In the United States alone there are well over 30 IC manufacturers producing millions of ICs per year. Each manufacturer uses a specific code and assigns a specific type number to the ICs it produces. That is, each manufacturer uses its own identifying initials followed by its own type number. For example, the 741 type of internally compensated op-amp was originally manufactured by Fairchild and is sold as the µA741, where “µA” represents the identifying initials used by Fairchild. Initials used by some of the well-known manufacturers of linear IC are as follows:

Fairchild             - µA
µAF National Semiconductor      - LM, LH, LF, TBA
Motorola              - MC, MFC
RCA                 - CA, CD
Texas Instruments         - SN
Signetics             - N/S, NE/SE, SU
Burr-Brown             - BB

Remember that the initials used by manufacturers in designating digital ICs may differ from those used for linear ICs. For example, DM and CD are the ini-tials used for digital monolithic and CMOS (complementary metal-oxide semi¬conductor) digital ICs, respectively, by National Semiconductor;

In addition to producing their own ICs, a number of manufacturers also pro¬duce one another’s popular IC’s. In second-sourcing such ICs, the manufacturers usually retain the original type number of the IC in their own IC designation. For example, Fairchild’s original juA741 is also manufactured by various other man¬ufacturers under their own designations, as follows:

National Semiconductor    - LM741
Motorola        - MCI 741
RCA            - CA3741
Texas Instruments    - SN52741
Signetics        - N5741

Note that the last three digits in each manufacturer’s designation are 741. All these op-amps have the same specifications and, therefore, behave the same.

More information is available in the linear industry’s cross-reference guides on the types of ICs manufactured by different manufacturers. An industry cross-reference guide is generally included in the manufacturer’s data book.

Since a number of manufacturers produce the same IC, for convenience we shall refer to such ICs by their type numbers and delete manufacturers’ identify-ing initials. For example, instead of referring to an op-amp as a µA741 or MC1741, We shall refer to it simply as a 741.

Some linear ICs are available in different classes, such as A, C, E, S, and SC.
For example, the 741. 741 A, 74IC. 741E. 741S, and 741SC are different versions Of the same op-amp. The 74lTs a military-grade op-amp (operating temperature range; -552-td 125°C) and the 74IC is a commercial-grade op-amp (operating temperature range: 0° to 70775°C). On the other hand, the 741A and 741E are improved versions of the 741 and 74IC, respectively, in that they have improved electrical specifications over their counterparts. The 74IC and 74IE are identical to the 741 and 741A except that the former have their performance guaranteed over a 0° to 70775°C temperature range, instead of -55° to 125°C. The 741S and 74ISC are military- and commercial-grade op-amps, respectively, with a higher slew rate (rate of change of output voltage per unit of time) than the 741 and 74IC.