# 74HC4040N vs. CD4040

J

#### Jerry

Jan 1, 1970
0
The circuit specifies (two off) the latter and I have the former.

They appear pin-compatible so... is there any reason why the 74HC4040N
won't substitute for a CD4040?

The project is a simple EPROM burner with 4040s counting through the

Jerry

A

#### Anthony Fremont

Jan 1, 1970
0
Jerry said:
The circuit specifies (two off) the latter and I have the former.

They appear pin-compatible so... is there any reason why the 74HC4040N
won't substitute for a CD4040?

What voltage is Vcc? The 74xx part is limited to ~5V, the CD4040 will work
with 15V.

J

#### Jerry

Jan 1, 1970
0
A PS:

....I ought to add that I've built the circuit with 74HC4040Ns and (you
guessed it!) it doesn't work...hmmm. Not unusual I agree but I've
checked this simple circuit a hundred times, watched the transistion
of the pulses from a parallel port and nothing but nothing seems to
trip the Q outputs to the correct states even though the clock and
reset lines appear to do what they're supposed to.

Of course, there may simply be a wrong connection/solder bridge/etc
but AFAIK it's clean and wired as it should be. I've even swapped out
the 74HC4040Ns for two others (had a bunch of them lying around) but
to no avail.

Groan...

J

#### Jerry

Jan 1, 1970
0
What voltage is Vcc? The 74xx part is limited to ~5V, the CD4040 will work
with 15V.

5v, the Vpp is derived seperately

S

#### Spehro Pefhany

Jan 1, 1970
0
The circuit specifies (two off) the latter and I have the former.

They appear pin-compatible so... is there any reason why the 74HC4040N
won't substitute for a CD4040?

Aside from Vdd range, the CD4040 is WAY slower at 5V Vdd, and has way
less drive current capability.
The project is a simple EPROM burner with 4040s counting through the

Jerry

Sounds like it ought to work unless the designer has done something a
bit strange-- maybe you should show us the schematic.

Best regards,
Spehro Pefhany

T

#### Tim Wescott

Jan 1, 1970
0
Jerry said:
A PS:

...I ought to add that I've built the circuit with 74HC4040Ns and (you
guessed it!) it doesn't work...hmmm. Not unusual I agree but I've
checked this simple circuit a hundred times, watched the transistion
of the pulses from a parallel port and nothing but nothing seems to
trip the Q outputs to the correct states even though the clock and
reset lines appear to do what they're supposed to.

Of course, there may simply be a wrong connection/solder bridge/etc
but AFAIK it's clean and wired as it should be. I've even swapped out
the 74HC4040Ns for two others (had a bunch of them lying around) but
to no avail.

Groan...
What is the maximum voltage reached by the parallel port output pulses?
CMOS parts need to see voltages close to the power rail, while the
parallel port is probably assumed to be OK with TTL-level voltages.

TTL parts into CMOS often works, but it often doesn't -- you should
check what you're getting, and what the 74HC4040 wants.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Do you need to implement control loops in software?
"Applied Control Theory for Embedded Systems" gives you just what it says.
See details at http://www.wescottdesign.com/actfes/actfes.html

W

#### Werty

Jan 1, 1970
0
Many HC are "new,improved" ...

HC105 FIFO is improved , you can circulate
it and still be tri-state ...

BTW ,,,anyone study Speed-pow pdt ?
What is the bad stuff ?
What dont work at 3.3vdc , ultra effecient ?
Notice the pitfalls , now , on SRAM S-P pdt!
You can buy SRAM thats less than 1 Mili-W
per mhz , but you can buy 50 MilliWatt
from JameCo .

? Has anyone got any recent bad experiences.

Notice DRAM is evolving into PSRAM .
They have improved DRAM , so much , it
will kill SRAM .
It uses about .0001 amps to refresh.

Im doin ARM , free OpSys . No English ,
No ASCII , no bloat ( loads at 8KB ) .

________________________________

J

#### Joerg

Jan 1, 1970
0
Jerry said:

I don't see any decoupling caps in there. If true then that ain't good.
Place a 0.1uF ceramic next to each chip, shortest possible connection
from VCC to ground (here it's called VSS). Also one at the output of the
7805. Might also need a 47uF or 100uF electrolytic at that point but I
don't know what the parallel port would say to its surge current.

CD4000 series chips are much slower and they can occasionally live
without decoupling caps. It's still better to have them. 74HC definitely
needs them.

J

#### Jerry

Jan 1, 1970
0
Tim: pulses at 5v which, on the clock and reset lines appear to be
'working' -- ie the reset is pulled low or else is at 5v, similarly
the clock, but the clock doesn't trip the Qs and the reset doesn't
reset 'em! (At least, not with any -- excuse the pun -- logic).

Rich: so put pullup resistors of between 4k7 and 10k across lines
going to the clock and reset? I'll try it...

Joerg: no decoupling caps at the moment but I think I can dig a few
out of my junkbox to try it.

Thanks everyone. I'll try the above and report back

W

#### Werty

Jan 1, 1970
0
Do you still do Taiwan ?

Im doin a PCB for ARM mcu ,

prices on STR710FZ2T6 are

taxed up triple .

I need to pay $4 , USA wants$10 . Quant' 2000 .

Mine is unique , will be bootable from

every hardware source , avail' ..

Drives LCD's , KB's even from the tiny 8KB

R

#### Rich Grise

Jan 1, 1970
0
Tim: pulses at 5v which, on the clock and reset lines appear to be
'working' -- ie the reset is pulled low or else is at 5v, similarly
the clock, but the clock doesn't trip the Qs and the reset doesn't
reset 'em! (At least, not with any -- excuse the pun -- logic).

Rich: so put pullup resistors of between 4k7 and 10k across lines
going to the clock and reset? I'll try it...

Not "across lines" - from the "clock" pin to +5v, and from the "reset"
pin to +5v:

+5V
|
[10K]
| ______
clk ----+----| HC4040
|_____

like that, one per each. (the truth is, I don't even know what you mean by
"across lines" here.)
Joerg: no decoupling caps at the moment but I think I can dig a few
out of my junkbox to try it.

I concur on the decoupling caps - locate them as close to the chip as
possible - I've even mounted them _underneath_ the board, so I can go
directly to Vcc and gnd, so that the switching noise "spike"(a very
narrow pulse) has the shortest possible path to go through to get to the
cap.
Thanks everyone. I'll try the above and report back

We'll appreciate the report.

Good Luck!
Rich

S

#### Spehro Pefhany

Jan 1, 1970
0
Do you still do Taiwan ?

For some values of "do". I'm just working on getting a couple of
companies into a partnership for sourcing and supporting some
specialized high-precision mechanical stuff from there at the moment.
I have not visited Formosa for a while now. 8-(
Im doin a PCB for ARM mcu ,

prices on STR710FZ2T6 are

taxed up triple .

I need to pay $4 , USA wants$10 . Quant' 2000 .

Some semiconductor prices will vary signficantly by geographic
location, but you can't always be sure they'll be less until you see
the quotes.
Mine is unique , will be bootable from

every hardware source , avail' ..

Drives LCD's , KB's even from the tiny 8KB

Try the ROC and the PRC. ST may be dumping parts there and/or the
price structure may be flatter.

Best regards,
Spehro Pefhany

W

#### Werty

Jan 1, 1970
0
Some semiconductor prices will vary signficantly by geographic
location, but you can't always be sure they'll be less until you see
the quotes.
______________________________

Wanna bet !

ST and Phillips and SamSung

will be the high volume suppliers of ARM 7 .

They will be able to price at \$4 , if your

country dont tax them out .

ATMEL and Intel ,AMD , H.P.

will lose all .

J

#### jasen

Jan 1, 1970
0
The circuit specifies (two off) the latter and I have the former.

this may seem like a stupid question, but do yo have
Q1 base connected the 7805 output.

J

#### Jerry

Jan 1, 1970
0
Tim: pulses at 5v which, on the clock and reset lines appear to be
'working' -- ie the reset is pulled low or else is at 5v, similarly
the clock, but the clock doesn't trip the Qs and the reset doesn't
reset 'em! (At least, not with any -- excuse the pun -- logic).
Rich: so put pullup resistors of between 4k7 and 10k across lines
going to the clock and reset? I'll try it...

Not "across lines" - from the "clock" pin to +5v, and from the "reset"
pin to +5v:

+5V
|
[10K]
| ______
clk ----+----| HC4040
|_____

like that, one per each. (the truth is, I don't even know what you mean by
"across lines" here.)

Sorry, I'm from Barcelona...

I can report success though, the project is working after using
decoupling capacitors and pullup resistors. Many thanks to all here
who helped -- invaluable!

Jerry

R

#### Rich Grise, Plainclothes Hippie

Jan 1, 1970
0
Sorry, I'm from Barcelona...

I can report success though, the project is working after using
decoupling capacitors and pullup resistors. Many thanks to all here
who helped -- invaluable!

Oh, for goodness' sake, there's no reason to apologize for where you're
from! I'm just wondering if you're confident enough with your English
(Which, by the way, you seem to be writing better than way too many
Americans these days), to translate what you meant by "across lines",
or were you just looking for words to express what we generally mean by
"pullups"?

Thanks, and welcome to the loony bin! ;-)

Cheers!
Rich

T

#### Tim Shoppa

Jan 1, 1970
0
Jerry said:
The circuit specifies (two off) the latter and I have the former.

They appear pin-compatible so... is there any reason why the 74HC4040N
won't substitute for a CD4040?

The project is a simple EPROM burner with 4040s counting through the

I have had difficulties with some brands of 74HC4060's (which are
similar to but not identical to the 4040).

In particular, the problem was that in some makers' 74HC4060's, the
built-in oscillator didn't oscillate reliably. I ended up just specing
the good old CD4060 which in my particular case does oscillate
reliably.

All that said, except for using "analog" sections in digital parts
(the oldtimes all know that all digital parts are made of analog
parts!) I've never had a problem when the only power supply was 5V
anyway.

Like any digital circuit using counters, you'll want at least some
bypassing and good construction techniques to make the circuit
reliable. CMOS (either CD40xx or 74HC40xx) is so much more forgiving
than regular TTL. And if the original circuit doesn't really work,
then the transliterated one won't work either .

Tim.