Electrical Engineering Stack Exchange is a question and answer site for electronics and electrical engineering professionals, students, and enthusiasts. It only takes a minute to sign up.
Sign up to join this community
In several datasheets for electronic components, I have seen a ∝ symbol used as a prefix for a time unit, usually seconds, writing as ∝s. As far as I know ∝ is not a valid SI prefix, so what does it mean? What unit is ∝s?
Comparing different datasheets, I assume it should be rather equivalent to micro prefix, but I'm really not sure.
You can see this use for example in the BT136 datasheet describing "Gate controlled turn-on time" and defining unit as ∝s.
In the common ISO 8859-1 encoding, µ is encoded as 0xB5.
In the Windows Symbol typeface, ∝ is encoded as 0xB5.
The Symbol font has been commonly used for Greek letters; µ is the only Greek letter that is available elsewhere. This appears to be a common mistake.
u, even though improperly used
\$\endgroup\$
It is most likely an encoding error in the PDF file. It is simply the wrong symbol.
Here's a section of the BT136 datasheet showing the dynamic characteristics:
It shows ∝s for several things, among them \$dV_{com}/dt\$.
Figure 12 also refers to \$dV_{com}/dt\$, but it uses units of microseconds (us.)
Figure 12 uses the common (also incorrect) convention of using a lower case "u" for micro rather than the correct µ symbol. The dynamic characteristics table probably had the correct symbol in whatever program was used to write the datasheet, but it got mangled in the conversion to PDF.