Know the meaning of Transistor and IC Codes

Transistors and ICs are coded so as to identify its semiconductor, use, type, make etc. By using the codes, it is easy to select the appropriate component for the circuit. See the meaning of these codes.

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It is the semiconductor device essential for almost all electronic circuits. Transistor semiconductor may be Silicon or Germanium. Majority of transistors are Silicon types and they can tolerate high temperature and current. The information for a transistor is shown as a code embossed or printed on its face. Transistor coding follows two systems namely European coding system and American coding system. In European coding system, two alphabets are used before the part number. The first alphabet represents the semiconductor used and the second alphabet represents its use. These are the alphabets in the codes.

First Letter

A – Germanium

B – Silicon

C – Gallium Arsenide

D – Indium Antimide

Second Letter

C – Audio frequency amplifier

D – Audio frequency power amplifier

F – Low power radiofrequency amplifier

P – High power radiofrequency amplifier

Thus the code of the transistor BC 547 can be expanded as

B-Silicon, C- Audio frequency amplifier – 547- Silicon Audio frequency 547


BD 139 – B-Silicon, D- Audio frequency power amplifier 139

AD 140 – A- Germanium, D- Audio frequency power amplifier 140

According to the American system of coding, the code begins with 2N which is followed by the number that indicates the time of design. A higher number indicates recent design.
Example is the transistor 2N 2222,
2N3055, 2N3904

IC Coding

Integrated circuits are of two groups. They are TTL (Transistor Transistor Logic) and CMOS (Complementary Metal Oxide Semiconductor). The most common TTL series is 7400 series and the most common CMOS series is 4000 series.

ICs are identified using the string of letters and numbers, code for manufacturer, subfamily and type of package.

Code for Manufacturer

DM – National Semiconductor

NS – National Semiconductor

SN – Texas instruments

M – Motorola

TI – Texas Instruments

NE – New Era Electronics

Code for Sub family

ALS – Advanced Low power Schottky

C – CMOS TTL Series

F – Fast

H – High Speed

HC – High speed CMOS

L – Low power

LS – Low power Schottky

CMOS Types have a Suffix

A – A series

B – Buffered B series

UB – Un buffered B series

For example the IC code SN 74 HC 04 can be expanded as

SN – Texas Instrument, 74 -TL Series, HC- High speed CMOS, 04 – part number