Pro Electron
Pro Electron or EECA is the European type designation and registration system for active components.
Pro Electron was set up in 1966 in Brussels, Belgium. In 1983 it was merged with the European Electronic Component Manufacturers Association and since then operates as an agency of the EECA.
The goal of Pro Electron is to allow unambiguous identification of electronic parts, even when made by several different manufacturers. To this end, manufacturers register new devices with the agency and receive new type designators for them.
Designation system
Examples of Pro Electron type designators are:- AD162 – Germanium power transistor for audio frequency use
- BY133 – Silicon rectifier
- BZY88C5V1 – Silicon 5.1 volt Zener diode
- CQY97 – light emitting diode
- ECC83 – 6.3 volt heater noval dual triode
- A63EAA00XX01 – Color TV picture tube
- SAA1300 – Digital integrated circuit
The three digits after the first two letters were essentially a sequence number, with a vestige of the valve-era convention that the first one or two digits would indicate the base type in examples such as in this family of general-purpose transistors:
| Package | NPN | PNP |
| TO-18 | BC10x | BC17x |
| Lockfit | BC14x | BC15x |
| TO-92 | BC54x | BC55x |
... where x may be:
- 7 for high voltage
- 8 for general purpose
- 9 for low noise/high gain
Differences between Pro Electron and earlier valve-naming conventions
- Unlike the tube naming convention, if there are two transistors in a single envelope, the type letter was never repeated - so a dual NPN RF transistor might get a type "BFM505" rather than something like "BFF505" for instance.
- Although some of the most popular devices conform to a pattern of serial numbers that identified package type and polarity, many do not.
- The letters assigned for the second character of transistor and diode type numbers differ in several ways, e.g.
- * "B" tends to be used for dual varicap diodes
- * "L" in the context of transistors designates RF power transistors; for valves it meant a high-power pentode tube
- * "Z" is used for semiconductor Zener diodes instead of rectifier valves.
Frequently used first letters in European active devices
- *A Germanium
- *B Silicon
- *C III-V semiconductors with a band gap of 1.3eV or more, like gallium arsenide in LEDs
- *D may be...
- **Semiconductors with a band gap less than 0.6eV, such as indium antimonide in infrared detectors, or
- ** 1.4V filament tubes
- *E tubes with a 6.3V heater
- *F Digital integrated circuits
- *P tubes for a 300mA series heater supply
- *R Devices without junctions, e.g. cadmium sulfide in a photoresistor
- *S Solitary digital integrated circuits
- *T Linear integrated circuits
- *U may be...
- ** tubes for a 100mA series heater supply, or
- ** Mixed digital/analogue integrated circuits
Electron tubes
- See Mullard–Philips tube designation for details. A brief summary of just the more common letters is:
/ \ \\__ last digit give serial number
/ \ \__ first digit indicate base, 9=Miniature 7-pin.
/ \___ one letter per valve unit in the tube:
D=1.4v or less A=single-diode
E=6.3v* B=double-diode
P=300mA C=triode
U=100mA F=pentode
L=pentode
Y=Single-phase rectifier
Z=Full-wave rectifier
* Note: some 6.3 volt heater types have a split heater allowing series or parallel operation.
Semiconductor diodes and transistors
The first letter gives the semiconductor type
The second letter denotes the intended use
| 2nd letter | Usage | Example |
| A | Low-power/small-signal diode | AA119, BA121 |
| B | Varicap diode | BB105G |
| C | Small signal transistor, RthG > 15K/W | BC546C |
| D | High-power, low-frequency power transistor, RthG ≤ 15K/W | BD139 |
| E | Tunnel diode | AE100 |
| F | Low-power, RF bipolar or FET, RthG > 15K/W | BF245 |
| G | Hybrid device | BGY32, BGY585 |
| H | Hall effect sensor/diode | |
| L | High-frequency, high-power transistor, RthG ≤ 15K/W | BLW34 |
| M | Ring modulator-type frequency mixer | |
| N | Opto-isolator | CNY17 |
| P | Radiation detector | BPW34 |
| Q | Radiation generator | CQY99 |
| R | Low-power control or switching device: thyristors, diacs, triacs, UJTs, programmable unijunction transistors, silicon bidirectional switch, opto-triacs etc. | BR100 |
| S | Low-power switching transistor, bipolar or MOSFET, RthG > 15K/W | BS170 |
| T | High-power control or switching device: thyristors, TRIACs, silicon bidirectional switch, etc. | BT138 |
| U | High-power switching transistors, bipolar or MOSFET, RthG ≤ 15K/W | BU508, BUZ11 |
| V | Antenna | |
| W | Surface-acoustic-wave device | |
| X | Frequency multiplier: varactor, step recovery diode | |
| Y | High-power rectifying diode | BY228 |
| Z | Avalanche, TVS, Zener diode | BZY91 |
The serial number
Following these two letters is a 3- or 4-digit serial number, assigned by Pro Electron. It is not always merely a sequence number; there is sometimes information conveyed in the number:- In early devices only, the serial number often indicated the case/package type ; modern surface-mount devices often begin with "8",
- early silicon transistors followed the convention of using a middle digit of 0-5 for NPN and 6-9 for PNP.
- the last digit often indicated a particular specification or application grouping, e.g. the AF117 and AF127 were similar IF amplifier devices in different cases; the BC109, BC149, BC169 and BC549 are similar low-noise transistors).
- some modern devices use letters, such as "B" to indicate HBT bipolar transistors.
Suffixes and version specifiers
- for small-signal transistors "A" to "C" often means low to high hFE, such as in: BC549C),
- numeric suffixes may be used as an alternative way to show hFE, or voltage rating.
- for voltage reference diodes letters show the tolerance and may be followed by the Vz value, e.g. 6V8 for 6.8 Volts or 18V for 18 volts.
- "R" can mean "reverse polarity".
| Prefix class | Usage | Example | Notes |
| AC | Germanium small signal transistor | AC127/01 | an AC127 with built-on heat-conducting block |
| AF | Germanium RF transistor | AFY40R | the "Y40" sequence number implies industrial uses, the "R" indicates reduced specifications |
| BC | Silicon, small-signal transistor | BC183LB | the "L" indicates Base-Collector-Emitter pinout while the "B" suffix indicates medium gain selection |
| BC | Silicon, small-signal transistor | BC337-25 | -25 indicates an hFE of around 250 |
| BD | Silicon Darlington-pair power transistor | BDT60B | the "B" suffix here indicates medium voltage |
| BF | Silicon RF BJT or FET | BF493S | a BF493 with a -350VCEO rating |
| BL | Silicon high-frequency, high-power | BSV52LT1 | SOT-23 package |
| BT | Silicon Thyristor or TRIAC | BT138/800 | 800V-rated TRIAC |
| BU | Silicon high-voltage | BU508D | a BU508 with integral damper diode |
| BZ | Silicon regulator diode | BZY88-C5V6 | "C" indicates 5% tolerance, "5V6" indicates 5.6Vz |
Note: A BC546 might only be marked "C546" by some manufacturers, thus possibly creating confusion with JIS abbreviated markings, because a transistor marked "C546" might also be a 2SC546.
Short summary of the most common semiconductor diode and transistor designations:
BC549C
/ |--- \___ variant
/ | \____ serial number
/ device type:
A=Ge A=Signal diode
B=Si C=LF low-power transistor
D=LF Power transistor
F=RF transistor
P=Photosensitive transistor etc.
T=Triac or thyristor
Y=Rectifier diode
Z=Zener diode
Usage in the Eastern Bloc
Poland, Hungary, Romania, and Cuba mostly used Pro Electron designations for discrete semiconductors just like Western Europe. Kombinat Mikroelektronik Erfurt in East Germany and Tesla used designations derived from the Pro Electron scheme. In particular, the first letter specifying the material differed while the second letter followed the table above.| Material | 1st letter Pro Electron | 1st letter KME East Germany | 1st letter Tesla |
| Germanium | A | G | G |
| Silicon | B | S | K |
| Compound materials | C | V | L |
| Multiple materials | C | M | — |
| 2nd letter | KME East Germany usage |
| B | Optoisolator |
| M | MOSFET |
| W | Sensors other than radiation detectors |
Examples: - Germanium power transistor from KME; - optoisolator from KME; KD503 - Silicon power transistor from Tesla; - LED from Tesla.
Integrated circuits
- Linear ICs begin with the letter "T", e.g. TAA570 limiter–amplifier and FM detector.
- Logic ICs begin with the letter "F".
- *The FJ family is TTL
- *The FC family is DTL
- *The FD family is MOS.
- Mixed analog/digital ICs begin with the letter "U", e.g. UAA180 LED bargraph A/D and driver.
// \ \__ serial number, gives the count and type of gates for example
// \___ H=gate J=flip-flop K=monostable Q=RAM R=ROM etc.
FC=DTL
FD=MOS
FJ=TTL
Unfortunately the serial number does not specify the same type of gate in each family, e.g. while an FJH131 is a quadruple 2-input NAND gate, an FCH131 is a dual 4-input NAND gate.