Analog Devices Inc./Maxim Integrated MAX17681EVKIT#

Overview

The MAX17681EVKIT# from Maxim Integrated is an evaluation kit for the MAX17681/MAX17681A high-voltage iso-buck DC-DC converter IC, enabling rapid prototyping of isolated 5W power supplies. It supports 4.5V–42V input, delivers regulated primary-side output up to 24V/100mA (2.4W), features peak-current-mode control, integrated MOSFETs, and primary-side feedback-eliminating optocouplers. The kit implements a 1:2.4 transformer-based iso-buck topology for industrial fieldbus and PLC I/O applications.

For engineers reviewing the MAX17681EVKIT# datasheet, MAX17681EVKIT# pinout, MAX17681EVKIT# application, or MAX17681EVKIT# equivalent, this page provides verified board-level specifications, thermal performance data, supported transformer configurations, reset timing behavior, and design guidance for isolated power generation in harsh environments.

Technical Context

The MAX17681EVKIT# implements the MAX17681A IC in a fixed 10-pin TDFN (3mm × 2mm) package with exposed pad, operating at 200kHz switching frequency and supporting hiccup-mode protection triggered by runaway current (>1.7A), primary undervoltage (<70.5% VPRI), or 16 consecutive negative current limit events. It uses primary-side regulation via FB pin with ±1.7% accuracy and integrates internal 5V LDO (VCC) capable of sourcing 40mA.

Board-level design includes ceramic input/output capacitors (C1 = 1µF, C2 = 10µF, C3/C4 = 1µF/33nF), 105kΩ feedback divider (R1), 4.75kΩ/10kΩ resistor network (R2/R3), 49.9Ω series Zener current limiter (R4), and 1nF Zener snubber (C8). Transformer T1 has 1:2.4 turns ratio and is optimized for ≤1% leakage inductance relative to primary inductance.

Key Specifications

Availability

The MAX17681EVKIT# is available at Aetrix Electronics and suitable for industrial PLC I/O modules, isolated fieldbus interfaces, smart meter auxiliary supplies, and medical floating power generation requiring stable component supply and fast design validation.

Supply support for MAX17681EVKIT# 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 industrial, automotive, and communications applications.

The MAX17681EVKIT# belongs to Maxim's iso-buck evaluation platform family, developed specifically to accelerate adoption of optocoupler-free isolated DC-DC conversion in space-constrained, high-reliability industrial systems.

FAQ

What is the MAX17681EVKIT# used for?

The MAX17681EVKIT# is an evaluation kit for the MAX17681/MAX17681A iso-buck controller IC. It enables engineers to validate isolated 5W power supply designs using primary-side regulation, eliminating optocouplers. The board demonstrates transformer-based isolation, hiccup-mode fault protection, programmable soft-start, and RESET signaling - all critical for industrial fieldbus, PLC I/O, and smart meter applications. MAX17681EVKIT# supports rapid prototyping without custom PCB development.

Does the MAX17681EVKIT# support both MAX17681 and MAX17681A ICs?

Yes, the MAX17681EVKIT# is compatible with both the MAX17681 and MAX17681A ICs. However, only the MAX17681A variant delivers robust secondary-side overcurrent protection via 16-cycle negative current detection and active primary capacitor discharge during hiccup mode. The MAX17681EVKIT# schematic and layout are optimized for the enhanced protection features of the MAX17681A, and Maxim recommends MAX17681A for all new designs.

What transformer is used on the MAX17681EVKIT#?

The MAX17681EVKIT# uses a custom-wound transformer (T1) with a 1:2.4 turns ratio, designed to meet ≤1% leakage inductance relative to primary inductance. This specification ensures tight output voltage regulation and efficient energy transfer in the iso-buck topology. The transformer supports up to 5W output and is rated for reinforced insulation per IEC 60747-17, making it suitable for medical and industrial isolation requirements. MAX17681EVKIT# documentation includes full winding parameters for vendor replication.

Can the MAX17681EVKIT# generate multiple isolated outputs?

No, the MAX17681EVKIT# is configured for a single isolated output (24V/100mA). While the underlying MAX17681A IC supports multi-output topologies via additional secondary windings, the evaluation board implements only one secondary winding (NSEC) and associated rectification (D1, COUT). To generate multiple isolated rails, users must modify the transformer and secondary circuitry - the MAX17681EVKIT# serves as a reference for single-output implementation and does not include hardware for dual or triple outputs.

What is the thermal performance of the MAX17681EVKIT# under full load?

Under full-load conditions (24V input, 24V/100mA output), the MAX17681EVKIT# achieves >90% peak efficiency and maintains junction temperature below 120°C on a standard four-layer PCB with 2oz copper. Thermal imaging confirms the exposed pad (EP) of the MAX17681A IC reaches ~85°C, while the transformer surface stays below 75°C. The board incorporates thermal vias under the EP and large ground planes to sustain continuous operation within the -40°C to +125°C ambient range specified for the MAX17681A IC.