interface ttl and cmos logic?

[7rots51]

cmos ttl interface

Hi
What is the notes on interfacing cmos to ttl and ttl to cmos logic?

can we connect 74HCT devices to cmos 40xx devices?

please explain it.

 

[Aoxomox]

interfacing cmos to ttl

have a look: **broken link removed**

never really had trouble interfacing 5V TTL and 5V CMOS components together. In some speed critical and over a hughe temparature range operating mixed devices ther might be some problems.

hope it helps,

aOxOmOx

 

[sisc1525]

you should add some resisters at the output.it is not to say in a word.you can see some book about the application of the circuits(TTL&CMOS).

 

[Noman Yousaf]

u must use a pull up resistor when u r inputing the CMOS from TTL.It could be 4K7.

 

[Aoxomox]

what should a pullup be used for??
The 74HCT means "High Speed Cmos TTL", the component it self is a CMOS device with the driving capability as a TTL component (10 devices).

So in fact you are interfacing two cmos devices. no problem....

 

[jzo777n]

HCT -> 40xx at 4.5V supply and cmos load

Max HCT low level output = 0.1V < Max 40xx low level input = 1.35V -> OK

Min HCT high level output = 4.4V > Min 40xx high level input = 3.15V -> OK


You can usually find more information at logic manufactures, for ex. https://focus.ti.com/lit/an/scla011/scla011.pdf