74*373 question

[Aubrey McIntosh]

Does the 74*373 have internal pullups or pulldowns on the
enable and latch pins?

What about the '573?

(Google my name for a valid email address)

 

spam@spam.vima.austin.tx.us (Aubrey McIntosh) wrote in message news:<b47434d.0310060452.66f14186@posting.google.com>...

Does the 74*373 have internal pullups or pulldowns on the
enable and latch pins?

What about the '573?

(Google my name for a valid email address)

Neither device type has, as far as I am aware.


regards
Alastair

 

[Peter Bennett]

On 6 Oct 2003 05:52:39 -0700, spam@spam.vima.austin.tx.us (Aubrey
McIntosh) wrote:

Does the 74*373 have internal pullups or pulldowns on the
enable and latch pins?

What about the '573?

No, in all cases. However, bipolar TTL parts (74nnn, 74LS, 74ALS) do
act as if they have pull-ups - the inputs are actually emitters of NPN
transistors, if I recall correctly.

For quick-and-nasty test purposes, it may be OK to leave TTL input
open if you want a HI, but you should really tie them high or low as
required.

For the CMOS variants (74C, 74HC, etc.), you _must_ tie unused inputs
high or low as required. An open CMOS input will be in a random
unknown state.

(Google my name for a valid email address)

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Peter Bennett, VE7CEI
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