OBSOLESCENCE MAKES THE HEART GROW FONDER...

OTL Asylum

OTL, Output Transformerless Amplifier User Group.

I spent some time with the Linear Technologies web site to see if I could find a reason why the LT1038 was made obsolete. I used to work in the integrated circuit industry, and I have some experience with small capitalization IC companies and how they manage their products.
No one likes to discontinue old products because the development costs were recovered long ago and they represent cash cows even at low sales levels. Sometimes, circumstances force these companies to do things they would not have chosen to do. I am speculating here, since I have no direct insight into Linear Technologies operations. Older manufacturing lines contain machines that may no longer be supported. Environmental contamination from older facilities may require them to be closed.
There are two possible reasons why the LT1038 was made obsolete. The obvious one is that LT has made the TO-3 metal package obsolete, and they possibly did not feel there was enough demand to requalify a 1980-era part in a plastic package. However, it is also possible that LT has had to shut down an older IC manufacturing line ("wafer fab" in the industry parlance) due to the widespread economic downturn or for the reasons above, that the LT1038 was made only in this facility, and that they did not feel it worth the investment to transfer the manufacturing technology ("process") to another fab.
I could not find direct evidence to determine whether the later is true, but do notice that the maximum voltage rating for the LT1083 family is 30 volts, while the LT1038 was rated at 35 volts. This tells me they use a newer process to make the LT1083, with shallower junctions and lower internal breakdown voltages. Also, this part number is first mentioned in a 1990 application note, while the LT1038 is mentioned in 1984.
The company press releases stop bragging about record profits about a year ago, but do not mention a fab shutdown. However, since this is not good news for a company forced to do it, it is not likely they would publicize the fact.
In addition to the LT1083/84/85 series of positive adjustable regulators, Linear Technologies offers the LT1575 controller ICs that require external NMOS FET drivers. The current capabilites of this arrangement are limited only by the drivers, and the IC is fast enough to eliminate the need for the tantalum output capacitor. This device does require a separate supply, however.
Ralph's policy of avoiding parts that may become obsolete quickly seems especially wise in this period of IC industry recession. The competitive pressures of smaller-faster-cheaper parts for the communications industry are driving ICs to surface-mount, low voltage, low power configurations that become useless for tube filament applications. Our hope is that the automotive industry will move to 48-volt battery standards and revive the higher-voltage IC technologies. As a hobbyist builder, I only hope they preserve a managable package configuration.

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Topic - OBSOLESCENCE MAKES THE HEART GROW FONDER... - Al 15:35:10 11/12/01 (2)

Re: OBSOLESCENCE MAKES THE HEART GROW FONDER... - Lew 07:55:54 11/13/01 (1)

Re: OBSOLESCENCE MAKES THE HEART GROW FONDER... - Paul Speltz 11:28:17 11/13/01 (0)

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