Many manufacturers use an extra letter as their own identification code.
If the device is from Philips it will sometimes have a lower case 'p' (or sometimes 't') added to the code;
Siemens devices usually have a lower case 's'.
For example, if the code is 1A, according to the table there are a number of possibilities:
- 1A BC846A Phi ITT N BC546A
- 1A FMMT3904 Zet N 2N3904
- 1A MMBT3904 Mot N 2N3904
- 1A IRLML2402 IR F n-ch mosfet 20V 0.9A
This has been a problem in the past, however recently manufacturers have been adding lower case letters which clarify the code.
Many recent Motorola devices have a small superscript letter after the device code, such as SAC .
(This smaller letter is merely a month of manufacture code.)
Many devices from Rohm Semiconductors which start with G have direct equivalents found in the rest of the number.
For example GD1 is the same as D1 which is a BCW31.
Some devices have a single coloured letter (usually on extremely small diode packages). Colour, if significant, is shown in small type after the code letter.
An 'L' suffix usually indicates a low-profile package, such as an SOT323 or SC70.
Reverse joggle devices do present a few problems. They oftern have an 'R' in the type number.
A reverse package is one where the lead have been bent up instead of down. So it's a mirror image of a conventional device.
Identification is usually possible from the code number, but some manufacturers use the same code. In these cases, it's a case of looking at the device with a magnifying glass.
The leads of most normal packages come out closer to the circuit board side of the device; conversely a reverse joggle package will have them coming out closer to the 'top' of the device.
Sometimes a series of devices, derived from the same die, have related type (not code) numbers.
Often an 'R' will indicate a reverse joggle package, and/or a 'W' indicate a smaller package variant, such as SOT343.
Sometimes similarities are also found in the code numbers. For example:
Recently some manufacturers have used a symbol or lower case letter to indicate the country of manufacture. These have been ignored in the alphabetical ordering. For example:
- '67' is the code for a BFP67 (SOT143 package) ,
- '67R' is the code for the reverse joggle variant BFP67R (SOT143R),
- 'W67' is the code for a SOT343 package version.
'Z-S' and 'ZtS ' are both 2PC4081Q devices made by Philips; the first made in Hong Kong and the second in Malaysia; this appears in the codebook classified under ZS.