page_title: 555 timer IC
section_title: History
hierarchical_section_title: 555 timer IC / History
caption_attribution_description: English: Die shot of the first 555 timer IC manufactured in 1971.
context_page_description: The 555 timer IC is an integrated circuit used in a variety of timer, delay, pulse generation, and oscillator applications. Derivatives provide two or four timing circuits in one package. It was commercialized in 1972 by Signetics and it was reported to still be in wide use as of 2013. Numerous companies have made the original bipolar timers and similar low-power CMOS timers too. In 2017, it was said over a billion 555 timers are produced annually by some estimates, and "probably the most popular integrated circuit ever made."
context_section_description: The timer IC was designed in 1971 by Hans Camenzind under contract to Signetics.  In 1968, he was hired by Signetics to develop a phase-locked loop (PLL) IC.  He designed an oscillator for PLLs such that the frequency did not depend on the power supply voltage or temperature.  Signetics subsequently laid off half of its employees due to the 1970 recession, and development on the PLL was thus frozen.  Camenzind proposed the development of a universal circuit based on the oscillator for PLLs and asked that he develop it alone, borrowing equipment from Signetics instead of having his pay cut in half. Other engineers argued the product could be built from existing parts; however, the marketing manager approved the idea.  
  The first design for the 555 was reviewed in the summer of 1971. Assessed to be without error, it proceeded to layout design. A few days later, Camenzind got the idea of using a direct resistance instead of a constant current source finding later that it worked. The change decreased the required 9 pins to 8 so the IC could be fit in an 8-pin package instead of a 14-pin package. This revised design passed a second design review with the prototypes completed in October 1971 as the NE555V (plastic DIP) and SE555T (metal TO-5).  The 9-pin copy had been already released by another company founded by an engineer who attended the first review and retired from Signetics; that firm withdrew its version soon after the 555 was released.  The 555 timer was manufactured by 12 companies in 1972 and it became a best selling product.
caption: Die of the first 555 chip (1971)
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