FAQ
Frequently Asked Questions
How does a 10/100 BASE-T transformer differ internally from a Gigabit one?
Each port uses half the channels: a 100M port takes two channels in one pairset, a Gigabit port four channels across two pairsets.
On the part that shows up as the transformer unit count — a single-port part here holds two units where a Gigabit single-port part holds four. The relationship works as a check on whether a stated data rate is trustworthy: divide unit count by port count, and two means 100M while four means Gigabit. Counting units is more reliable than reading a title or a part number. All parts in this family are listed in the 10/100 BASE-T range.
What port counts and packages does the 10/100 family offer?
Port counts run from single to five, with single-port parts making up more than half, and the packages are predominantly through-hole — the reverse of the Gigabit family.
The breakdown is 23 single-port, 6 dual-port, 3 triple-port, 4 quad-port and 2 five-port; by package, 22 through-hole against 16 surface-mount. The difference is meaningful in practice: 100M ports appear heavily in industrial control, building systems and retrofits, whose boards are often wave-soldered rather than reflowed. Pin counts range from 12 to 72, with 16-pin the most common. Browse the full list in the 10/100 BASE-T range.
Are there many PoE parts in the 10/100 family?
Very few — of the 38 parts in this family, only three state a current capability and an applicable IEEE class; the rest carry no power capability at all.
Where a port has to be powered over the cable, the choice here is narrow, and it is worth settling that before moving on to package. Take care not to mistake the DC bias on the inductance line for power capability: that bias is a test condition for verifying magnetising behaviour, not current available to a load. Whether a part can deliver power is decided by a separate line naming current capability and an IEEE class. The Gigabit family offers a much wider range of PoE grades; this family is listed in the 10/100 BASE-T range.
What temperature grades does the 10/100 family cover?
Most parts are commercial grade, but this family spans the widest range of high-temperature options in the whole category.
Of the 38 parts, 26 are commercial grade and 9 are industrial wide-temperature, while three more each occupy a grade of their own, reaching upper limits of +105 °C, +125 °C and +150 °C. Two cautions apply: commercial grade starts at 0 °C and rules out equipment that powers up below freezing, and storage range must not be read as an operating range. Grades are listed per part in the 10/100 BASE-T range.
What isolation grades does the 10/100 family offer, and how is one chosen?
Most parts sit at the standard grade, with two at a middle grade and one considerably higher.
The choice does not follow "higher is better" but follows how the system's safety documentation is written — whether the clause calls for a short-duration high voltage or a longer mid-voltage. One point is easily missed: the test duration differs between grades, and a higher voltage usually corresponds to a much shorter application time, so the voltages cannot be compared on their own. Send us the clause and VOOHU will confirm which part matches. Ratings are listed per part in the 10/100 BASE-T range.
After filtering by pin count and pitch, what still has to be checked?
Row spacing has to be confirmed against the drawing — it is not among the site's filter fields, and it decides whether the part drops into an existing hole pattern.
Among the 20-pin parts in this family there are three incompatible hole patterns, and the triple-port parts use two between them, yet all of them show the same Pitch value. Ordering on a filter result alone risks receiving a part that will not fit. Two more items need checking: internal port count, since the same pin count does not imply the same number of ports, and capability grade, since temperature, isolation and power capability are often the only difference between parts sharing a package. Drawings are linked from each part in the 10/100 BASE-T range.
