Analog Devices Inc./Maxim Integrated MAX14938GWE+

Overview

MAX14938GWE+ from Maxim Integrated is a 2.75kVRMS galvanically isolated half-duplex RS-485/PROFIBUS-DP transceiver with integrated 5V LDO, ±35kV HBM ESD protection on A/B pins, 20Mbps data rate, and true fail-safe receiver. It enables robust industrial serial communication across ground-potential differences in programmable logic controllers and HVAC systems.

For engineers reviewing the MAX14938GWE+ datasheet, MAX14938GWE+ pinout, MAX14938GWE+ application, or MAX14938GWE+ equivalent, key selection criteria include isolation voltage rating (2750VRMS/60s), cable-side power architecture (VLDO input → VDDB output), differential driver output voltage (≥2.1V into 54Ω), receiver input impedance (¼-unit load), and thermal shutdown threshold (+160°C).

Technical Context

The MAX14938GWE+ implements capacitive galvanic isolation between UART-side (GNDA/VDDA) and cable-side (GNDB/VDDB) domains, supporting up to 20Mbps signaling while breaking ground loops. Its integrated LDO accepts 4.68V–14V at VLDO and delivers regulated 4.5V–5.5V at VDDB with 300mA current limit.

True fail-safe operation guarantees RXD = high when A/B are open, shorted, or connected to a terminated bus; receiver thresholds are fixed at –200mV to –50mV. Driver outputs feature foldback current limiting and thermal shutdown at +160°C, while common-mode transient immunity exceeds 35kV/μs.

Key Specifications

Pinout & Package

MAX14938GWE+ uses a wide-body 16-pin SOIC package (W SOIC) with 8mm creepage and clearance, rated for 2750VRMS isolation. Pin 1 is VDDA; pins 2 and 8 are GNDA; pins 9 and 15 are GNDB; pin 16 is VDDB; pin 11 is VLDO; pins 12 and 13 are A and B; pin 14 is NC.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar isolated RS-485 transceiver applications.

Compared with ADM2483BRWZ and ISO1500DWR, MAX14938GWE+ uniquely combines 20Mbps speed, integrated 5V LDO, ±35kV ESD, and thermal shutdown - making it optimal for new PROFIBUS-DP and high-noise industrial RS-485 designs requiring minimal external components and maximum robustness.

Availability

MAX14938GWE+ is available at Aetrix Electronics and suitable for industrial automation equipment, programmable logic controllers, and HVAC systems requiring stable component supply, long-term lifecycle assurance, and certified isolation performance.

Supply support for MAX14938GWE+ 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 high-reliability ICs for industrial, automotive, and communications markets.

The MAX14938GWE+ belongs to Maxim's isolated interface product line, engineered specifically for noise-immune, ground-loop-free serial communication in harsh industrial environments with demanding safety and EMC requirements.

FAQ

What is the isolation voltage rating of the MAX14938GWE+ and how is it certified?

The MAX14938GWE+ provides 2750VRMS galvanic isolation for 60 seconds, certified to UL1577 and CSA Bulletin 5A standards. It achieves this via on-chip high-voltage capacitors and meets IEC 60747-5-5 requirements for VIORM (630VPEAK), VIOWM (445VRMS), and creepage/clearance (8mm). This rating applies specifically to the MAX14938GWE+ in its wide-body SOIC package.

Does the MAX14938GWE+ require external components to operate its integrated LDO?

Yes - the MAX14938GWE+ LDO requires external 0.1µF and 1µF capacitors connected between VLDO and GNDB, and between VDDB and GNDB, placed as close as possible to the device. The LDO activates when VLDO is supplied with 4.68V–14V; leaving VLDO unconnected or tied to GNDB disables the LDO and requires an external 4.5V–5.5V supply on VDDB.

How does the true fail-safe feature of the MAX14938GWE+ improve system reliability?

The MAX14938GWE+ true fail-safe circuitry guarantees RXD = high when A/B are open, shorted, or connected to a terminated bus with all drivers disabled. This eliminates bus contention uncertainty and prevents spurious logic-low states during fault conditions - removing the need for external fail-safe bias resistors and improving startup stability in multi-node RS-485 networks.

Can the MAX14938GWE+ drive a full PROFIBUS-DP Class 3 network without additional components?

Yes - the MAX14938GWE+ meets PROFIBUS-DP Class 3 requirements with ≥2.1V differential output into worst-case loading (two 220Ω terminations plus 390Ω pull-ups/pull-downs), 20Mbps capability, and ±35kV HBM ESD protection. Its integrated LDO can also power external termination resistors, enabling fully self-contained PROFIBUS node implementation.

What thermal protection mechanisms are built into the MAX14938GWE+?

The MAX14938GWE+ includes two thermal protections: (1) driver foldback current limiting that reduces output current during sustained short circuits, and (2) thermal shutdown that forces A/B into high-impedance state when junction temperature exceeds +160°C. Recovery occurs automatically when temperature falls below +145°C, ensuring safe operation under overload or poor heatsinking conditions.