ne555 and 7555 - Electronic Circuits Projects Diagrams Free

preetijoli · 20th June 2009, 09:50 AM

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 · 20th June 2009, 10:47 AM

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 · 20th June 2009, 03:54 PM

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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20th June 2009, 09:50 AM	#1
preetijoli	ne555 and 7555 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?

20th June 2009, 10:47 AM	#2
Hero999	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. __________________ I do not answer private messages asking for help because no one else can: benefit from advice I may give or correct me if I'm wrong. Please ask on the open forum if you have a question and I'll be happy to help, if I know the answer.

20th June 2009, 03:54 PM	#3
audioguru	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. __________________ Uncle $crooge