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jonatan
Joined: 10 Jun 2002
Posts: 39
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 07 Aug 2004 23:06 whats is the meaning of high fan-out circuits? |
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Please,
Someone could explain the question below..
whats is the meaning of high fan-out circuits?
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dumbfrog
Joined: 17 Jul 2004
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| 08 Aug 2004 0:06 Re: whats is the meaning of high fan-out circuits? |
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fan-out relates to the drive stength of your circuit block
high fan-out circuit means that your circuit can drive BIG capacitance loading
ie. a 16mA LVCMOS driver is a high fan-out circuit
sometime people refers fanout as how many identical circuit your circuit can drive.
ie. faout#= ONE cricuit A output can drive X number of circuit A
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davyzhu
Joined: 23 May 2004
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| 08 Aug 2004 3:18 whats is the meaning of high fan-out circuits? |
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In a word, large current, and can drive a lot of input gates connected to this output gate.
Davy Zhu
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Adam
Joined: 04 Aug 2004
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| 08 Aug 2004 7:15 Re: whats is the meaning of high fan-out circuits? |
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| dumbfrog wrote: |
ie. a 16mA LVCMOS driver is a high fan-out circuit
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Whats a LVCMOS driver?
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dumbfrog
Joined: 17 Jul 2004
Posts: 191
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| 08 Aug 2004 16:37 Re: whats is the meaning of high fan-out circuits? |
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LVCMOS is the most common I/O.
16mA is the current that this output buffer can source and sink.
(sometime they don't usually teach students these stuffs in school, but u can learn on your own by reading datasheets and application notes)
this edaboard is a good place 2.
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rajesh13
Joined: 07 Jul 2004
Posts: 126
Location: Milky Way
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| 09 Aug 2004 6:37 Re: whats is the meaning of high fan-out circuits? |
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| This 16mA is the current @ the specified Vol & Voh. The actual saturation current is much higher (around 100mA )
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delay
Joined: 11 Jun 2004
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Location: Van Allen Belt
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| 09 Aug 2004 7:26 Re: whats is the meaning of high fan-out circuits? |
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| When dealing with standard TTL, a driver gate can "drive" the inputs of approx. 10 unit loads, or 10 other gates. This number 10 means that the standard TTL driver gate has whats called a FANOUT of 10. In other words, if you attempt to put an 11th unit load on the output of a standard TTL gate, NONE OF THE OTHER UNIT LOADS WILL WORK RELIABLY. This is because the voltage level available to each unit load input goes DOWN with each load attached. If you exceed the driver gates FANOUT spec. The voltage level to each unit load input will fall below a "valid high" input for TTL.
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platonas
Joined: 14 Aug 2004
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| 16 Aug 2004 6:05 Re: whats is the meaning of high fan-out circuits? |
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Usually Fan-out refers to simillar logic families interfacing. CMOS to CMOS interfacing or TTL to TTL. It is the abillity of a logic output stage to drive - supply - more than one inputs. In other words it is how mach current an output stage can supply and still maintain the specified output voltage levels that can clearly be distinguished as LOGIC 1 and LOGIC 0 by the next stage.
Regards
Platonas
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Andre3000
Joined: 25 Aug 2004
Posts: 18
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| 25 Aug 2004 20:09 whats is the meaning of high fan-out circuits? |
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| This devices can drive a lot of gates in their outputs
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starfish
Joined: 08 Jul 2004
Posts: 73
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| 30 Sep 2004 18:31 Re: whats is the meaning of high fan-out circuits? |
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Fan out means the ability of an IC so that it's signals don't decay and can be understood by other devices.....
For example if one IC gives a logic 1 of +5v , then Fan out means how many other IC's connected to this can understand the same meaning.....of logic 1.....i:e related to the signal strength.........
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