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What is the diffierence between TTL and CMOS?

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Full Member level 4
Dec 17, 2006
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what is the diffierence between TTL and CMOS? Which is better?

cmos cd4000 series

they belong to digital logic families......
TTL is implemented using BJT and CMOS using p and n mosfet....
TTL has higher power dissipation than CMOS......

any digital book[morris mano,floyd,wakerley] will have details about this....

ttl 4783

TTL:High power dissipation,non-rail-to-rail logic gate
CMOS:low dissipation,rait-to-rail logic gate.

new ics in standard cd4000 cmos logic

TTL is obsolete by now and many manufacturers are no longer making it.

As a piece of history, back around 1960 the funding for developing this technology was done by the US military.

Re: TTL and CMOS [hlp]

Now people when talking about TTL and CMOS they talk about the logic level, not much about technology.

flatulent may be wrong when saying that "TTL now obsolete and many manufacturers stop producing it", CMOS CD4000 series are at the same situation, guys.

TTL at the first stage was BJT ICs (7400 standard series), and CMOS, of course, CMOS.
TTL (7400 series): - higher power consumption, then low fan out (BJT version).
- high speed (tens or hundreds MHz).
- less noise immunity due to its logic level.

CMOS (CD4000 series): - low power consumption, high fanout. However, they consume power much when increasing frequency.
- low speed (a few MHz).
- better noise immunity.
- wide range of supply voltage.

Now manufacturers combine 2 pro features in one, for example: 74HC00, 74HCT00 series, they are CMOS but with TTL logic level, TTL pinout. So you can see TTL logic level must be lasted very long.

7400 series and CD4000 series are now obsolete. You can see them in the market with sources from, for examples, China manufacturers.

Re: TTL and CMOS [hlp]

in few words
if you want high speed you can choose the ttl family IC
if you want the low power consumption you can choose the cmos family IC
you can find the same IC in the 2 families but of course with different names

TTL and CMOS [hlp]

1..transisstor cosumes power always whereas mosfet only during TRANSITION form conducting to non conducting and vice versa...
power consumption for CMOS is less than that of BJT
2..CMOS is immune to noise than BJT

Re: TTL and CMOS [hlp]

TTl is made using BJT's and high power is dissipated in it and also have high speed
while CMOS uses n type and p type mosfets and is low power device.

TTL and CMOS [hlp]

both are logic famalies. cmos is the best.

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