LM8560, the Eternal Chip From the 1980 Years
owl writes:
LM8560, the eternal chip from the 1980 years:
Almost everybody has had one, or even has still one of it at home. Almost everybody who had it, kept it in his/her immediate proximity while sleeping...
The LM8560 is the integrated circuit (IC), which was built in almost all the digital alarm clocks and clock radios, with numeric LED display, that have been produced from around 1985, or even the first 1980 years, up to the 2010 years. A very few and last models are still produced in year 2023. But they are fading out.Alarm clocks and clock radios with numeric LED displays are disappearing today, being replaced by LCD displays, merely because of trend reasons. Furthermore, the red color for the LED displays is also becoming rare, because of trend reasons as well, being replaced by green, or worse, by blue LEDs.It doesn't matter whether it was a major brand, like Sony or a no-name brand sold for 10 at a discounter market, the brain of the alarm clock was almost always the same. The now 'obsolete' but timeless LM8560, originally made by the Japanese Sanyo.The LM8560 is a low power consumption MOS integrated circuit.
[...] An electronic clock consists essentially of 2 different parts. A frequency generator, that generates a stable frequency and one part counts the waves coming from the generated frequency. Counting the waves that pass, the passing of seconds is counted. In quartz watches, the frequency generator is a quartz oscillator. In addition, if you want obtain a very good accuracy in quartz clocks, it is necessary to add some components to make the quartz frequency adjustable. A calibration process has to be performed individually during the manufacturing of each clock. This increases the time and cost for the workers needed for the manufacturing.The LM8560 does not need any calibration operation. As soon as it is assembled, it is ready to use with no mistakes! It contains only the counter and the logic for to manage the alarm and clock functions. It has no frequency generator.The LM8560 simply counts the waves coming from the AC power outlet. It can be 50 Hz or 60 Hz, depending on the Countries. In my case it is 50 Hz. It means that 50 waves per second come in. Every 50 counted waves, one second of time is counted. Every 60 counted seconds the minute digits are increased by one. Every 60 minutes the hour digits are increased by one.In addition to the counter and the logic for the clock/alarm functions, the LM8560 contains the circuit to drive directly the LED display.
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