![]() Inside we find three large 5s showing the chip’s function. ![]() Thomson (a French company) long ago merged with SGS of Italy to become STMicroelectronics, which is one of the largest semiconductor manufacturers today. Today I’ll show a couple of them, starting with the oldest one I found in my collection: a TDB0555DP by Thomson. Originally released by Signetics, it was quickly copied by most other semiconductor manufacturers of the day. ![]() It’s a rather clever setup with two dozen transistors forming two comparators, a flip-flop and an output driver. In Chapter 11, Camenzind shows the schematic of the original 555 timer: I highly recommend reading it (available on paper or as a free download) if you’re interested in analog IC design. There are many ICs that can generate square or triangle waves, but I can’t think of any chip that can function as a one-shot, a flip-flop, Schmitt trigger, or one of a million different oscillator types like the 555 can.ĭesigned by Hans Camenzind in 1972, its story is described in detail in Camenzind’s own book Designing Analog Chips. ![]() Quite unlike the 741, which established op amps as a common IC type, the 555 has remained largely in a class of its own. Released just three years after the 741, it similarly took the world by storm, selling billions of units over five decades. If there’s a classic analog chip even more iconic than the 741 op amp, it has to be the 555 timer.
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