AC/DC Power Adapter Case study of short-term resolution of peak current issues through semi-customization

The power would repeatedly shut off during startup, and the cause was unknown... What was happening with the commercially available third-party AC/DC Power Adapter the customer was using? In this article, we briefly summarize the issues from both procurement and technical perspectives and the approach to resolving them, based on a case in which we actually solved a customer's problem. This content offers valuable insights for companies considering measures against peak current. We hope you will take a moment to read it.

Case Study: Resolving Power Supply Issues Caused by Online-Sourced Products

This article presents a case in which the use of a general-purpose AC/DC Power Adapter from another manufacturer, procured through an online shop, triggered overheating, shutdowns, and non-compliance with standards, making short-term replacement unavoidable. We resolved the issue with our semi-custom power supply solution.

"The AC adapter shuts down due to inrush current at startup."
"We do not know how to properly match the Products with the AC/DC Power Adapter."

In addition to the information required for adoption decisions (cost / delivery time / regulatory compliance / mass production risk), we also briefly introduce the replacement procedure and key points for compatibility evaluation.

Customer Challenges and Background

In the customer's production lot, an issue occurred in which the existing AC/DC Power Adapter (DC6V 2.8A unit from another manufacturer) repeatedly experienced sudden voltage drops and recovery due to inrush current at startup. In addition, changes in the internal layout of the competitor's adapter raised concerns about fluctuations in the OCP threshold. The customer consulted us to resolve these issues.

Target device: Equipped with a motor (instantaneous peak current generated at startup)
Symptom: Voltage drops and recovers repeatedly when the switch is turned on (appearing in the latest lot)
Procurement perspective: The internal layout of the competitor's adapter purchased from an online shop was changed multiple times, possibly causing fluctuations in the OCP (overcurrent protection) threshold

Our Solution

Key Points in Our Response

Item	Current Situation	Notes / Assumptions
Peak Current	4.2A instantaneous (measured value)	Verification of alignment with OCP threshold required
OCP Setting	Competitor product: estimated 2.8A	Set with sufficient margin to prevent malfunction

Process Flow

Customer Requirement Hearing

Confirm defect symptoms, timing of occurrence, and usage environment

Cause Analysis and On-site Measurement

Measure current waveform and estimate overload protection operating point

Design Review and Prototyping

Determine optimal settings with the UV324 series and define semi-custom specifications

Evaluation and Verification

Operation check, safety testing, and long-term operation testing

Mass Production Implementation

Update BOM, finalize manufacturing procedures, and establish quality control system

Customer Reporting

Explain results, effects, and future supply structure

[Key Point] Optimize overcurrent protection and leverage an existing series to withstand instantaneous peak loads

Based on the hearing results, we identified that the power supply shutdown was caused by activation of the overcurrent protection function. Using our UV324 series, we created a semi-custom specification in which overload protection does not activate up to 4.2A MAX. This enabled us to propose improvements that balanced cost efficiency and development speed.

Results After Implementation

The defect symptoms were eliminated, and the issue of repeated power drops and restarts no longer occurred
Identifying the root cause provided reassurance from both procurement and technical perspectives
Optimization of overload protection ensured stable operation even during peak current
Semi-customization enabled successful mass production implementation in a short period
A policy for continued adoption was established, securing a stable supply system

Customer Feedback

"The defect symptoms have been resolved, and we are very reassured that the cause was properly identified. We would like to continue using UNIFIVE's Products going forward."

- Development Representative, Septic Tank and Wastewater Treatment Equipment Manufacturer

For Those Facing Similar Issues

When matching a Products with an adapter, devices that use motors or amplifiers may draw currents exceeding their rated values instantaneously, which can cause operational failures.

If you are using adapters with such equipment, please feel free to consult us. We will provide advice and propose optimal custom or semi-custom solutions.