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ne555 and 7555

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preetijoli

New Member
whats the difference between ne555 and cmos version of 555.
i m doin a project which requires 555 , i m using ne555, when the output of 555 goes high, it give 3.8 volt with 5V power supply. How can i get 5v high output by using 5V supply only? by using cmos version? is there any way in which output 3.8V can be converted to 5V without using another chip? how exactly?
 

Hero999

Banned
Look at the datasheets.

The 7555 only uses a fraction of the current of the NE555.

At low currents the output swing of the 7555 is nearly rail-to-rail.

I can't remember what the 555's is, I think it's 0.7V negative to 1.4V positive, check the data sheet, I could be wrong.

The NE555 can supply 200mA, the 7555 can only supply 100mA. Check the data sheet, I'm sure the saturation of the 7555 can exceed that of the 555 under certain conditions.
 

audioguru

Well-Known Member
Most Helpful Member
The output of a Cmos 555 (7555 or LMC555 or TLC555) can reach +5.0V with a +5.0V supply only when its load current is zero (an input of a FET or a Cmos IC).
With a +5.0V supply the output high voltage with a 2mA load is a minimum of +4.4V for an LMC555.
With a +5.0V supply the output high voltage with a 1mA load is a minimum of +4.1V for a TLC555.
With a +5.0V supply the output high voltage with a 0.8mA load is a minimum of +4.0V for an ILM7555.
 
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