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Long Live the 555 Timer IC

Hans Camenzind, the designer of the popular 555 timer IC died this week in Silicon Valley.  He was 78.  My condolences to his family and friends.  Hans came to the U.S. from Switzerland in 1960.  He worked for a number of the early semiconductor startup companies before joining Signetics.  He designed the 555 while there in 1970.  The 555 was introduced in 1971 and was widely second sourced.  It is not likely he actually knew he was designing what has to be the world’s most widely used IC.  What EE has not used the 555 at one time or another?

Hans went on to found several companies like InterDesign and Array Design where he continued to design circuits.  In the mean time, the 555 became the base IC for many designs in the 1970s and 1980s.  Too bad he was not able to collect a royalty on each of the billions of chips sold.

Amazingly, the 555 timer is still around.  Millions are still sold each year, not only of the original bipolar design but also newer CMOS versions.  Its flexibility is incredible and many articles and books have been written about it.  And every now and then a new or rejuvenated design shows up.  Besides its use as a basic one shot timer, it is used as a free-running clock, VCO, phase-locked loop, comparator, PWM modulator, frequency divider and DC-DC converter.  And the 555 is still widely taught in colleges and universities because of the many principles it teaches like RC time constants and basic pulse generation circuitry.

There are not too many other legacy ICs that have survived over the years.  I believe the 555 is king of longevity.  Another long time favorite is the 741 op amp and its many derivatives.  Then there is the 8051 microcontroller which is still used in many forms in new designs.  I am probably leaving some out but I need to be reminded.  I have used all of those parts myself in past designs.

It is hard to say how many new designs use the 555.  I suspect adoption may be dwindling but the continuing massive sales of this device may say otherwise.  The basic timing and clock functions can easily be duplicated with a cheap embedded controller and I suspect that is what most new engineers would use today in a new design.  However, for other analog/linear uses the 555 still rules.

Anyway, let’s give Hans a silent respectful good bye and thank you with applause for his endlessly useful creation.

TAGS: Analog
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