output voltage drop of 555 timer ic

[mozikluv]

hi,

i have another question about the famous 555 timer, is the output voltage of pin 3 always about 2v lower than the supply voltage?

thanx

 

[laroche73]

555 output

The 555 uses a bipolar totem-pole output. If you want rail-to-rail output swings, you might try using the CMOS version, the 7555 or mc1455. The CMOS version has a much lower drive capability, though. The output only swings close to the supply rails if you're driving one or two TTL loads.

 

[mozikluv]

bipolar totem pole circuit

hi laroche 73,

thanx for your informative reply, would you care to show the circuit of this bipolars, how they are connected and how they are used?

thanx

 

[laroche73]

555 output stage

This link shows the internals of the 555, along with the theory of operation and a fairly detailed description of each pins' operation. (Q20 - Q24 make up the output stage).

**broken link removed**

 

[mozikluv]

555 innards

hi laroche 73,

thanx, thats the thing i have been looking