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[1] 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 (hFE and hfe) groupings, as well as complementary PNP types. Some manufacturers have specified their parts with a higher power dissipation rating (Ptot) 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
| Case | Ptot | Polarity | ≥ 70 VCBO ≥ 64 VCEO | 50 VCBO | 30 VCBO | Low-Noise (<4 dB) 30 VCBO | Low-Noise (<4 dB) 50 VCBO | Notes/Source |
|---|---|---|---|---|---|---|---|---|
| TO-18 (C-B-E)  Emitter is closest to tab | 300 mW | NPN | BC190 64 VCEO | BC107 BC107A BC107B 45 VCEO |
BC108 BC108A BC108B BC108C 20 VCEO |
BC109 BC109B BC109C 20 VCEO | Philips Semiconductor Handbook Oct 1966 | |
| PNP | BC177 45 VCEO | BC178 25 VCEO | BC179 25 VCEO | Philips Application Book: Audio Amplifier Systems, 1971 | ||||
| Lockfit (C-B-E)  |
250 mW | NPN | BC147 45 VCEO | BC148 20 VCEO | BC149 20 VCEO | a discontinued plastic case with leads that lock into a PCB's holes. | ||
| PNP | BC157 45 VCEO | BC158 25 VCEO | BC159 20 VCEO | |||||
| TO92B (E-C-B)  | 300 mW | NPN | BC167 45 VCEO | BC168 20 VCEO | BC169 20 VCEO | |||
| PNP | BC257 45 VCEO | BC258 25 VCEO | BC259 20 VCEO | (Also: BC256 64 VCBO) | ||||
| TO92F (C-B-E)  |
300 mW* | NPN | BC174 64 VCEO | BC171 BC237 45 VCEO | BC172 BC238 20 VCEO | BC173 BC239 20 VCEO | *Fairchild's power rating is 500 mW Some devices have pre-formed leads with the base bent backwards like a TO-18 pinout (e.g. MEL). | |
| PNP | BC307 45 VCEO | BC308 25 VCEO | BC309 20 VCEO | |||||
| TO92A (E-B-C) | 310 mW | NPN | BC317 45 VCEO | BC318 30 VCEO | BC319 20 VCEO | Note: 150 mA rating; BC318 VCBO 40 V to 45 V[2] | ||
| PNP | BC320 45 VCEO | BC321 30 VCEO | BC322 20 VCEO | |||||
| TO92F (C-B-E) | 500 mW* | NPN | BC546 65 VCEO | BC547 45 VCEO | BC548 30 VCEO | BC549 30 VCEO | BC550 45 VCEO | from Mullard 1977 and Fairchild 2001 specifications; *Some manufacturers specify a 625 mW rating |
| PNP | BC556 65 VCEO | BC557 45 VCEO | BC558 30 VCEO | BC559 30 VCEO | BC560 45 VCEO | |||
| SOT-23 | 150 mW | NPN | BC846 65 VCEO | BC847 45 VCEO | BC848 30 VCEO | BC849 30 VCEO | BC850 45 VCEO | Surface-mount |
| PNP | BC856 65 VCEO | BC857 45 VCEO | BC858 30 VCEO | BC859 30 VCEO | BC860 45 VCEO |
(See also: for a neat summary of some of the family).
Noise figure (at 1 kHz, for a 2 kilohm source, BW = 200 Hz, IC=0.2 mA/VCE=5 V) is <10 dB for those not tabulated as "Low Noise".
Current ratings
All types have a maximum collector current of 100 mA, except that the original Philips tentative data dated 4.4.1966 specified a maximum collector current of 100 mA peak (ICM) for the BC107/8/9, and Telefunken originally specified a maximum collector current of 50 mA for the BC109, but since at least 1973 all have revised collector currents of 100 mA average or 200 mA peak, except that the BC317-BC322 range have a 150 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 (hFE)[3] groups (see BC548 Gain groupings).
Other characteristics
Transistors in this family:
- require a base-emitter voltage (VBE(on)) in the range of 0.55 to 0.7 Volts for a collector current of 2mA when the Collector voltage is 5 Volts.[4]
- Will have a saturation voltage (VCE(sat)) of at most 0.2 Volts (typically 0.07 Volts) at a collector current of 10 mA and a base current of 0.5 mA (when the base voltage is typically 0.73 Volts; 0.83 Volts maximum).
- Has greater than unity current gain up to a frequency (fT) of at least 150 MHz, typically 250 MHz, at a collector current of 10 mA (typically 85 MHz and a collector current of 0.5 mA)
References
- ""MiniWatt:" DIGEST" (PDF). Vol 7 Number 2. Philips Australia. February 1968. Retrieved 17 March 2014.
- "Micro Electronics datasheet for BC107-9, BC167-9, BC237-9,BC317-9" (PDF). Archived from the original (PDF) on 13 January 2012. Retrieved 2 August 2015.
- "BC546 through BC550".
- "BC107/BC108 Series Low Power Bipolar Transistors - culticomp" (PDF).
Further reading
- Historical Databooks
- Small-Signal Transistor Data Book, 1386 pages, 1984, Motorola.
- Transistor and Diode Data Book, 1236 pages, 1973, Texas Instruments.