How to Identify Integrated Circuit Chips
By Ed Wagner
Attempting to identify an integrated circuit (IC) can be confusing as there is no standardized numbering system. Manufacturers use their own data sheets and identification numbers. It may be difficult to find a cross reference for a similar part from another manufacturer. However, there are three approaches to finding this information: data sheets, electronic parts retailers and the equipment manufacturer's schematics and part list.
Identify the manufacturer first. Sometimes the company name is printed on the IC, but others may be obscure symbols. Use a reference document in a electronic retailer catalog or an online source. Always look at the IC identifiers under magnification because the print is often very small and some numbers may be difficult to read. There are usually three printed lines on each IC: the manufacturer's vendor code, the part number and a date code, though they may not be in that order.
Look up data sheets in the manufacturer's printed catalog. This may be most beneficial when trying to identify an obsolete part. Manufacturers print catalogs detailing their entire product line, often broken down into "families" of related parts. The data sheets contain all the engineering specifications for each part as well as a drawing of its outline and how it should be configured in a circuit board.
Look up a part number in an electronic retailer's catalog. Some datasheets are available, but not all. Try searching with only a section of the part number. For instance, instead of searching with "74ACT32SCX" try "74ACT32" or "ACT32" to view a wider variety of parts, some of which may be interchangeable with the full part number.
Use the technical specifications for a piece of equipment to find part numbers and alternates. Some schematic diagrams indicate part numbers. Manufacturers may have a parts list included with the schematic, and in a few cases, that list will include alternate part numbers. 74ACT32SCX, for instance, lists CD74ACT32M and SN74ACT32DR as direct replacements in a manufacturer's repair manual.
- Keep notes of any part orders with the date and any alternate part numbers. It allows for quick reference rather than a tedious search for those alternate numbers.
- Please be aware that some part numbers are proprietary; that is, they are used by the manufacturer alone and will not cross reference to any other available part, making repairs difficult or impossible.
I'm a professional electronics technician working on commercial aircraft. My main responsibility is the Honeywell Enhanced Ground Proximity Warning Computer, a 486-based machine that uses GPS information to compare aircraft position, speed and altitude against a simplified terrain map of the planet. This is a flight critical system on modern aircraft, but it's not the sole focus of my work. I've done maintenance on aircraft electronics beginning with the largely electro-mechanical systems on 727s and DC-10s, mostly on autopilots but including navigation and communication radios as well. I enjoy explaining technology to people unacquainted with it, and try to write as simply and directly as possible.