op-amp replacement for digital line driver?

[Liav]

Hi! I'm trying to source a replacement part for a board I didn't
design. For some reason, a digital line driver was used by mistake.
I'm not entirely sure what the originally intended IC was to be (the
pcb is part of a break-out shield for a Bare Bones Arduino, with nine
2A channels that drive various actuators and three sensor channels for
control).

The incorrect chip is an 74HCT125N (quad buffer/line driver). One of
the engineering consultants has suggested looking for a somewhat pin
compatible quad op-amp and shorting the negative input to the output.

I'm not super-familiar with the pin-outs on op-amps, so I thought I'd
see if I could find any recommendations. The datasheet for the line
driver is up at: http://www.datasheetcatalog.com/datasheets_pdf/7/4/H/C/74HCT125N.shtml

The I/Os for the line driver are:

1: 1oE: output Enable (inverted)
2: 1A: data in
3: 1Y: data out
4: 2oE: output Enable (inverted)
5: 2A: data in
6: 2Y: data out
7: GND

8: 3oE: output Enable (inverted)
9: 3A: data in
10: 3Y: data out
11: 4oE: output Enable (inverted)
12: 4A: data in
13: 4Y: data out
14: Vcc

Any suggestions would be greatly appreciated!

Cheers,
L

 

[Tim Wescott]

On 04/05/2011 11:36 AM, Liav wrote:

On Apr 5, 2:21 pm, George Herold<gher...@teachspin.com> wrote:

I don't know of any 'non-standard' quad opamps. The standard quad
opamp has a pinout that looks nothing like that. For starters, the
power pins are in the middle of the package, (pins 4 and 11).

I suspect this might be a bit of a goose chase.

I don't know what your "engineering consultant" was thinking, but I
think you're right.

You probably need an adapter board, or a board spin, or a _lot_ of green
wires.

--

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

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

 

[George Herold]

On Apr 5, 1:18 pm, Liav <liav.ko...@gmail.com> wrote:

Hi! I'm trying to source a replacement part for a board I didn't
design. For some reason, a digital line driver was used by mistake.
I'm not entirely sure what the originally intended IC was to be (the
pcb is part of a break-out shield for a Bare Bones Arduino, with nine
2A channels that drive various actuators and three sensor channels for
control).

The incorrect chip is an 74HCT125N (quad buffer/line driver). One of
the engineering consultants has suggested looking for a somewhat pin
compatible quad op-amp and shorting the negative input to the output.

I'm not super-familiar with the pin-outs on op-amps, so I thought I'd
see if I could find any recommendations. The datasheet for the line
driver is up at:http://www.datasheetcatalog.com/datasheets_pdf/7/4/H/C/74HCT125N.shtml

The I/Os for the line driver are:

1: 1oE: output Enable (inverted)
2: 1A: data in
3: 1Y: data out
4: 2oE: output Enable (inverted)
5: 2A: data in
6: 2Y: data out
7: GND

8: 3oE: output Enable (inverted)
9: 3A: data in
10: 3Y: data out
11: 4oE: output Enable (inverted)
12: 4A: data in
13: 4Y: data out
14: Vcc

Any suggestions would be greatly appreciated!

Cheers,
L

I don't know of any 'non-standard' quad opamps. The standard quad
opamp has a pinout that looks nothing like that. For starters, the
power pins are in the middle of the package, (pins 4 and 11).

Sorry,
George H.

 

[Liav]

On Apr 5, 1:18 pm, Liav <liav.ko...@gmail.com> wrote:

Hi! I'm trying to source a replacement part for a board I didn't
design. For some reason, a digital line driver was used by mistake.
I'm not entirely sure what the originally intended IC was to be (the
pcb is part of a break-out shield for a Bare Bones Arduino, with nine
2A channels that drive various actuators and three sensor channels for
control).

The incorrect chip is an 74HCT125N (quad buffer/line driver). One of
the engineering consultants has suggested looking for a somewhat pin
compatible quad op-amp and shorting the negative input to the output.

I'm not super-familiar with the pin-outs on op-amps, so I thought I'd
see if I could find any recommendations. The datasheet for the line
driver is up at:http://www.datasheetcatalog.com/datasheets_pdf/7/4/H/C/74HCT125N.shtml

The I/Os for the line driver are:

1: 1oE: output Enable (inverted)
2: 1A: data in
3: 1Y: data out
4: 2oE: output Enable (inverted)
5: 2A: data in
6: 2Y: data out
7: GND

8: 3oE: output Enable (inverted)
9: 3A: data in
10: 3Y: data out
11: 4oE: output Enable (inverted)
12: 4A: data in
13: 4Y: data out
14: Vcc

Any suggestions would be greatly appreciated!

Cheers,
L

Ack. Sorry, I made a bit of a mistake with the right hand side of the
pinout:

8: 3Y,
9: 3A
10: 3oE
11: 4Y
12: 4A
13: 4oE
14: Vcc

 

[Liav]

On Apr 5, 2:21 pm, George Herold <gher...@teachspin.com> wrote:

I don't know of any 'non-standard' quad opamps.  The standard quad
opamp has a pinout that looks nothing like that.  For starters, the
power pins are in the middle of the package, (pins 4 and 11).

I suspect this might be a bit of a goose chase.

L

 

[whit3rd]

I'm finding the question unclear. If the 'digital line driver' is a mistake,
is some or all of the pinout really relevant?
You mentioned 2A drive on the 'shield' (interface board),
is that function supposed to be part of this chip?

What are the inputs of the intended function, and
what are the outputs? 'Enable' and 'data in' are
appropriate labels for tristate logic inputs, is
the output intended to be tristate logic? Or is
it open-collector drive?

And, if this is 'a board I didn't design' but is
for an Arduino, is it something that can be traced
to a schematic/parts list online?

 

[Jasen Betts]

On 2011-04-05, Liav <liav.koren@gmail.com> wrote:

Hi! I'm trying to source a replacement part for a board I didn't
design. For some reason, a digital line driver was used by mistake.

why was this considered a mistake?

Any suggestions would be greatly appreciated!

look for another consultant?

--
⚂⚃ 100% natural