Transistor Codes And Equivalents

[Ellyn Krucke]

TransistorTutorial Includes:

Transistor basics Gain: Hfe, hfe & Beta Transistor specifications Transistor and diode numbering codes Choosing replacement transistors There are many thousands of different types of diode, bipolar transistor and FET. These semiconductor devices have different characteristics according to the way they are designed and made.

Initially manufacturers had to give their own numbers to devices, but soon standard part numbering schemes were used for semiconductor devices including diodes, bipolar transistors and FETs - both JFETs and MOSFETs.

Even though there are standard numbering systems these days, there are many specialised transistors and other semiconductor devices on the market, and these often carry the makers individual part numbers on them. Fortunately many of these are easily identifiable as the devices from particular manufacturers.

Also with the rise of the Internet, the specifications and other details of transistors and many other electronic components are easily found and their full data-sheets can be viewed. Despite this, it is still a very convenient to understand transistor numbering schemes from which it is easy and quick to understand their broad performance.

There are many different ways of organising a numbering scheme. In the early days of thermionic valve (vacuum tube) manufacture, each manufacturer gave a number to the types they manufactured. In this way there were vast numbers of different numbers for devices many of which were virtually identical. It soon became obvious that a more structured approach was required, so that the same device could be bought regardless of the manufacturer.

The same is true for semiconductor devices, and manufacturer independent numbering schemes are used for diodes, bipolar transistors and FETs. In fact there a few semiconductor numbering schemes in use:

The aim of the the industry standard numbering schemes is to allow for the identification and description of electronic components and in this case semiconductor devices including diodes, bipolar transistors and field effect transistors, to have common electronic components and component numbering across several manufacturers. To achieve this, manufacturers register a definition for new electronic components with the relevant agency and then receive a new part number.

This approach enables electronic equipment manufacturing companies to have second sources for their components and in this way assure the supply for large scale manufacturing and also to reduce the effects of obsolescence.

The Pro-Electron numbering scheme to provide a standardised scheme for semiconductor numbering - in particular diodes, transistors and field effect transistors was set up in 1966 at a meeting in Brussels, Belgium.

The scheme for the numbering of semiconductor diodes, bipolar transistors and FETs was based around the format of the system developed by Mullard and Philips for thermionic valve or vacuum tube numbering that had existed since the early 1930s. In this the first letter designated the heater voltage and current, the second and subsequent letters the individual functions within the glass envelope and the remaining numbers indicated the valve based and the serial number for the type.

The Pro-Electron scheme took this and used letters that were seldom used for the heater descriptions to designate the semiconductor type and then used the second letter to define the function. Similarities existed between the valve / tube designations and those used for the semiconductor devices. For example, "A" was used for a diode, etc.

The characters following the first two letters form the serial number of the device. Those intended for domestic use have three numbers, but those intended for commercial or industrial use have letter followed by two numbers, i.e. A10 - Z99.

This is useful to both manufacturers and users because when transistors are manufactured, there is a large spread in the levels of gain. They can then be sorted into groups and marked according to their gain.

Using the numbering scheme it can be seen that a transistor with the part number BC107 is a silicon low power audio transistor and a BBY10 is silicon variable capacitance diode for industrial or commercial use. A BC109C for example is a silicon low power audio transistor with a high gain

JEDEC, Joint Electron Device Engineering Council is an independent industry semiconductor engineering trade organisation and standardisation body. It provides many functions, one of which is the standardisation of semiconductor, and in this case, diode, bipolar transistor and field effect transistor part numbering.

The earliest origins of JEDEC can be traced back to 1924 when the Radio Manufacturers Association was established - many years later this became the Electronic Industries Association, EIA. In 1944, the Radio Manufacturers Association and the National Electronic Manufacturers Association established a body called the Joint Electron Tube Engineering Council, JETEC. This was set up with the aim of assigning and coordinating type numbers of electron tubes, (thermionic valves).

Initial numbering of the semiconductor devices followed the broad outlines of the tube of valve numbering scheme that had been developed: "1" stood for "No filament / heater" and the "N" stood for "crystal rectifier".

The first digit for semiconductor device numbering was repurposed from indicating no filament to the number of PN junctions in the semiconductor device, and the numbering system was described in EIA/JEDEC EIA-370.

Sometimes extra letters are added to the part number and these often refer to refer to the manufacturer. M means the manufacturer is Motorola, while TI means Texas Instruments, although an A added to the part number often means a revision of the specification, e.g. 2N2222A transistors are widely available and these are an updated version of the 2N2222. Interpreting these numbers sometimes requires a little background knowledge.

Following the serial number a suffix can be used to indicate the device has been type approved, i.e. there is a guarantee that it has been manufactured under the right conditions to produce the required semiconductor device.

Despite the fact that there are industry organisations in place to generate device numbers, some manufacturers wanted to produce devices that were unique to them. In some areas it would provide a device with a unique selling point that other manufacturers could not copy.

This is a patent infringement suit in which Plaintiff claims Defendant has infringed two of its patents, the "'155 Patent" and the "'670 Patent."[1] Defendant *1080 claims the '155 Patent is invalid under 35 U.S.C. 102, and that both the '155 and '670 Patents are unenforceable due to inequitable conduct before the U.S. Patent and Trademark Office. (Filing 250, Order on Final Pretrial Conference, at 7-8.) I now issue my findings of fact and conclusions of law pursuant to Fed.R.Civ.P. 52(a).[2]

1. The products at issue in this case relate to patient or resident departure monitoring systems, also known as wanderer monitoring systems. Wanderer monitoring systems are used in nursing homes, hospitals, assisted living centers, and other care facilities to monitor patients or residents who have a tendency to wander due to Alzheimer's Disease or other forms of dementia. The products are used in health care facilities, particularly in nursing homes, to provide an alarm when a resident attempts to leave the facility, thereby alerting the staff so the resident can be located and returned to the facility. (Tr. 86-90.)

3. The Defendant, R.F. Technologies, Inc. ("RFT"), is a Wisconsin corporation engaged in the business of designing, engineering, manufacturing, and selling a variety of medical monitoring equipment, including wanderer monitoring systems which it sells under the trademark "Code Alert." (Filing 250, Order on Final Pretrial Conference, at 2; Tr. 946-47.) The RFT products at issue following this court's ruling on Defendant's motion for judgment as a matter of law[3] are the CA600, CA9000, CA9100, and the CA9120. (Tr. 921-940.)

6. At issue in Claim 1 of the '155 Patent (as noted above by the italicized language) is whether the RFT CA9000, CA9100, CA9120, and CA600 have (1) a "means responsive to the opening of the door to enable the sensing module to respond to the signal transmitted by the transmitter module to produce an output response"; (2) a "sensing module including a receiving circuit and associated sensing means located adjacent to the door opening to be monitored"; and (3) a "means to enable the receiving circuit in the sensing module whereby the receiving circuit can respond to signals transmitted by the transmitter module to produce a response for energizing the alarm means." (Tr. 1429-1434; Ex. 509.)

9. During the prosecution history of the '155 Patent, Claims 1 and 6 were amended. Specifically, in the amendment to Claim 1, the applicant added the term "sensing module" and expressly defined it as including the receiving circuit. Likewise, the description of the receiving device mounted adjacent to the doorway in Claim 6 was amended to include "a receiving circuit therein." (Ex. 513, Amendment Dated 1/27/87, at 2-3; Tr. 240-41.)

12. At issue is whether the signal light on the face of the control unit for the CA9120 and CA600 meets the above italicized elements of Claims 1 and 6. (Tr. 1453-1458.) STI also accused the CA9100 of having a signal light on the face of the control unit. However, as demonstrated at trial, the CA9100 does not have a signal light on the face of the control unit. (Tr. 1455.)

13. During the prosecution history of the '670 Patent, the claims were originally rejected over prior art. (Tr. 1449; Ex. 59.) To distinguish the prior art, the applicant's attorney argued that the claimed combination in Claims 1 and 6 "permits a nurse monitoring a central station to be alerted to a wanderer about to leave without being unduly alarmed by other circumstances." (Tr. 1453; Ex. 59, Amendment Dated 1/18/93, at 7.)

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