Analog Devices Inc./Maxim Integrated MAXREFDES125#

Overview

MAXREFDES125# from Maxim Integrated is a non-isolated 24V-to-5.1V, 20W industrial reference design board built around the MAX17536 synchronous step-down controller. It delivers up to 4A output current with peak efficiency of 96.5% at 24V input, operates across 17V–36V input range, and supports PWM/PFM/DCM mode selection via jumper configuration for flexible power management in space-constrained PLC and sensor systems.

For engineers reviewing the MAXREFDES125# datasheet, MAXREFDES125# pinout, MAXREFDES125# application, or MAXREFDES125# equivalent, this page provides verified board-level specifications, mode-select jumper configurations, measured efficiency curves across load and control modes, transient response data at 24V input, and integration guidance for industrial embedded power subsystems.

Technical Context

The MAXREFDES125# implements a high-voltage synchronous buck topology using the MAX17536 controller, which integrates a high-side MOSFET and employs peak current-mode control. It supports three selectable operating modes-PWM (constant frequency, negative inductor current allowed), PFM (pulse-skipping, higher light-load efficiency), and DCM (constant frequency without pulse skipping, intermediate efficiency)-each configured via JU1 jumper position.

Input undervoltage lockout (EN/UVLO) is set to 14.5V using an external resistor divider, and soft-start timing is internally controlled. The board features hiccup-mode overcurrent protection, internal loop compensation, and dual VCC supply paths (VIN or EXTVCC) to optimize efficiency across input voltage ranges.

Key Specifications

Availability

MAXREFDES125# is available at Aetrix Electronics and suitable for industrial PLCs, process control sensors, and telecom power supplies requiring stable component supply, rapid prototyping validation, and production-ready reference design reuse.

Supply support for MAXREFDES125# 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 reference design series targets rapid evaluation and system integration of Maxim's power controllers, with MAXREFDES125# specifically engineered to demonstrate robust, high-efficiency 20W DC-DC conversion in harsh industrial settings.

FAQ

What is the input voltage range supported by the MAXREFDES125#?

The MAXREFDES125# supports an input voltage range of 17V to 36V, enabling reliable operation across standard 24V industrial DC buses with tolerance for transients and brownouts. This range is implemented using the MAX17536 controller's 4.5V–60V input capability, with UVLO set to 14.5V via external resistors. The MAXREFDES125# has been tested and validated across the full 17V–36V span under varying load conditions.

How is operating mode selected on the MAXREFDES125#?

Operating mode (PWM, PFM, or DCM) on the MAXREFDES125# is selected via jumper JU1: shunt position 1–2 (default) configures PWM mode; position 2–3 selects DCM mode; and open position enables PFM mode. These settings directly configure the MODE/SYNC pin logic state at power-up, as defined in the MAX17536 datasheet. Each mode affects switching behavior, light-load efficiency, and output ripple characteristics of the MAXREFDES125#.

What is the output voltage accuracy and regulation method used on the MAXREFDES125#?

The MAXREFDES125# delivers a nominal 5.1V output with ±0.255V (±5%) tolerance, achieved using the MAX17536's precision feedback comparator and internal 0.6V reference. Output voltage is set by an external resistor divider from VOUT to FB, with compensation optimized for stability across all three operating modes. Lab measurements confirm regulation remains within spec from 0A to 4A load at 24V input.

Does the MAXREFDES125# include overcurrent or short-circuit protection?

Yes, the MAXREFDES125# implements hiccup-mode overcurrent protection via the MAX17536 controller. When current limit is exceeded, the device shuts down, waits a fixed recovery time, then attempts restart-repeating until fault clears. This limits average power dissipation during sustained overload or short-circuit events, protecting both the MAXREFDES125# board and downstream circuitry without requiring external components.

Can the MAXREFDES125# be integrated directly into a larger system as a power module?

Yes, the MAXREFDES125# is designed for modular integration: it features through-board mounting pins spaced 15.24mm (0.6in) between power and ground, and 27.94mm (1.1in) from input to output side. Its 20mm × 35mm footprint and jumper-configurable modes allow it to serve as a drop-in 5.1V/4A power subsystem in host PCBs-verified in applications including PLC backplanes and sensor node carriers where space and thermal constraints are critical.