You said you wanted to understand, one day you may want to use a 555 as a monostable.You're going to have to help me. What exactly am I looking for in that graph?
hi,Here's another question that could fit in with the 555. Do any of these IC's have a limit on current that can be supplied to them on VCC/VDD? It seems that all is every talked about is voltage. Does current not matter or is it one of those "uses what it needs" kind of deals?
To be clear, when they are talking about source current they are talking about how much is coming into the 555 on pin 8 and not how much it is sourcing on the output. Right?hi,
Look at these two images.
The 7555 is a CMOS version of the 555, earlier 555's were TTL.
hi agu,Hi Eric,
Whose datasheet of the 7555 Cmos timer did you post?
It has an error on the output sourcing left side whene it says output sinking by mistake.
It also has the sourcing current at room temperature where its current is fairly high but its sinking current is at a high temperature where its current is fairly low.
Most Cmos 555's have a max sourcing current of only 10mA and a sinking current of 50mA to 100mA when their supply voltage is at almost max.
Right, but when they are talking about supply current, do they mean Supplying the 555 or supplying to circuit on output.Hi Axro,
The output sinks when its voltage is low and the output sources when its voltage is high.
Look at the graphs to see the big difference the supply voltage has on how much output current is available. Also look at the high voltage drop.
The supply current is the current used by the IC and its load into pin8.Right, but when they are talking about supply current, do they mean Supplying the 555 or supplying to curcuit on output.
Woops!, I'll take another look, sorry about that.!!Hi Eric,
You did not post the "sourcing" graph. Here it is with a comparison of the sourcing and sinking output currents when the voltage drop is half the supply voltage: