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Topic: 74HC595 vs 74LS95 shift register (Read 4077 times) previous topic - next topic


I'm a beginner working through tutorials........
My project is to convert serial input to parallel, lighting up a bank of LEDs.

The textbook says to use a 74HC595 8 bit shift register, but my local electronics shop had only 74LS95 4 bit shift registers.  OK, so I'll use that with 4 LEDs and serial data from 0 to 15, no problem.

But the 74HC595 has pins:
Shift register clock input
Storage register clock input

whereas the 74LS95 has pins:
Serial clock input
Parallel clock input

Are these equivalent?  If so, which is which?
Or do I need to use some other pin/s entirely on the 74LS95


I'm fairly sure that those chips are identical for your purpose. (The HC version is higher speed so pulse risetimes will be shorter.)


Yes, but on the 74LS95, which should be the latch pin and which the clock pin?
There is also a pin called the Mode Control Pin.  Should that be the latch pin?


I'm fairly sure that those chips are identical for your purpose.

Same number of pins? Pin functions are identical. Just different manufacturers use different descriptions for the pins' functions.


May 25, 2012, 11:59 am Last Edit: May 25, 2012, 12:41 pm by pwillard Reason: 1
1) They are not identical, especially since one is 4 bit one is 8 bit and one has an integrated latch and the other does not.
2) TTL series parts EVOLVED over time... so higher part numbers often replaced or were improvements to similar lower numbers (IE: 7490 and 74LS390 are related, where 390 was essentially a DUAL packaged 7490, etc)
3) The 7495 has a parallel or serial load option and does not have a built in latch, so you would really need to add a 7475 to your 7495.  You won't use the 7495's parallel load feature so your operating mode will be SERIAL. (The 7495  does have serial DATA and CLK (2 pins) so if you add the latch IC, you can emulate a 4-bit version of the 74595.  

Added note:  The 74HC595 has a reason for its popularity... it has all the parts you need in one package and is readily available.


Thank you for your explanation, pwillard.
It was very clear.

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