Need PTH equivalent of 74AHC

[scott216]

I was reading Paul Stoffregen's article on better SPI bus design and he recommend using a tri-state buffer chip and shows how on an Adafruit product they us a 74AHC1G125.  I'm looking for a through hole version of the 74AHC1G125 for my project.  I don't know anything about buffer chips so I'm not sure how to pick one on my own. On Digikey I didn't see a through hole version of the 74AHC series chip - except 14-pin DIP.  Can someone recommend an 8-pin DIP chip for this application?

[T3sl4co1l]

Not knowing exactly what you're doing with it, I'd guess a 74HC model would be fine.  It's going to be a quad.  Whatever devices are unused, ground their inputs so they aren't floating.

Tim

[rob77]

i doubt you will find the modern AHC(T) versions in through hole the older HC(T) and AC(T) are common in THT but the new ones are mainly (only? ) SMT.

[marshallh]

Hope you're not going to be using a breadboard. What's the problem with smd?

[w2aew]

I was reading Paul Stoffregen's article on better SPI bus design and he recommend using a tri-state buffer chip and shows how on an Adafruit product they us a 74AHC1G125.  I'm looking for a through hole version of the 74AHC1G125 for my project.  I don't know anything about buffer chips so I'm not sure how to pick one on my own. On Digikey I didn't see a through hole version of the 74AHC series chip - except 14-pin DIP.  Can someone recommend an 8-pin DIP chip for this application?

I doubt you'll find any "single gate" versions in a DIP package. If you must got PTH, then use the regularly available quad parts and simply not use the unused gates (but use pull up/down on unused inputs).

[Zero999]

Yes, you won't find the 74AHC1G125 in through hole. Omit the 1G part of the number and you have the quad, which is available in through hole.
http://www.digikey.com/product-detail/en/SN74AHC125N/296-4531-5-ND/375724

The whole point of the 1G parts is to save space, hence why they're all SMT.

[scott216]

Thanks for the info.  Looks like if I want to stick with through hole I have to use a bigger chip.  I could use SMT, but I'm making my PCB on my Shapeoko CNC mill and it's a bit easier to make boards with through hole parts.

I'm using it with a Moteino - which is like an Arduino Uno with a radio and an Wiznet Ethernet module.

[nctnico]

If it has to be 8 pin dip you can consider using an RS485 driver chip in 8 pin DIP package.

[mikeselectricstuff]

Remember you only need it for devices that don't tristate their output when unselected, which isn't very common.

[scott216]

Remember you only need it for devices that don't tristate their output when unselected, which isn't very common.

Is there a way to test my device to see if it tri-states or not?

Edit -I found the answer to testing tri-state  in the article I linked too in the original post.  I forgot that it said how to test for tri-state behavior.

[mikeselectricstuff]

Is there a way to test my device to see if it tri-states or not?

Read the datasheet!

[scott216]

Is there a way to test my device to see if it tri-states or not?

Read the datasheet!

I'm using an Ethernet module from sparkfun and it used a Wiznet 5100 chip. The data sheet for the wiznet sheet is:
http://www.sparkfun.com/datasheets/DevTools/WIZnet/W5100_Datasheet_v1_1_8.pdf

The data sheet is 70 pages, so I didn't read the whole thing, but searched on "state" and "MISO" and didn't see anything about tri-state.

The other device is a Moteino which uses this RFM69 transceiver.
https://lowpowerlab.com/shop/index.php?_route_=RFM69W&search=rfm69

The link  to the data sheet is
http://www.hoperf.com/upload/rf/RFM69W-V1.3.pdf
Again, I couldn't determine anything about it's tri-state behavior.

[Monkeh]

The other device is a Moteino which uses this RFM69 transceiver.
https://lowpowerlab.com/shop/index.php?_route_=RFM69W&search=rfm69

The link  to the data sheet is
http://www.hoperf.com/upload/rf/RFM69W-V1.3.pdf
Again, I couldn't determine anything about it's tri-state behavior.

"A transfer always starts by the NSS pin going low. MISO is high impedance when NSS is high."

Page 44.

READ the datasheet, don't skim it.

The W5100 datasheet is indeed crap and doesn't state explicitly. It does, however, show as high impedance on the timing diagram, for what little that's worth.

[scott216]

"A transfer always starts by the NSS pin going low. MISO is high impedance when NSS is high."

Page 44.

READ the datasheet, don't skim it.

The W5100 datasheet is indeed crap and doesn't state explicitly. It does, however, show as high impedance on the timing diagram, for what little that's worth.

Thanks.  I'm pretty a noob with electronics and most of the stuff on a data sheet is Greek to me, but I'm trying to learn bit by bit.

[T3sl4co1l]

You can learn a lot from taking the time to think about things in datasheets: what they're talking about, why they put them there, and what things they're bullshitting you on.  The latter takes more experience to compare and contrast, but provides endless fodder for games of "datasheet bingo".

Tim