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CSS555 EEPROM Programmer: Celebrate 50 years of 555 IC's!

Create amazingly long delays using this super low power 555 timer

This year the world famous 555 timer IC celebrates its 50th anniversary! A lot of things have happened with IC’s since then but the 555 timer IC still has its following. Most designers know that today you can buy CMOS versions of the classic 555 timer if you need a timer for projects that have to save on power. However, not many seem to know about the CSS555 timer. This IC is very special in many ways. First of all, it is only uses 1/10th of the power that the otherwise low power CMOS 555 IC’s use (e.g. TLC555). Second, the CSS555 has a built in EEPROM that allows you to program it to multiply the delay time by a factor from 1 (standard 555) to 1 million. This is fantastic as long time delays with 555 timers have always required the use of very large electrolytic capacitors. Thus, with the CSS555 you can skip that and stick to orders of magnitude smaller ceramic capacitors. That saves on spaces and makes the circuit more reliable in general. Take a look at the two capacitors in the photo below. The one to the left is a 10uF ceramic capacitor and the one to the right is a 1000uF electrolytic capacitor. With a regular 555 timer (e.g. NE555 or TLC555) and using the same time delay resistor, the larger electrolytic capacitor would give a time delay that is 100 times longer than the delay created by the much smaller ceramic capacitor. However, with a CSS555 timer you could program it to have a 1, 000, 000 multiplication factor. If you do that, it means that you can get a time delay from the smaller ceramic capacitor that is 10, 000 longer (!) than what the larger capacitor would give you with a regular 555 timer….”

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