Cascading 74HC595 into TPIC6B595

Other Hardware General Electronics
1

Hi everyone! Been lurking here a while, I've learned so much! Thank you!

I designed some boards containing 74HC595 shift registers which can be daisy-chained into each other. Everything works great, and can be expanded into infinity. Very happy!

Recently I've come across a need for higher wattage to control other devices and discovered the TPIC6B595. I'd like to make some boards for a set of these.

As far as I can tell -
(maybe I'm ignorant, so please correct me if I'm wrong...)
a shift register is a shift register, SIPO in this case, CLOCK, LATCH, DATA... other than mapping the pin differences out correctly, and power supply requirements, would there be any reason this wouldn't work? I haven't seen any mention of this anywhere online.

If not I can always use a 74HC595 with a ULN2803. Cost would be higher, and shift-register density per board will be lower, and I might have to drink a little.

Thanks everyone!

2

Look at the data sheet for the new device you want to string along on your shift register to infinity.

I suspect you will find zero problems, the '595 ending to the part number is a good sign, I doubt a coincidence.

I just gave it 90 seconds and it looks like you just wanna be careful to find the same signals then fearlessly use them and expect it to just work.

a7

3

Two main differences.

  1. the TPIC is 5volt only
  2. the outputs are sink only (like the ULN2803)

Leo..

4

Also, the /OE of the 74 part is called /G on the TPIC6B595.

The TPIC6B595 does not provide an inverted last bit output. Which must be a disappointment to someone, don't know who.

Pins are not at all the same, so just stay on top of which chip you are playing with and keep the datasheet nearby.

a7

5

Sorry for my intrusion, but both ICs invert the Serial_Out pin.

The symbols are slightly different, but have the same end result.

For ref:
" inverter - Is there any characteristics difference indicated by this two symbols ? - Electrical Engineering Stack Exchange

From 74HC595 and TPIC6B595 .

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image734×170 10.2 KB

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For a project I have chained 24 TPIC chips, and driven them with 4Mhz SPI, without a problem.
Leo..

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TPIC IS 5V!? I missed that critical tidbit! Glad I asked! I'll need to adjust my existing power supply, currently 3.3v. Everything else existing should be tolerant... minor regulator replacement in my power supply... and Bob's my uncle.

I did know the outputs were GND, but that's OK because I am coming from a remote 12V source, this was actually very convenient.

Thank you!

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THX, that's better.

But does that mean daisy chaining either device is harder?

The QH output is after the parallel load to the outputs, so the only signal for the next SR is inverted? Between one and the next?

The wokwi is useless at the beach ona tablet, don't worry too much I'll figure it out.

a7

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That's easy enough, but the question was can you cascade them up with 74HC595?

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Thanks, I did map out the pins and put /G and /OE together in my napkin drawing, we're good there!

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Yes.

FWIW I see what my problem has been... QH' is not /QH, it is in fact the last bit in the register and is before the output register, which if not present would allow use of QH.

a7

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