Peak Load or Continuous Power? Describe the Load Cycle Before Buying

Give the supplier a timeline, not just a maximum

An equipment team may describe its requirement as “120 watts,” while purchasing receives quotations with different continuous and peak ratings. Before choosing a supply, define what that number represents. Is it required throughout operation, only at startup, or during a repeating action?

A useful brief includes the lower operating load, the highest load, how long each lasts and how often the sequence repeats. Identify whether those values were measured, calculated or estimated. If the operating sequence is still being developed, show the open assumptions so the supplier can qualify its proposal.

A peak rating comes with conditions

TDK-Lambda's technical article on peak power ratings explains that manufacturers specify both the permitted peak level and its duration. It also distinguishes ratings evaluated using RMS power from those using average power, and discusses the effect of cooling and operating conditions. The applicable datasheet and application notes therefore matter as much as the headline wattage.

Do not infer short-term overload capability from an ordinary continuous rating. Ask for a documented operating envelope for the exact proposed model. The cited article describes TDK-Lambda designs; it does not establish peak capability for any Voltivo Power catalog item.

Same peak, different purchasing requirement

Consider this illustrative load schedule at a fixed output voltage. These are invented planning values, not product specifications or test results:

Schedule A

120 W for 2 seconds, followed by 30 W for 18 seconds. Full cycle: 20 seconds.

Schedule B

120 W for 10 seconds, followed by 30 W for 10 seconds. Full cycle: 20 seconds.

Both schedules reach 120 W, but their time-weighted average loads differ. For A, (120 × 2 + 30 × 18) ÷ 20 = 39 W. For B, (120 × 10 + 30 × 10) ÷ 20 = 75 W. Their peak duty cycles are 10% and 50%, respectively.

This arithmetic describes the two load schedules only. It does not establish a suitable supply rating: a candidate must still meet the peak level, duration, repetition and all other documented limits. An average-power calculation cannot replace an RMS-based criterion where the manufacturer requires one.

Write the cycle so it cannot be misread

Use unambiguous time labels. State both the peak duration and the complete interval from the start of one peak to the start of the next. If you instead provide only the time between peaks, label it explicitly. Add a simple timing sketch or recorded trace where available.

Include output voltage, baseline and maximum current, expected startup sequence, operating modes and whether multiple loads can overlap. Ask the engineering team to identify the most demanding credible sequence, including repeated user actions. A normal cycle and a one-time startup event should have separate descriptions.

For installation context, attach the enclosure and cooling arrangement, expected ambient conditions, input range and cable configuration. Keep these references consistent with the configuration intended for sample review.

Ask each quotation to answer the same questions

Request a response against the same revision of your load brief. The supplier should identify the proposed model, the supporting document revision, the continuous rating under the stated conditions and any documented peak capability being relied upon. Ask it to identify unresolved conditions rather than answering only “sufficient wattage.”

Have your technical reviewer compare the proposed operating envelope with the complete load sequence. Plan sample evaluation in the intended equipment and record the result against that configuration. If the operating mode or repetition rate later changes, reopen the review instead of carrying forward an old approval automatically.

Send Voltivo Power your load timeline, output requirements, installation details, destination markets and quantity to discuss a suitable configuration. Where peak operation has not been documented, keep it an open technical question before placing an order.