrained PCB layouts, stability without output capacitors, and low dynamic impedance (0.3–0.8 Ω) across its full operating current range.

Technical Context

The MAX6138AEXR25+T implements a laser-trimmed bandgap core to achieve precise 2.5000 V reverse breakdown voltage with minimal drift. Its two-terminal architecture eliminates the need for a dedicated reference output pin - voltage regulation occurs between Pin 1 (+) and Pin 2 (–), with Pin 3 designated as no-connect (N.C.) and optionally tied to Pin 2.

It operates as a shunt regulator: reverse current (60 µA–15 mA) flows from cathode (Pin 1) to anode (Pin 2), maintaining a stable 2.5 V across the terminals. The device exhibits low dynamic impedance (≤0.8 Ω at 1 mA) and remains stable with any capacitive load, eliminating external compensation requirements.

Key Specifications

Pinout & Package

MAX6138AEXR25+T is housed in a 3-pin SC70 surface-mount package (1.8 mm × 1.8 mm, 0.95 mm height). Pin 3 is unconnected (N.C.) and must be left floating or tied to Pin 2 per datasheet guidance.

Key Features

Applications

Equivalent & Alternatives

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

Compared with LM4040C25IDBZR and ADR3425ARJZ-R7, the MAX6138AEXR25+T uniquely combines 0.1% accuracy, 25 ppm/°C guarantee, SC70-3 size, and true two-terminal shunt operation-enabling drop-in replacement in space-limited, high-precision analog signal chains without layout or topology changes.

Availability

MAX6138AEXR25+T is available at Aetrix Electronics and suitable for portable medical sensors, industrial data acquisition systems, and automotive cabin control units requiring stable component supply, guaranteed initial accuracy, and long-term voltage reference stability.

Supply support for MAX6138AEXR25+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 ultra-compact, high-accuracy shunt voltage references optimized for space-constrained, battery-powered, and high-reliability systems where stability, low noise, and guaranteed tempco are critical.

FAQ

What is the exact output voltage tolerance of the MAX6138AEXR25+T at +25°C?

The MAX6138AEXR25+T guarantees a reverse breakdown voltage of 2.5000 V with a tolerance of ±0.0025 V (±0.1%) at +25°C, as confirmed in the Electrical Characteristics table for the MAX6138A grade. This corresponds to a minimum of 2.4975 V and maximum of 2.5025 V under nominal conditions, enabling direct interfacing with 2.5 V reference inputs without trimming.

Can the MAX6138AEXR25+T operate stably without an external output capacitor?

Yes, the MAX6138AEXR25+T is internally compensated and does not require an external output capacitor for stability. It remains stable with any capacitive load, including large bulk capacitance on the reference node - a key advantage over many series references that mandate specific bypass capacitors to avoid oscillation.

What is the minimum shunt current required for regulation in the MAX6138AEXR25+T?

The MAX6138AEXR25+T requires a minimum shunt current (I_RMIN) of 65 µA to maintain regulation across its full temperature range (–40°C to +85°C), as specified in the Electrical Characteristics table for the 2.5 V variant. Operation below this threshold may result in loss of voltage accuracy and increased output impedance.

How is Pin 3 used on the MAX6138AEXR25+T SC70-3 package?

Pin 3 of the MAX6138AEXR25+T is designated N.C. (No Connection) and must be left floating or connected directly to Pin 2 (anode/–) per the official datasheet. It is not electrically active and serves only as a mechanical pad; connecting it elsewhere may compromise thermal performance or reliability.

Does the MAX6138AEXR25+T support operation at elevated temperatures beyond +85°C?

No - the MAX6138AEXR25+T is rated for operation from –40°C to +85°C only. Its absolute maximum junction temperature is +150°C, but electrical specifications (including 0.1% accuracy and 25 ppm/°C tempco) are guaranteed only within the –40°C to +85°C ambient range. Operation above +85°C violates the specified operating conditions and voids parametric guarantees.