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Hello,
What is the Fanout for a single digital IO Pin.in LPC2368/LPC2378 Controller.
Regrdas, Ibrahim
What does the Datasheet say?
I serched for that.but i couldn't find the Fanout i the data sheet.Could you pls tel me where i should serch?
You normally don't compute fan-out anymore.
It was meaningful for TTL chips like the 74xx and 74LSxx series when connecting chips inside the series, where each input was one unit load. You could find multiplication factors when mixing two logic gates from different series.
But what is "the same family" when you are talking about a microcontroller?
Fan-out stopped being meaningful when switching to CMOS logic because the input currents are so tiny compared to the drive capability. For DC levels, you suddenly got a fan-out of 1000 or 10000.
When using CMOS logic, it is normally more interesting to keep track of capacitances. The amount of capacitive load on an output affects how fast it can turn on/turn off. It is only when driving bipolar transistors, LEDs, some special buffer chips and similar that you need to worry about the DC currents.
As usual, it is the datasheets that contains all the meaningful figures. Then it is up to you to make sense out of the figures.
Note that this has nothing to do with Keil.
"Fanout" would have to be specified in terms of some standard load. That was fine way back in the days when all your logic was 74-series TTL - but is rather meaningless to today's microcontrollers.
Therefore, you just need to look at the output capabilities - current, capacitance, etc - specified in the Datasheet, and ensure that your load does not exceed them!