Analog Devices Inc./Maxim Integrated MAXREFDES111A#

Overview

MAXREFDES111A# from Maxim Integrated is a fully assembled, tested, and certified isolated 24V-to-5V flyback power supply reference design delivering 2W (5V at 400mA) with ±5% output accuracy, 79% peak efficiency at 24V input, and galvanic isolation up to 1500V. It implements the MAX17498B peak-current-mode controller with internal n-channel MOSFET, fixed 500kHz switching frequency, and through-hole mounting for rapid prototyping in industrial control systems.

For engineers reviewing the MAXREFDES111A# datasheet, MAXREFDES111A# pinout, MAXREFDES111A# application, or MAXREFDES111A# equivalent, key selection criteria include input voltage range (18–36V), output regulation tolerance, transformer compatibility (e.g., Wurth 750315847), hiccup-mode overcurrent protection, and thermal shutdown behavior under sustained load.

Technical Context

The MAXREFDES111A# is a complete hardware implementation of a primary-side regulated, optocoupler-feedback flyback converter. It uses the MAX17498B controller with integrated 500kHz oscillator, EN/UVLO (18V startup / 36V OVI), soft-start (5ms via C10), and cycle-by-cycle current limiting (1.3A peak set by R6).

Galvanic isolation is achieved via a surface-mount transformer (Wurth 750315847 qualified), supporting 1500V RMS withstand. Output regulation relies on secondary-side TL431 shunt regulator (U3) and PC817 optocoupler (U2), enabling precise feedback across the isolation barrier without auxiliary windings.

Key Specifications

Availability

MAXREFDES111A# is available at Aetrix Electronics and suitable for industrial control and automation, programmable logic controller (PLC) power domains, and isolated sensor interface power supplies requiring stable component supply and rapid evaluation readiness.

Supply support for MAXREFDES111A# 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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power-management ICs for industrial, automotive, and communications applications.

The MAXREFDES series delivers pre-validated, production-ready reference designs-MAXREFDES111A# specifically targets compact, isolated DC-DC conversion for harsh industrial environments where reliability, safety certification, and transformer flexibility are critical.

FAQ

What is the input voltage range supported by the MAXREFDES111A#?

The MAXREFDES111A# operates over an input voltage range of 18V to 36V DC. This range accommodates standard 24V industrial supplies while providing headroom for line transients and brownout conditions. The EN/UVLO threshold is set to 18V, and overvoltage protection triggers at 36V using resistor dividers R3–R5. These thresholds are fixed in the MAXREFDES111A# layout and not user-adjustable without component changes.

Does the MAXREFDES111A# require external programming or configuration to operate?

No, the MAXREFDES111A# is a fully assembled and factory-tested reference board requiring no configuration. All key parameters-including 500kHz switching frequency, 18V startup, 36V OVI, 5V output regulation, and 5ms soft-start-are implemented with fixed passive components. Users only need to apply 24V DC input and connect a load to VOUT/GNDO terminals to verify operation per the documented Quick Start procedure.

Which transformer is qualified for use with the MAXREFDES111A#?

The MAXREFDES111A# is qualified with the Wurth Electronics transformer part number 750315847. This SMT transformer provides the required turns ratio, leakage inductance, and 1500V isolation rating. While MAXREFDES111B# and MAXREFDES111C# use Sumida and HanRun transformers respectively, only the Wurth 750315847 is validated for the MAXREFDES111A# variant per official design documentation.

What protection features does the MAXREFDES111A# include?

The MAXREFDES111A# incorporates multiple hardware-level protections: input undervoltage lockout (EN/UVLO) at 18V, input overvoltage protection (OVI) at 36V, hiccup-mode overcurrent protection (1.3A peak primary current limit), and thermal shutdown. These functions are implemented by the MAX17498B controller and do not rely on firmware or external supervision, ensuring fail-safe behavior in unattended industrial deployments.

Can the MAXREFDES111A# be used in safety-certified systems?

The MAXREFDES111A# achieves 1500V RMS galvanic isolation and meets functional insulation requirements per IEC 60950-1 and IEC 62368-1. While it is not itself UL/CSA certified as a standalone power supply, its design complies with creepage/clearance rules and isolation test levels required for incorporation into end-equipment seeking safety certification-provided system-level validation and layout adherence are maintained.