Analog Devices Inc./Maxim Integrated MAX6138CEXR30+T

Overview

MAX6138CEXR30+T from Maxim Integrated is a precision two-terminal shunt-mode bandgap voltage reference with a fixed reverse breakdown voltage of 3.000V, ±0.5% initial accuracy (Grade C), 25ppm/°C max temperature coefficient, and 60μA–15mA operating current range. It delivers stable reference performance in space-constrained portable battery-powered systems requiring low-noise, capacitor-free regulation.

For engineers reviewing the MAX6138CEXR30+T datasheet, MAX6138CEXR30+T pinout, MAX6138CEXR30+T application, or MAX6138CEXR30+T equivalent, key selection criteria include its SC70-3 package footprint, 3.0V output tolerance over –40°C to +85°C, dynamic impedance under 0.8Ω at 1mA, 45µV_RMS wideband noise (10Hz–10kHz), and guaranteed stability without external capacitors.

Technical Context

The MAX6138CEXR30+T implements a laser-trimmed bandgap core with BiCMOS process technology to achieve precise 3.000V reverse breakdown voltage across its full industrial temperature range. Its two-terminal architecture operates as a programmable current sink, maintaining regulation by dynamically adjusting shunt current between 60μA and 15mA while rejecting supply and load variations.

Unlike series references, it requires no input-to-output headroom and functions independently of load current direction-its cathode (Pin 1) and anode (Pin 2) define a bidirectional terminal pair, with Pin 3 designated NC (must float or tie to Pin 2). Stability is ensured across all capacitive loads without compensation components.

Key Specifications

Pinout & Package

MAX6138CEXR30+T is housed in a 3-pin SC70 surface-mount package (1.8mm × 1.8mm, 0.95mm height), RoHS-compliant, with thermal pad omitted. Pin 3 is No Connection (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 LM4040C30IDBZR, the MAX6138CEXR30+T provides superior thermal stability (25ppm/°C vs. 100ppm/°C) and 50% smaller footprint, making it optimal for miniaturized, temperature-sensitive designs where 3.0V reference integrity is critical.

Availability

MAX6138CEXR30+T is available at Aetrix Electronics and suitable for portable medical sensors, battery-powered data loggers, and industrial process transmitters requiring stable component supply with guaranteed long-term availability.

Supply support for MAX6138CEXR30+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 product line delivers ultra-compact, high-accuracy shunt voltage references optimized for space- and power-constrained systems where traditional three-terminal references are impractical.

FAQ

What is the maximum shunt current rating for MAX6138CEXR30+T?

The MAX6138CEXR30+T supports a continuous shunt current up to 15mA under normal operation, with absolute maximum reverse current rated at 20mA. Exceeding 15mA may cause regulation degradation, and sustained operation above 20mA risks permanent damage. The device's dynamic impedance remains low (<0.8Ω) across its full 60μA–15mA operating range, ensuring stable 3.000V output in MAX6138CEXR30+T-based circuits.

Can MAX6138CEXR30+T be used with large output capacitors?

Yes - the MAX6138CEXR30+T is explicitly designed to remain stable with any value of output capacitance, including ceramic, tantalum, or electrolytic types. Unlike many shunt references, it does not require external compensation and exhibits no phase margin degradation or oscillation risk, even with 100µF or greater capacitors. This feature simplifies design and improves reliability in MAX6138CEXR30+T applications involving noisy supplies or long trace routing.

What is the purpose of Pin 3 on MAX6138CEXR30+T?

Pin 3 on MAX6138CEXR30+T is designated N.C. (No Connection) and must either be left floating or connected directly to Pin 2 (anode). It is not electrically active and serves no functional role in regulation. Incorrect connection - such as tying Pin 3 to a different potential - can alter internal bias conditions and degrade MAX6138CEXR30+T accuracy or stability. This requirement is strictly enforced in the datasheet and applies to all MAX6138 variants.

How does the temperature coefficient of MAX6138CEXR30+T compare to LM4040?

The MAX6138CEXR30+T guarantees a maximum temperature coefficient of 25ppm/°C over –40°C to +85°C, whereas the LM4040C30IDBZR specifies 100ppm/°C. This fourfold improvement means MAX6138CEXR30+T introduces ≤±0.63mV drift across its full temperature range versus ±2.5mV for the LM4040 - a critical advantage in precision measurement systems where thermal gradients cannot be controlled. Both share 0.5% initial accuracy, but MAX6138CEXR30+T delivers superior thermal performance in the same voltage grade.

Is MAX6138CEXR30+T compatible with lead-free reflow processes?

Yes - MAX6138CEXR30+T is RoHS-compliant and qualified for standard lead-free reflow soldering per JEDEC J-STD-020. Its SC70-3 package withstands peak temperatures up to +260°C for 30 seconds, matching typical Pb-free profile requirements. The device's BiCMOS construction ensures robustness against thermal stress, and no special prebake or moisture sensitivity handling is required. Always verify landing pad geometry using Maxim's land pattern no. 90-0208 for reliable MAX6138CEXR30+T assembly.