Input Specificationとは

Issue No. 11 of Adapter NEWS featured "Input Specification," the second part of the AC adapter terminology series. It also includes explanations about the relationship between input voltage and frequency, and between input current and inrush current of the AC/DC Power Adapters — Desktop & Wall-Mount, so be sure to check it out.

Input Specifications

This article explains input specifications as a terminology guide for AC adapters.

Below is an example of input specifications from the specification sheet of an AC adapter from Unifive.

This time, we will explain five items: "AC input voltage", "AC input voltage range", "AC input frequency", "AC input current", and "AC inrush current".

Example of Input Specifications from a Unifive Product Specification

Item Specification Minimum Typical Maximum
AC input voltage Single-phase AC 100V~200V
AC input voltage range Single-phase AC 90V 264V
AC input frequency Single-phase AC 47Hz 50/60Hz 63Hz
AC input current Input voltage (typical) and full load 0.365A 0.44A
AC inrush current Input voltage (typical) and full load 40A
CEC efficiency Complies with CEC Level V requirements 82.22%
Standby power consumption Complies with CEC Level V requirements 0.3W
Leakage current Maximum input voltage 0.25mA

The image below shows an example of AC adapter usage. You plug the AC plug into a household outlet and connect the DC plug to an electric product such as a PC for use.

"Input Specification" defines the usage conditions of the AC plug side.

Diagram of AC adapter usage example

Input Voltage and Frequency

AC INPUT VOLTAGE and AC INPUT FREQUENCY define the voltage and frequency that can be input into the AC adapter.

The two items AC VOLTAGE RANGE specify the upper and lower limits of the AC input voltage.

If the voltage is below the lower limit, normal output voltage cannot be obtained. If a voltage higher than the upper limit is applied, not only will the AC adapter not operate properly, but there is also a risk of damage. Please use with caution.

Item Specification Minimum Typical Maximum
AC input voltage Single-phase AC 100V~200V
AC input voltage range Single-phase AC 90V 264V
AC input frequency Single-phase AC 47Hz 50/60Hz 63Hz

Input Current and Inrush Current

AC INPUT CURRENT refers to the current that flows on the input side when the AC adapter is used at its rated output current. The typical value is specified.

Since the input current varies for each adapter, the maximum value is specified so that it is not exceeded even with product variation.

When using multiple AC adapters with power strips or similar electrical fixtures, care must be taken to ensure that the total of typical values does not exceed the fixture’s capacity.

Item Specification Minimum Typical Maximum
AC input current Input voltage (typical) and full load 0.365A 0.44A
AC inrush current Input voltage (typical) and full load 40A

Image showing AC adapter's outlet capacity

AC INRUSH CURRENT is defined as the instantaneous current that flows when an AC adapter that has not been powered for a while is plugged into an outlet.

The waveform observed with an oscilloscope is shown below.

A large current flows, but since it only occurs momentarily when connecting to power, there is generally little risk to wiring devices. However, noise may be emitted into the surrounding space, so caution is advised if electrically sensitive products are being used nearby.

Waveform of inrush current as observed on oscilloscope

That concludes Part 1 of the AC adapter terminology guide on Input Specifications.

If you have any questions about other terms or specifications, or if you're wondering "Which AC adapter should I use for this purpose?", please feel free to contact us through the inquiry form on our website.

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