TTL chips

[Robotduck]

Hello:
Do we still use TTL chips in digital applications ?

Thanks!

 

[KlausST]

Hi,

How is this question related to ASIC?
Are you talking about old PCBs or new designs?
Are you talking about true bipolar transistor logic (SN7400) , or just TTL levels compatible logic (74HCT00)?

Klaus

 

[Robotduck]

Hi,

How is this question related to ASIC?
Are you talking about old PCBs or new designs?
Are you talking about true bipolar transistor logic (SN7400) , or just TTL levels compatible logic (74HCT00)?

Klaus

I am talking about true Bipolar transistor logic - high power TTL series, low power Schottky TTL. Are these currently being used in any analog or digital applications ?

 

[crutschow]

I am talking about true Bipolar transistor logic - high power TTL series, low power Schottky TTL. Are these currently being used in any analog or digital applications ?

Not likely in any new applications, as they are mostly obsolete, power hungry, and aren't particularly compatible with CMOS signals.

There are a bunch of 74x00 CMOS devices (where x equals C, HC, etc.) that have the same functions as their bipolar counterparts with the same last 4 or 5 digit part number, which may be used in some glue logic applications between a micro and external devices.

 

[dick_freebird]

Most people would use HCMOS for slow and relatively robust.
I expect the only folks using bipolar logic these days are those
who're stuck with a legacy system or a mandate for electrical
dead-compatibility with same (like, is HCT "TTL compatible"
anything like "TTL identical"? Not really. Some folks are real
fussy about specs being specs).

Or maybe folks who live under sanctioned regimes and can't
get cool stuff like '80s CMOS logic.

--- Updated Feb 15, 2022 ---

Not likely in any new applications, as they are mostly obsolete, power hungry, and aren't particularly compatible with CMOS signals.

Actually you could (if you really wanted) put a LSTTL input up against
a 1.8, 2.5, 3.3V output and get pretty acceptable noise margin and no
impact really to the TTL gate's power draw, and have yourself a "5V
TTL" signal from it. Drive a power MOSFET driver. Whatever. But a
CMOS gate on a 5V rail driven by any of those voltages will be
chowing a lot of shoot-through current (read the fine print on "zero
static Idd" test conditions). Even the "TTL compatible" (HCT) ones.