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BC108 family

The BC107, BC108 and BC109 are general-purpose low power silicon NPN bipolar junction transistors found very often in equipment and electronics books/articles from Europe, Australia and many other countries from the 1960s. They were created by Philips and Mullard in 1963 and introduced in April 1966. Initially in metal (TO-18) packages, the range expanded over time to include other package types, higher voltage ratings, and a better selection of gain (h<sub>FE</sub> and h<sub>fe</sub>) groupings, as well as complementary PNP types. Some manufacturers have specified their parts with a higher power dissipation rating (P<sub>tot</sub>) than others.

The BC548 is an example of the modern low-cost member of this family, still in a through-hole package, while the BC848 is the surface-mount version.

Table of BC107 to BC860 variants

(See also: http://pdf1.alldatasheet.net/datasheet-pdf/view/97721/MICRO-ELECTRONICS/BC168.html for a neat summary of some of the family).

Noise figure (at 1&nbsp;kHz, for a 2 kilohm source, BW = 200&nbsp;Hz, I<sub>C</sub>=0.2&nbsp;mA/V<sub>CE</sub>=5 V) is <10&nbsp;dB for those not tabulated as "Low Noise".

Current ratings

All types have a maximum collector current of 100&nbsp;mA, except that the original Philips tentative data dated 4.4.1966 specified a maximum collector current of 100&nbsp;mA peak (I<sub>CM</sub>) for the BC107/8/9, and Telefunken originally specified a maximum collector current of 50&nbsp;mA for the BC109, but since at least 1973 all have revised collector currents of 100&nbsp;mA average or 200&nbsp;mA peak, except that the BC317-BC322 range have a 150&nbsp;mA (continuous) rating.

A, B and C gain groupings

The above devices' type numbers may be followed by a letter "A" to "C" to indicate low to high gain (h<sub>FE</sub>) groups (see BC548 Gain groupings).

Other characteristics

Transistors in this family:

  • require a base-emitter voltage (V<sub>BE(on)</sub>) in the range of 0.55 to 0.7 volts for a collector current of 2&nbsp;mA when the Collector voltage is 5 volts.
  • Will have a saturation voltage (V<sub>CE(sat)</sub>) of at most 0.2 volts (typically 0.07 volts) at a collector current of 10&nbsp;mA and a base current of 0.5&nbsp;mA (when the base voltage is typically 0.73 volts; 0.83 volts maximum).
  • Has greater than unity current gain up to a frequency (f<sub>T</sub>) of at least 150&nbsp;MHz, typically 250&nbsp;MHz, at a collector current of 10&nbsp;mA (typically 85&nbsp;MHz and a collector current of 0.5&nbsp;mA)
  • These transistors can be found in the list of suitable TUN transistors ("Transistor Universal Npn") by the [Elektor] magazine for their circuits that require general purpose Silicon transistors meeting certain minimum standards.
  • These transistors have PNP complementary types, with only the second digit changed (to a number normally greater than 4) to indicate the reversed polarity, e.g. a BC177 is PNP version of the BC108, and a BC559 is a PNP version of a BC549.
  • Note that this "family" of transistors do not include every transistor with a type number beginning "BC" and ending in "7", "8" or "9". For example, the BC328 and BC338 transistors are not included in the Elektor list (and not "family" members), despite sharing some similarities.

See also

References

Further reading

Historical Databooks