An Interview with Hans Camenzind


Oral History Ė Hans Camenzind



There must be a wide range of applications for the 555.

Yes. Several spacecraft have them.And, many, many toys.Thatís the range.Itís a bipolar product, which is pretty hardy, so nothing had to be done (for space applications), except they test it.So, they write a special test spec for some applications.Not the way it is made, there is no difference in the manufacture of it, but there is a difference in testing, like temperature cycling- they torture the poor little thing.


Letís discuss your background now and how you came to develop the 555.You had worked at PR Mallory before joining Signetics?

Well, yes.I spent six years at PR Mallory, in the research lab. When I realized they didnít want to go into production, I interviewed every single company that made linear integrated circuits.Sylvania, Westinghouse, Texas Instruments, Motorola, Fairchild, Signetics, Sprague, and then decided on Signetics, which was a rapidly growing company.They had a chance to surpass Fairchild, which was number one then. But they badly stumbled two years later.They started losing money like crazy.So I resigned Ė I took a leave of absence to write a book.I told them I didnít want to come back, but I would work as a consultant and independent designer, and I proposed the 555 design.



Go To Camenzind Oral History,Page 4




Oral History Ė Hans Camenzind (Continued)



This photo illustrates some aspects of the evolution of the 555 over the past 30 years.†† The IC in the top left, marked as ď555Ē, is a very early production unit from Signetics.It has a date code of week 3, 1973, which places this unit within the first year or so of production.Although only the ď555Ē marking is visible in the photograph, if the unit is viewed directly from the top, the additional markings (Signetics logo, date code and lot number are visible). The unit on the top right is a Signetics production device from a decade later.Not much of a visible change, but many millions of units were manufactured in the intervening ten years.The small unit at the bottom of the photo is a recent (2001) 555 manufactured by Singapore Technologies. It is pin for pin compatible with Hansís original 555 bipolar design, but is a CMOS, surface mount device.†† Hansís IEEE Spectrum article describes his CMOS redesign of the 555.††††


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