Analog Devices Inc./Maxim Integrated MAXREFDES111C#

Overview

MAXREFDES111C# from Maxim Integrated is an isolated 24V-to-5V, 2W flyback DC-DC reference design board featuring the MAX17498B peak-current-mode controller, 500kHz fixed switching frequency, ±5% output voltage accuracy, and galvanic isolation up to 1500V. It delivers 400mA at 5V with 20% overrange capability and fits on a compact 36mm × 20mm PCB for industrial power supply prototyping.

For engineers reviewing the MAXREFDES111C# datasheet, MAXREFDES111C# pinout, MAXREFDES111C# application, or MAXREFDES111C# equivalent, this reference design provides verified performance data including 79% peak efficiency at 24V input, hiccup-mode OCP, thermal shutdown, soft-start (5ms), and EN/UVLO + OVI protection set to 18V start / 36V shutdown thresholds.

Technical Context

The MAXREFDES111C# implements a primary-side regulated, transformer-isolated flyback topology using the MAX17498B controller with internal 500kHz oscillator, integrated n-channel MOSFET switch, and cycle-by-cycle current limiting. Input voltage range is 18V–36V; output is tightly regulated 5V ±5% via optocoupler-based feedback across the isolation barrier.

It uses HanRun HR041087 surface-mount transformer for 1500V isolation, includes RCD snubber (R1/C3/D1) for leakage energy clamping, and features through-hole mounting pins (15mm power-to-ground, 28mm input-to-output spacing) for rapid system integration without rework.

Key Specifications

Availability

MAXREFDES111C# is available at Aetrix Electronics and suitable for industrial control and automation, programmable logic controller (PLC) auxiliary power, and isolated sensor interface power supplies requiring stable component supply, quick-turn evaluation, and production-ready reference design files.

Supply support for MAXREFDES111C# 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 is Maxim's family of fully tested, production-ready reference designs focused on solving common isolated and non-isolated power conversion challenges in harsh industrial environments.

FAQ

What is the input voltage range supported by the MAXREFDES111C#?

The MAXREFDES111C# supports an input voltage range of 18V to 36V DC, with programmable undervoltage lockout (EN/UVLO) set to 18V and overvoltage protection (OVI) set to 36V. This ensures reliable operation across industrial 24V nominal systems, including brownout and surge conditions. The MAXREFDES111C# maintains regulation and protection throughout this range using resistor dividers R3–R5 and the MAX17498B's dedicated UVLO/OVI pins.

Which transformer is used in the MAXREFDES111C# reference design?

The MAXREFDES111C# uses the HanRun HR041087 surface-mount transformer, qualified specifically for this variant to provide 1500V AC galvanic isolation and optimized coupling for the 500kHz flyback operation. Unlike MAXREFDES111A# (Wurth 750315847) and MAXREFDES111B# (Sumida 06343-T588), the HR041087 is the only transformer validated for MAXREFDES111C# per Maxim's documentation.

Does the MAXREFDES111C# include protection features beyond overcurrent?

Yes, the MAXREFDES111C# integrates multiple protection mechanisms: hiccup-mode overcurrent protection (OCP), thermal shutdown, soft-start (5ms), input undervoltage lockout (18V start), and input overvoltage protection (36V shutdown). These are implemented via the MAX17498B controller and external resistors (R3–R5) and capacitor (C10), ensuring robust operation in adverse industrial environments without additional circuitry.

What is the output ripple performance of the MAXREFDES111C# at full load?

At full load (500mA), the MAXREFDES111C# delivers 5V output with peak-to-peak ripple + spike of 50mV, as measured with 24V input. This performance is achieved using the secondary-side diode D3, inductor L1, and output capacitors specified in the BOM. Ripple remains within specification across the full 0–480mA load range due to the optocoupler-regulated feedback loop and fixed-frequency control.

Can the MAXREFDES111C# be used directly in production systems?

The MAXREFDES111C# is a fully assembled, tested, and documented reference design intended for both evaluation and drop-in use in low-volume production. Its through-hole mounting pins, RoHS-compliant construction, and complete design files (schematic, BOM, Gerber) enable direct integration into industrial control and sensor systems. While not a certified safety module, its 1500V isolation and protection features make it suitable for functional-isolation applications where certification is handled at the system level.