| 1. Define the Power-Supply Requirements |
| Output voltage and current | List each required output, its nominal voltage, continuous current, peak current, and permitted tolerance. | For example, a single-output design may require 24 V DC at 5 A. Confirm the load profile and allowable ripple against the product specification. | Send a complete electrical specification rather than requesting a unit based on wattage alone. |
| Rated output power | Calculate continuous power as output voltage multiplied by output current; account for simultaneous loading of multiple outputs. | A 24 V, 5 A output is rated at 120 W. Check derating guidance for ambient temperature, mounting orientation, and altitude. | Ask for the rated-power curve and the conditions under which the rating applies. |
| AC input range and frequency | Specify the countries of use, nominal mains voltage, frequency, and any expected input variation. | Many global-input products specify a range such as 100–240 V AC, 50/60 Hz; the exact range must be confirmed for the selected model. | Verify operation at both the lowest and highest required input conditions. |
| Efficiency and standby power | Request efficiency at defined input voltage and load points, plus no-load or standby consumption where relevant. | Efficiency varies with topology, output rating, input voltage, and load. Compare like-for-like test conditions; external power supplies may be subject to market-specific energy rules. | Obtain the test report or datasheet efficiency curve and identify applicable energy requirements for each destination market. |
| Thermal and environmental conditions | Define operating and storage temperature, airflow, humidity, vibration, and installation location. | Manufacturer datasheets commonly state an operating-temperature range and output derating above a specified temperature. Do not assume full power across the entire range. | Request thermal test data for the intended enclosure and cooling arrangement. |
| Mechanical format and cooling | Specify board-mount, open-frame, enclosed, DIN-rail, or external-adapter format; include dimensions, connectors, and cooling constraints. | Mechanical dimensions and airflow clearances are model-specific. Fanless designs may have different derating limits from fan-cooled designs. | Review a dimensioned drawing and confirm connector, mounting, and clearance details before tooling or approval. |
| Protection and safety features | Confirm overvoltage, overcurrent, short-circuit, and overtemperature behavior, as applicable to the product. | Protection modes and recovery behavior differ by design; verify details in the datasheet and test documentation. | Ask for protection thresholds, restart behavior, and evidence from relevant safety evaluations. |
| 2. Evaluate Supplier Capability and Compliance |
| Product safety standards | Identify the applicable end-product category and the safety standard required in each target market. | IEC 62368-1 is used for many audio/video and information and communication technology products. Applicability depends on the equipment and jurisdiction. | Request certificates or reports that match the exact model, revision, and intended use; confirm recognition with the relevant certification body or compliance specialist. |
| EMC performance | Define emissions and immunity requirements for the end product and installation environment. | CISPR 32 addresses emissions for multimedia equipment; IEC 61000-4 series documents cover common immunity test methods. Applicable limits depend on product classification and market. | Request model-specific EMC reports and check whether testing used the same cables, load, and configuration as the planned application. |
| Materials and restricted substances | Set market-specific requirements for hazardous-substance restrictions and supply-chain material declarations. | EU RoHS and REACH requirements may apply to products placed on the EU market; scope, exemptions, and documentation obligations depend on the product. | Request current declarations and supporting material information for the exact product and revision. |
| Quality management | Assess the supplier’s quality system, change control, traceability, corrective-action process, and production testing. | ISO 9001 certification can provide evidence of a quality-management system, but it does not by itself certify a particular power supply. | Review the certificate scope and validity, audit relevant processes, and ask how component substitutions are controlled. |
| Production test coverage | Clarify routine production tests, test limits, sampling plans, and retained records. | Common checks may include output regulation, startup, protection functions, and dielectric-strength testing where required by the design and applicable standards. | Agree on a test plan, acceptance criteria, and the format of lot-level test records before placing a production order. |
| Engineering and customization | Assess support for output adjustments, connectors, wiring, enclosure, labeling, firmware, or other application-specific needs. | Customization can affect tooling, certification, lead time, minimum order quantity, and change-control requirements. | Document all deviations from the standard product and require written approval of drawings and specifications. |
| 3. Compare Quotations and Manage Supply Risk |
| Quotation completeness | Compare unit price, currency, Incoterms, tooling, packaging, certification costs, payment terms, and quote validity. | A low unit price may exclude testing, documentation, freight, duties, or customization charges. | Use a common request-for-quotation template so that every supplier quotes the same scope and delivery basis. |
| Minimum order quantity and lead time | Request sample, pilot, and production quantities, with lead times for each stage. | MOQ and lead time are supplier-, product-, and component-availability-specific; there is no universal benchmark that applies to all SMPS products. | Confirm current capacity, component constraints, order cut-off dates, and the consequences of forecast changes in writing. |
| Samples and qualification | Plan engineering samples, design validation, compliance testing, and a controlled pilot build. | Sample performance does not automatically represent mass-production consistency. Qualification should cover the intended load, input, temperature, and installation conditions. | Approve a golden sample and define a formal process for production release and future design changes. |
| Warranty and failure analysis | Clarify warranty duration, return authorization, repair or replacement process, and failure-analysis responsibilities. | Warranty terms vary by contract and product; confirm exclusions, shipping responsibility, and response times. | Include service expectations and corrective-action timelines in the purchase agreement. |
| Continuity of supply | Assess component lifecycle management, alternative-part approval, capacity planning, and end-of-life notification. | Semiconductor and passive-component availability can affect lead times and approved configurations. | Request a documented change-notification process and evaluate a qualified second source for business-critical products. |
| Final supplier decision | Score technical fit, compliance evidence, quality controls, commercial terms, responsiveness, and supply resilience. | Weight criteria according to application risk; a regulated or safety-critical product may prioritize qualification evidence over initial unit cost. | Complete a written supplier evaluation, close open technical questions, and approve the final specification before issuing the purchase order. |