Hi there,

I just bought some 555 timers from the electronics shop and the old boy who sold it to me said it should run at 5v. He showed me another 555 (CMOS) that would run up to something like 16v.

When I looked up the datasheets on the net, the generic 555 timer sheet said it was OK to run fine 9v.

How can i tell what it should run at? Aside of reading a generic spec sheet on the internet, Is there any sensible test I can do to find its maximum operating voltage?

I mean I'm running it at 9v and it seems to run fine.

Thanks!

 

If you exceed the maximum rated voltage of the timer, you will most likely destroy it, or at least stress it to the point that it will no longer perform to the manufacturer's specifications.

There should be a complete part number on the top of the IC's, along with a manufacturer's logo and/or code. You should find the manufacturer's datasheet for your particular timers and read it.

If you keep the supply voltage in the range of 5v to 16v, you should be OK. Some are rated for operation at up to 18v. The only way to be certain is to look at the manufacturers' datasheet.

 

In general conventional 555's are rated for 15VDC. CMOS 555s are usually rated for 18VDC. As Wookie says, the datasheet is the ultimate authority.

 

Even if it runs at higher voltage than the one specified, don't keep it that way. The datasheet specifies the rated voltage as the voltage that the device can be run safely in most conditions, and considering other factors such as heat dissipation. That means that you can run a standard 555 timer at 20V in Siberia but not in the Sahara desert.

The datasheet is really the ultimate authority. No way to make it different.