Analog Devices Inc./Maxim Integrated MAX17681AEVKITD#

Overview

The MAX17681AEVKITD# from Maxim Integrated is an evaluation kit for the MAX17681A high-voltage iso-buck DC-DC converter IC, enabling rapid prototyping of isolated 5W power supplies using primary-side regulation and no optocoupler. It supports input voltages from 4.5V to 42V, delivers up to 24V/100mA secondary output via a 1:2.4 transformer, and implements robust secondary-side overcurrent protection with hiccup-mode recovery. The kit includes all critical passive components, layout-optimized TDFN footprint, and test points for VIN, VPRI, VOUT, SS, COMP, and RESET.

For engineers reviewing the MAX17681AEVKITD# datasheet, MAX17681AEVKITD# pinout, MAX17681AEVKITD# application, or MAX17681AEVKITD# equivalent, this kit provides validated reference design, thermal performance data, load transient waveforms, Bode plot stability analysis (6.7kHz crossover, 80° phase margin), and hiccup-mode behavior under secondary short-circuit - essential for industrial PLC I/O, smart meter, and medical isolated supply development.

Technical Context

The MAX17681AEVKITD# implements the MAX17681A's peak-current-mode control architecture with synchronous primary-side switching, programmable soft-start (via 3300pF SS capacitor), and active primary-capacitor discharge during hiccup timeout. It validates the IC's 1.65A peak current limit, 1.25A sink limit, and 16-consecutive-negative-current-limit detection for secondary fault response.

This kit demonstrates the full signal chain: EN/UVLO resistor-divider programming (105kΩ), FB voltage divider (10kΩ/4.75kΩ) setting 0.9V feedback reference, COMP RC compensation network, and open-drain RESET monitoring with 1024-cycle delay. It operates across –40°C to +125°C ambient, confirming thermal shutdown at 165°C with 10°C hysteresis and junction-to-ambient θ_JA = 67.3°C/W on four-layer board.

Key Specifications

Availability

The MAX17681AEVKITD# is available at Aetrix Electronics and suitable for industrial PLC I/O modules, smart meter auxiliary supplies, and isolated fieldbus interface designs requiring stable component supply, pre-validated thermal management, and documented hiccup-mode recovery behavior.

Supply support for MAX17681AEVKITD# 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 medical applications, with emphasis on high-reliability, small-footprint solutions.

The MAX17681A product line targets isolated DC-DC conversion in space-constrained industrial systems, eliminating optocouplers while maintaining ±1.7% feedback accuracy, -40°C to +125°C operation, and robust secondary fault handling.

FAQ

What is the MAX17681AEVKITD# used for?

The MAX17681AEVKITD# is an evaluation kit for the MAX17681A iso-buck DC-DC controller IC. It provides a fully assembled, tested reference design to validate isolated 5W power supply performance - including efficiency, thermal behavior, hiccup-mode recovery under secondary short-circuit, and loop stability - without requiring custom PCB layout or component selection. Engineers use MAX17681AEVKITD# to accelerate development of PLC I/O, smart meter, and medical equipment power stages.

Does the MAX17681AEVKITD# support both MAX17681 and MAX17681A ICs?

No - the MAX17681AEVKITD# is specifically configured for the MAX17681A, which adds robust secondary-side overcurrent protection and active primary-capacitor discharge during hiccup mode. While the board's TDFN footprint and basic circuit match both variants, features like 16-consecutive-negative-current-limit detection, smooth post-fault soft-start, and secondary short-circuit indication via RESET are only functional with the MAX17681A IC installed. Using MAX17681 on this board omits those capabilities.

What transformer is used on the MAX17681AEVKITD# board?

The MAX17681AEVKITD# uses a custom-wound transformer labeled T1 with a 1:2.4 turns ratio (NPRI:NSEC), optimized for the iso-buck topology. This ratio scales the regulated 9.6V primary output (VPRI) to 24V secondary output (VOUT) at 100mA. The transformer includes tight coupling to minimize leakage inductance (<1% of LPRI), critical for maintaining ±1.7% output regulation without secondary feedback.

How is hiccup-mode behavior verified on the MAX17681AEVKITD#?

Hiccup-mode behavior is validated on the MAX17681AEVKITD# through controlled secondary short-circuit testing. When a short is applied to VOUT, the MAX17681A detects 16 consecutive negative current limit events, triggers hiccup timeout (32,768 cycles), actively discharges the primary capacitor via low-side switch conduction, then performs synchronized soft-start of both primary and secondary outputs upon recovery - all observable via oscilloscope on LX, VPRI, VOUT, and RESET pins.

Can the MAX17681AEVKITD# be used to evaluate different output voltages?

Yes - the MAX17681AEVKITD# supports output voltage adjustment by modifying the FB resistor divider (R2 = 4.75kΩ, R1 = 10kΩ for 24V) and selecting appropriate transformer turns ratio. For example, changing R1 to 20kΩ sets VPRI ≈ 12V, enabling 12V/200mA output with same T1; alternative transformers (e.g., 1:1.2) allow 12V or 5V outputs. All adjustments maintain the MAX17681A's 0.9V feedback reference and ±1.7% regulation accuracy.